The History and Practice of the Art of Photography by SnellingPart 2 out of 3
The directions given for its use are as follows: Mix one-third of a bottle with a wine glass full of water, coat the plate over dry iodine to a dark gold color, then over the accelerator to a violet, then back over dry iodine, or chloride of iodine, from three to five seconds. Chloride of Bromine.--M. Bissou, a French experimentalist, has found that bromine associated with chlorine, prepared in a similar manner to chloride of iodine, already described, a solution of bromine being substituted for the iodine, is a very sensitive solution; by means of it daguerreotype proofs are obtained in half a second, and, thus very fugitive subjects are represented, making it the very best compound for taking children. So quick is its operation, that even persons or animals may be taken in the act of walking. Hungarian Liquid.--This, I believe, has never been used here, or imported into this country, and the composition of it is not generally known, even in Europe, where it has taken precedence of all others. It acts quickly and with considerable certainty. It is used by diluting it with from ten to fifteen times its bulk of water, putting a sufficient quantity into the jar to cover the bottom. The plate being previously iodized to a light yellow, is submitted to this mixture till it assumes a light rose tint. Bromine and Fluoric Acid, in combination, are used by some Daguerrean artists as a sensitive, but any of the above compounds are better; besides this, the fluoric acid is a dangerous poison, and the quick made from it will not repay the risk to the health in using it. As I have before said, great caution should be observed in examining the color of the plate, even by the feeble light allowed, which, when attained, must be immediately placed in the holder belonging to the camera and covered with the dark slide. You then pass to the THIRD OPERATION.--Submitting the Plate to the action of Light in the Camera.--Experience alone must guide the operator as to the time the plate should be exposed to the influence of the light; this being dependent on a variety of circumstances, as clearness of the atmosphere-- and here, a reference to the hygrometer will be of advantage-- time of day, object to be taken, and the degree of sensitiveness imparted to the plate by the quickstuff. As I have before said, the artist should be careful to see that the interior of the camera is clean and free from dust, as the small particles flying about, or set in motion by the sliding of the holder into the box, attach themselves to the plate, and cause the little black spots, by which an otherwise good picture is frequently spoiled. Care should also be taken in withdrawing the dark slide, in front of the plate, from the holder, as the same effect may be produced by a too hasty movement. The lens is the last thing to be uncovered, by withdrawing the cap c. fig. 5., which should not be done until you have placed the sitter in the most desirable position. When, according to the judgment and experience of the operator, the plate has remained long enough to receive a good inpression, the cap is replaced over the lens, and the dark slide over the plate, which is then removed from the camera. Daguerreotypists generally mark time by their watches, arriving at the nearest possible period for producing a good picture by making several trials. As a ready method of marking short intervals of time is, however, a very important consideration, and as any instrument which will enable an artist to arrive at the exact period, must be an improvement, and worthy of universal adoption, I will here describe one invented by Mr. Constable of England, which he calls a Sand Clock, or Time Keeper.--"It consists of a glass tube, about twelve inches long, by one in diameter, half filled with fine sand, similar to that used for the ordinary minute glasses, and, like them, it has a diaphram, with a small hole in the centre through which the sand runs. The tube is attached to a board which revolves on a centre pin; on the side is a graduated scale, divided into half seconds; the tube is also provided with a moveable index. This instrument is attached, in a conspicuous place, to the wall. The glass tube being revolved on its centre, the index is set to the number of half seconds required, and the sand running down, the required time is marked without the possibility of error. In practice it will be found to be a far more convenient instrument for the purpose than either a clock or a seconds watch, and is applicable both for the camera and mercury box." If the artist finds it desirable or necessary to take the object to be copied in its right position, that is reverse the image on the spectrum, he can do so by attaching a mirror (which may be had of Mr. Anthony, or Mr. Roach) to the camera tube, at an angle of forty-five degrees. If, after taking the plate from the camera, it be examined, no picture will yet be visible, but this is brought about by the FOURTH PROCESS.--Bringing out the Picture, or rendering it Visible.-- We now come to the use of the mercury bath, Fig. 11. To the bath a thermometer is attached, to indicate the proper degree of beat required, which should never be raised above 170 deg. Fahrenheit. The plate maybe put into one of the frames (see Fig. 11,) over the mercury, face downwards, and examined from time to time, by simply raising it with the fingers, or a pair of plyers. This operation, as well as the others, should take place in the dark closet. [hipho_26.gif] Sometimes, to prevent the necessity of raising the plate, an additional cover or top is made use of. It consists of a box fitted closely to the inner rim of the bath, and having an inclined top (a, Fig. 27.) The top is cut through and fitted with frames for each size of plate, like those already described, and in the back is a piece of glass (b,) through which to view the progress of mercurialization, and an additional piece (c,) on one side, colored yellow, to admit the light. The outline only of the top is here given, in order to show every portion of it at one view. The picture, being fully developed, is now taken out and examined; it must not, however, be exposed to too strong a light. If any glaring defects be perceived, it is better not to proceed with it, but place it on one side to be re-polished; if, on the contrary, it appears perfect, you may advance to the FIFTH OPERATION.--Fixing the Image so that the light can no longer act upon it.--The following articles are required for this purpose: Two or three porcelain or glass dishes, in form, something like fig. 24. A plate support, fig. 25. Few, I believe, now make use of this, although it is a very convenient article. Hyposulphite of Soda, A pair of Plyers. In Europe, they also use a drying apparatus, Fig. 27, but this, like the plate support, [hipho_27.gif] is a matter of little consequence, and may be dispensed with. I will, however, describe it, for the benefit of those who may wish to use it. A vessel made of copper or brass, tinned inside, and large enough to take in the largest plate, but not more than half an inch wide, is the most convenient. It must be kept perfectly clean. Hot distilled water is poured into it, and the temperature kept up by a spirit lamp. Hyposulphite of Soda.--Having made a solution of hyposulphite of soda, and well filtered it--the strength is immaterial; about half an ounce of the salt to a pint of distilled water is sufficient--pour it into one of the porcelain dishes, put into another plain, and into a third distilled water. Immerse the plate with its face downwards into the hyposulphite, and the whole of the sensitive is removed, and the light has no farther action upon it; it is then to be removed from the hyposulphite and plunged into the plain water, or placed upon the support, fig. 25, and the water poured over it. It is then washed in a similar manner with the distilled water and well examined, to see that not the slightest particle of dust rests on the suface. The next step is to dry it. This may be readily accomplished by holding the plate with your plyers, and pouring distilled water over it--if it is hot, so much the better. Apply the spirit lamp to the back, at the corner held by the plyers, at the same time facilitating the operation with the breath; pass the lamp gradually downwards, finishing at the extreme corner. The last drop may now be removed by a little bibulous paper. A single drop, even, of distilled water allowed to dry on any part of the surface, is certain to leave a stain which no after process can remove. To illustrate the necessity for having perfectly clean water, and free from all foreign matter--only to be avoided by using that which is distilled-- in these processes, I will relate a little anecdote. An operator in this city (New York) frequently made complaint to me, that his plates were occasionally very bad; coming out all over in little black and white spots and spoiling many very good pictures, regretting at the same time that perfect plates were not made, for he had lost many customers in consequence of these defects. These complaints being somewhat periodical, I suggested that the fault might be in the hyposulphite, or chloride of gold solutions, or particles of dust floating about in the room, and not in the plate. A few days after he stated, that his plates having served him again in the same way, he procured a fresh supply of hyposulphite of soda and chloride of gold, but after applying them the result was no better. He then, by my advice, thoroughly cleaned his wash dishes, bottles and water pail, made fresh solutions and had no further trouble, becoming satisfied that the plates suffered an undue share of censure. SIXTH PROCESS.--Gilding the Picture.--This is an improvement the honor of which is due to M. Figeau, and may take place either before the drying process, or at any subsequent period; but it improves the picture so materially that it should never be neglected. The articles necessary for gilding are-- A Pair of Plyars; or a Gilding Stand (see fig. 19) and Chloride of Gold; or Hyposulphite of Gold. The latter is imported by Mr. E. Anthony, 205 Broadway, New York, and is decidedly the best article for the purpose. One bottle simply dissolved in a quart of water will make a very strong solution, and gives a richness to the picture impossible to be obtained from the chloride of gold. The process is precisely similar to that described below for chloride of gold, taking care to cease the moment the bubbles are well defined over the surface of the plate. Many Daguerreotypists, after a superficial trial, discard the hyposulphite of gold as inferior; but I have no hesitation in asserting that the fault lies with themselves; for in every case within my knowledge, where its use has been persisted in until the correct method has been ascertained and the nature of the gilding has become familiar, it is always preferred. In illustration of this fact I will relate an anecdote: A gentleman to whom it had been recommended, purchased a bottle, and after making one or two trials of it, wrote to his correspondent--"Send me two bottles of chloride of gold, for I want no more of the hyposulphite; it is good for nothing." A few weeks after he sent for three bottles of the condemned article, confessing that be had found fault unnecessarily; for, that since he had become familiar to its use, he must acknowledge its superiority, and would use no other gilding. The Solution of Chloride of Gold is prepared by dissolving in a pint of distilled water, fifteen grains of chrystalized chloride of gold. This solution will be of a yellow tint. In another pint of distilled water dissolve fifty-five grains of hyposulphite of soda; pour gradually, in very small quantities, the gold into the hyposulphite of soda, stirring the solution at intervals; when finished the mixture should be nearly colorless. Place the plate on its stand, or hold it in the plyers, in a perfectly horrizontal position--silver surface upward--having previously slightly turned up the edges, so that it may hold the solution. Wet the surface with alcohol, letting any superfluous quantity drain off. The alcohol is of no farther use than to facilitate the flowing of the gold mixture over the surface. Now pour on, carefully, as much of the preparation of gold as will remain on the plate. The under part of the plate is then to be heated as uniformly as possible with the spirit lamp; small bubbles will arrise, and the appearance of the portrait or view very sensibly improved. The process must not be carried too far, but as soon as the bubbles disappear the lamp should be removed, and the plate immersed in distilled water, and dried as before directed. 7th. COLORING THE PICTURE.