Scientific American Supplement, No. 415, December 15, 1883
by
Various
Part 1 out of 2
Produced by Produced by Josephine Paolucci, Don Kretz, Juliet Sutherland,
Charles Franks and the DP Team
[Illustration]
Scientific American Supplement No. 415
NEW YORK, DECEMBER 15, 1883
Scientific American Supplement. Vol. XVI, No. 415.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
TABLE OF CONTENTS.
I. CHEMISTRY AND METALLURGY.--Carbon in Steel.
Heat developed in Forging.
Recent Studies on the Constitution of Alkaloids.--Extract from
a lecture delivered before the Philadelphia College of Pharmacy.
--By SAML.P. SADTLER.
II. ENGINEERING AND MECHANICS.--Apparatus for Extracting
Starch from Potatoes.--With engraving.
A Simple Apparatus for describing Ellipses.--By Prof. E.J.
HALLOCK. 1 figure.
A Novel Propeller Engine.--With full description and numerous
engravings.--By Prof. MACCORD.
The New Russian Torpedo Boat, the Poti.--With engraving.
A New Steamer Propelled by Hydraulic Reaction--Figures showing
plan and side views of the steamer.
A New Form of Flexible Band Dynamometer.--By Prof. W.C.
UNWIN. 4 figures.
III. TECHNOLOGY.--Enlarging on Argentic Paper and Opals.--By
A. GOODALL.
The Manufacture and Characteristics of Photographic Lenses.
Improved Developers for Gelatine Plates.--By DR. EDER.
The Preparation of Lard for Use in Pharmacy.--By Prof. REDWOOD.
Anti-Corrosion Paint.
Manufacture of Charcoal in Kilns.--Different kilns used.
IV. ART, ARCHITECTURE, AND ARCHAEOLOGY.--The German
National Monument.--With two engravings of the statues of
Peace and War.
The Art Aspects of Modern Dress.
Artisans' Dwellings, Hornsey, London.--With engraving.
Discovery of Ancient Church In Jerusalem.
V. ELECTRICITY, HEAT. ETC.--See's Gas Stove.--With engraving.
Rectification of Alcohol by Electricity. 3 engravings showing
Apparatus for Hydrogenizing Impure Spirits. Electrolyzing
Apparatus, and Arrangement of the Siemens Machine.
VI. GEOLOGY.--On the Mineralogical Localities in and around New
York City.--By NELSON H. DARTON.
VII. NATURAL HISTORY.--The Zoological Society's Gardens, London.--With
full page engravings showing the new Reptile House, and the
Babiroussa family.
VIII. HORTICULTURE.--The Kauri Pine--Damarra Australis.--
With engraving.
How to Successfully Transplant Trees.
IX. MEDICINE, HYGIENE, ETC.--On the Treatment of Congestive
Headache.--By Dr. J.L. CORNING.
The Use of the Mullein Plant in the Treatment of Pulmonary
Consumption.--By Dr. J.B. QUINLAN.
Action of Mineral Waters and of Hot Water upon the Bile.
Vivisection.--Apparatus Used.--Full page of engravings.
Insanity from Alcohol.--Intemperance a fruitful as well as
inexhaustible source for the increase of insanity.--By Dr. A. BAER,
Berlin.
Plantain as a Styptic.--By J.W. COLCORD.
Danger from Flies.
* * * * *
THE GERMAN NATIONAL MONUMENT.--WAR AND PEACE.
In our SUPPLEMENT No. 412 we gave several engravings and a full
description of the colossal German National monument "Germania," lately
unveiled on the Niederwald slope of the Rhine. We now present, as
beautiful suggestions in art, engravings of the two statues, War and
Peace, which adorn the corners of the monumental facade. These figures
are about twenty feet high. The statue of War represents an allegorical
character, partly Mercury, partly mediaeval knight, with trumpet in one
hand, sword in the other. The statue of Peace represents a mild and
modest maiden, holding out an olive branch in one hand and the full horn
of peaceful blessings in the other. Between the two statues is a
magnificent group in relief representing the "Watch on the Rhine." Here
the Emperor William appears in the center, on horseback, surrounded by a
noble group of kings, princes, knights, warriors, commanders, and
statesmen, who, by word or deed or counsel, helped to found the
empire--an Elgin marble, so to speak, of the German nation.
