The History and Practice of the Art of Photography by Snelling

Part 1 out of 3

THE HISTORY AND PRACTICE OF THE ART OF PHOTOGRAPHY;

OR THE PRODUCTION OF PICTURES THROUGH THE AGENCY OF LIGHT.

CONTAINING ALL THE INSTRUCTIONS NECESSARY FOR THE COMPLETE
PRACTICE OF THE DAGUERREAN AND PHOTOGENIC ART, BOTH ON METALIC,
PLATES AND ON PAPER.

By HENRY H. SNELLING.

ILLUSTRATED WITH WOOD CUTS.

New York: PUBLISHED BY G. P. PUTNAM, 155 Broadway, 1849.

Entered according to act of Congress in the year 1849, by H. H. Snelling,
in the Clerk's office, of the District Court of the Southern District
of New York.

New York: PRINTED BY BUSTEED & McCOY, 163 Fulton Street.

TO EDWARD ANTHONY, ESQ., AN ESTEEMED FRIEND.

Whose gentlemanly deportment, liberal feelings, and strict integrity
have secured him a large circle of friends, this work is Respectfully
Dedicated By the AUTHOR.

PREFACE.

The object of this little work is to fill a void much complained
of by Daguerreotypists--particularly young beginers.

The author has waited a long time in hopes that some more able pen
would be devoted to the subject, but the wants of the numerous,
and constantly increasing, class, just mentioned, induces him
to wait no longer.

All the English works on the subject--particularly on the practical
application, of Photogenic drawing--are deficient in many minute details,
which are essential to a complete understanding of the art.
Many of their methods of operating are entirely different from,
and much inferior to, those practised in the United States:
their apparatus, also, cannot compare with ours for completeness,
utility or simplicity.

I shall, therefore, confine myself principally--so far as Photogenic
drawing upon metalic plates is concerned--to the methods
practised by the most celebrated and experienced operators,
drawing upon French and English authority only in cases
where I find it essential to the purpose for which I design
my work, namely: furnishing a complete system of Photography;
such an one as will enable any gentleman, or lady, who may wish
to practise the art, for profit or amusement, to do so without
the trouble and expense of seeking instruction from professors,
which in many cases within my own knowledge has prevented
persons from embracing the profession.

To English authors I am principally indebted for that portion
of my work relating to Photogenic drawing on paper.
To them we owe nearly all the most important improvements in that
branch of the art. Besides, it has been but seldom attempted
in the United States, and then without any decided success.
Of these attempts I shall speak further in the Historical
portion of this volume.

Every thing essential, therefore, to a complete knowledge of the whole art,
comprising all the most recent discoveries and improvements down to the day
of publication will be found herein laid down.

INTRODUCTION

New York, January 27, 1849.
E. ANTHONY, ESQ.

Dear Sir,--In submiting the accompanying "History and Practice
of Photography to your perusal, and for your approbation, I do
so with the utmost confidence in your ability as a practical man,
long engaged in the science of which it treats, as well as your
knowledge of the sciences generally; as well as your regard for candor.
To you, therefore, I leave the decision whether or no I have
accomplished my purpose, and produced a work which may not only
be of practical benefit to the Daguerrean artist, but of general
interest to the reading public, and your decision will influence
me in offering it for, or withholding it from, publication.

If it meets your approbation, I would most respectfully ask permission
to dedicate it to you, subscribing myself,
With esteem,
Ever truly yours,
HENRY H. SNELLING

New York, February 1st, 1849.
Mr. H. H. SNELLING.

Dear Sir--Your note of January 27th, requesting permission
to dedicate to me your "History and Practice of Photography,"
I esteem a high compliment, particularly since I have read
the manuscript of your work.

Such a treatise has long been needed, and the manner in which you have handled
the subject will make the book as interesting to the reading public as it
is valuable to the Daguerrean artist, or the amateur dabbler in Photography.
I have read nearly all of the many works upon this art that have emanated
from the London and Paris presses, and I think the reader will find in yours
the pith of them all, with much practical and useful information that I
do not remember to have seen communicated elsewhere.

There is much in it to arouse the reflective and inventive
faculties of our Daguerreotypists. They have heretofore stumbled
along with very little knowledge of the true theory of their art,
and yet the quality of their productions is far in advance
of those of the French and English artists, most of whose
establishments I have had the pleasure of visiting I feel therefore,
that when a sufficient amount of theoretic knowledge shall have
been added to this practical skill on the part of our operators,
and when they shall have been made fully acquainted with what has
been attained or attempted by others, a still greater advance
in the art will be manifested.

A GOOD Daguerreotypist is by no means a mere machine following
a certain set of fixed rules. Success in this art requires
personal skill and artistic taste to a much greater degree
than the unthinking public generally imagine; in fact more than
is imagined by nine-tenths of the Daguerreotypists themselves.
And we see as a natural result, that while the business numbers
its thousands of votaries, but few rise to any degree of eminence.
It is because they look upon their business as a mere mechanical
operation, and having no aim or pride beyond the earning of their
daily bread, they calculate what will be a fair per centage
on the cost of their plate, case, and chemicals, leaving MIND,
which is as much CAPITAL as anything else (where it is exercised,)
entirely out of the question.

The art of taking photographs on PAPER, of which your work
treats at considerable length, has as yet attracted but little
attention in this country, though destined, as I fully believe,
to attain an importance far superior to that to which the
Daguerreotype has risen.

The American mind needs a waking up upon the subject, and I
think your book will give a powerful impulse in this direction.
In Germany a high degree of perfection has been reached,
and I hope your countrymen will not be slow to follow.

Your interesting account of the experiments of Mr. Wattles
was entirely new to me, and is another among the many evidences
that when the age is fully ripe for any great discovery,
it is rare that it does not occur to more than a single mind.

Trusting that your work will meet with the encouragement which your trouble
in preparing it deserves, and with gratitude for the undeserved compliment
paid to me in its dedication,

I remain, very sincerely,
Your friend and well wisher,
E. ANTHONY.

PHOTOGRAPHY.

CHAP. I.

A BRIEF HISTORY OF THE ART.

As in all cases of great and valuable inventions in science and art
the English lay claim to the honor of having first discovered
that of Photogenic drawing. But we shall see in the progress
of this history, that like many other assumptions of their authors,
priority in this is no more due them, then the invention of steamboats,
or the cotton gin.

This claim is founded upon the fact that in 1802 Mr. Wedgwood
recorded an experiment in the Journal of the Royal Institution
of the following nature.

"A piece of paper, or other convenient material, was placed upon
a frame and sponged over with a solution of nitrate of silver;
it was then placed behind a painting on glass and the light traversing
the painting produced a kind of copy upon the prepared paper,
those parts in which the rays were least intercepted being
of the darkest hues. Here, however, terminated the experiment;
for although both Mr. Wedgwood and Sir Humphry Davey experimented
carefully, for the purpose of endeavoring to fix the drawings
thus obtained, yet the object could not be accomplished,
and the whole ended in failure."

This, by their own showing, was the earliest attempt of the English savans.
But this much of the principle was known to the Alchemists at an early date--
although practically produced in another way--as the following experiment,
to be found in old books, amply proves.

"Dissolve chalk in aquafortis to the consistence of milk, and add to it
a strong solution of silver; keep this liquor in a glass bottle well stopped;
then cutting out from a piece of paper the letters you would have appear,
paste it on the decanter, and lay it in the sun's rays in such a manner
that the rays may pass through the spaces cut out of the paper and fall
on the surface of the liquor the part of the glass through which the rays
pass will be turned black, while that under the paper remains white;
but particular care must be observed that the bottle be not moved
during the operation."

Had not the alchemists been so intent upon the desire to discover
the far famed philosopher's stone, as to make them unmindful
of the accidental dawnings of more valuable discoveries,
this little experiment in chemistry might have induced them
to prosecute a more thorough search into the principle,
and Photogenic art would not now, as it is, be a new one.

It is even asserted that the Jugglers of India were for many ages
in possession of a secret by which they were enabled, in a brief space,
to copy the likeness of any individual by the action of light.
This fact, if fact it be, may account for the celebrated magic
mirrors said to be possessed by these jugglers, and probable cause
of their power over the people.

However, as early as 1556 the fact was established that a combination
of chloride and silver. called, from its appearance, horn silver,
was blackened by the sun's rays; and in the latter part of the last
century Mrs. Fulhame published an experiment by which a change
of color was effected in the chloride of gold by the agency of light;
and gave it as her opinion that words might be written in this way.
These incidents are considered as the first steps towards the discovery
of the Photogenic art.

Mr. Wedgwood's experiments can scarcely be said to be any improvement
on them since he failed to bring them to practical usefulness,
and his countrymen will have to be satisfied with awarding
the honor of its complete adaptation to practical purposes, to MM.
Niepce and Daguerre of France, and to Professors Draper,
and Morse of New-York.

These gentlemen--MM. Niepce and Daguerre--pursued the subject simultaneously,
without either, however being aware of the experiments of his colleague
in science. For several years, each pursued his researches individually
until chance made them acquainted, when they entered into co-partnership,
and conjointly brought the art almost to perfection.

M. Niepce presented his first paper on the subject to the Royal
Society in 1827, naming his discovery Heliography. What led him
to the study of the principles of the art I have no means, at present,
of knowing, but it was probably owing to the facts recorded
by the Alchemists, Mrs. Fulhame and others, already mentioned.
But M. Daguerre, who is a celebrated dioramic painter,
being desirous of employing some of the singularly changeable salts
of silver to produce a peculiar class of effects in his paintings,
was led to pursue an investigation which resulted in the discovery
of the Daguerreotype, or Photogenic drawing on plates of copper
coated with silver.

To this gentleman--to his liberality--are we Americans
indebted for the free use of his invention; and the large
and increasing class of Daguerrean artists of this country
should hold him in the most profound respect for it.
He was not willing that it should be confined to a few
individuals who might monopolise the benefits to be derived
from its practice, and shut out all chance of improvement.
Like a true, noble hearted French gentleman he desired that his
invention should spread freely throughout the whole world.
With these views he opened negociations with the French government
which were concluded most favorably to both the inventors,
and France has the "glory of endowing the whole world of
science and art with one of the most surprising discoveries
that honor the land."

Notwithstanding this, it has been patented in England and the result
is what might have been expected: English pictures are far below
the standard of excellence of those taken by American artists.
I have seen some medium portraits, for which a guinea each had
been paid, and taken too, by a celebrated artist, that our poorest
Daguerreotypists would be ashamed to show to a second person,
much less suffer to leave their rooms.