--I very much doubt the propriety of coloring the daguerreotypes, as I am of opinion, that they are little, if any, improved by the operation, at least as it is now generally practised. There are several things requisite in an artist to enable him to color a head, or even a landscape effectively, and correctly, and I must say that very few of these are possessed by our operators as a class. These requirements are, a talent for drawing--taste--due discrimination of effect--strict observance of the characteristic points in the features of the subject--quick perception of the beautiful, and a knowledge of the art of mixing colors, and blending tints. The method now pursued, I do not hesitate to say, and have no fears of being contradicted by those capable of critisizing is on the whole ruinous to any daguerreotype, and to a perfect one absolutely disgusting. The day may come when accurate coloring may be obtained in the camera. Until that day, if we cannot lead taste into the right channel, we will endeavor to give such instructions that Daguerreotypists may proceed with this part of his work with a better understanding of the principles involved. For this purpose I have prepared a short chapter on the art of coloring, which may be found in the latter part of this volume. To Preserve Daguerreotypes they must be well sealed and secured in a case, or frame. These, of course, are selected according to the taste of the customer, the principal requisite being good glass. Most Daguerreotypists prefer the white French plate glass--and many think, very erroneously, that none is good unless it is thick-- but the great desideratum is clearness and freedom from blisters; even glass a little tinged with green or yellow is to be preferred to the French plate when cloudy or blistered and there is very little of it comes to this market that is not so. It is to be hoped that some of our glass factories will manage to manufacture an article expressly for daguerreotypes; and I would recommend them to do so, for they would find it quite an item of profit annually. Before enclosing the picture in the case you should be careful to wipe the glass perfectly clean, and blow from the picture any particles of dust which may have fallen upon it. Then take strips of sticking paper, about half or three quarters of an inch wide, and firmly and neatly secure it to the glass, having first placed a "mat" between them to prevent the plate being scratched by the glass. TO MAKE SEALING PAPER.--Dissolve one ounce of gum arabic, and a quarter of an ounce of gum tragicanth in a pint of water; then add a teaspoonful of benzoin. Spread this evenly on one side of good stout tissue paper; let it dry, and then cut it up in stripes, about half or three quarters of an inch wide, for use. If it becomes too soft for summer use, add gum arabic; if too hard and cracking, add benzoin or gum tragicanth; if it gets too thick, add water. COLORED DAGUERREOTYPES ON COPPER.--To effect this, take a polished plate of copper and expose it to the vapor of iodine, or bromine, or the two substances combined; or either of them in combination with chlorine. This gives a sensitive coating to the surface of the plate, which may then be submitted to the action of light in the camera. After remaining a sufficient time in the camera, the plate is taken out and exposed to the vapor of sulphuretted hydrogen. This vapor produces various colors on the plate, according to the intensity with which the light has acted on the different parts; consequently a colored photographic picture is obtained. No further process is necessary as exposure to light does not effect the picture. By this process we have an advantage over the silvered plate, both in economy, and in the production of the picture in colors. INSTANTANTANEOUS PICTURES BY MEANS OF GALVANISM.--It will be seen by the following valuable communication that galvanism can be successfully applied in producing pictures instantly; a process of great importance in securing the likeness of a child, or in taking views of animated nature. Colonel Whitney informs me that he once took a view of the steeple of the St. Louis Court House after sundown by this means) and also secured the image of a man in the act of stepping into a store, and before he had time to place his foot, raised for that purpose, on the door step. Mr. Whitney is well known as the talented editor of the Sunday Morning news. New York, January 16, 1849. Mr. H. H. SNELLING. Dear Sir,--As you are about publishing a history of the Daguerreotype, and request a description of my mode of taking pictures instantaneously by the aid of galvanism, I comply with great pleasure. In the year 1841, while practicing the art in St. Louis, Mo., I was at times, during the summer, much troubled with the electric influence of the atmosphere, especially on the approach of a thunder-storm. At such times I found the coating of my plates much more sensitive than when the atmosphere was comparatively free from the electric fluid, and the effect was so irregular that no calculation could counteract the difficulty. This satisfied me that electricity was in some measure an important agent in the chemical process, and it occurred to me that the element might be turned to advantage. I determined, therefore, to enter on a series of experiments to test my theory. Finding it impossible to obtain an electric machine, and unwilling to abandon the examination, it occurred to me, that the galvanic influence might answer the same purpose. I therefore proceeded to make a galvanic battery in the following simple manner. I obtained a piece of zinc about two inches long, one inch wide, and an eighth of an inch thick. On this I soldered a narrow strip of copper, about six inches long, the soldered end laid on one side of the zinc, and extending its whole length. The battery was completed by placing the zinc in a glass tumbler, two-thirds full of dilute sulphuric acid, strong enough to produce a free action of the metals. The upper end of the copper slip extending above the tumbler was sharpened to a point, and bent a little over the glass. The method of using, was thus:--After preparing the plate in the usual manner and placing it in the camera, in such manner as to expose the back of the plate to view, the battery was prepared by placing the zinc in the acid, and as soon as the galvanic fluid began to traverse (as could be known by the effervessence of the acid, operating on the zinc and copper) the cap of the camera was removed, and the plate exposed to the sitter; at the same instant the point of the battery was brought quickly against the back of the plate, and the cap replaced instantly. If the plate is exposed more than an instant after the contact the picture will generally be found solarized. By this process I have taken pictures of persons in the act of walking, and in taking the pictures of infants and young children I found it very useful. Very respectfully yours, THOMAS R. WHITNEY. CHAP. VII PAPER DAGUERREOTYPES.--ETCHING DAGUERREOTYPES. Mr. Hunt describes a process, discovered by himself by which the Daguerrean art may be applied to paper. His description is as follows:-- "Placing the paper on some hard body, wash it over on one side-- by means of a very soft camel's hair pencil--with a solution of sixty grains of bromide of potassium, in two fluid ounces of distilled water, and then dry it quickly by the fire. Being dry, it is again washed over with the same solution, and dried as before. A solution of nitrate of silver-- one hundred grains to an ounce of distilled water--is to be applied over the same surface, and the paper quickly dried in the dark. In this state the papers may be kept for use. "When they are required, the above solution of silver is to be plentifully applied, and the paper placed wet in the camera, the greatest care being taken that no day light-- not even the faintest gleam--falls upon it until the moment when you are prepared, by removing the dark slide, to permit the light, radiating from the object you wish to copy, to act in producing the picture. After a few seconds the light must be again shut off, and the camera removed into a dark room." The necessity of removing the camera is now avoided by the use of the dark slide, already described, covering the picture in the holder, which alone may be removed.--Amer. Aut. "It will be found by taking the paper from the holder, that there is but a very faint outline--if any--yet visible. Place it aside, in perfect darkness until quite dry; then place it in the mercurial vapor box (meaning bath) and apply a very gentle heat to the bottom. The moment the mercury vaporizes, the picture will begin to develope itself. The spirit lamp must now be removed for a short time, and when the action of the mercury appears to cease, it is to be very carefully applied again, until a well defined picture is visible. The vaporization must then be suddenly stopped, and the photograph removed from the box. The drawing will then be very beautiful and distinct; but much detail is still clouded, for the developement of which it is only necessary to place it in the dark and suffer it to remain undisturbed for some hours. There is now an inexpressible charm about the pictures, equaling the delicate beauty of the daguerreotype; but being very susceptible of change, it must be viewed by the light of a taper only. The nitrate of silver must now be removed from the paper, by well washing it in soft water, to which a small quantity of salt has been added, and it should afterwards be soaked in water only. When the picture has been dried, wash it quickly over with a soft brush dipped in a warm solution of hyposulphite of soda, and then wash it for some time in distilled water, in order that all the hyposulphite may be removed. The drawing is now fixed and we may use it to procure positive copies, (the original being termed a negative,) many of which may be taken from one original." "The action of light on this preparation, does indeed appear to be instantaneous. The exquisite delicacy of this preparation may be imagined, when I state that in five seconds in the camera, I have, during sunshine, obtained perfect pictures, and that when the sky is overcast, one minute is quite sufficient to produce a most decided effect." "This very beautiful process is not without its difficulties; and the author cannot promise that, even with the closest attention to the above directions, annoying failures will not occur. It often happens that some accidental circumstance--generally a projecting film or a little dust--will occasion the mercurial vapor to act with great energy on one part of the paper, and blacken it before the other portions are at all effected. Again, the mercury will sometimes accumulate along the lines made by the brush, and give a streaky appearance to the picture, although these lines are not at all evident before the mercurial vapor was applied. (A brush sufficiently large--and they may be easily obtained-- will, in a measure, prevent this difficulty.--Amer Au.) I have stated that the paper should be placed wet in the camera; the same paper may be used dry, which often is a great convenience. When in the dry state a little longer exposure is required; and instead of taking a picture in four or five seconds, two or three minutes are necessary." The durability of daguerreotypes has been, and is still, doubted by many, but experiment has proved that they are more permanent than oil paintings or engravings. ETCHING DAGUERREOTYPES.--There are several methods of accomplishing this object; discovered and applied by different individuals. The first process was published at Vienna by Dr. Berres, and consisted in covering the plate with the mucilage of gum arabic, and then immersing the plate in nitric acid of different strengths. Mr. Figeau, of whom I have already spoken, likewise discovered a process for the engraving of Daguerreotypes; and founded on the belief that the lights of a Daguerreotype plate consists of unaltered silver, while the dark or shadows consists of mercury or an amalgam of mercury with silver. He finds that a compound acid, consisting of a mixture of nitric, nitrous, and muriatic acids, or of nitric mixed with nitrate of potass and common salt, has the property of attaching the silver in presence of the mercury without acting upon the latter. Bi-chloride of copper answers the purpose also, but less completely. "When the clean surface of a Daguerreotype plate is exposed to the action of this menstruum, particularly if warm, the white parts, or lights are not altered, but the dark parts are attacked, and chloride of silver is formed, of which an insoluable coating is soon deposited, and the action of the acid soon ceases. This coat of chloride of silver is removed by a solution of ammonia, and then the acid applied again, and so on, until the depth of biting in is sufficient. However, it is not possible, by repeating this process, to get a sufficient force of impression; a second operation is required, in order to obtain such a depth as will hold the ink, to give a dark impression; for this purpose the whole plate is covered with drying oil; this is cleared off with the hand, exactly in the way a copper plate printer cleans his plate. The oil is thus left in the sinkings, or dark bitten in parts only. The whole plate is now placed in a suitable apparatus, and the lights or prominent parts of the face are gilt by the electrotype process. The whole surface is now touched with what the French engravers call the "Resin Grain," (grain de resine), a species of partial stopping out, and it is at once bitten in to a sufficient depth with nitric acid, the gilding preserving the lights from all action of the acid. The resin grain gives a surface to the corroded parts suitable for holding the ink, and the plate is now finished and fit to give impressions resembling aquatint. But as silver is so soft a metal that the surface of the plate might be expected to wear rapidly, the discoverer proposes to shield it by depositing over its whole surface a very thin coat of copper by the electrotype process; which when worn may be removed at pleasure down to the surface of the noble metal beneath, and again a fresh coat of copper deposited; and so an unlimited number of impressions obtained without injuring the plate itself." If, as has been asserted, steel may be rendered sufficiently sensitive, to take photographic impressions, to what a revolution will the art of engraving be subject by the discovery of this process. CHAP. VIII. PHOTOGENIC DRAWING ON PAPER. We shall now proceed to describe the various processes for Photogenic drawing on paper; first, however, impressing on the mind of the experimenter, the necessity which exists for extreme care in every stage of the manipulation. In this portion of my work I am entirely indebted to the works of Professors Hunt, Fisher and others. I. APPARATUS AND MATERIALS.