[Illustration: WAR. THE GERMAN NATIONAL MONUMENT. PEACE.]
* * * * *
A writer in the London _Lancet_ ridicules a habit of being in great
haste and terribly pressed for time which is common among all classes of
commercial men, and argues that in most cases there is not the least
cause for it, and that it is done to convey a notion of the tremendous
volume of business which almost overwhelms the house. The writer further
says that, when developed into a confirmed habit, it is fertile in
provoking nervous maladies.
* * * * *
THE ART ASPECTS OF MODERN DRESS.
At a recent conversazione of the London Literary and Artistic Society,
Mr. Sellon read a paper upon this subject. Having expressed his belief
that mere considerations of health would never dethrone fashion, the
lecturer said he should endeavor to show on art principles how those who
were open to conviction could have all the variety Fashion promised,
together with far greater elegance than that goddess could bestow, while
health received the fullest attention. Two excellent societies, worthy
of encouragement up to a certain point, had been showing us the folly
and wickedness of fashionable dress--dress which deformed the body,
crippled the feet, confined the waist, exposed the chest, loaded the
limbs, and even enslaved the understanding. But these societies had been
more successful in pulling down than in building up, and blinded with
excess of zeal were hurrying us onward to a goal which might or might
not be the acme of sanitative dress, but was certainly the zero of
artistic excellence. The cause of this was not far to seek. We were
inventing a new science, that of dress, and were without rules to guide
us. So long as ladies had to choose between Paris fashions and those of
Piccadilly Hall, they would, he felt sure, choose the former. Let it be
shown that the substitute was both sanitary and beautiful, capable of an
infinite variety in color and in form--in colors and forms which never
violated art principle, and in which the wearer, and not some Paris
liner, could exercise her taste, and the day would have been gained.
This was the task he had set himself to formulate, and so doing he
should divide his subject in two--Color and Form.
In color it was desirable to distinguish carefully between the meaning
of shade, tint, and hue. It was amazing that a cultured nation like the
English should be so generally ignorant of the laws of color harmony. We
were nicely critical of music, yet in color were constantly committing
the gravest solecisms. He did not think there were seventeen interiors
in London that the educated eye could wander over without pain. Yet what
knowledge was so useful? We were not competent to buy a picture, choose
a dress, or furnish a house without a knowledge of color harmony, to say
nothing of the facility such knowledge gave in all kinds of painting on
porcelain, art needlework, and a hundred occupations.
An important consideration in choosing colors for dress was the effect
they would have in juxtaposition. Primary colors should be worn in dark
shades; dark red and dark yellow, or as it was commonly called, olive
green, went well together; but a dress of full red or yellow would be
painful to behold. The rule for full primaries was, employ them
sparingly, and contrast them only with black or gray. He might notice in
passing that when people dressed in gray or black the entire dress was
usually of the one color unrelieved. Yet here they had a background that
would lend beauty to any color placed upon it.
Another safe rule was never to place together colors differing widely in
hue. The eye experienced a difficulty in accommodating itself to sudden
changes, and a species of color discord was the consequence. But if the
colors, even though primaries, were of some very dark or very light
shade, they become harmonious. All very dark shades of color went well
with black and with each other, and all very light shades went well with
white and each other.
A much-vexed question with ladies was, "What will suit my complexion?"
The generally received opinion was that the complexion was pink, either
light or dark, and colors were chosen accordingly, working dire
confusion. But no one living ever had a pink complexion unless a painted
one. The dolls in the Lowther Arcade were pink, and their pink dresses
were in harmony. No natural complexion whatever was improved by pink;
but gray would go with any. The tendency of gray was to give prominence
to the dominant hue in the complexion. When an artist wished to produce
flesh color he mixed white, light red, yellow ocher, and terra vert. The
skin of a fair person was a gray light red, tinged with green; the color
that would brighten and intensify it most was a gray light sea green,
tinged with pink--in other words, its complementary. A color always
subtracted any similar color that might exist in combination near it.