CALOTYPE, the name given to one of the methods of Photogenic drawing
on paper, discovered, and perfected by Mr. Fox Talbot of England,
is precisely in the same predicament, not only in that country
but in the United States, Mr. Talbot being patentee in both.
He is a man of some wealth, I believe, but he demands so high
a price for a single right in this country, that none can be found
who have the temerity to purchase.

The execution of his pictures is also inferior to those taken by
the German artists, and I would remark en passant, that the Messrs.
Mead exhibited at the last fair of the American Institute, (of 1848,)
four Calotypes, which one of the firm brought from Germany last Spring,
that for beauty, depth of tone and excellence of execution surpass
the finest steel engraving.

When Mr. Talbot's patent for the United States expires
and our ingenious Yankee boys have the opportunity, I have
not the slightest doubt of the Calotype, in their hands,
entirely superceding the Daguerreotype.

Let them, therefore, study the principles of the art as laid down in
this little work, experiment, practice and perfect themselves in it,
and when that time does arrive be prepared to produce that degree
of excellence in Calotype they have already obtained in Daguerreotype.

It is to Professor Samuel F. B. Morse, the distinguished inventor
of the Magnetic Telegraph, of New York, that we are indebted
for the application of Photography, to portrait taking.
He was in Paris, for the purpose of presenting to the scientific world
his Electro-Magnetic Telegraph, at the time, (1838,) M. Daguerre
announced his splendid discovery, and its astounding results having
an important bearing on the arts of design arrested his attention.
In his letter to me on the subject, the Professor gives
the following interesting facts.

"The process was a secret, and negociations were then in progress,
for the disclosure of it to the public between the French government
and the distinguished discoverer. M. Daguerre had shown his
results to the king, and to a few only of the distinguished savans,
and by the advice of M. Arago, had determined to wait the action
of the French Chambers, before showing them to any other persons.
I was exceedingly desirous of seeing them, but knew not
how to approach M. Daguerre who was a stranger to me.
On mentioning my desire to Robert Walsh, Esq., our worthy Consul,
he said to me; 'state that you are an American, the inventor
of the Telegraph, request to see them, and invite him in turn
to see the Telegraph, and I know enough of the urbanity and
liberal feelings of the French, to insure you an invitation.'
I was successfull in my application, and with a young friend,
since deceased, the promising son of Edward Delevan, Esq., I
passed a most delightful hour with M. Daguerre, and his enchanting
sun-pictures. My letter containing an account of this visit,
and these pictures, was the first announcement in this country
of this splendid discovery."

"I may here add the singular sequel to this visit. On the succeeding day
M. Daguerre paid me a visit to see the Telegraph and witness its operations.
He seemed much gratified and remained with me perhaps two hours;
two melancholy hours to him, as they afterwards proved; or while
he was with me, his buildings, including his diorama, his studio,
his laboratory, with all the beautiful pictures I had seen the day before,
were consumed by fire. Fortunately for mankind, matter only was consumed,
the soul and mind of the genius, and the process were still in existence."

On his return home, Professor Morse waited with impatience
for the revelation of M. Daguerre's process, and no sooner was it
published than he procured a copy of the work containing it,
and at once commenced taking Daguerreotype pictures.
At first his object was solely to furnish his studio with
studies from nature; but his experiments led him into a belief
of the practicability of procuring portraits by the process,
and he was undoubtedly the first whose attempts were attended
with success. Thinking, at that time, that it was necessary
to place the sitters in a very strong light, they were all taken
with their eyes closed.

Others were experimenting at the same time, among them
Mr. Wolcott and Prof. Draper, and Mr. Morse, with his
acustomed modesty, thinks that it would be difficult to say
to whom is due the credit of the first Daguerreotype portrait.
At all events, so far as my knowledge serves me, Professor Morse
deserves the laurel wreath, as from him originated the first
of our inumerable class of Daguerreotypists; and many of his
pupils have carried the manipulation to very great perfection.
In connection with this matter I will give the concluding
paragraph of a private letter from the Professor to me; He says.

"If mine were the first, other experimenters soon made better results,
and if there are any who dispute that I was first, I shall have no argument
with them; for I was not so anxious to be the first to produce the result,
as to produce it in any way. I esteem it but the natural carrying out of
the wonderful discovery, and that the credit was after all due to Daguerre.
I lay no claim to any improvements."

Since I commenced the compilation of this work, I have had the pleasure
of making the acquaintance of an American gentleman--James M. Wattles Esq.--
who as early as 1828--and it will be seen, by what I have already stated,
that this is about the same date of M. Niepce's discovery--had his attention
attracted to the subject of Photography, or as he termed it "Solar picture
drawing," while taking landscape views by means of the camera-obscura.
When we reflect upon all the circumstances connected with his experiments,
the great disadvantages under which be labored, and his extreme youthfullness,
we cannot but feel a national pride--yet wonder--that a mere yankee boy,
surrounded by the deepest forests, hundred of miles from the populous
portion of our country, without the necessary materials, or resources
for procuring them, should by the force of his natural genius make
a discovery, and put it in practical use, to accomplish which,
the most learned philosophers of Europe, with every requisite apparatus,
and a profound knowledge of chemistry--spent years of toil to accomplish.
How much more latent talent may now be slumbering from the very same cause
which kept Mr. Wattles from publicly revealing his discoveries, viz;
want of encouragement--ridicule!

At the time when the idea of taking pictures permanently on paper by
means of the camera-obscura first occurred to him, he was but sixteen
years of age, and under the instructions of Mr. Charles Le Seuer,
(a talented artist from Paris) at the New Harmony school, Indiana.
Drawing and painting being the natural bent of his mind, be was
frequently employed by the professors to make landscape sketches
in the manner mentioned. The beauty of the image of these landscapes
produced on the paper in the camera-obscura, caused him to pause
and admire them with all the ardor of a young artist, and wish
that by some means, he could fix them there in all their beauty.
From wishing he brought himself to think that it was not only possible
but actually capable of accomplishment and from thinking it could,
he resolved it should be done.

He was, however, wholly ignorant of even the first principles
of chemistry, and natural philosophy, and all the knowledge he was
enabled to obtain from his teachers was of very little service to him.
To add to this, whenever he mentioned his hopes to his parents,
they laughed at him, and bade him attend to his studies and let
such moonshine thoughts alone--still he persevered, though secretly,
and he met with the succes his peseverance deserved.

For the truth of his statement, Mr. Wattles refers to some of our
most respectable citizens residing at the west, and I am in hopes
that I shall be enabled to receive in time for this publication,
a confirmation from one or more of these gentlemen. Be that as it may,
I feel confident in the integrity of Mr. Wattles, and can give his
statement to the world without a doubt of its truth.

The following sketch of his experiments and their results will,
undoubtedly, be interesting to every American reader and although
some of the profound philosophers of Europe may smile at his
method of proceeding, it will in some measure show the innate
genius of American minds, and prove that we are not far behind
our trans-atlantic brethren in the arts and sciences.

Mr. Wattles says: "In my first efforts to effect the desired object,
they were feeble indeed, and owing to my limited knowledge of chemistry--
wholly acquired by questioning my teachers--I met with repeated failures
but following them up with a determined spirit, I at last produced,
what I thought very fair samples--but to proceed to my experiments."

"I first dipped a quarter sheet of thin white writing paper in a weak
solution of caustic (as I then called it) and dried it in an empty box,
to keep it in the dark; when dry, I placed it in the camera and watched
it with great patience for nearly half an hour, without producing
any visible result; evidently from the solution being to weak.
I then soaked the same piece of paper in a solution of common potash,
and then again in caustic water a little stronger than the first,
and when dry placed it in the camera. In about forty-five minutes I
plainly percieved the effect, in the gradual darkening of various parts
of the view, which was the old stone fort in the rear of the school garden,
with the trees, fence, &c. I then became convinced of the practicability
of producing beautiful solar pictures in this way; but, alas! my
picture vanished and with it, all--no not all--my hopes. With renewed
determination I began again by studying the nature of the preparation,
and came to the conclusion, that if I could destroy the part not acted
upon by the light without injuring that which was so acted upon,
I could save my pictures. I then made a strong solution of sal.
soda I had in the house, and soaked my paper in it, and then washed
it off in hot water, which perfectly fixed the view upon the paper.
This paper was very poor with thick spots, more absorbent than other parts,
and consequently made dark shades in the picture where they should
not have been; but it was enough to convince me that I had succeeded,
and that at some future time, when I had the means and a more
extensive knowledge of chemistry, I could apply myself to it again.
I have done so since, at various times, with perfect success;
but in every instance laboring under adverse circumstances."

I have very recently learned, that, under the present patent laws
of the United States, every foreign patentee is required to put
his invention, or discovery, into practical use within eighteen
months after taking out his papers, or otherwise forfeit his patent.
With regard to Mr. Talbot's Calotype patent, this time has nearly,
if not quite expired, and my countrymen are now at perfect
liberty to appropriate the art if they feel disposed.
From the statement of Mr. Wattles, it will be perceived that this
can be done without dishonor, as in the first instance Mr. Talbot
had no positive right to his patent.

Photography; or sun-painting is divided, according to the methods
adopted for producing pictures, into

DAGUERREOTYPE, CHROMATYPE,
CALOTYPE, ENERGIATYPE,
CHRYSOTYPE, ANTHOTYPE and
CYANOTYPE, AMPHITYPE.

CHAP. II.

THE THEORY ON LIGHT.--THE PHOTOGRAPHIC PRINCIPLE

Some philosophers contend that to the existence of light alone we owe
the beautiful effects produced by the Photogenic art, while others give
sufficient reasons for doubting the correctness of the assumption.
That the results are effected by a principle associated with light and
not by the luminous principle itself, is the most probable conclusion.
The importance of a knowledge of this fact becomes most essential
in practice, as will presently be seen. To this principle Mr. Hunt
gives the name of ENERGIA.

THE NATURE of Light is not wholly known, but it is generally believed
to be matter, as in its motions it obeys the laws regulating matter.
So closely is it connected with heat and electricity that there can be little
doubt of their all being but different modifications of the same substance.
I will not, however, enter into a statement of the various theories of
Philosophers on this head, but content myself with that of Sir Isaac Newton;
who supposed rays of light to consist of minute particles of matter,
which are constantly emanating from luminous bodies and cause vision,
as odoriferous particles, proceeding from certain bodies, cause smelling.