--Paper.--The principal difficulty to be contended with in using paper, is the different power of imbibition which we often find possessed in the same sheet, owing to trifling inequalities in its texture. This is, to a certain extent, to be overcome by a careful examination of each sheet, by the light of a candle or lamp at night, or in the dark. By extending each sheet between the light and the eye, and slowly moving it up and down, and from left to right, the variations in its texture will be seen by the different quantities of light which pass through it in different parts; and it is always the safest course to reject every sheet in which inequalities exist. Paper sometimes contains minute portions of thread, black or brown specks, and other imperfections, all of which materially interfere with the process. Some paper has an artificial substance given to it by sulphate of lime (Plaster of Paris); this defect only exists, however, in the cheaper sorts of demy, and therefore can be easily avoided. In all cases such paper should be rejected, as no really sensitive material can be obtained with it. Paper-makers, as is well known, often affix their name to one half the sheet; this moiety should also be placed aside, as the letters must frequently come out with annoying distinctness. Well sized paper is by no means objectionable, indeed, is rather to be preferred, since the size tends to exalt the sensitive powers of the silver. The principal thing to be avoided, is the absorption of the sensitive solution into the pores; and it must be evident that this desideratum cannot be obtained by unsized paper. Taking all things into consideration, the paper known as satin post would appear to be preferable, although the precautions already recommended should be taken in its selection. Brushes.--The necessary solutions are to be laid upon the paper by brushes. Some persons pass the paper over the surface of the solutions, thus licking up, as it were, a portion of the fluid; but this method is apt to give an uneven surface; it also rapidly spoils the solutions. At all events, the brush is the most ready and the most effectual means. Distilled Water.--All the water used, both for mixing the solutions, washing the paper, or cleaning the brushes, must be distilled, to obtain good results, for reasons before specified. Blotting Paper.--In many instances, the prepared paper requires to be lightly dried with bibulous paper. The best description is the white sort. In each stage of the preparation distinct portions of bibulous paper must be used. If these be kept seperate and marked, they can be again employed for the same stage; but it would not do, for example, to dry the finished picture in the same folds in which the sensitive paper had been pressed. A very convenient method is to have two or three quarto size books of bibulous paper, one for each seperate process. Nitrate of Silver.--In the practice of the photographic art, much depends on the nitrate of silver. Care should be taken to procure the best; the crystalized salt is most suitable for the purpose. While in the form of crystal it is not injured by exposure to light, but the bottles containing the solutions of this salt should at all times be kept wrapped in dark paper, and excluded from daylight. II. DIFFERENT METHODS OF PREPARING THE PAPER.--Preparation of the Paper.-- Dip the paper to be prepared into a weak solution of common salt. The solution should not be saturated, but six or eight times diluted with water. When perfectly moistened, wipe it dry with a towel, or press it between bibulous paper, by which operation the salt is uniformly dispersed through its substance. Then brush over it, on one side only, a solution of nitrate of silver. The strength of this solution must vary according to the color and sensitiveness required. Mr. Talbot recommends about fifty grains of the salt to an ounce of distilled water. Some advise twenty grains only, while others say eighty grains to the ounce. When dried in a dark room, the paper is fit for use. To render this paper still more sensitive, it must again be washed with salt and water, and afterwards with the same solution of nitrate of silver, drying it between times. This paper, if carefully made, is very useful for all ordinary photographic purposes. For example, nothing can be more perfect than the images it gives of leaves and flowers, especially with a summer's sun; the light, passing through the leaves, delineates every ramification of their fibres. In conducting this operation, however, it will be found that the results are sometimes more and sometimes less satisfactory, in consequence of small and accidental variations in the proportions employed. It happens sometimes that the chloride of silver formed on the surface of the paper is disposed to blacken of itself, without any exposure to light. This shows that the attempt to give it sensibility has been carried too far. The object is, to approach as nearly to this condition as possible without reaching it; so that the preparation may be in a state ready to yield to the slightest extraneous force, such as the feeblest effect of light. Cooper's Method.--Soak the paper in a boiling hot solution of chlorate of potash (the strength matters not) for a few minutes; then take it out, dry it, and wet it with a brush, on one side only, dipped in a solution of nitrate of silver, sixty grains to an ounce of distilled water, or, if not required to be so sensitive, thirty grains to the ounce will do. This paper possesses a great advantage over any other, for the image can be fixed by mere washing. It is, however, very apt to become discolored even in the washing, or shortly afterwards, and is, besides, not so sensitive, nor does it become so dark as that made according to Mr. Talbot's method. Daguerre's Method.--Immerse the paper in hydrochloric (or as it is more commonly called, muriatic) ether, which has been kept sufficiently long to become acid; the paper is then carefully and completely dried, as this is essential to its proper preparation. It is then dipped into a solution of nitrate of silver, and dried without artificial heat in a room from which every ray of light is carefully excluded. By this process it acquires a very remarkable facility in being blackened on a very slight exposure to light, even when the latter is by no means intense. The paper, however, rapidly loses its extreme sensitiveness to light, and finally becomes no more impressionable by the solar beams than common nitrate paper. Bromide Paper.--Of all common photographic paper, the best, because the least troublesome in making, and the most satisfactory in result, is that which is termed bromine paper, and which is thus prepared:--Dissolve one hundred grains of bromide of potassium in one ounce of distilled water, and soak the paper in this solution. Take off the superfluous moisture, by means of your bibulous paper, and when nearly dry, brush it over on one side only, with a solution of one hundred grains of nitrate of silver to an ounce of distilled water. The paper should then be dried in a dark room, and, if required to be very sensitive, should a second time be brushed over with the nitrate of silver solution. In preparing the papers mentioned above, there are two circumstances which require particular attention. In the first place, it is necessary to mark the paper on the side spread with the solutions of nitrate of silver, near one of the extreme corners. This answers two purposes: in the first place it serves to inform the experimemtalist of the sensitive surface; and secondly, it will be a guide as to which portion of the papers has been handled during the application of the solution, as the impress of the fingers will probably come out upon the photograph. The second caution is, that the application of the sensitive solution (nitrate of silver,) and the subsequent drying of the paper, must be always conducted in a perfectly dark room, the light of a candle alone being used. III. PHOTOGENIC PROCESS ON PAPER.--Method.--The simplest mode is to procure a flat board and a square of glass, larger in size than the object intended to be copied. On the board place the photographic paper [hipho_29.gif] with the prepared side upwards, and upon it the object to be copied; over both lay the glass and secure them so that they are in close connection by means of binding screws or clamps, similar to g. g. fig. 29. Should the object to be copied be of unequal thickness, such as a leaf, grass, &c., it will be necessary to place on the board, first, a soft cushion, which may be made of a piece of fine flannel and cotton wool. By this means the object is brought into closer contact with the paper, which is of great consequence, and adds materially to the clearness of the copy. The paper is now exposed to diffused daylight, or, still better, to the direct rays of the sun, when that part of the paper not covered by the object will become tinged with a violet color, and if the paper be well prepared, it will in a short time pass to a deep brown or bronze color. It must then be removed, as no advantage will be obtained by keeping it longer exposed; on the contrary, the delicate parts yet uncolored will become in some degree affected. The photogenic paper will now show a more or less white and distinct representation of the object. The apparatus figured at 29 consists of a wooden frame similar to a picture frame; a piece of plate glass is fixed in front; and it is provided with a sliding cover of wood, c., which is removed when the paper is ready to be exposed to the action of the light. The back, d., which is furnished with a cushion, as just described, is made to remove for the purpose of introducing the object to be copied, and upon it the prepared paper; the back is then replaced, and, by aid of the cross piece and screw, e., the whole is brought into close contact with the glass. The objects best delineated on these photographic papers, are lace, feathers, dried plants, particularly the ferns, sea-weeds and the light grasses, impressions of copper plate and wood engravings, particularly if they have considerable contrast of light and shade--(these should be placed with the face downwards, having been previously prepared as hereafter directed)-- paintings on glass, etchings, &c. To fix the Drawings.