Thus red beside orange altered it to yellow; blue beside pink altered it
to cerise. Hence, if a person was so unfortunate as to have a muddy
complexion, the worst color they could wear would be their own
complexion's complementary--the best would be mud color, for it would
clear their complexion.
Passing on to the consideration of form in costume, the lecturer urged
that the proper function of dress was to drape the human figure without
disguising or burlesquing it. An illustration of Miss Mary Anderson,
attired in a Greek dress as Parthenia, was exhibited, and the lecturer
observed that while the dress once worn by Greek women was unequaled for
elegance, Greek women were not in the habit of tying their skirts in
knots round the knees, and the nervous pose of the toes suggested a more
habitual acquaintance with shoes and stockings.
An enlargement from a drawing by Walter Crane was shown as illustrating
the principles of artistic and natural costume--costume which permitted
the waist to be the normal size, and allowed the drapery to fall in
natural folds--costume which knew nothing of pleats and flounces, stays
and "improvers"--costume which was very symbolization and embodiment of
womanly grace and modesty.
A life-sized enlargement of a fashion plate from _Myra's Journal_, dated
June 1, 1882, was next shown. The circumference of the waist was but 123/4
in., involving an utter exclusion of the liver from that part of the
organization, and the attitude was worthy of a costume which was the _ne
plus ultra_ of formal ugliness.
Having shown another and equally unbecoming costume, selected from a
recent issue by an Oxford Street firm, the lecturer asked, Why did women
think small waists beautiful? Was it because big-waisted women were so
frequently fat and forty, old and ugly? A young girl had no waist, and
did not need stays. As the figure matured the hips developed, and it was
this development which formed the waist. The slightest artificial
compression of the waist destroyed the line of beauty. Therefore, the
grown woman should never wear stays, and, since they tended to weaken
the muscles of the back, the aged and weak should not adopt them. A
waist really too large was less ungraceful than a waist too small. Dress
was designed partly for warmth and partly for adornment. As the uses
were distinct, the garments should be so. A close-fitting inner garment
should supply all requisite warmth, and the outer dress should be as
thin as possible, that it might drape itself into natural folds. Velvet,
from its texture, was ill adapted for this. When worn, it should be in
close fitting garments, and in dark colors only. It was most effective
when black.
Turning for a few moments, in conclusion, to men's attire, the lecturer
suggested that the ill-success of dress reformers hitherto had been the
too-radical changes they sought to introduce. We could be artistic
without being archaic. Most men were satisfied without clothes fairly in
fashion, a tolerable fit, and any unobtrusive color their tailor
pleased. He would suggest that any reformation should begin with color.
* * * * *
ARTISANS' DWELLINGS, HORNSEY.
The erection of artisans' dwellings is certainly a prominent feature in
the progress of building in the metropolis, and speculative builders who
work on a smaller scale would do well not to ignore the fact. The
Artisans, Laborers, and General Dwellings Company (Limited) has been
conspicuously successful in rearing large blocks of dwellings for
artisans, clerks, and others whose means necessitates the renting of a
convenient house at as low a rental as it is possible to find it. We
give an illustration of a terrace of first-class houses built by the
above company, who deserve great praise for the spirited and liberal
manner in which they are going to work on this the third of their London
estates--the Noel Park Estate, at Hornsey. On the estates at Shaftesbury
and Queen's Parks they have already built about three thousand houses,
employing therein a capital of considerably over a million sterling,
while at Noel Park they are rapidly covering an estate of one hundred
acres, which will contain, when completed, no less than two thousand six
hundred houses, to be let at weekly rentals varying from 6s. to 11s.
6d., rates and taxes all included. The object has been to provide
separate cottages, each in itself complete, and in so doing they have
not made any marked departure from the ordinary type of suburban terrace
plan, but adopting this as most favorable to economy, have added many
improvements, including sanitary appliances of the latest and most
approved type.