The effects of light upon other bodies, and how light is effected
by them, involve some of the most important principles, which if
properly understood by Daguerreotypists would enable them to improve
and correct many of the practical operations in their art.
These effects we shall exhibit in this and the following chapters.
Before we enter on this subject it will be necessary to become
familiar with the

DEFINITIONS of some of the terms used in the science of optics.

Luminous bodies are of two kinds; those which shine by their own light,
and those which shine by reflected light.

Transparent bodies are such as permit rays of light to pass through them.

Translucent bodies permit light to pass faintly, but without
representing the figure of objects seen through them.

Opaque bodies permit no light to pass through them, but reflect light.

A ray is a line of light.

A beam is a collection of parallel rays.

A pencil is a collection of converging, or diverging rays.

A medium is any space through which light passes.

Incident rays are those which fall upon the surface of a body.

Reflected rays are those which are thrown off from a body.

Parallel rays are such as proceed equally distant from each other
through their whole course.

Converging rays are such as approach and tend to unite at any one point,
as at b. fig. 3.

Diverging rays are those which continue to recede from each other,
as at e. Fig. 3.

A Focus is that point at which converging rays meet.

MOTION OF LIGHT--Rays of light are thrown off from luminous bodies
in every direction, but always in straight lines, which cross each
other at every point; but the particles of which each ray consists
are so minute that the rays do not appear to be impeded by each other.
A ray of light passing through an aperture into a dark room,
proceeds in a straight line; a fact of which any one may be convinced
by going into a darkened room and admiting light only through
a small aperture.

Light also moves with great velocity, but becomes fainter as it recedes
from the source from which it eminates; in other words, diverging rays
of light diminish in intensity as the square of the distance increases.
For instance let a fig. 1, represent the luminous body from
[hipho_1.gif]
which light proceeds, and suppose three square boards, b. c. d.
severally one, four and sixteen square inches in size be placed;
b one foot, c two feet, and d four feet from a, it will be
perceived that the smallest board b will throw c into shadow;
that is, obstruct all rays of light that would otherwise fall on c,
and if b were removed c would in like manner hide the light
from d--Now, if b recieve as much light as would fall on c whose
surface is four times as large, the light must be four times
as powerful and sixteen times as powerful as that which would
fall on the second and third boards, because the same quantity
of light is diffused over a space four and sixteen times greater.
These same rays may be collected and their intensity again increased.

Rays of light are reflected from one surface to another; Refracted,
or bent, as they pass from the surface of one transparent
medium to another; and Inflected, or turned from their course,
by the attraction of opaque bodies. From the first we
derive the principles on which mirrors are constructed;
to the second we are indebted for the power of the lenses,
and the blessings of sight,--for the light acts upon the retina
of the eye in the same manner as on the lens of a camera.
The latter has no important bearing upon our subject.

When a ray of light falls perpendicularly upon an opaque body,
it is reflected bark in the same line in which it proceeds;
in this case the reflected ray returns in the same path
the incident ray traversed; but when a ray falls obliquely, it is
reflected obliquely, that is, it is thrown off in opposite direction,
and as far from the perpendicular as was the incident ray, as shown
at Fig. 2; a representing the incident ray and b the reflected.
The point, or angle c made by
[hipho_2.gif]
the incident ray, at the surface of the reflector e f, with a line c d,
perpendicular to that surface, is called the angle of incidence,
while the angle formed by the reflected ray b and the perpendicular line
d is called the angle of reflection, and these angles are always equal.

It is by this reflection of light that objects are made visible;
but unless light falls directly upon the eye they are invisible,
and are not sensibly felt until after a certain series of
operations upon the various coverings and humors of the eye.
Smooth and polished surfaces reflect light most powerfully,
and send to the eye the images of the objects from which the light
proceeded before reflection. Glass, which is transparent--
transmitting light--would be of no use to us as a mirror,
were it not first coated on one side with a metalic amalgam,
which interrupts the rays in their passage from the glass into
the air, and throws them either directly in the incident line,
or in an oblique direction. The reason why trees,
rocks and animals are not all mirrors, reflecting other forms
instead of their own, is, that their surfaces are uneven,
and rays of light reflected from an uneven surface are diffused
in all directions.

Parallel rays falling obliquely upon a plane mirror are reflected parallel;
converging rays, with the same degree of convergence; and diverging
rays equally divergent.

Stand before a mirror and your image is formed therein,
and appears to be as far behind the glass as you are before it,
making the angle of reflection equal to that of incidence,
as before stated. The incident ray and the reflected
ray form, together, what is called the passage of reflection,
and this will therefore make the actual distance of an image
to appear as far again from the eye as it really is.
Any object which reflects light is called a radiant.
The point behind a reflecting surface, from which they appear
to diverge, is called the virtual focus.

Rays of light being reflected at the same angle at which they
fall upon a mirror, two persons can stand in such a position
that each can see the image of the other without seeing his own.
Again; you may see your whole figure in a mirror half your length,
but if you stand before one a few inches shorter the whole cannot
be reflected, as the incident ray which passes from your feet into
the mirror in the former case, will in the latter fall under it.
Images are always reversed in mirrors.

Convex mirrors reflect light from a rounded surface and disperse
the rays in every direction, causing parallel rays to diverge,
diverging rays to diverge more, and converging rays to converge less--
They represent objects smaller than they really are--because the angle
formed by the reflected ray is rendered more acute by a convex than
by a plane surface, and it is the diminishing of the visual angle,
by causing rays of light to be farther extended before they meet
in a point, which produces the image of convex mirrors. The greater
the convexity of a mirror, the more will the images of the objects
be diminished, and the nearer will they appear to the surface.
These mirrors furnish science with many curious and pleasing facts.

Concave mirrors are the reverse of convex; the latter being rounded outwards,
the former hollowed inwards--they render rays of light more converging--
collect rays instead of dispersing them, and magnify objects while the
convex diminishes them.

Rays of light may be collected in the focus of a mirror to such intensity as
to melt metals. The ordinary burning glass is an illustration of this fact;
although the rays of light are refracted, or passed through the glass
and concentrated into a focus beneath.

When incident rays are parallel, the reflected rays converge to a focus,
but when the incident rays proceed from a focus, or are divergent,
they are reflected parallel. It is only when an object is nearer to a
concave mirror than its centre of concavity, that its image is magnified;
for when the object is farther from the mirror, this centre will appear
less than the object, and in an inverted position.

The centre of concavity in a concave mirror, is an imaginary
point placed in the centre of a circle formed by continuing
the boundary of the concavity of the mirror from any one point
of the edge to another parallel to and beneath it.

REFRACTION OF LIGHT:--I now pass to the consideration of the passage
of light through bodies.

A ray of light failing perpendicularly through the air upon a surface
of glass or water passes on in a straight line through the body;
but if it, in passing from one medium to another of different density,
fall obliquely, it is bent from its direct course and recedes from it,
either towards the right or left, and this bending is called refraction;
(see fig. 3, b.) If a ray of light passes from a rarer into a denser medium
it is refracted towards a perpendicular in that medium; but if it passes from
a denser into rarer it is bent further from a perpendicular in that medium.
Owing to this bending of the rays of light the angles of refraction
and incidence are never equal.

Transparent bodies differ in their power of bending light--
as a general rule, the refractive power is proportioned to
the density--but the chemical constitution of bodies as well
as their density, is found to effect their refracting power.
Inflamable bodies possess this power to a great degree.

The sines of the angle of incidence and refraction (that is,
the perpendicular drawn from the extremity of an arc to the diameter
of a circle,) are always in the same ratio; viz: from air into water,
the sine of the angle of refraction is nearly as four to three,
whatever be the position of the ray with respect to the refracting surface.
From air into sulphur, the sine of the angle of refraction is as two to one--
therefore the rays of light cannot be refracted whenever the sine
of the angle of refraction becomes equal to the radius* of a circle,
and light falling very obliquely upon a transparent medium ceases
to be refracted; this is termed total reflection.

* The RADIUS of a circle is a straight line passing from the centre
to the circumference.

Since the brightness of a reflected image depends upon the quantity of light,
it is quite evident that those images which arise from total reflection
are by far the most vivid, as in ordinary cases of reflection a portion
of light is absorbed.

I should be pleased to enter more fully into this branch
of the science of optics, but the bounds to which I am
necessarily limited in a work of this kind will not admit of it.
In the next chapter, however, I shall give a synopsis of Mr. Hunt's
treatise on the "Influence of the Solar Rays on Compound Bodies,
with especial reference to their Photographic application"--
A work which should be in the hands of every Daguerreotypist,
and which I hope soon to see republished in this country.
I will conclude this chapter with a brief statement of the
principles upon which the Photographic art is founded.

SOLAR and Steller light contains three kinds of rays, viz:

1. Colorific, or rays of color.

2. Calorific, or rays of heat.

3. Chemical rays, or those which produce chemical effects.

On the first and third the Photographic principle depends.
In explaining this principle the accompanying wood cuts,
(figs. 3 and 4) will render it more intelligible.

If a pencil of the sun's rays fall upon a prism, it is bent in passing
through the transparent medium; and some rays being more refracted
than others, we procure an elongated image of the luminous beam,
exhibiting three distinct colors, red, yellow and blue, which are
to be regarded as primitives--and from their interblending, seven,
as recorded by Newton, and shown in the accompanying wood cut.
These rays being absorbed, or reflected differently by various bodies,
give to nature the charm of color. Thus to the eve is given the pleasure
we derive in looking upon the green fields and forests, the enumerable
varieties of flowers, the glowing ruby, jasper, topaz, amethist, and emerald,
the brilliant diamond, and all the rich and varied hues of nature,
both animate and inanimate.
[hipho_3.gif]

Now, if we allow this prismatic spectrum (b. fig. 3.) to fall upon
any surface (as at c.) prepared with a sensitive photographic compound,
we shall find that the chemical effect produced bears no relation
to the intensity of the light of any particular colored ray,
but that, on the contrary, it is dispersed over the largest portion
of the spectrum, being most energetic in the least luminous rays,
and ever active over an extensive space, where no traces of light
can be detected. Fig. 4, will give the student a better idea
of this principle. It is a copy of the kind of impression
which the spectrum, spoken of, would make on a piece of paper
covered with a very sensitive photographic preparation.
The white space a. corresponds with the most luminous, or yellow ray,
(5, fig. 3) over limits of which all chemical change is prevented.
A similar action is also produced by the lower end of the red ray c;
but in the upper portion, however we find a decided change
(as at d). The most active chemical change, you will percieve,
is produced by the rays above the yellow a; viz. 4, 3, 2 and 1
(as at b) the green (4) being the least active, and the blue
(3) and violet (1) rays the most so, the action still continuing
far beyond the point b which is the end of the luminous image.
[hipho_4.gif]

Suppose we wish to copy by the Daguerreotype, or Calotype process,
any objects highly colored--blue, red and yellow, for instance predominating--
the last of course reflects the most light, the blue the least;
but the rays from the blue surface will make the most intense impression,
whilst the red radiations are working very slowly, and the yellow
remains entirely inactive. This accounts for the difficulty experienced
in copying bright green foliage, or warmly colored portraits; a large
portion of the yellow and red rays entering into the composition of both--
and the imperfections of a Daguerreotype portrait of a person with a
freckled face depends upon the same cause.