--Mr. Talbot recommends that the drawings should be dipped in salt and water, and in many instances this method will succeed, but at times it is equally unsuccessful. Iodide of potassium, or, as it is frequently called, hydriodate of potash, dissolved in water, and very much diluted, (twenty-five grains to one ounce of water,) is a more useful preparation to wash the drawings with; it must be used very weak or it will not dissolve the unchanged muriate only, as is intended but the black oxide also, and the drawing be thereby spoiled. But the most certain material to be used is the hyposulphite of soda. One ounce of this salt should be dissolved in about a pint of distilled water. Having previously washed the drawing in a little lukewarm water, which of itself removes a large portion of the muriate of silver which is to be got rid of, it should be dipped once or twice in the hyposulphite solution. By this operation the muriate which lies upon the lighter parts will become so altered in its nature as to be unchanged by light, while the rest remains dark as before. It will be evident from the nature of the process, that the lights and shadows of an object are reversed. That which is originally opaque will intercept the light, and consequently those parts of the photogenic paper will be least influenced by light, while any part of the object which is transparent, by admitting the light through it, will suffer the effect to be greater or less in exact proportion to its degree of transparency. The object wholly intercepting the light will show a white impression; in selecting, for example, a butterfly for an object, the insect, being more or less transparent, leaves a proportionate gradation of light and shade, the most opaque parts showing the whitest. It may be said, therefore, that this is not natural, and in order to obtain a true picture--or, as it is termed, a positive picture-- we must place our first acquired photograph upon a second piece of photogenic paper. Before we do this, however, we must render our photograph transparent, otherwise the opacity of the paper will mar our efforts. To accomplish this object, the back of the paper containing the negative, or first acquired photograph, should be covered with white or virgin wax. This may be done by scraping the wax upon the paper, and then, after placing it between two other pieces of paper, passing a heated iron over it. The picture, being thus rendered transparent, should now be applied to a second piece of photogenic paper, and exposed, in the manner before directed, either to diffused day-light or to the direct rays of the sun. The light will now penetrate the white parts, and the second photograph be the reverse of the first, or a true picture of the original. Instead of wax, boiled linseed oil--it must be the best and most transparent kind--may be used. The back of the negative photograph should be smeared with the oil, and then placed between sheets of bibulous paper. When dry the paper is highly transparent. IV. APPLICATION OF PHOTOGENIC DRAWING.--This method of photogenic drawing may be applied to useful purposes, such as the copying of paintings on glass by the light thrown through them on the prepared paper-- Imitations of etchings, which may be accomplished by covering a piece of glass with a thick coat of white oil paint; when dry, with the point of a needle, lines or scratches are to be made through the white lead ground, so as to lay the glass bare; then place the glass upon a piece of prepared paper, and expose it to the light. Of course every line will be represented beneath of a black color, and thus an imitation etching will be produced. It is also applicable to the delineation of microscopic objects, architecture, seulpture, landscapes and external nature. A novel application of this art has been recently suggested, which would doubtless prove useful in very many instances. By rendering the wood used for engravings sensitive to light, impressions may be at once made thereon, without the aid of the artist's pencil. The preparation of the wood is simply as follows:--Place its face or smooth side downwards, in a plate containing twenty grains of common salt dissolved in an ounce of water; here let it remain for five minutes, take it out and dry it; then place it again face downwards in another plate containing sixty grains of nitrate of silver to an ounce of water; here let it rest one minute, when taken out and dried in the dark it will be fit for use, and will become, on exposure to the light, of a fine brown color. Should it be required more sensitive, it must be immersed in each solution a second time, for a few seconds only. It will now be very soon effected by a very diffused light. This process may be useful to carvers and wood engravers not only to those who cut the fine objects of artistical design, but still more to those who cut patterns and blocks for lace, muslin, calico-printing, paper hangings, etc., as by this means the errors, expense and time of the draughtsman may be wholly saved, and in a minute or two the most elaborate picture or design, or the most complicated machinery, be delineated with the utmost truth and clearness. CHAP. IX. CALOTYPE AND CHRYSOTYPE. The materials and apparatus necessary for the Calotype process are-- Two or Three Shallow Dishes, for holding distilled water, iodide, potassium, &c.--the same water never being used for two different operations. White Bibulous Paper. Photogenic Camera--Fig. 9. Pressure Frame--Fig 29. Paper, of the very best quality--directions for the choice of which have been already given. A Screen of Yellow Glass. Camels' or Badgers' hair Brushes:--A seperate one being kept for each wash and solution, and which should be thoroughly cleansed immediately after using in distilled water. That used for the gallo-nitrate is soon destroyed, owing to the rapid decomposition of that preparation. A Graduated Measure. Three or Four Flat Boards, to which the paper may be fixed with drawing pins. A Hot Water Drying Apparatus, for drying the paper will also be found useful. In preparing the Calotype paper, it is necessary to be extremely careful, not only to prevent the daylight from impringing upon it, but also to exclude, if possible, the strong glare of the candle or lamp. This may be effected by using a shade of yellow glass or gauze, which must be placed around the light. Light passing through such a medium will scarcely affect the sensitive compounds, the yellow glass intercepting the chemical rays. Preparation of the Iodized Paper.--Dissolve one hundred grains of crystalized nitrate of silver in six ounces of distilled water, and having fixed the paper to one of the boards, brush it over with a soft brush on one side only with this solution, a mark being placed on that side whereby it may be known. When nearly dry dip it into a solution of iodide of potassium, containing five hundred grains of that salt dissolved in a pint of water. When perfectly saturated with this solution, it should be washed in distilled water, drained and allowed to dry. This is the first part of the process, and the paper so prepared is called iodized paper. It should be kept in a port-folio or drawer until required: with this care it may be preserved for any length of time without spoiling or undergoing any change. Mr. Cundell finds a stronger solution of nitrate of silver preferable, and employs thirty grains to the ounce of distilled water: he also adds fifty grains of common salt to the iodide of potassium, which he applies to the marked side of the paper only. This is the first process. Preparation of the paper for the Camera.--The second process consists in applying to the above a solution which has been named by Mr. Talbot the "Gallo-Nitrate of Silver;" it is prepared in the following manner: Dissolve one hundred grains of crystalized nitrate of silver in two ounces of distilled water, to which is added two and two-third drachms of strong acetic acid. This solution should be kept in a bottle carefully excluded from the light. Now, make a solution of gallic acid in cold distilled water: the quantity dissolved is very small. When it is required to take a picture, the two liquids above described should be mixed together in equal quantities; but as it speedily undergoe decomposition, and will not keep good for many minutes, only just sufficient for the time should be prepared, and that used without delay. It is also well not to make much of the gallic acid solution, as it will not keep for more than a few days without spoiling. A sheet of the iodized paper should be washed over with a brush with this mixed solution, care being taken that it be applied to the marked side. This operation must be performed by candle light. Let the paper rest half a minute, then dip it into one of the dishes of water, passing it beneath the surface several times; it is now allowed to drain, and dried by placing its marked side upwards, on the drying apparatus. It is better not to touch the surface with bibulous paper. It is now highly sensitive, and ready to receive the impression. In practice it is found better and more economical not to mix the nitrate of silver and gallic acid, but only to brush the paper with the solution of the nitrate. Mr. Talbot has recently proposed some modifications in his method of preparing the calotype paper. The paper is first iodized in the usual way; it is then washed over with a saturated solution of gallic acid in distilled water and dried. Thus prepared he calls it the io-gallic paper: it will remain good for a considerable time if kept in a press or portfolio. When required for use, it is washed with a solution of nitrate of silver (fifty grains to the ounce of distilled water), and it is then fit for the camera. Exposure in the Camera.--The calotype paper thus prepared possesses a very high degree of sensibility when exposed to light, and we are thus provided with a medium by which, with the aid of the photogenic camera, we may effectually copy views from nature, figures, buildings, and even take portraits from the shadows thrown on the paper by the living face. The paper may be used somewhat damp. The best plan for fixing it in the camera is to place it between a piece of plate glass and some other material with a flat surface, as a piece of smooth slate or an iron plate, which latter, if made warm, renders the paper more sensitive, and consequently the picture is obtained more rapidly. Time of Exposure.--With regard to the time which should be allowed for the paper to remain in the camera, no direct rules can be laid down; this will depend altogether upon the nature of the object to be copied, and the light which prevails. All that can be said is, that the time necessary for forming a good picture varies from thirty seconds to five minutes, and it will be naturally the first object of the operator to gain by experience this important knowledge. Bringing Out the Picture.--The paper when taken from the camera, which should be done so as to exclude every ray of light--and here the dark slide of the camera plate holder becomes of great use-- bears no resemblance to the picture which in reality is formed. The impression is latent and invisible, and its existence would not be suspected by any one not acquainted with the process by previous experiment. The method of bringing out the image is very simple. It consists in washing the paper with the gallo-nitrate of silver, prepared in the way already described, and then warming it gently, being careful at the same time not to let any portion become perfectly dry. In a few seconds the part of the paper upon which the light has acted will begin to darken, and finally grow entirely black, while the other parts retain their original color. Even a weak impression may be brought out by again washing the paper in the gallo-nitrate, and once more gently warming it. When the paper is quite black, as is generally the case, it is a highly curious and beautiful phenomenon to witness the commencement of the picture, first tracing out the stronger outlines, and then gradually filling up all the numerous and complicated details. The artist should watch the picture as it developes itself, and when in his judgment it has attained the greatest degree of strength and clearness, he shall stop further proceedings by washing it with the fixing liquid. Here again the mixed solution need not be used, but the picture simply brushed over with the gallic acid. The Fixing Process.