The most important entrance to Noel Park is by Gladstone Avenue, a road
60 ft. wide leading from the Green Lanes to the center of the estate. On
either side of this road the houses are set back 15 ft., in front of
which, along the edge of the pavement, trees of a suitable growth are
being planted, as also on all other roads on the estate. About the
center of Gladstone Avenue an oval space has been reserved as a site for
a church, and a space of five acres in another portion of the estate has
been set apart to be laid out as a recreation ground, should the
development of the estate warrant such an outlay. The remaining streets
are from 40 ft. to 50 ft. in width, clear of the garden space in front
of the houses. Shops will be erected as may be required.
[Illustration: SUGGESTIONS IN ARCHITECTURE.--A ROW OF COMFORTABLE
DWELLINGS.]
The drainage of the estate has been arranged on the dual system, the
surface water being kept separate from the sewage drains. Nowhere have
these drains been carried through the houses, but they are taken
directly into drains at the back, having specially ventilated manholes
and being brought through at the ends of terraces into the road sewers;
the ventilating openings in the roads have been converted into inlet
ventilators by placing upcast shafts at short intervals, discharging
above the houses. This system of ventilation was adopted on the
recommendation of Mr. W.A. De Pape, the engineer and surveyor to the
Tottenham Local Board.
All the houses are constructed with a layer of concrete over the whole
area of the site, and a portion of the garden at back. Every room is
specially ventilated, and all party walls are hollow in order to prevent
the passage of sound. A constant water supply is laid on, there being no
cisterns but those to the water-waste preventers to closets. All water
pipes discharge over open trapped gullies outside.
The materials used are red and yellow bricks, with terracotta sills, the
roofs being slated over the greater part, and for the purpose of forming
an agreeable relief, the end houses, and in some cases the central
houses, have red tile roofs, the roofs over porches being similarly
treated. The houses are simply but effectively designed, and the general
appearance of the finished portion of the estate is bright and cheerful.
All end houses of terraces have been specially treated, and in some
cases having rather more accommodation than houses immediately
adjoining, a slightly increased rental is required. There are five
different classes of houses. The first class houses (which we illustrate
this week) are built on plats having 16 ft. frontage by 85 ft. depth,
and containing eight rooms, consisting of two sitting rooms, kitchen,
scullery, with washing copper, coal cellar, larder, and water-closet on
ground floor, and four bedrooms over. The water-closet is entered from
the outside, but in many first-class houses another water-closet has
been provided on the first floor, and one room on this floor is provided
with a small range, so that if two families live in the one house they
will be entirely separated. The rental of these houses is about 11s. to
11s. 6d. per week. Mr. Rowland Plumbe, F.R.I.B.A., of 13 Fitzroy Square,
W., is the architect.--_Building and Engineering Times_.
* * * * *
ENLARGING ON ARGENTIC PAPER AND OPALS.
By A. GOODALL.
[Footnote: Read before the Dundee and East of Scotland Photographic
Association.]
The process of making gelatino bromide of silver prints or enlargements
on paper or opal has been before the public for two or three years now,
and cannot be called new; but still it is neither so well known nor
understood as such a facile and easy process deserves to be, and I may
just say here that after a pretty extensive experience in the working of
it I believe there is no other enlarging process capable of giving
better results than can be got by this process when properly understood
and wrought, as the results that can be got by it are certainly equal to
those obtainable by any other method, while the ease and rapidity with
which enlarged pictures can be made by it place it decidedly ahead of
any other method. I propose to show you how I make a gelatino bromide
enlargement on opal.
[Mr. Goodall then proceeded to make an enlargement on a 12 by 10 opal,
using a sciopticon burning paraffin; after an exposure for two and
a-half minutes the developer was applied, and a brilliant opal was the
result.]