A yellow, hazy atmosphere, even when the light is very bright,
will effectually prevent any good photographic result--
and in the height of summer, with the most sensative process,
it not unfrequently happens that the most anoying failures
arise from this agency of a yellow medium. A building
painted of a yellow color, which may reflect the sun's rays
directly into the operator's room will have the same effect.
Daguerreotypists, being ignorant of these facts, are very apt
to charge their want of success to the plates, or chemicals,
or any thing but the real cause; and it would be well to bear
these facts constantly in mind and as far as possible avoid them.
This, may be accomplished, in a measure, by a choice of location
or by having the glass of your windows tinged with blue; or a screen
of thin blue paper may be interposed between the light and sitter.
In selecting subjects, all striking contrasts in color should
be avoided, and sitters for portraits should be cautioned
not to wear anything that may produce the effect spoken of--
dark dresses always being the best.

The action of light both combines and decomposes bodies.
For instance, chlorine and hydrogen will remain in a glass vessel without
alteration if kept in the dark; but if exposed to the rays of the sun,
they immediately enter into combination, and produce hydrochloric acid.
On the other hand, if colorless nitric acid be exposed to the sun,
it becomes yellow, then changes to red, and oxygen is liberated
by the partial decomposition effected by the solar rays.

Of the organic substances none are more readily acted upon by light
than the various combinations of silver.

Of these some are more, and others less sensitive. If Chloride of silver,
which is a white precipitate formed by adding chloride of sodium (common salt)
to a solution of nitrate of silver, be exposed to diffused light,
it speedily assumes a violet tint, and ultimately becomes nearly black.
With iodide of silver, bromide of silver, ammonio-nitrate of silver,
and other salts of this metal, the result will be much the same.

Some bodies, which under the influence of light, undergo chemical changes,
have the power of restoring themselves to their original condition in
the dark. This is more remarkably displayed in the iodide of platinum,
which readily recieves a photogenic image by darkening over the
exposed surfaces, but speedily loses it by bleaching in the dark.
The ioduret of Daguerre's plate, and some other iodides, exhibit the
same peculiarity--This leads us to the striking fact, that bodies
which have undergone a change of estate under the influence of day-light
have some latent power by which they can renovate themselves.
Possibly the hours of night are as necessary to inanimate nature as they
are to the animate. During the day, an excitement which we do not heed,
unless in a state of disease, is maintained by the influence of light
and the hours of repose, during which the equilibrium is restored,
are absolutely necessary to the continuance of health.

Instead of a few chemical compounds of gold and silver,
which at first were alone supposed to be photographic,
we are now aware that copper, platinum, lead, nikel, and indeed,
probably all the elements, are equally liably to change under
the sun's influence. This fact may be of benefit to engravers,
for if steel can be made to take photographic impressions,
the more laborious process of etching may be dispensed with.
In fact, in the latter part of this work, a process is described
for etching and taking printed impressions from Daguerreotype plates.
As yet this process has produced no decided beneficial results--
but future experiments may accomplish some practical discovery
of intrinsic value to the art of engraving.

A very simple experiment will prove how essential light is to the coloring
of the various species comprising the vegetable and animal kingdoms.
If we transplant any shrub from the light of day into a dark cellar,
we will soon see it lose its bright green color, and become perfectly white.

Another effect of light is that it appears to impart to bodies some power
by which they more readily enter into chemical combination with others.
We have already said that chlorine and hydrogen, if kept in the dark, will
remain unaltered; but if the chlorine alone be previously exposed to the sun,
the chlorine thus solarised will unite with the hydrogen in the dark.
Sulphate of iron will throw down gold or silver from their solutions slowly
in the dark; but if either solution be first exposed to sunshine, and the
mixture be then made, in the dark, the precipitation takes place instantly.
Here is again, evidence of either an absorption of some material agent from
the sunbeam, or an alteration in the chemical constitution of the body.
It was from understanding these principles and applying them that philosophers
were enabled to produce the Calotype, Daguerreotype, &c. For the effects
and action of light on the camera, see Chapter V.

Some advances have been made towards producing Photographic
impressions in color--the impossibility of which some of our
best and oldest artists have most pertinaciously maintained.
The colored image of the spectrum has been most faithfully copied,
ray for ray, on paper spread with the juice of the Cochorus Japonica,
(a species of plant) and the fluoride of silver;
and on silver plate covered with a thin film of chloride.
The day may be still remote when this much to be desired
decideratum shall be accomplished in portrait taking;
but I am led to hope that future experiments may master
the secret which now causes it to be looked upon, by many,
as an impossibility.

That great advantages have resulted, and that greater still will
result from the discovery of the Photographic art, few will deny.
The faithful manner in which it copies nature, even to the most
minute details, renders it of much value to the painter; but a few minutes
sufficing to take a view that formerly would have occupied several days.
Its superiority in portraits, over miniature or oil painting has been
tacitly acknowledged by the thousands who employ it to secure their own,
or a friends likeness, and by the steady increase in the number of
artists who are weekly, aye daily springing up in every town and village
in the land.

CHAP. III.

SYNOPSIS OF MR. HUNT'S TREATISE ON "THE INFLUENCE OF THE
SOLAR RAYS ON COMPOUND BODIES, WITH ESPECIAL REFERENCE TO
THEIR PHOTOGRAPHIC APPLICATION."

OXIDE OF SILVER exposed for a few hours to good sunshine,
passes into a more decided olive color, than characterises it
when first prepared by precipitation from nitrate of silver.
Longer exposure renders this color very much lighter,
and the covered parts, are found much darker, than those on which
the light has acted directly. In some instances where the oxide
of silver has been spread on the paper a decided whitening
process in some parts, after a few days exposure, is noticed.
Oxide of silver disolved in ammonia is a valuable photographic fluid;
one application of a strong solution forming an exceedingly
sensitive surface. The pictures on this paper are easily fixed
by salt or weak ammonia.

NITRATE OF SILVER.--This salt in a state of purity, does not appear
to be sensibly affected by light, but the presence of the smallest
portion of organic matter renders it exceedingly liable to change
under luminous influence.

If a piece of nitrated paper is placed upon hot iron,
or held near the fire, it will be found that at a heat just
below that at which the paper chars, the salt is decomposed.
Where the heat is greatest, the silver is revived,
and immediately around it, the paper becomes a deep blue;
beyond this a pretty decided green color results,
and beyond the green, a yellow or yellow brown stain is made.
This exhibits a remarkable analogy between heat and light,--
before spoken of in chap. II--and is of some practical
importance in the preparation of the paper.

PRISMATIC ANALYSIS.--The method of accomplishing the prismatic decomposition
of rays of light by the spectrum has already been described on pages 22
and 23. The color of the impressed spectrum, on paper washed with nitrate
of silver, is at first, a pale brown, which passes slowly into a deeper shade;
that portion corresponding with the blue rays becoming a blue brown;
and under the violet of a peculiar pinkey shade, a very decided green tint,
on the point which corresponds with the least refrangible blue rays,
may be observed, its limits of action being near the centre of the yellow ray,
and its maximum about the centre of the blue, although the action up to
the edge of the violet ray is continued with very little diminution of effect;
beyond this point the action is very feeble.

When the spectrum is made to act on paper which has been
previously darkened, by exposure to sunshine under cupro-sulphate
of ammonia, the phenomena are materially different.
The photographic spectrum is lengthened out on the red or negative
side by a faint but very visible red portion, which extends
fully up to the end of the red rays, as seen by the naked eye.
The tint of the general spectrum, too, instead of brown is
dark grey, passing, however, at its most refracted or positive
end into a ruddy brown.

In its Photographic application, the nitrate of silver is the most valuable
of the salts of that metal, as from it most of the other argentine compounds
can be prepared, although it is not of itself sufficiently sensible to light
to render it of much use.

CHLORIDE OF SILVER.--This salt of silver, whether in its
precipitated state, or when fused, changes its color to a fine
bluish grey by a very short exposure to the sun's rays.
If combined with a small quantity of nitrate, the change is
more rapid, it attains a deep brown, then slowly passes into
a fine olive, and eventually, after a few weeks, the metalic
silver is seen to be revived on the surface of the salt.
Great differences of color are produced on chlorides of silver
precipitated by different muriates. Nearly every variety
in combination with the nitrate, becomes at last of the same
olive color, the following examples, therefore, have reference
to a few minutes exposure, only, to good sunshine; it must
also be recollected that the chloride of silver in these cases
is contaminated with the precipitant.

Muriate of ammonia precipitates chloride to darken to a fine
chocolate brown, whilst muriate of lime produces a brick-red color.
Muriates of potash and soda afford a precipitate, which darkens
speedly to a pure dark brown, and muriatic acid, or aqueous chlorine,
do not appear to increase the darkening power beyond the lilac
to which the pure chloride of silver changes by exposure.
This difference of color appears to be owing to the admixture
of the earth or alkali used with the silver salt.

The prismatic impression on paper spread with the chloride of
silver is often very beautifully tinted, the intensity of color
varying with the kind of muriate used. Spread paper with muriate
of ammonia or baryta and you obtain a range of colors nearly
corresponding with the natural hues of the prismatic spectrum.
Under favorable circumstances the mean red ray, leaves a red impression,
which passes into a green over the space occupied by the yellow rays.
Above this a leaden hue is observed, and about the mean blue ray,
where the action is greatest, it rapidly passes through brown
into black, and through the most refrangible rays it gradually
declines into a bluish brown, which tint is continued throughout
the invisible rays. At the least refrangible end of the spectrum,
the very remarkable phenomenon has been observed, of the extreme red
rays exerting a protecting influence, and preserving the paper from
that change, which it would otherwise undergo, under the influence
of the dispersed light which always surrounds the spectrum.
Not only the extreme red ray exerts this very peculiar property,
but the ordinary red ray through nearly its whole length.

In photographic drawing this salt is of the utmost importance.
Mr. Talbot's application of it will be given hereafter in another
portion of this work.