--In order to fix the picture thus obtained, first dip it into water; then partly dry it with bibulous paper, and wash it with a solution of bromide of potassium--containing one hundred grains of that salt dissolved in eight or ten ounces of distilled water. The picture is again washed with distilled water, and then finally dried. Instead of bromide of potassium, a solution of hyposulphite of soda, as before directed, may be used with equal advantage. The original calotype picture, like the photographic one described in the last chapter, is negative, that is to say, it has its lights and shades reversed, giving the whole an appearance not conformable to nature. But it is easy from this picture to obtain another which shall be conformable to nature; viz., in which the lights shall be represented by lights, and the shades by shades. It is only necessary to take a sheet of photographic paper (the bromide paper is the best), and place it in contact with a calotype picture previously rendered transparent by wax or oil as before directed. Fix it in the frame, Fig. 29, expose it in the sunshine for a short time, and an image or copy will be formed on the photogenic paper. The calotype paper itself may be used to take the second, or positive, picture, but this Mr. Talbot does not recommend, for although it takes a much longer time to take a copy on the photogenic paper, yet the tints of such copy are generally more harmonious and agreeable. After a calotype picture has furnished a number of copies it sometimes grows faint, and the subsequent copies are inferior. This may be prevented by means of a process which revives the strength of the calotype pictures. In order to do this, it is only nesessary to wash them by candlelight with gallo-nitrate of silver, and then warm them. This causes all the shades of the picture to darken considerably, while the white parts are unaffected. After this the picture is of course to be fixed a second time. It will then yield a second series of copies, and, in this way, a great number may frequently be made. The calotype pictures when prepared as we have stated, possess a yellowish tint, which impedes the process of taking copies from them. In order to remedy this defect, Mr. Talbot has devised the following method. The calotype picture is plunged into a solution consisting of hyposulphite of soda dissolved in about ten times its weight of water, and heated nearly to the boiling point. The picture should remain in about ten minutes; it must then be removed, washed and dried. By this process the picture is rendered more transparent, and its lights become whiter. It is also rendered exceedingly permanent. After this process the picture may be waxed, and thus its transparency increased. This process is applicable to all photographic papers prepared with solutions of silver. Having thus fully, and it is hoped clearly, considered the process, it may be necessary before dismissing the calotype from notice, to add one or two remarks from the observations and labors of some who have experimented in this art. Dr. Ryan in his lectures before the Royal Polytechnic Institution, has observed, that in the iodizing process the sensitiveness of the paper is materially injured by keeping it too long in the solution of iodide of potassium, owing to the newly formed iodide of silver being so exceedingly solvable in excess of iodide of potassium as in a few minutes to be completely removed. The paper should he dipped in the solution and instantly removed. There is another point, too, in the preparation of the iodized paper in which suggestions for a slight deviation from Mr. Talbot's plan have been made. In the first instance, it is recommended that the paper be brushed over with the iodide of potassium, instead of the nitrate of silver, transposing, in fact, the application of the first two solutions. The paper, having been brushed over with the iodide of potassium in solution, is washed in distilled water and dried. It is then brushed over with nitrate of silver, and after drying is dipped for, a moment in a fresh solution of iodide of potassium of only one-fourth the strength of the first, that is to say, one hundred and twenty-five grains of the salt to a pint of water. After this it is again washed and dried. The advantage derived from this method, is a more sensitive paper, and a more even distribution of the compounds over the surface. Another deviation from Mr. Talbot's method has been suggested, as follows: Brush the paper over with a solution of one hundred grains of nitrate of silver to an ounce of water. When nearly, but not quite, dry, dip it into a solution of twenty-five grains of iodide of potassium to one ounce of distilled water, drain it, wash it in distilled water and again drain it. Now brush it over with aceto-nitrate of silver, made by dissolving fifty grains of nitrate of silver in one ounce of distilled water, to which is added one sixth of its volume of strong acetic acid. Dry it with bibulous paper, and it is ready for receiving the image. When the impression has been received, which will require from one to five minutes according to the state of the weather, it must be washed with a saturated solution of gallic acid to which a few drops of the aceto-nitrate of silver, made as above, have been added. The image will thus be gradually brought out, and may be fixed with hyposulphite of soda. To obtain the positive picture, paper must be used brushed over with an ammonio-nitrate of silver, made thus: forty grains of nitrate of silver is to be dissolved in one ounce of distilled water, and liquid ammonia cautiously added till it re-dissolves the precipitate. A pleasing effect may be given to calotype, or indeed to all photographic pictures, by waxing them at the back, and mounting them on white paper, or if colored paper be used, various beautiful tones of color are produced. POSITIVE CALOTYPE. At a meeting of the British Association, Professor Grove described a process by which positive calotype pictures could be directly obtained; and thus the necessity to transfer by which the imperfections of the paper are shown, and which is moreover a troublesome and tedious process, is avoided. As light favors most chemical actions, Mr. Grove was led to believe that a paper darkened by the sun (which darkening is supposed to result from the precipitation of silver) might be bleached by using a solvent which would not attack the silver in the dark, but would do so in the light. The plan found to be the most successful is as follows: ordinary calotype paper is darkened till it assumes a deep brown color, almost amounting to black; it is then redipped into the ordinary solution of iodide of potassium, and dried. When required for use it is drawn over dilute nitric acid-- one part acid to two and a half parts water. In this state, those parts exposed to the light are rapidly bleached, while the parts not exposed remain unchanged. It is fixed by washing in water, and subsequently in hyposulphite of soda, or bromide of potassium. Mr. Grove also describes a process for converting a negative calotype into a positive one, which promises, when carried out, to be of great utility. Let an ordinary calotype image or portrait be taken in the camera, and developed by gallic acid; then drawn over iodide of potassium and dilute nitric acid and exposed to full sunshine; while bleaching the dark parts, the light is redarkening the newly precipitated iodide in the lighter portions and thus the negative picture is converted into a positive one. The calotype process has been applied to the art of printing, in England, but it possesses no advantages whatever over the method, with type, now so gloriously brought to perfection; and I can hardly think it will ever be made of any utility. For the benefit of the curious, however, I will give Mr. Talbot's method. Some pages of letter-press are taken printed on one side only; and waxed, to render them more transparent; the letters are then cut out and sorted. To compose a new page lines are ruled on a sheet of white paper, and the words are formed by fixing the seperate letters in their proper order. The page being ready, a negative photograph is produced from it, from which the requisite number of positive photogenic copies may be obtained. Another method, which requires the use of the camera, consists in employing large letters painted on rectangular pieces of wood, colored white. These are arranged in lines on a tablet or board, by slipping them into grooves which keep them steady and upright, thus forming a page on an enlarged scale. It is now placed before a camera, and a reduced image of it of the required size is thrown upon the sensitive paper. The adjustments must be kept invariable, so that the consecutive pages may not vary from one another in the size of the type. Mr. Talbot has patented his process, but what benefit he expects to derive from it, I am at a loss to determine. Enlarged copies of calotype or Daguerreotype portraits may be obtained by throwing magnified images of them, by means of lenses, upon calotype paper. THE CHRYSOTYPE. A modification of Mr. Talbot's process, to which the name of Chrysotype was given by its discoverer, Sir John Herschel, was communicated in June 1843 to the Royal Society, by that distinguished philosopher. This modification would appear to unite the simplicity of photography with all the distintness and clearness of calotype. This preparation is as follows. The paper is to be washed in a solution of ammonio-citrate of iron; it must then be dried, and subsequently brushed over with a solution of the ferro-sesquicyanuret of potassium. This paper, when dried in a perfectly dark room, is ready for use in the same manner as if otherwise prepared, the image being subsequently brought out by any neutral solution of gold. Such was the first declaration of his discovery, but he has since found that a neutral solution of silver is equally useful in bringing out the picture. Photographic pictures taken on this paper are distinguished by a clearness of outline foreign to all other methods. CHAP. X. CYANOTYPE--ENERGIATYPE--CHROMATYPE--ANTHOTYPE--AMPHITYPE AND "CRAYON DAGUERREOTYPE." The several processes enumerated at the head of this chapter, are all discoveries of English philosophers, with the exception of the third and last named. Anthotype was first attempted by M. Ponton a French savan, although it was reserved to Mr. Hunt to bring the process to its present state. The "Crayon Daguerreotype" is an improvement made by J. A Whipple, Esq., of Boston I. CYANOTYPE; So called from the circumstance of cyanogen in its combinations with iron performing a leading part in the process. It was discovered by Sir John Herschel. The process is a simple one, and the resulting pictures are blue. Brush the paper over with a solution of the ammonio-citrate of iron. This solution should be sufficiently strong to resemble sherry wine in color. Expose the paper in the usual way, and pass over it very sparingly and evenly a wash of the common yellow ferro-cyanate of potass. As soon as the liquid is applied, the negative picture vanishes, and is replaced by a positive one, of a violet blue color, on a greenish yellow ground, which at a certain time possesses a high degree of sharpness, and singular beauty of tint. A curious process was discovered by Sir John Herschel, by which dormant pictures are produced capable of developement by the breath, or by keeping in a moist atmosphere. It is as follows. If nitrate of silver, specific gravity 1.200 be added to ferro-tartaric acid, specific gravity 1.023, a precipitate falls, which is in a great measure redissolved by a gentle heat, leaving a black sediment, which, being cleared by subsidence, a liquid of a pale yellow color is obtained, in which the further addition of the nitrate causes no turbidness. When the total quantity of the nitrated solution added amounts to about half the bulk of the ferro-tartaric acid, it is enough. The liquid so prepared does not alter if kept in the dark. Spread on paper, and exposed wet to the sunshine (partly shaded) for a few seconds, no impression seems to be made, but by degrees, although withdrawn from the action of light, it developes itself spontaneously, and at length becomes very intense. But if the paper be thoroughly dried in the dark, (in which state it is of a very pale greenish yellow color,) it possesses the singular property of receiving a dormant or invisible picture, to produce which from thirty to sixty seconds' exposure to sunshine is requisite. It should not be exposed too long, as not only is the ultimate effect less striking, but a picture begins to be visibly produced, which darkens spontaneously after it is withdrawn. But if the exposure be discontinued before this effect comes on, an invisible impression is the result, to develope which all that is necessary is to breathe upon it, when it immediately appears, and very speedily acquires an extraordinary intensity and sharpness, as if by magic. Instead of the breath, it may be subject to the regular action of aqueous vapor, by laying it in a blotting paper book, of which some of the outer leaves on both sides have been dampened, or by holding over warm water. II. ENERGIATYPE. Under this title a process has been brought forward by Mr. Hunt. It consists of the application of a solution of succinic acid to paper, which is subsequently washed over with nitrate of silver. The image is then to be taken either in the camera or otherwise, as required, and is brought out by the application of the sulphate of iron in solution. Although this process has not come into general use, its exact description may be interesting to the general reader, and we therefore subjoin it. The solution with which the paper is first washed is to be prepared as follows: succinic acid, two drachms; common salt, five grains; mucilage of gum arabic, half a fluid drachm; distilled water, one fluid drachm and a half. When the paper is nearly dry, it is to be brushed over with a solution of nitrate of silver, containing a drachm of the salt, to an ounce of distilled water. It is now ready for exposure in the camera. To bring out the dormant picture it is necessary to wash it with a mixture of a drachm of concentrated solution of the green sulphate of iron and two drachms and a half of mucilage of gum arabic. Subsequently, however, it has been found that the sulphate of iron produces upon all the salts of silver effects quite as beautiful as in the succinate. On the iodide, bromide, acetate, and benzoate, the effects are far more pleasing and striking. When pictures are produced, or the dormant camera image brought out, by the agency of sulphate of iron, it is remarkable how rapidly the effect takes place. Engravings can be thus copied almost instantaneously, and camera views obtained in one or two minutes on almost any preparation of silver. The common sulphate of copper solution has the same