We now come to the paper process, and most effective enlargements can be
made by it also; indeed, as a basis for coloring, nothing could well be
better. Artists all over the country have told me that after a few
trials they prefer it to anything else, while excellent and effective
plain enlargements are easily made by it if only carefully handled. A
very good enlargement is made by vignetting the picture, as I have just
done, with the opal, and then squeezing it down on a clean glass, and
afterward framing it with another glass in front, when it will have the
appearance almost equal to an opal. To make sure of the picture adhering
to the glass, however, and at the same time to give greater brilliancy,
it is better to flow the glass with a 10 or 15 grain solution of clear
gelatine before squeezing it down. The one fault or shortcoming of the
plain argentic paper is the dullness of the surface when dry, and this
certainly makes it unsuitable for small work, such as the rapid
production of cartes or proofs from negatives wanted in a hurry; the
tone of an argentic print is also spoken of sometimes as being
objectionable; but my impression is, that it is not so much the tone as
the want of brilliancy that is the fault there, and if once the public
were accustomed to the tones of argentine paper, they might possibly
like them twice as well as the purples and browns with which they are
familiar, provided they had the depth and gloss of a silver print; and
some time ago, acting on a suggestion made by the editor of the
_Photographic News_, I set about trying to produce this result by
enameling the paper with a barium emulsion previous to coating it with
the gelatinous bromide of silver. My experiments were successful, and we
now prepare an enamel argentic paper on which the prints stand out with
brilliancy equal to those on albumenized paper. I here show you
specimens of boudoirs and panels--pictures enlarged from
C.D.V.--negatives on this enamel argentic.
[Mr. Goodall then passed round several enlargements from landscape and
portrait negatives, which it would have been difficult to distinguish
from prints on double albumenized paper.]
I have already spoken of the great ease and facility with which an
argentic enlargement may be made as compared with a collodion transfer,
for instance; but there is another and more important point to be
considered between the two, and that is, their durability and
permanence. Now with regard to a collodion transfer, unless most
particular care be taken in the washing of it (and those who have made
them will well know what a delicate, not to say difficult, job it is to
get them thoroughly freed from the hypo, and at the same time preserve
the film intact), there is no permanence in a collodion transfer, and
that practically in nine cases out of ten they have the elements of
decay in them from the first day of their existence. I know, at least in
Glasgow, where an enormous business has been done within the last few
years by certain firms in the club picture trade (the club picture being
a collodion transfer tinted in oil or varnish colors), there are
literally thousands of pictures for which thirty shillings or more has
been paid, and of which the bare frame is all that remains at the
present day; the gilt of the frames has vanished, and the picture in
disgust, perhaps, has followed it. In short, I believe a collodion
transfer cannot be made even comparatively permanent, unless an amount
of care be taken in the making of it which is neither compatible nor
consistent with the popular price and extensive output. How now stands
the case with an argentic enlargement? Of course it may be said that
there is scarcely time yet to make a fair comparison--that the argentic
enlargements are still only on their trial.
I will give you my own experience. I mentioned at the outset that seven
or eight years ago I had tried Kennet's pellicle and failed, but got one
or two results which I retained as curiosities till only a month or two
ago; but up to that time I cannot say they had faded in the least, and I
have here a specimen made three years ago, which I have purposely
subjected to very severe treatment. It has been exposed without any
protection to the light and damp and all the other noxious influences of
a Glasgow atmosphere, and although certainly tarnished, I think you will
find that it has not faded; the whites are dirty, but the blacks have
lost nothing of their original strength. I here show you the picture
referred to, a 12 by 10 enlargement on artist's canvas, and may here
state, in short, that my whole experience of argentic enlargements leads
me to the conclusion that, setting aside every other quality, they are
the most permanent pictures that have ever been produced. Chromotypes
and other carbon pictures have been called permanent, but their
permanence depends upon the nature of the pigment employed, and
associated with the chromated gelatine in which they are produced, most
of pigments used, and all of the prettiest ones, being unable to
withstand the bleaching action of the light for more than a few weeks.
Carbon pictures are therefore only permanent according to the degree in
which the coloring matter employed is capable of resisting the
decolorizing action of light. But there is no pigment in an argentic
print, nothing but the silver reduced by the developer after the action
of light; and that has been shown by, I think, Captain Abney, to be of a
very stable and not easily decomposed nature; while if the pictures are
passed through a solution of alum after washing and fixing, the gelatine
also is so acted upon as to be rendered in a great degree impervious to
the action of damp, and the pictures are then somewhat similar to carbon
pictures without carbon.