IODIDE OF SILVER--Perfectly pure, undergoes very little change
under the influence of light or heat; but if a very slight
excess of the nitrate of silver be added it becomes infinitely
more senitive than the chloride

The spectrum impressed upon paper prepared with a weak solution of
the hydriodate of potash presents some very remarkable peculiarities.
The maximum of intensity is found at the edge of the most refrangible
violet rays, or a little beyond it, varying slightly according to the kind
of paper used, and the quantity of free nitrate of silver present.
The action commences at a point nearly coincident with the mean red
of the luminous spectrum, where it gives a dull ash or lead color,
while the most refrangible rays impress a ruddy snuff-brown,
the change of tint coming on rather suddenly about the end of
the blue or beginning of the violet rays of the luminous spectrum.
Beyond the extreme violet rays, the action rapidly diminishes,
but the darkening produced by these invisible rays, extends a
very small space beyond the point at which they cease to act on
the chloride of silver.

In its photographic application, it is, alone, of very little use;
but in combination with other reagents it becomes exquisitely sensitive.
With gallic acid and the ferrocyanate of potash it forms two of the most
sensitive photographic solutions with which we are acquainted.
These are used in the calotype process.

IODURET OF SILVER.--If upon a plate of polished silver we place
a small piece of iodine, and apply the heat of a lamp beneath
the plate for a moment, a system of rings is speedily formed.
The first ring, which spreading constantly forms the exterior
of the circle, is of a bright yellow color; within this,
there arises, sucessively, rings of green, red and blue colors,
and then again a fine yellow circle, centred by a greyish spot
on the place occupied by the iodine. On exposing these to the light,
the outer yellow circle almost instantly changes color,
the others slowly, in the order of their position, the interior
yellow circle resisting for a long time the solar influence.
These rings must be regarded as films of the ioduret of silver,
varying, not only in thickness, but in the more or less perfect
states of combination in which the iodine and metal are.
The exterior circle is an ioduret in a very loose state
of chemical agregation; the attractive forces increase as we
proceed towards the centre, where a well formed ioduret,
or probably a true iodide of silver, is formed, which is acted
upon by sunlight with difficulty. The exterior and most
sensitive film constitutes the surface of Daguerreotype plates.
The changes which these colored rings undergo are remarkable;
by a few minutes exposure to sunlight, an inversion of nearly
all the colors takes place, the two first rings becoming a deep
olive green; and a deep blue inclining to black.

The nature of the change which the ioduret of silver undergoes
on Daguerreotype plates, through the action of light,
Mr. Hunt considers to be a decided case of decomposition,
and cites several circumstances in proof of his position.
These with other facts given by Mr. Hunt in his great work
on the Photographic art, but to volumnious to include in a
volume of the size to which I am obliged to cofine myself,
should be thoroughly studied by all Daguerreotypists.

PRISMATIC ANALYSIS.--The most refrangible portion of the spectrum,
(on a Daguerreotype plate) appears, after the plate has been
exposed to the vapor of mercury, to have impressed its colors;
the light and delicate film of mercury, which covers that portion,
assuming a fine blue tint about the central parts, which are
gradually shaded off into a pale grey; and this is again surrounded
by a very delicate rose hue, which is lost in a band of pure white.
Beyond this a protecting influence is powerfully exerted;
and notwithstanding the action of the dispersed light,
which is very evident over the plate, a line is left,
perfectly free from mercurial vapor, and which, consequently,
when viewed by a side light, appears quite dark.
The green rays are represented by a line of a corresponding tint,
considerably less in size than the luminous green rays.
The yellow rays appear to be without action, or to act negatively,
the space upon which they fall being protected from the
mercurial vapor; and it consequently is seen as a dark band.
A white line of vapor marks the place of the orange rays.
The red rays effect the sensitive surface in a peculiar manner;
and we have the mercurial vapor, assuming a molecular arrangement
which gives to it a fine rose hue; this tint is surrounded by a
line of white vapor, shaded at the lowest extremity with a very
soft green. Over the space occupied by the extreme red rays,
a protecting influence is again exerted; the space is retained
free from mercurial vapor and the band is found to surround
the whole of the least refrangible rays, and to unite itself
with the band which surrounds the rays of greatest refrangibility.
This band is not equally well defined throughout its whole extent.
It is most evident from the extreme red to the green;
it fades in passing through the blue, and increases again,
as it leaves the indigo, until beyond the invisible chemical
rays it is nearly as strong as it is at the calorific end
of the spectrum.

Images on Daguerreotype plates which have been completely obliterated
by rubbing may be restored, by placing it in a tolerably strong solution
of iodine in water.

BROMIDE OF SILVER.--This salt, like the iodide, does not appear to be readily
changed by the action of light; but when combined with the nitrate of silver
it forms a very sensitive photographic preparation.

Paper prepared with this salt, blackens over its whole extent with nearly
equal intensity, when submitted to the prismatic spectrum. The most
characteristic peculiarity of the spectrum is its extravagant length.
Instead of terminating at the mean yellow ray, the darkened portion
extends down to the very extremity of the visible red rays.
In tint it is pretty uniformly of a grey-black over its whole extent,
except that a slight fringe of redness is perceptible at the least
refracted end. Beyond the red ray, an extended space is protected
from the agency of the dispersed light, and its whiteness maintained;
thus confirming the evidence of some chemical power in action,
over a space beyond the luminous spectrum, which corresponds with
the rays of the least refrangibility.

This salt is extensively used in photographic drawing.

PREPARATIONS OF GOLD.--Chloride of Gold, freed from an excess
of acid is slowly changed under the action of light;
a regularly increasing darkness taking place until it
becomes purple, the first action of the light being to whiten
the paper, which, if removed from the light at this stage,
will gradually darken and eventually develope the picture.
This process may be quickened by placing the paper in cold water.

Chloride of gold with nitrate of silver gives a precipitate of a yellow
brown color. Paper impregnated with the acetate of lead, when washed
with perfectly neutral chloride of gold, acquires a brownish-yellow hue.
The first impression of light seems rather to whiten than darken the paper,
by discharging the original color, and substituting for it a pale
greyish tint, which by slow degrees increases to a dark slate color;
but if arrested, while yet, not more than a moderate ash grey, and held
in a current of steam, the color of the parts acted upon by light--
and of that only--darkens immediately to a deep purple.

Here I must leave the subject of the action of light upon metalic compounds--
referring to Mr. Hunts work for any further information the student may
desire on the other metals--as I find myself going beyond my limits.
I cannot, however, entirely dismiss the subject without giving a few examples
of the action of light on the juices of plants, some of which produce
very good photographic effect.

CORCHORUS JAPONICA--The juice of the flowers of this plant
impart a fine yellow color to paper, and, so far as ascertained,
is the most sensitive of any vegetable preparation;
but owing to its continuing to change color even in the dark,
photographic images taken on paper prepared with it soon fade out.

WALL FLOWER.--This flower yields a juice, when expressed
with alcohol, from which subsides, on standing, a bright
yellow finely divided faecula, leaving a greenish-yellow
transparent liquid, only slightly colored supernatant.
The faecula spreads well on paper, and is very sensitive to light,
but appears at the same time to undergo a sort of chromatic analysis,
and to comport itself as if composed of two very distinct
coloring principles, very differently affected. The one on
which the intensity and sub-orange tint of the color depends,
is speedily destroyed, but the paper is not thereby fully whitened.
A paler yellow remains as a residual tint, and this on
continued exposure to the light, slowly darkens to brown.
Exposed to the spectrum, the paper is first reduced nearly
to whiteness in the region of the blue and violet rays.
More slowly, an insulated solar image is whitened in the less
refrangible portion of the red. Continue the exposure,
and a brown impression begins to be percieved in the midst
of the white streak, which darkens slowly over the region
between the lower blue and extreme violet rays.

THE RED POPPY yields a very beautiful red color, which is entirely
destroyed by light. When perfectly dried on paper the color becomes blue.
This blue color is speedily discharged by exposure to the sun's rays,
and papers prepared with it afford very interesting photographs.--
Future experiments will undoubtedly more fully develope the photogenic
properties of flowers, and practically apply them.

Certain precautions are necessary in extracting the coloring matter
of flowers. The petals of fresh flowers, carefully selected,
are crushed to a pulp in a mortar, either alone or with the addition
of a litte 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.
If alcohol be not added, it must be applied immediately,
as the air changes or destroys the color instantly.

Most flowers give out their coloring matter to alcohol or water--
but the former is found to weaken, and in some cases to discharge
altogether these colors; but they are in most cases restored in drying.
Paper tinged with vegetable colors must be kept perfectly dry
and in darkness.

To secure an eveness of tint on paper it should be first moistened on
the back by sponging, and blotting off with bibulous paper. It should then
be pinned on a board, the moist side downwards, so that two of its edges--
the right and lower ones--project a little over those of the board.
Incline the board twenty or thirty degrees to the horizon,
and apply the tincture with a brush in strokes from right to left,
taking care not to go over the edges which rests on the board,
but to pass clearly over those that project; and also observing
to carry the tint from below upwards by quick sweeping strokes,
leaving no dry spaces between them. Cross these with other strokes
from above downwards, leaving no floating liquid on the paper.
Dry as quickly as possible, avoiding, however, such heat as may
injure the tint

CHAP. IV.

A FEW HINTS AND SUGGESTIONS TO DAGUERREOTYPISTS.

There are very few who may not be capable of practising the Photographic art,
either on paper, or metalic plates--but, like all other professions,
some are more clever in its various processes than others.

Impatience is a great drawback to perfect success,
and combined with laziness is a decided enemy. Besides this,
no one can excel in Photography who does not possess a natural
taste for the fine arts, who is not quick in discerning grace
and beauty--is regardless of the principles of perspective,
foreshorting and other rules of drawing, and who sets about
it merely for the sake of gain--without the least ambition
to rise to the first rank, both in its practice and theory.
There is no profession or trade in which a slovenly manner
will not show itself, and none where its effects will be more
apparent than this.

In order to be great in any pursuit, we must be ourselves,
and keep all things, in order. In your show and reception rooms,
let neatness prevail; have your specimens so placed--
leaning slightly forward--as to obtain the strongest light
upon them, and at the same time prevent that glassiness
of apearance which detracts so materially from the effect they
are intended to produce. If possible, let the light be of a
north-western aspect, mellowed by curtains of a semitransparent hue.
Your show-cases, at the door, should be kept well cleaned.
I have often been disgusted while attempting to examine portraits
in the cases of our artists, at the greasy coating and marks
of dirty fingers upon the glass and frame enclosing them.
Believe it, many a good customer is lost for no other reason.