property. III. CHROMATYPE. Many efforts have been made to render chromatic acid an active agent in the production of photographs. M. Ponton used a paper saturated with bichromate of potash, and this was one of the earliest photogenic processes. M. Becquerel improved upon this process by sizing the paper with starch previous to the application of the bichromate of potash solution, which enabled him to convert the negative picture into a positive one, by the use of a solution of iodine, which combined with that portion of the starch on which the light had not acted. But by neither of these processes could clear and distinct pictures be formed. Mr. Hunt has, however, discovered a process which is so exceedingly simple, and the resulting pictures of so pleasing a character, that, although it is not sufficiently sensitive for use in the camera, it will be found of the greatest value for copying botanical specimens, engravings, or the like. The paper to be prepared is washed over with a solution of sulphate of copper--about one drachm to an ounce of water--and partially dried; it is then washed with a moderately strong solution of bichromate of potash, and dried at a little distance from the fire. Paper thus prepared may be kept any length of time, in a portfolio, and are always ready for use. When exposed to the sunshine for a time, varying with the intensity of the light, from five to fifteen or twenty minutes, the result is generally a negative picture. It is now to be washed over with a solution of nitrate of silver, which immediately produces a very beautiful deep orange picture upon a light dim colored, or sometimes perfectly white ground. This picture must be quickly fixed, by being washed in pure water, and dried. With regard to the strength of the solutions, it is a remarkable fact, that, if saturated solutions be employed, a negative picture is first produced, but if the solutions be three or four times their bulk of water, the first action of the sun's rays darkens the picture, and then a very bleaching effect follows, giving an exceedingly faint positive picture, which is brought out with great delicacy by the silver solution. It is necessary that pure water should be used for the fixing, as the presence of any muriate damages the picture, and here arises another pleasing variation of the Chromatype. If the positive picture be placed in a very weak solution of common salt the image slowly fades out, leaving a faint negative outline. If it now be removed from the saline solution, dried, and again exposed to sunshine, a positive picture of a lilac color will be produced by a few minutes exposure. Several other of the chromates may be used in this process, but none is so successful as the chromate of copper. IV. ANTHOTYPE. The expressed juice, alcholic, or watery infusion of flowers, or vegetable substances, may be made the media of photogenic action. This fact was first discovered by Sir John Herschel. We have already given a few examples of this in the third chapter. Certain precautions are necessary in extracting the coloring matter of flowers. The petals of fresh flowers are carefully selected, and crushed to a pulp in a marble mortar, either alone or with the addition of a little alcohol, and the juice expressed by squeezing the pulp in a clean linen or cotton cloth. It is then to be spread upon paper with a flat brush, and dried in the air without artificial heat. If alcohol be not added, the application on paper must be performed immediately, as the air (even in a few minutes), irrecoverably changes or destroys their color. If alcohol be present this change is much retarded, and in some cases is entirely prevented. Most flowers give out their coloring matter to alcohol or water. Some, however, refuse to do so, and require the addition of alkalies, others of acid, &c. Alcohol has, however, been found to enfeeble, and in many cases to discharge altogether these colors; but they are, in most cases, restored upon drying, when spread over paper. Papers tinged with vetegable colors must always be kept in the dark, and perfectly dry. The color of a flower is by no means always, or usually, that which its expressed juice imparts to white paper. Sir John Herschel attributes these changes to the escape of carbonic acid in some cases; to a chemical alteration, depending upon the absorption of oxygen, in others; and again in others, especially where the expressed juice coagulates on standing, to a loss of vitality, or disorganization of the molecules. To secure an eveness of tint on paper, the following manipulation is recommended:--The paper should be moistened on the back by sponging and blotting off. It should then be pinned on a board, the moist side downwards, so that two of its edges (suppose the right-hand and lower ones) shall project a little beyond those of the board. The board then being inclined twenty or thirty degrees to the horizon, the alcoholic tincture (mixed with a very little water, if the petals themselves be not very juicy) is to be applied with a brush in strokes from left to right, taking care not to go over the edges which rest on the board; but to pass clearly over those that project; and observing also to carry the tint from below upwards by quick sweeping strokes, leaving no dry spaces between them, but keeping up a continuity of wet spaces. When all is wet, cross them by another set of strokes from above downwards, so managing the brush as to leave no floating liquid on the paper. It must then be dried as quickly as possible over a stove, or in a warm current of air, avoiding, however, such heat as may injure the tint. In addition to the flowers already mentioned in my third chapter, the following are among those experimented upon and found to give tolerable good photographic sensitives. I can only enumerate them, referring the student, for any further information he may desire on the subject, to Mr. Hunt's work; although what I have said above is sufficient for all practical purposes; and any one, with the ambition, can readily experiment upon them, without further research, on any other flower he may choose. Viola Odorata--or sweet sented violet, yields to alcohol a rich blue color, which it imparts in high perfection to paper Senecio Splendens--or double purple groundsel, yields a beautiful color to paper. The leaves of the laurel, common cabbage, and the grasses, are found sufficiently senstive. Common Merrigold yields an invaluable faecula, which appears identical with that produced by the Wall-flower, and Cochorus japonica mentioned before, and is very sensitive, but photographs procured upon it cannot be preserved, the color is so fugitive. From an examination of the researches of Sir John Herschel on the coloring matter of plants, it will be seen that the action of the sun's rays is to destroy the color, effecting a sort of chromatic analysis, in which two distinct elements of color are separated, by destroying the one and leaving the other outstanding. The action is confined within the visible spectrum, and thus a broad distinction is exhibited between the action of the sun's rays on vegetable juices and on argentine compounds, the latter being most sensibly affected by the invisible rays beyond the violet. It may also be observed, that the rays effective in destroying a given tint, are in a great many cases, those whose union produces a color complementary to the tint destroyed, or, at least, one belonging to that class of colors to which such complementary tint may be preferred. For instance, yellows tending towards orange are destroyed with more energy by the blue rays; blues by the red, orange and yellow rays; purples and pinks by yellow and green rays. V. AMPHITYPE. This process is a discovery of Sir John Herschel and receives its name from the fact that both negative and positive photographs can be produced by one process. The positive pictures obtained by it have a perfect resemblance to impressions of engravings with common printer's ink. The process, although not yet fully carried out, promises to be of vast utility. Paper proper for producing an amphitype picture may be prepared either with the ferro-tartrate or the ferro-citrate of the protoxide, or the peroxide of mercury, or of the protoxide of lead, by using creams of these salts, or by successive applications of the nitrates of the respective oxides, singly or in mixture, to the paper, alternating with solutions of the ammonia-tartrate or the ammonia-citrate of iron, the latter solution being last applied, and in more or less excess. I purposely avoid stating proportions, as I have not yet been able to fix upon any which certainly succeed. Paper so prepared and dried takes a negative picture, in a time varying from half an hour to five or six hours, according to the intensity of the light; and the impression produced varies in apparent force from a faint and hardly perceptible picture to one of the highest conceivable fulness and richness both of tint and detail, the color being in this case a superb velvety brown. This extreme richness of effect is not produced unless lead be present, either in the ingredients used, or in the paper itself. It is not, as I originally supposed, due to the presence of free tartaric acid. The pictures in this state are not permanent. They fade in the dark, though with very different degrees of rapidity, some (especially if free tartaric or citric acid be present) in a few days, while others remain for weeks unimpaired, and require whole years for their total obliteration. But though entirely faded out in appearance, the picture is only rendered dormant, and may be restored, changing its character from negative to positive, and its colors from brown to black, (in the shadows), by the following process:--A bath being prepared by pouring a small quantity of solution of pernitrate of mercury into a large quantity of water, and letting the subnitrated precipitates subside, the picture may be immersed in it, (carefully and repeatedly clearing off all air bubbles,) and allowed to remain till the picture (if any where visible,) is entirely destroyed; or if faded, till it is judged sufficient from previous experience; a term which is often marked by the appearance of a feeble positive picture, of a bright yellow hue, on the pale yellow ground of the paper. A long time (several weeks) is often required for this, but heat accelerates the action, and it is often completed in a few hours. In this state the picture is to be very thoroughly rinsed and soaked in pure warm water, and then dried. It is then to be well ironed with a smooth iron, heated so as barely not to injure the paper, placing it, for greater security against scorching, between clean smooth paper. If then the process have been successful, a perfectly black positive picture is at once developed. At first it most commonly happens that the whole picture is sooty or dingy to such a degree that it is condemned as spoiled, but on keeping it between the leaves of a book, especially in a moist atmosphere, by extremely slow degrees this dinginess disappears, and the picture disengages itself with continually increasing sharpness and clearness, and acquires the exact effect of a copper-plate engraving on a paper more or less tinted with a pale yellow. I ought to observe, that the best and most uniform specimens which I have procured have been on paper previously washed with certain preparations of uric acid, which is a very remarkable and powerful photographic element. The intensity of the original negative picture is no criterion of what may be expected in the positive. It is from the production by one and the same action of light, of either a positive or negative picture according to the subsequent manipulations, that I have designated the process, thus generally sketched out, by the term Amphitype,--a name suggested by Mr. Talbot, to whom I communicated this singular result; and to this process or class of processes (which I cannot doubt when pursued will lead to some very beautiful results,) I propose to restrict the name in question, though it applies even more appropriately to the following exceedingly curious and remarkable one, in which silver is concerned: At the last meeting I announced a mode of producing, by means of a solution of silver, in conjunction with ferro-tartaric acid, a dormant picture brought into a forcible negative impression by the breath or moist air. (See Cyanotype.) The solution then described, and which had at that time been prepared some weeks, I may here incidentally remark, has retained its limpidity and photogenic properties, quite unimpaired during the whole year since elapsed, and is now as sensitive as ever,-- a property of no small value. Now, when a picture (for example an impression from an engraving) is taken on paper washed with this solution, it shows no sign of a picture on its back, whether that on its face is developed or not; but if, while the actinic influence is still fresh upon the face, (i.e., as soon as it is removed from the light), the back be exposed for a very few seconds to the sunshine, and then removed to a gloomy place, a positive picture, the exact complement of the negative one on the other side, though wanting of course in sharpness if the paper be thick, slowly and gradually makes its appearance there, and in half an hour or an hour acquires a considerable intensity. I ought to mention that the "ferro-tartaric acid" in question is prepared by precipitating the ferro-tartrate of ammonia (ammonia-tartrate of iron) by acetate of lead, and decomposing the precipitate by dilute sulphuric acid. When lead is used in the preparation of Amphitype paper, the parts upon which the light has acted are found to be in a very high degree rendered water proof.