I may now say a few words on the defects and failures sometimes met with
in working this process; and first in regard to the yellowing of the
whites. I hear frequent complaints of this want of purity in the whites,
especially in vignetted enlargements, and I believe that this almost
always arises from one or other of the two following causes:
First. An excess of the ferrous salt in the ferrous oxalate developer;
and when this is the case, the yellow compound salt is more in
suspension than solution, and in the course of development it is
deposited upon, and at the same time formed in, the gelatinous film.
The proportions of saturated solution of oxalate to saturated solution
of iron, to form the oxalate of iron developer, that has been
recommended by the highest and almost only scientific authority on the
subject--Dr. Eder--are from 4 to 6 parts of potassic oxalate to 1 part
of ferrous sulphate.
Now while these proportions may be the best for the development of a
negative, they are not, according to my experience, the best for
gelatine bromide positive enlargements; I find, indeed, that potassic
oxalate should not have more than one-eighth of the ferrous sulphate
solution added to it, otherwise it will not hold in proper solution for
any length of time the compound salt formed when the two are mixed.
The other cause is the fixing bath. This, for opals and vignetted
enlargements especially, should always be fresh and pretty strong, so
that the picture will clear rapidly before any deposit has time to take
place, as it will be observed that very shortly after even one iron
developed print has been fixed in it a deposit of some kind begins to
take place, so that although it may be used a number of times for fixing
prints that are meant to be colored afterward it is best to take a small
quantity of fresh hypo for every enlargement meant to be finished in
black and white. The proportions I use are 8 ounces to the pint of
water. Almost the only other complaints I now hear are traceable to
over-exposure or lack of intelligent cleanliness in the handling of the
paper. The operator, after having been dabbling for some time in hypo,
or pyro, or silver solution, gives his hands a wipe on the focusing
cloth, and straightway sets about making an enlargement, ending up by
blessing the manufacturer who sent him paper full of black stains and
smears. Argentic paper is capable of yielding excellent enlargements,
but it must be intelligently exposed, intelligently developed, and
cleanly and carefully handled.
* * * * *
THE MANUFACTURE AND CHARACTERISTICS OF PHOTOGRAPHIC LENSES.
At a recent meeting of the London and Provincial Photographic
Association Mr. J. Traill Taylor, formerly of New York, commenced his
lecture by referring to the functions of lenses, and by describing the
method by which the necessary curves were computed in order to obtain a
definite focal length. The varieties of optical glass were next
discussed, and specimens (both in the rough and partly shaped state)
were handed round for examination. The defects frequently met with in
glass, such as striae and tears, were then treated upon; specimens of
lenses defective from this cause were submitted to inspection, and the
mode of searching for such flaws described. Tools for grinding and
polishing lenses of various curvatures were exhibited, together with a
collection of glass disks obtained from the factory of Messrs. Ross &
Co., and in various stages of manufacture--from the first rough slab to
the surface of highest polish. Details of polishing and edging were gone
into, and a series of the various grades of emery used in the processes
was shown. The lecturer then, by means of diagrams which he placed upon
the blackboard, showed the forms of various makes of photographic
lenses, and explained the influence of particular constructions in
producing certain results; positive and negative spherical aberration,
and the manner in which they are made to balance each other, was also
described by the aid of diagrams, as was also chromatic aberration. He
next spoke of the question of optical center of lenses, and said that
that was not, as had been hitherto generally supposed, the true place
from which to measure the focus of a lens or combination. This place was
a point very near the optical center, and was known as the "Gauss"
point, from the name of the eminent German mathematician who had
investigated and made known its properties, the knowledge of which was
of the greatest importance in the construction of lenses. A diagram was
drawn to show the manner of ascertaining the two Gauss points of a
bi-convex lens, and a sheet exhibited in which the various kinds of
lenses with their optical centers and Gauss points were shown. For this
drawing he (Mr. Taylor) said he was indebted to Dr. Hugo Schroeder, now
with the firm of Ross & Co. The lecturer congratulated the
newly-proposed member of the Society, Mr. John Stuart, for his
enterprise in securing for this country a man of such profound
acquirements. The subject of distortion was next treated of, and the
manner in which the idea of a non distorting doublet could be evolved
from a single bi-convex lens by division into two plano-convex lenses
with a central diaphragm was shown. The influence of density of glass
was illustrated by a description of the doublet of Steinheil, the parent
of the large family of rapid doublets now known under various names. The
effect of thickness of lenses was shown by a diagram of the ingenious
method of Mr. F. Wenham, who had long ago by this means corrected
spherical aberration in microscopic objective. The construction of
portrait lenses was next gone into, the influence of the negative
element of the back lens being especially noted. A method was then
referred to of making a rapid portrait lens cover a very large angle by
pivoting at its optical center and traversing the plate in the manner of
the pantoscopic camera. The lecturer concluded by requesting a careful
examination of the valuable exhibits upon the table, kindly lent for the
occasion by Messrs. Ross & Co.