In your operating room, dust should be carefully excluded.
It should be furnished with nothing apt to collect and retain dust;
a carpet is therefore not only a useless article, but very improper.
A bare floor is to be prefered; but if you must cover it use matting.
There is no place about your establishment where greater
care should be taken to have order and cleanliness; for it
will prevent many failures often attributed to other causes.
"A place for every thing, and every thing in its place," should be
an absolute maxim with all artists. Do not oblige the ladies,
on going away from your rooms, to say--"That H. is a slovenly man;
see how my dress is ruined by sitting down in a chair that looked
as if it had just come out of a porter house kitchen and had not
been cleaned for six months."

In choosing your operating room, obtain one with a north-western aspect,
if possible; and either with, or capable of having attached,
a large skylight. Good pictures may be taken without the sky-light,
but not the most pleasing or effective.

A very important point to be observed, is to keep the camera perfectly
free from dust. The operator should be careful to see that the slightest
particle be removed, for the act of inserting the plate-holder will set
it in motion, if left, and cause those little black spots on the plate,
by which an otherwise good picture is spoiled. The camera should be
so placed as to prevent the sun shining into the lenses.

In taking portraits, the conformation of the sitter should be minutely
studied to enable you to place her or him in a position the most
graceful and easy to be obtained. The eyes should be fixed on some
object a little above the camera, and to one side--but never into,
or on the instrument, as some direct; the latter generally gives
a fixed, silly, staring, scowling or painful expression to the face.
Care should also be taken, that the hands and feet, in whatever position,
are not too forward or back ward from the face when that is in good focus

If any large surface of white is present, such as the shirt front,
or lady's handkerchief, a piece of dark cloth (a temporary bosom
of nankeen is best,) may be put over it, but quickly withdrawn
when the process is about two thirds finished.

A very pleasing effect is given to portraits, by introducing,
behind the sitter, an engraving or other picture--if a painting,
avoid those in which warm and glowing tints predominate.
The subject of these pictures may be applicable to the taste
or occupation of the person whose portrait you are taking.
This adds much to the interest of the picture, which is otherwise
frequently dull, cold and inanimate.

Mr. J. H. Whitehurst of Richmond, Va., has introduced a revolving
background, which is set in motion during the operation, and produces
a distinctness and boldness in the image not otherwise to be obtained.
The effect upon the background of the plate is equally pleasing;
it having the appearance of a beautifully clouded sky.

In practising Photographic drawing on paper, the student
must bear in mind that it is positively essential, to secure
success in the various processes, to use the utmost precaution
in spreading the solutions, and washes from the combination
of which the sensitive surfaces result. The same brush should
always be used for the same solution, and never used for any other,
and always washed in clean water after having been employed.
Any metalic mounting on the brushes should be avoided,
as the metal precipitates the silver from its solution.
The brushes should be made of camels or badger's hair and sufficiently
broad and large to cover the paper in two or three sweeps;
for if small ones be employed, many strokes must be given,
which leave corresponding streaks that will become visible
when submitted to light, and spoil the picture.

These few preliminary hints and suggestions, will, I trust,
be of some service to all who adopt this pleasing art as a profession;
and will, with a due attention to the directions given in the practical
working of the Daguerreotype, Calotype, etc., ensure a corresponding
measure of success.

CHAP. V.

DAGUERREOTYPE APPARATUS.

The entire Daguerreotype process is comprised in seven
distinct operations; viz:

1.--Cleaning and polishing the plate.

2.--Applying the sensitive coating.

3--Submitting the plate to the action of light in the camera.

4.--Bringing out the picture; in other words rendering it visible.

5.--Fixing the image, or making it perminent--so that the light
may no longer act upon it.

6.--Gilding: or covering the picture with a thin film of gold--
which not only protects it, but greatly improves its distinctness
and tone of color.

7.--Coloring the picture.

For these various operations the following articles--
which make up the entire apparatus of a Daguerrean artist--
must be procured

1.--THE CAMERA.--(Fig. 5.). The Camera Obscura of the Italian
philosophers, although highly appreciated, on account of the magical
character of the pictures it produced, remained little other
than a scientific toy, until the discovery of M. Daguerre.
The value of this instrument is now great, and the interest of
the process which it so essentially aids, universally admitted.
A full description of it will therefore be interesting.
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The camera is a dark box (a), having a tube with lenses (b) placed
in one end of it, through which the radiations from external
objects pass, and form a diminished picture upon the ground glass
(g) placed at the proper distance in the box to receive it;
the cap c covering the lenses at b until the plate is ready
to receive the image of the object to be copied.

Thus a (fig. 6.) representing the lens, and b the object desired to
be represented, the rays (c, c) proceeding from it fall upon the lens,
and are transmitted to a point, which varies with the curvature of
the glass, where an inverted image (d) of b is very accurately formed.
At this point, termed the focus, the sensitive photographic material
is placed for the purpose of obtaining the required picture.

The great disideratum in a photographic camera is perfect lenses.
They should be achromatic, and the utmost
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transparency should be obtained; and under the closest
inspection of the glass not the slightest wavy appearance,
or dark spot should be detected; and a curvature which as much
as possible prevents spherical aberration should be secured.
The effect produced by this last defect is a convergence
of perpendiculars, as for instance; two towers of any building,
would be represented as leaning towards each other; and in a
portrait the features would seem contracted, distorted and
mingled together, so as to throw the picture out of drawing
and make it look more like a caricature than a likeness.
If the lens be not achromatic, a chromatic aberration takes place,
which produces an indistinct, hazy appearance around the edges
of the picture, arising from the blending of the rays.

The diameter and focal length of a lens must depend in a great measure
on the distance of the object, and also on the superficies of the plate
or paper to be covered. For portraits one of 1 1/2 inches diameter,
and from 4 1/2 to 5 1/2 inches focus may be used; but for distant views,
one from 2 inches to 3 inches diameter, and from 8 to 12 inches focal
length will answer much better. For single lenses, the aperture
in front should be placed at a distance from it, corresponding to
the diameter, and of a size not more than one third of the same.
A variety of movable diaphrams or caps, to cover the aperture in front,
are very useful, as the intensity of the light may be modified by them
and more or less distinctness and clearness of delineation obtained.
These caps alway come with Voitlander instruments and should be secured
by the purchaser.

Though the single acromatic lens answers very well for copying engravings;
taking views from nature or art, for portraits the double should always
be used. The extensive manufacture of the most approved cameras,
both in Europe and in this country, obviates all necessity for any one
attempting to construct one for their own use. Lenses are now made so
perfect by some artisans that, what is called the "quick working camera"
will take a picture in one second, while the ordinary cameras require
from eight to sixty.

The camera in most general use is that manufactured by Voitlander and Son
of Germany. Their small size consists of two seperate acromatic lenses;
the first, or external one, has a free aperture of 1 1/2 inches; the second,
or internal, 1 5/8 inches; and both have the same focus, viz: 5 3/4 inches.
The larger size differs from the smaller. The inner lens is an achromatic
3 1/4 inches diameter, its focal length being 30 inches. The outer lens
is a meniscus--that is bounded by a concave and convex spherical surface
which meet--having a focal length of 18 inches. For every distant view,
the aperture in front is contracted by a diaphram to 1/8 of an inch.
By this means the light is reflected with considerable intensity and
the clearness and correctness of the pictures are truly surprising.

THE AMERICA instruments are constructed on the same principle
and many of them are equally perfect. Mr. Edward Anthony
of 205 Broadway, New York city, has constructed, and sold
cameras fully equal to the German and for which Voitlander
instruments have been refused in exchange by the purchaser.

The ordinary camera box (see fig. 5, a) varies in size
to suit the tube, and is termed medium, half, or whole.
Within the box is a slide to assist in regulating the focus,
and in enlarging or diminishing the picture. In one end of this
slide is a springed groove into which the ground-glass spectrum
(g fig. 5) is slid, for the purpose of more conveniently arranging
the focus. After the plate is prepared it is placed in the holder--
partly seen at e, fig. 5, and covered with the dark slide f, fig. 5;
the spectrum is then withdrawn and the holder takes its place,
and the lids d, d, are closed after removing the dark slide f.
The plate is now ready to receive the image, and the cap c
may be removed to admit the light into the box.

A camera constructed by Voitlander is thus described by Mr. Fisher.
"It is made entirely of brass, so that variations of climate has
no effect upon it. It is very portable and when packed in its box,
with all the necessary apparatus and materials for practising
the Daguerreotype art, occupies but very little space.
It is not, however, well adapted for the Calotype process."

"The brass foot A (fig. 7.), is placed on a table, or other firm support,
and the pillar B. screwed into it; the body of the camera, C, C is laid
into the double forked bearing D. D. The instrument is now properly
adjusted by means of the set screws, e, e, e, in the brass foot,
or it may be raised, lowered, or moved, by the telescope stand,
and when correct, fixed by the screw b. The landscape to be delineated
is viewed either through the
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small lens, g, or with the naked eye on the ground glass plate H,
the focus being adjusted by the screw I. The optical part of the instrument
consist of the small set of achromatic lenses already described.
When the portrait or view is deleniated on the ground glass
to the entire satisfaction of the operator, the brass cap L is
placed over the lens, and the entire body is removed away into
the dark, taking care not to disturb the position of the stand.
The body is now detached at the part H, and the prepared paper
or plate enclosed in the brass frame work introduced in its place;
the whole is again placed upon the pedestal, the brass cap L is removed,
by which the paper or plate is exposed to the full influence
of the light, after which the cap is again replaced.

Mr. Woodbridge, of this city, has constructed an instrument for taking full
length portraits on plates 10 by 13 inches, which is worthy of some notice.
It is a double camera, consisting of two boxes, placed in a frame,
one above the other, and so arranged as to slide easily up and down.
After the focus has been adjusted, on the object, in both cameras,
the plate is put into the upper box, in the manner already described,
until the superior portion of the figure is complete; it is then
placed in the second box and the lower extremities obtained.
The adjustment of the instrument is so complete that
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a perfect union of the parts is effected in the picture without the least
possible line of demarkation being visible. Fig. 8 gives a front view
of this instrument.

Fig. 9 represents Talbot's Calotype Camera,--a very beautiful instrument.

The copying camera box has an extra slide in the back end,
by which it may be considerably lengthened at pleasure.