--Sir J. Herschel. This process is a new invention of our countryman, J. A. Whipple, Esq., of Boston, and has been patented by M. A. Root, Esq., of Philadelphia. It will be seen, however, from the previous pages of my work that Mr. Root is mistaken in regard to his being the first improvement patented in this country, althongh it is unquestionably the first by an American. Of this improvement Mr. Root says: VI. "CRAYON DAGUERREOTYPE." "The improvement to which you refer is denominated "The Crayon Daguerreotype." This invention made by Mr. J. A. Whipple, is the only improvement in Daguerreotyping, I believe, for which Letters Patent for the United States were ever issued. The pictures produced by this process--which is of the simplest description imaginable--have the appearance and effect of very fine "Crayon Drawings," from which the improvement takes its name. Some of our most distinguished artists have given it their unqualified admiration. Among them, our Mezzotinto Engravers, especially John Sartain, Esq., who, from his rich embellishments to most of the leading Magazines and Annuals of the country, as well as from the celebrity of the superb Magazine which bears his name, is so well known and so well qualified to judge of its merits. As an auxiliary to the artist, in furnishing heads to the Magazines, or other works, it is invaluable; the great object which it accomplishes being to give a finer effect and more distinct expression to all the features-- the whole power of the instrument being directed to, and confined to the head." "The late hour at which this subject has been brought to our notice prevents so full a description as we would otherwise have been glad to furnish. The New England States have been disposed of; negotiations for any of the others can be made through M. A. Root, 140 Chestnut street, Philadelphia." "A series of beautiful portraits are about being prepared by the "Crayton Process" for the express purpose of being placed on the exhibition at the "Art Union," when amateurs, artists, and the public generally will have an opportunity of witnessing its effect. We are especially gratified with this striking improvement, from the advantages which it promises to the Daguerrean art." "It is admirably designed to excite a new interest on the subject through the community, and in this way--and from its tendency to render the art more generally useful, and to elevate and distinguish it-- to make it to all a matter of more general importance." "Yours respectfully, "M. A. ROOT." In our second edition, we hope--with Mr. Root's permission-- to lay the whole process before the public, although our artists must bear in mind that Mr. Root's patent secures to him the exclusive right of its application. CHAP. XI. ON THE PROBABILITY OF PRODUCING COLORED PICTURES BY THE SOLAR RADIATIONS-- PHOTOGRAPHIC DEVIATIONS--LUNAR PICTURES--DRUMMOND LIGHT. Having before noticed the fact that some advances had been made towards taking Daguerreotypes in color, by means of solar rays, and expressed the hope that the day was not far distant when this might be accomplished, I here subjoin Mr. Hunt's remarks on this subject. Mr. Biot, in 1840, speaking of Mr. Fox Talbot's beautiful calotype pictures, considers as an illusion "the hope to reconcile, not only the intensity but the tints of the chemical impressions produced by radiations, with the colors of the object from which these radiations emanated." It is true that three years have passed away, and we have not yet produced colored images; yet I am not inclined to consider the hope as entirely illusive. It must be remembered that the color of bodies depends entirely upon the arrangement of their molecules. We have numerous very beautiful experiments in proof of this. The bi-niodide of mercury is a fine scarlet when precipitated. If this precipitate is heated between plates of glass, it is converted into crystals of a fine sulphur yellow, which remain of that color if undisturbed, but which becomes very speedily scarlet if touched with any pointed instrument. This very curious optical phenomena has been investigated by Mr. Talbot and by Mr. Warrington. Perfectly dry sulphate of copper is white; the slightest moisture turns it blue. Muriate of cobalt is of a pale pink color; a very slight heat, by removing a little moisture, changes it to a green. These are a few instances selected from many which might be given. If we receive a prismatic spectrum on some papers, we have evidence that the molecular or chemical disturbance bears some relation to the color of each ray, or, in other words, that colored light so modifies the action of ENERGIA that the impression it makes is in proportion to the color of the light it accompanies, and hence there results a molecular arrangement capable of reflecting colors differently. Some instances have been given in which the rays impressed correspond with the colors of the luminous rays in a very remarkable manner.* One of the most decided cases is that of the paper prepared with the fluoride of soda and nitrate of silver. Sir John Herschel was, however, the first to obtain any good specimens of photographically impressed prismatic colorations. * See Mr. Hunt's "Researches on Light." It was noticed by Daguerre that a red house gave a reddish image on his iodized silver plate in the camera obscura; and Mr. Talbot observed, very early in his researches, that the red of a colored print was copied of a red color, on paper spread with the chloride of silver.** ** In 1842, I had shown me a picture of a house in the Bowery, which had been repaired a few days previous, and in the wall a red brick left. This brick was brought out on the Daguerreotype plate of precisely the same color as the brick itself. The same artist also exhibited to me, the full length portrait of a gentleman who were a pair of pantaloons having a blue striped figure. This blue stripe was fully brought out, of the same color, in the picture.--AMER. ED. "In 1840 I communicated to Sir John Herschel some very curious results obtained by the use of colored media, which he did me the honor of publishing in one of his memoirs on the subject from which I again copy it." "A paper prepared with muriate of barytes and nitrate of silver, allowed to darken whilst wet in the sunshine to a chocolate color, was placed under a frame containing a red, a yellow, a green, and a blue glass. After a week's exposure to diffused light, it became red under the red glass, a dirty yellow under the yellow glass, a dark green under the green, and a light olive under the blue. "The above paper washed with a solution of salt of iodine, is very sensitive to light, and gives a beautiful picture. A picture thus taken was placed beneath the above glasses, and another beneath four flat bottles containing colored fluids. In a few days, under the red glass and fluid, the picture became a dark blue, under the yellow a light blue, under the green it remained unchanged, whilst under the blue it became a rose red, which in about three weeks changed into green. Many other experiments of a similar nature have been tried since that time with like results. "In the summer of 1843, when engaged in some experiments on papers prepared according to the principles of Mr. Talbot's calotype, I had placed in a camera obscura a paper prepared with the bromide of silver and gallic acid. The camera embraced a picture of a clear blue sky, stucco-fronted houses, and a green field. The paper was unavoidably exposed for a longer period than was intended--about fifteen minutes,--a very beautiful picture was impressed, which, when held between the eye and the light, exhibited a curious order of colors. The sky was of a crimson hue, the houses of a slaty blue, and the green fields of a brick red tint. Surely these results appear to encourage the hope, that we may eventually arrive at a process by which external nature may be made to impress its images on prepared surfaces, in all the beauty of their native coloration." PHOTOGRAPHIC DEVIATIONS. Before taking leave of the subject of photogenic drawing, I must mention one or two facts, which may be of essential service to operators. It has been observed by Daguerre, and others, in Europe, and probably by some of our own artists, that the sun two hours after it has passed the meridian, is much less effective in the photographic process, than it is two hours previous to its having reached that point. This may depend upon an absorptive power of the air, which may reasonably be supposed to be more charged with vapor two hours before noon. The fuse of the hygrometer may possibly establish the truth or falsity of this supposition. The fact, however, of a better result being produced before noon being established, persons wishing their portraits taken, will see the advantage of obtaining an early sitting, if they wish good pictures. On the other hand, if the supposition above mentioned prove true, a too early sitting must be avoided. If we take a considerable thickness of a dense purple fluid, as, for instance, a solution of the ammonia-sulphate of copper, we shall find that the quantity of light is considerably diminished, at least four-fifths of the luminous rays being absorbed, while the chemical rays permeate it with the greatest facility, and sensitive preparations are affected by its influence, notwithstanding the deficiency of light, nearly as powerfully as if exposed to the undecomposed sunbeams. It was first imagined that "under the brilliant sun and clear skies of the south, photographic pictures would be produced with much greater quickness than they could be in the atmosphere of Paris. It is found, however, that a much longer time is required. Even in the clear and beautiful light of the higher Alps, it has been proved that the production of the photographic picture requires many minutes more, even with the most sensitive preparations, than it does in London. It has also been found that under the brilliant light of Mexico, twenty minutes, and half an hour, are required to produce effects which in England would occupy but a minute; and travellers engaged in copying the antiquities of Yucatan have on several occasions abandoned the use of the photographic camera, and taken to their sketch books. Dr. Draper* has observed a similar difference between the chemical action of light in New York and Virginia. This can be only explained by the supposition that the intensity of the light and heat of these climes interferes with the action of the ENERGIC rays on those sensitive preparations which are employed. * I would here take occasion to remark that our country man, Dr. Draper, is very frequently quoted by Mr, Huut in his "Researches." LUNAR PICTURES--DRUMMOND LIGHT. The Roman Astronomers state that they have procured Daguerreotype impressions of the Nebula of the sword of Orion. Signor Rondini has a secret method of receiving photographic images on lithographic stone; on such a prepared stone they have succeeded in impressing an image of the Nebula and its stars; "and from that stone they have been enabled to take impressions on paper, unlimited in number, of singular beauty, and of perfect precision." Experiments have, however, proved that "no heating power exists in the moon's rays, and that lunar light will not act chemically upon the iduret of silver." It was at one time supposed that terrestrial or artificial light possessed no chemical rays, but this is incorrect--Mr. Brande discovered that although the concentrated light of the moon, or the light even of olefiant gas, however intense, had no effect on chloride of silver, or on a mixture of chloride and hydrogen, yet the light emitted by electerized charcoal blackens the salt. At the Royal Polytechnic Institution pictures have been taken by means of sensitive paper acted upon by the Drummond Light; but it must of course be distinctly understood, that they are inferior to those taken by the light of the sun, or diffused daylight. If our operators could manage to produce good pictures in this way they would put money in their pockets, as many who cannot find time during the day would resort to their rooms at night. I throw out the hint in hopes some one will make the experiment. I have learned, since the above was written, that an operator in Boston succeeded a short time since in procuring very good pictures by the aid of the Drummond Light; but that the intensity of the light falling directly upon the sitter's face caused great difficulty, and he abandoned it. This may, probably, be remedied by interposing a screen of very thin tissue paper tinged slightly of a bluish color. CHAP. XII. ON COLORING DAGUERREOTYPES. Nearly, if not quite all the various colors used in painting may be made from the five primitive colors, black, white, blue, red and yellow, but for the Daguerrean artist it would be the best policy to obtain such as are required by their art already prepared. In a majority of cases, the following will be found sufficient, viz. Carmine. Prussian Blue. White. Chrome Yellow, Gamboge, Yellow Ochre; or all three.