II.--CAMERA STAND.--The best constructed stands are made
of maple or blackwallnut wood, having a cast iron socket
(a, fig. 12,) through which the sliding rod b passes, and into
which the legs c, c, with iron screw ferules are inserted.
The platform d is made of two pieces, hinged together,
as at e, and having a thumb screw for the purpose of elevating
or depressing the instrument.
[hipho_9.gif]

III. MERCURY BATH.--Fig. 13 gives a front view of the mercury bath
now in general use in this country for mercurializing and bringing
out the picture. It is quite an improvement on those first used.
To make it more portable it is in three pieces, a b and c;
having a groove e on one side to receive the thermometre tube and scale
by which the proper degree of heating the mercury is ascertained.
Into the top are nicely fitted two or three iron frames, with shoulders,
for the plate to rest in, suitable for the different sizes of plates.
The bath is heated by means of a spirit lamp placed under it.
From two to four ounces of highly purified mercury are put into
the bath at a time.

IV. PLATE BLOCKS AND VICES.--There are several kinds of this article in use;
I shall describe the two best only.

Fig. 10 gives an idea of the improvement on the English hand block.
The top a is perfectly flat
[hipho_10.gif]
and smooth--a little smaller than the plate, so as to permit the latter
to project a very little all around--having at opposite angles c c
two clasps, one fixed the other moveable, but capable of being fastened
by the thumb screw d, so as to secure the plate tightly upon the block.
This block turns upon a swivle, b, which is attached to the table
by the screw c, This block is only used for holding the plate while
undergoing the first operation in cleaning.
[hipho_11.gif]

Fig. 11, shows the form of Lewis' newly patented plate vice,
which for durability, simplicity and utility is preferable to all others.
It consists of a simple platform and arm of cast iron, the former,
a, having a groove, d, in the centre for fixing the different sizes
of plate beds, e--and the latter supporting the leaves, e f.
On this vice which is secured to a table, or bench, the plate
receives its finishing polish with rouge, or prepared lampblack.
Mr. Lewis gives the following directions for its use. "As the cam
wears tighten it with the adjusting screw (g) so as to allow the lever
(f) to fall back into a horizontal position; the plate being in its
place at the time. Oil the wearing parts occasionally."

Some Daguerreotypists, however, use a foot lathe with buff wheels
of various forms; but this vice is sufficient for all ordinary purposes.

V. COATING BOXES.--The usual form for iodine and
[hipho_12.gif]
[hipho_13.gif]
bromine boxes is see, at figs. 14 and 15. They are far
superior to those in use with the English operators.
Each consists of a wooden box (a,) having firmly embeded within it
a stout glass jar (c), the edges of which are ground.
Over this is placed the sliding cover b, double the length
of the box, one half occupied by a piece of ground glass
(e), tightly pressed upon the glass pot by a spring (i) beneath
the cross bar g, and fits the pot so accurately that it
effectually prevents the escape of the vapor of the iodine,
bromine or other accelerating liquid contained therein.
The other half of the lid is cut through, shoulders being
left at the four angles for the different sizes of frames,
designed to recieve the plate while undergoing the coating process.
When the plate is put into the frame, the cover b is shoved
under the second lid h and when coated to the proper degree,
it resumes its former position and the plate is placed in the holder
of the camera box. To test the tightness of the box, light a piece
of paper, put it into the pot and cover it with the sliding lid.
The burning paper expels the air from the pot, and if it
be perfectly tight you may raise the whole box by the lid.

VI. GLASS FUNNELS.--Are a necessary article to the Daguerreotypist,
for filtering water, solutions, &c.
[hipho_14.gif]

VII. GILDING STAND.--For nervous persons the gilding stand is
a useful article. It is adjusted to a perfect level by thumb
screws placed in its base.

VIII. SPIRIT LAMPS.--The most useful and economical of those
made are the Britania, as they are less liable to break;
and the tube for the wick being fastened to the body by a screw
renders it less liable to get out of order or explode.
Glass is the cheapest, and for an amateur will do very well,
but for a professed artist the Britania should always be obtained.

IX. COLOR BOX.--These are generally found on sale at the shops,
and usually contain eight colors, four brushes and a gold cup.
The artist would, however, do well to obtain, all the colors mentioned
in the last chapter of this work, and be sure to get the very best,
as there are various qualities of the same color, particularly carmine,
which is very expensive, and the cupidity of some may induce them
to sell a poor article for the sake of larger profits.
[hipho_15.gif]

STILL.--Daguerreotypists should always use distilled water for solutions,
and washing the plate, as common water holds various substances in solution
which detract very materially from the excellence of a photograph,
and often gives much trouble, quite unaccountable to many.
For the purpose of distilling water the apparatus represented at Fig. 16
is both convenient and economical.

It may be either wholly of good stout tin, or of sheet iron tinned
on the inside, and may be used over a common fire, or on a stove.
A is the body, which may be made to hold from one to four gallons of water,
which is introduced at the opening b, which is then stopped by a cork.
The tube d connects the neck a of the still with the worm tub,
or refrigerator B, at e, which is kept filled with cold water by means
of the funnel c, and drawn off as fast as it becomes warm by the cock f.
The distilled water is condensed in the worm--and passes off at the cock b,
under which a bottle, or other vessel, should be placed to receive it.
The different joints are rendered tight by lute, or in its absence,
some stiff paste spread upon a piece of linen and wrapped around them
will answer very well; an addition of sealing wax over all will make
them doubly secure.
[hipho_16.gif]

HYGROMETER.--This is an instrument never to be found, I believe,
in the rooms of our operators, although it would be of much use to them,
for ascertaining the quantity of moisture floating about the room;
and as it is necessary to have the atmosphere as dry as possible to prevent
an undue absorption of this watery vapor by the iodine &c., and to
procure good pictures,--its detection becomes a matter of importance.
Mason's hygrometer, manufactured by Mr. Roach and sold by Mr. Anthony,
205 Broadway, New York is the best in use.

It consists of two thermometre tubes placed, side by side,
on a metalic scale, which is graduated equally to both tubes.
The bulb of one of these tubes communicates, by means of a
net-work of cotton, with a glass reservoir of water attached
to the back of the scale. Fig. 17 and 18 represent a front
and back view of this instrument.

Fig. 17 is the front view, showing the tubes with their respective scales;
the bulb b being covered with the network of cotton communicating with
the reservoir c fig. 18, at d.
[hipho_17.gif]
[hipho_18.gif]
The evaporation of the water from this bulb decreases the temperature
of the mercury in the tube b in proportion to the dryness of the atmosphere,
and the number of degrees the tube b indicates below that of the other,
shows the real state of the atmosphere in the room; for instance,
if b stands at forty and a at sixty-one the room is in a state
of extreme dryness, the difference of twenty-one degrees between
the thermometers--let a stand at any one point--gives this result.
If they do not differ, or there is only four or five degrees variation,
the atmosphere of the room is very moist and means should be taken
to expel the superfluous quantity.

HEAD RESTS.--The button head rest with chair back clip, A fig.
19--is much the best for travelling artists, as it can be taken apart,
into several pieces and closely packed; is easily and firmly
fixed to the back of a chair by the clamp and screw a and b,
and is readily adjusted to the head, as the buttons c, c and arms d,
d are movable.

Sometimes the button rest is fixed to a pole, which is screwed to the chair;
but this method is not so secure and solid as the clip and occupies more room
in packing. Both the pole and clip, are furnished in some cases with brass
band rests instead of the button; but the only recommendation these can
possibly possess in the eyes of any artist, is their cheapness.
[hipho_19.gif]

For a Daguerreotypist permanently located the independent iron head-rest,
B fig. 19, is the most preferable, principally on account of its solidity.
It is entirely of iron, is supported by a tripod a) of the same metal and can
be elevated by means of a rod (b) passing through the body of the tripod,
to a height sufficient for a person, standing, to rest against.

GALVANIC BATTERY.--This article is used for the purpose of giving
to imperfectly coated plates a thicker covering of silver.
The form of battery now most universally employed for electrotype,
and other galvanic purposes, is Smee's--Fig. 20. It consists
[hipho_20.gif]
of a piece of platinized silver, A, on the top of which is
fixed a beam of wood, B, to prevent contact with the silver.
A binding screw C is soldered on to the silver plate to connect
it with any desired object, by means of the copper wire, e.
A plate of amalgamated zinc, D, varying with the fancy of the operator
from one half to the entire width of the silver is placed on each side
of the wood. This is set into a glass vessel, P,--the extreme ends
of the wood resting upon its edge--on which the acid with which it
is charged has no effect. The jar is charged with sulphurid acid,
(common oil of vitriol) diluted in eight parts its bulk of water.
The zinc plates of the battery have been amalgamated with quicksilver,
and when the battery is set into the jar of acid there should be no
action percieved upon them when the poles F, G, are not in contact.
Should any action be percieved, it indicates imperfect amalgamation;
this can be easily remedied by pouring a little mercury upon them
immediately after removing them from the acid, taking care to get
none upon the centre plate A.

Directions for use.--A sheet of silver must be attached
to the wire connected with the centre plate A of the battery,
and placed in the silver solution--prepared as directed below.
The plate to be silvered is first cleaned with diluted sulphuric acid,
and then attached to the wire, G, proceeding from the zinc
plates D, D, and placed in the silver solution, opposite the silver
plate attached to the pole F, and about half an inch from it.
A slight effervescence will now be percieved from the battery,
and the silver will be deposited upon the Daguerreotype plate,
while at the same time a portion of the silver plate is dissolved.

To prepare the solution of silver.--Dissolve one ounce
of chloride of silver in a solution of two ounces of cyanide
of potassium, previously dissolved in one quart of water.
The oxide of silver may be used instead of the chloride.
This solution is put into a tumbler, or other vessel.
[hipho_21.gif]
[hipho_22.gif]

This battery with the necessary articles for using it may be obtained
of E. Anthony, 205 Broadway, New York city.

The other articles required by every operator may be simply enumerated, viz:

Stickng, or sealing paper.

A pair of pliers, or forceps.

Porcelain pans or dishes, for applying the hyposulphite of soda and washing
after the imagine is fixed, something in form like fig. 23.

A support for holding the plate while being washed, like fig. 24
[hipho_25.gif]

BUFF STICKS.--Fig. 25.--These are usually from one to three feet in length,
and about three inches wide--some think two and a half sufficient.
The underside, which is convex, is covered with a strip of finely
prepared buckskin, or velvet, well padded with cotton or tow.

All the articles enumerated in this chapter may be obtained,
of the very best quality and at the most reasonable rates,
of Mr. E. Anthony, 205, Broadway, New York.

CHAP. VI.

THE DAGUERREOTYPE PROCESS.

The process of taking Daguerreotype pictures differs very materially
from all others of the photographic art, inasmuch as the production
of the image is effected upon plates of copper coated with silver.
The silver employed should be as pure as possible; the thickness of the plate
is of little consequence, provided there be sufficient silver to bear
the cleaning and polishing--is free from copper spots, is susceptible
of a high polish, an exquisitely sensitive coating and a pleasing tone.
These qualities are possessed to an eminent degree by the French plates.

Having already enumerated the various processes--and the apparatus
necessary for the manipulation, I will here give a list of the
chemicals to be used, and then proceed to explain them more fully.
The requisite chemicals are--

NITRIC ACID, ROUGE,
DRY IODINE, MERCURY,
DRYING POWDER, HYPOSULPHITE OF SODA,
CYANIDE OF POTASSIUM, CHLORIDE OF GOLD; OR
ROTTENSTONE, HYPOSULPHITE OF GOLD.
TRIPOLI, CHLORIDE OF SILVER.
CHLORIDE OF IODINE, } their compounds, or other
BROMINE } accelerating mixtures.

FIRST OPERATION.--Cleaning and polishing the plate.--
For this purpose the operator will require the--

Plate Blocks,

Plate Vice

Spirit Lamp,

Polishing Buffs,

Nitric Acid, diluted in fifteen times its bulk of water

Galvanic Battery, to galvanize the plate, if it is too imperfect to be
used without, previous cleaning it, as directed in the last chapter.

Rottenstone,

Tripoli, which is too often dispensed with.

Rouge, or lampblack--the first being most preferable.
The English operators mix the two together.

Prepared cotton Wool, or Canton flannel. If the first is used,
it should be excluded from the dust, as it is not so easily
cleansed as the latter.

The plate is secured, with its silver side upward, to the block,
by the means described on page 58--having previously turned the edges
backward all around. The amount of cleaning a plate requires,
depends upon the state it is in. We will suppose one in the
worst condition; dirty, scratched, and full of mercury spots,
all of which imperfections are more or less to be encountered.
The mercury spots are to be removed by burning the plate.
To do this hold the plate over the flame of a spirit lamp,
more particularly under the mercury spots, until they,
assume a dull appearance, when the lamp is to be removed,
and the plate allowed to cool, after which it is attached
to the block.

Place the block upon the swivle, and hold it firmly with the left hand;
take a small knot or pellet of cotton, or, if you like it better,
a small piece of canton flannel--wet it with a little diluted nitric acid;
then sift some finely prepared rottenstone--Davie's,* if you can get it--
upon it, and rub it over the plate with a continual circular motion,
till all traces of the dirt and scratches are removed; then wipe off
the rottenstone with a clean piece of cotton, adopting, as before,
a slight circular motion, at the same time wiping the edges of the plate.
Even the back should not be neglected, but throughly cleansed from any
dirt or greasy film it may have received from handling.

* Sold by E. Anthony.

When this is thoroughly accomplished, mix a portion of your tripoli
with the dilute nitric acid, to the consistence of thick cream.
Then take a pellet of cotton and well polish the plate with this mixture,
in the same manner as with the rottenstone. Continue the process till,
on removing the tripoli with a clean pellet, the plate exhibits
a clear, smooth, bright surface, free from all spots, or scratches.
Any remains of the acid on the plate may be entirely removed By
sifting on it a little Drying powder, and then wiping it carefully
off with a fine camels hair brush, or duster. The finishing polish
is now to be given.

For this purpose the rouge--or a mixture of rouge and lamp-black, in
the proportion of one part of the former to seven of the latter--is used.
It should be kept either in a muslin bag, or wide mouth bottle,
over which a piece of muslin is tied--in fact, both the rottenstone
and tripoli should be preserved from the dust in the same manner.
With a little of this powder spread over the buff--described on page 53--
the plate recieves its final polish; the circular motion is changed
for a straight one across the plate, which, if intended for a portrait,
should be buffed the narrow way; but if, for a landscape or view of a house,
the length way of the plate.

The operation of cleaning the plate at first appears difficult
and tedious, and many have been deterred from attempting this
interesting art on that account; but, in reality, it is more
simple in practice than in description, and with a little
patience and observation, all difficulties are easily overcome.
Great care must be taken to keep the buff free from all
extraneous matter, and perfectly dry, and when not in use it
should be wrapped up in tissue paper, or placed in a tight box.

The plate should be buffed immediately before the sensitive
coating is given; particles of dust are thus effectually removed;
the temperature of the plate is also increased by the friction,
and the required tint more readily obtained.

SECOND OPERATION.--Applying the sensative coating.--The apparatus
and chemicals required, are an

Iodine box--see fig. 14 page 53.

Bromine box--similar to the iodine box but a trifle deeper.

Dry Iodine.

Bromine, or a compound of Bromine and Chloride of Iodine,
or other sensitive mixture.

Most of our best operators use the compound Bromine and
Chloride of Iodine. In the early days of the Daguerreotype,
Iodine alone was used in preparing the plate, and although
it still plays a very important part, other preparations,
called accelerating liquids, quickstuff, &c., are used,
and the discovery of which has alone ensured the application
of the Daguerreotype successfully to portrait taking--for
when first introduced among us it took from five to ten minutes
to produce a tolerable good view, while now but the fraction
of a minute is required to obtain an accurate likeness.

To iodize the plate perfectly it must be placed over the iodine vapor
immediately after buffing. Scatter from a sixteenth to the eighth
of an ounce of dry iodine over the bottom of your coating box,
and slightly cover it with cotton wool. The plate is then dropped
into the frame b, fig. 12, with its silvered surface downward,
and thrust under the lid h. The bright surface of the plate
is soon coated with a film of iodine of a fine yellow color;
it is then removed and placed over the accelerating solution.
It is not absolutely necessary to perform this operation
in the dark, although a bright light should be avoided.
Not so the next part of the process, viz; giving the plate its
extreme sensitiveness, or coating with the accelerating liquids.
In this great caution should be used to prevent the slightest
ray of light impringing directly on the plate, and in
examining the color reflected light should always be used.
A convient method of examining the plate, is to make a small hole
in the partition of the closet in which you coat, and cover it
with a piece of tissue paper; by quickly turning the plate so that
the paper is reflected upon it the color is very distinctly shown.
Most of our operators are not so particular in this respect
as they should be.

ACCELERATING LIQUID.--Of these there are several kinds, which differ
both in composition and action--some acting very quickly,
others giving a finer tone to the picture although they are
not so expeditious in there operations; or in other words,
not so sensitve to the action of light. These are adopted
by Daguerreotypists according to their tastes and predjudices.
They are all applied in the same way as the coating of iodine.
The following are the best.

Bromine water--This solution is much used in France, and, I shall
therefore give its preparation, and the method of using it,
in the words of M. Figeau. "Put into a bottle of pure water,
a large excess of bromine; shake the mixture well, and before using it,
let all the bromine be taken up. An ascertained quantity of this
saturated water is then diluted in a given quantity of distilled water,
which gives a solution of bromine that is always identical."
M. Figeau recommends one part of the saturated solution to thirty
parts its bulk of water; but M. Lesebour finds it more manageable
if diluted with forty times. In case pure distilled, or rain water
cannot be procured, a few drops of nitric acid--say six to the quart--
should be added to the common water.

Put into the bromine box a given quantity of this solution,
sufficient to well cover the bottom; the plate, having been
iodized to a deep yellow, is placed over it; the time
the plate should be exposed must be ascertained by making
a few trials; it averages from twelve to forty seconds.
When once ascertained, it is the same for any number of plates,
as the solution, which of course would become weaker and weaker,
is changed after every operation, the same quantity being
always put into the pot.

Chloride of Iodine.--This is prepared by introducing chlorine
gass into a glass vessel containing iodine; the iodine
is liquified, and the above named compound is the result.
Operators need not, however, be at the trouble and expense of
preparing it, as it can be obtained prefectly pure of Mr. Anthony,
205 Broadway, N. Y., as also all of the chemicals herein enumerated.
The compound is diluted with distilled water, and the plate submitted
to its action till it is of a rose color. Chloride of iodine alone,
is seldom if ever used now by American operators, as it does not
sufficiently come up to their locomotive principle of progression.
The next is also eschewed by the majority, although many of our
best artists use no other, on account of the very fine tone it
gives to pictures.

Bromide of Iodine.--This is a compound of bromine and chloride
of iodine. In mixing it, much depends upon the strength of
the ingredients; an equal portion of each being generally used.
Perhaps the best method of preparing it, is to make a solution in
alcohol of half an ounce of chloride of iodine, and add the bromine
drop by drop, until the mixture becomes of a dark red color;
then dilute with distilled water, till it assumes a bright yellow.
Put about half an ounce of this compound into the pot, and coat
over it to a violet color, change the solution when it becomes
too weak to produce the desired effect.

Another.--Mix half an ounce of bromine with one ounce of chloride
of iodine, add two quarts pure distilled water, shake it well and let
it stand for twelve hours then add twenty-five drops of muriatic acid,
and let it stand another twelve hours, occasionally shaking it up well.
Dilute six parts of this solution in sixteen of water. Coat over dry
iodine to a deep yellow, then over the sensitive to a deep rose color--
approaching purple--then back, over dry iodine from four to eight seconds.

Roach's Tripple Compound.--This is one of the very best
sensitive solutions, and is very popular among Daguerreotypists.
To use this, take one part in weight, say one drachm,
of the compound and dilute it with twelve of water; coat over
dry iodine to yellow, then over the compound to a rosy red.
The effect in the camera is quick, and produces a picture
of a fine white tone.

Gurney's Sensitive.--This is another preparation of bromine,
and gives a fine tone. To two parts of water add one of
the sensitive, and put just sufficient in the box to cover
the bottom, or enable you to coat in from eight to ten seconds.
Coat over dry iodine to a dark yellow, and over the quick
till you see a good change, then back over the dry iodine
from two to three seconds.

Bromide of Lime, or Dry Sensitive.--This is a compound but
recently introduced, and is becoming somewhat of it favorite,
owing principally to the slight trouble it gives in its preparation,
and the tone it imparts to the picture. To prepare it,
fill your jar about half or quarter full of dry slacked lime,
then drop into it bromine, till it becomes a bright orange red.
The plate is generally coated over this compound,
after the iodine coating to yellow, to a violet, or plum color;
but it will work well under any circumstances, the color being
of little consequence, if coated from thirty to ninety seconds,
according to its strength.

Mead's Accelerator.--I merely mention this as being in
the market, not knowing any thing in regard to its merits.

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