* *Gamboge is best for drapery; Ochre for the face. Light Red. Indigo. Burnt Sienna. Bistre, or Burnt Umber. If, in coloring any part of a lady's or gentleman's apparel, it is found necessary to produce other tints and shades, the following combinations may be used: Orange--Mix yellow with red, making it darker or lighter by using more or less red. Purple--This is made with Prussian blue, or indigo and red. Carmine and Prussian blue producing the richest color, which may be deepened in the shadows by a slight addition of indigo or brown. Greens--Prussian blue and gamboge makes a very fine green, which may be varied to suit the taste of the sitter or operator, by larger portions of either, or by adding white, burnt sienna, indigo, and red, as the case may require. These combinations, under different modifications, give almost endless varieties of green. Brown--May be made of different shades of umber, carmine and lamp-black. Neutral tint--Is composed of indigo and lamp-black. Crimson--Mix carmine and white, deepening the shaded parts of the picture with additional carmine. Flesh Color--The best representative of flesh color is light red, brightened in the more glowing or warmer parts, with carmine, softened off in the lighter portions with white, and shaded with purple and burnt sienna. Lead Color--Mix indigo and white in proportions to suit. Scarlet--Carmine and light red. For Jewelry cups of gold and silver preparations accompany each box for Daguerreotypists, or may be procured separately. The method of laying colors on Daguerreotypes is one of considerable difficulty, inasmuch as they are used in the form of perfectly dry impalpable powder. The author of this little work is now experimenting, in order, if possible, to discover some more easy, artistic and unexceptionable method. If successful, the result will be published in a future edition. The rules we shall give for coloring Daguerreotypes depends, and are founded, upon those observed in miniature painting, and are intended more as hints to Daguerrean artists, in hopes of leading them to attempt improvements, than as instructions wholly to be observed. The writer is confident that some compound or ingredient may yet be discovered which, when mixed with the colors, will give a more delicate, pleasing, and natural appearance to the picture than is derived from the present mode of laying them on, which in his estimation is more like plastering than coloring. IN COLORING DAGUERREOTYPES, the principal shades of the head are to be made with bistre, mixed with burnt sienna, touching some places with a mixture of carmine and indigo. The flesh tints are produced by the use of light red, deepened towards the shaded parts with yellow ochre, blue and carmine mixed with indigo, while the warmer, or more highly colored parts have a slight excess of carmine or lake. Color the shades about the mouth and neck with yellow ochre, blue, and a very little carmine, heightening the color of the lips with carmine and light red, letting the light red predominate on the upper, and the carmine on the lower lip; the shades in the corner of the mouth being touched slightly with burnt sienna, mixed with carmine. In coloring the eyes, the artist will of course be guided by nature, observing a very delicate touch in laying on the colors, so as to preserve as much transparency as possible. A slight touch of blue-- ultramarine would be best if it would adhere to the Daguerreotype plate-- in the whites of the eye near the iris, will produce a good effect. In coloring the heads of men it will be necessary to use the darker tints with more freedom, according to the complexion of the sitter. For women, the warmer tints should predominate, and in order to give that transparency so universal with the softer sex-- and which gives so much loveliness and beauty to the face-- a little white may be judiciously intermingled with the red tints about the lighter portions of the face. In taking a picture of a lady with light or auburn hair, by the Daguerrean process, much of the beauty of the face is destroyed, on account of the imperfect manner in which light conveys the image of light objects to the spectrum of the camera. This may be obviated in some measure by proper coloring. To do this, touch the shaded parts with burnt sienna and bistre, filling up the lighter portions with yellow ochre, delicate touches of burnt sienna, and in those parts which naturally have a bluish tint, add very delicate touches of purple-- so delicate in fact as hardly to be perceived. The roots of the hair at the forehead should also be touched with blue, and the eyebrows near the temples made of a pinkish tint. The chin of a woman is nearly of the same color as the cheeks in the most glowing parts. In men it is stronger, and of a bluish tint, in order to produce the effect given by the beard. In portraits of women--the middle tints on the side of the light, which are perceived on the bosom and arms, are made of a slight mixture of ochre, blue and lake, (or carmine), to which add, on the shaded sides, ochre, bistre and purple, the latter in the darker parts. The tints of the hands should be the same as the other parts of the flesh, the ends of the fingers being a little pinkish and the nails of a violet hue. If any portion of the fleshy parts is shaded by portions of the dress, or by the position of the hand, this shade should be colored with umber mixed with purple. TO COLOR THE DRAPERY.--Violet Velvet--Use purple made of Prussian blue and carmine, touching up the shaded parts with indigo blue. Green Velvet--Mix Prussian blue and red-orpiment, shade with purple, and touch up the lights with a little white. Red Velvet--Mix a very little brown with carmine, shading with purple, marking the lights in the strongest parts with pure carmine, and touch the most brilliant slightly with white. White Feathers--May be improved by delicately touching the shaded parts with a little blue mixed with white. White muslin, linen, lace, satin, silk, etc., may also be colored in the same way, being careful not to lay the color on too heavily. FURS--Red Furs may be imitated by using light red and a little masticot, shaded with umber. Gray Furs--black and white mixed and shaded with bistre. Sable--white shaded lightly with yellow ochre. These few directions are quite sufficient for the art, and it is quite unnecessary for me to pursue the subject further. I would, however, remark that the Daguerreotypists would find it greatly to their advantage to visit the studies of our best artists, our public galleries of paintings, and statuary, and wherever else they can obtain a sight of fine paintings, and study the various styles of coloring, atitudes, folds of drapery and other points of the art. In coloring Daguerreotypes, artists will find the magnifying glass of much advantage in detecting any imperfections in the plate or in the image, which may be remedied by the brush. In selecting brushes choose those most susceptible of a fine point, which may be escertained by wetting them between the lips, or in a glass of water. CHAP. XIII. THE PHOTOGRAPHOMETER. The last number (for March, 1849) of the "London Art-Journal, gives the following description of a recent improvement in Photographic Manipulation, and as I am desirous of furnishing everything new in the art, I stop the press to add it, entire, to my work. "Since the photographic power of the solar rays bears no direct relation to their luminous influence, it becomes a question of considerable importance to those who practice the beautiful art of photography, to have the means of readily measuring the ever changing activity of this force. Several plans more or less successful, have been devised by Sir John Herschel, Messrs. Jordan, Shaw and Hunt. The instrument, however, which is now brought forward by Mr. Claudet, who is well known as one of our most successful Daguerreotypists, appears admirably suited to all those purposes which the practical man requires. The great difficulty which continually annoys the photographic amateur and artist, is the determination of the sensibility of each tablet employed, relatively to the amount of radiation, luminous and chemical, with which he is working. With the photographometer of Mr. Claudet this is easily ascertained. The following woodcuts and concise description will sufficiently indicate this useful and simple apparatus. [hipho_30.gif] "For an instrument of this kind it is important in the first place to have a motion always uniform, without complicated or expensive mechanism. This is obtained by means founded upon the principle of the fall of bodies sliding down an inclined plane. The sensitive surface is exposed to the light by the rapid and uniform passage of a metal plate, A, B, (Fig. 31,) having openings of different length, which follow a geometric progression. It is evident that the exposure to light will be the same for each experiment, because the plate furnished with the proportional openings falls always with the same rapidity, the height of the fall being constant, and the angle of the inclined plane the same. Each opening of this moveable plate allows the light to pass during the same space of time, and the effect upon the sensitive surface indicates exactly the intensity of the chemical rays. The rapidity of the fall may be augmented or diminished by altering the inclination of the plane by means of a graduated arc, C, D, (Fig. 30,) furnished with a screw, E, by which it may be fixed at any angle. The same result may be obtained by modifying the height of the fall or the weight of the moveable plate. The photogenic surface, whether [hipho_31.gif] it be the Daguerreotype plate, the Talbotype paper, or any other preparation sensitive to light, is placed near the bottom of the inclined plane, F. It is covered by a thin plate of metal, pierced with circular holes, which correspond to the openings of the moveable plate at the moment of the passage of the latter, during which the sensitive surface receives the light wherever the circular holes leave it exposed. "The part of the apparatus which contains the sensitive surface is an independent frame, and it slides from a dark box into an opening on the side of the inclined plane. "A covering of black cloth impermeable to light is, attached to the sides of the moveable plate, enveloping the whole inclined plane, rolling freely over two rollers, R, R, placed the one at the upper and the other at the lower part of the inclined plane. This cloth prevents the light striking the sensitive surface before and after the passage of the moveable plate. "It will be seen that this apparatus enables the experimentalist to ascertain with great precision the exact length of time which is required to produce a given amount of actinic change upon any sensitive photographic surface, whether on metal or paper. Although at present some calculation is necessary to determine the difference between the time which is necessary for exposure in direct radiation, and to the action of the secondary radiations of the camera obscura; this is, however, a very simple matter, and it appears to us exceedingly easy to adapt an instrument of this description to the camera itself. "By this instrument Mr. Claudet has already determined many very important points. Among others, he has proved that on the most sensitive Daguerreotype plate an exposure of .0001 part of a second is sufficient to produce a decided effect. "Regarding photography as an auxiliary aid to the artist of no mean value, we are pleased to record a description of an instrument which, without being complicated, promises to be exceedingly useful. In this opinion we are not singular; at a recent meeting of the Photographic Club, to which this instrument was exhibited, it was with much real satisfaction that we learned that several of our most eminent artists were now eager and most successful students in Photography. The beautiful productions of the more prominent members of this club excited the admiration of all, particularly the copies of architectural beauties, and small bits of landscape, by Messrs. Cundell and Owen. We think that now the artist sees the advantage he may derive from the aid of science, that both will gain by the union." I hope the above description will induce our townsman, Mr. Roach, to successfully produce an instrument that will meet the wants of our artists in that part of the Daguerrean process referred to. FINIS.
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