* * * * *
IMPROVED DEVELOPERS FOR GELATINE PLATES.
By Dr. Eder.
We are indebted to Chas. Ehrmann, Esq., for the improved formulas given
below as translated by him for the _Photographic Times_.
Dr. Eder has for a considerable time directed especial attention to the
soda and potash developers, either of which seems to offer certain
advantages over the ammoniacal pyrogallol. This advantage becomes
particularly apparent with emulsions prepared with ammonia, which
frequently show with ammoniacal developer green or red fog, or a fog of
clayish color by reflected, and of pale purple by transmitted light.
Ferrous oxalate works quite well with plates of that kind; so do soda
and potassa developers.
For soda developers, Eder uses a solution of 10 parts of pure
crystallized soda in 100 parts of water. For use, 100 c.c. of this
solution are mixed with 6 c.c. of a pyrogallic solution of 1:10, without
the addition of any bromide.
More pleasant to work with is Dr. Stolze's potassa developer. No. 1:
Water, 200 c.c.; chem. pure potassium carbonate, 90 gr.; sodium
sulphite, 25 gr. No. 2: Water 100 c.c.; citric, 11/2 gr.; sodium sulphite,
25 gr.; pyrogallol., 12 gr. Solution No. 2 is for its better keeping
qualities preferable to Dr. Stolze's solution.[A] The solutions when in
well stoppered bottles keep well for some time. To develop, mix 100 c.c.
of water with 40 min. of No. 1 and 50 min. of No. 2. The picture appears
quickly and more vigorously than with iron oxalate. If it is desirable
to decrease the density of the negatives, double the quantity of water.
The negatives have a greenish brown to olive-green tone. A very fine
grayish-black can be obtained by using a strong alum bath between
developing and fixing. The same bath after fixing does not act as
effectual in producing the desired tone. A bath of equal volumes of
saturated solutions of alum and ferrous sulphate gives the negative a
deep olive-brown color and an extraordinary intensity, which excludes
all possible necessities of an after intensification.
[Footnote A: 100 c.c. water; 10 c.c. alcohol; 10 gr. pyrogallol; 1 gr.
salicylic acid.]
The sensitiveness with this developer is at least equal to that when
iron developer is used, frequently even greater.
The addition of bromides is superfluous, sometimes injurious. Bromides
in quantities, as added to ammoniacal pyro, would reduce the
sensitiveness to 1/10 or 1/20; will even retard the developing power
almost entirely.
Must a restrainer be resorted to, 1 to 3 min. of a 1:10 solution of
potassium bromide is quite sufficient.
* * * * *
THE PREPARATION OF LARD FOR USE IN PHARMACY.
[Footnote: Read at an evening meeting of the Pharmaceutical Society of
Great Britain, November 7, 1883.]
By Professor REDWOOD.
I have read with much, interest the paper on "Ointment Bases,"
communicated by Mr. Willmott to the Pharmaceutical Conference at its
recent meeting, but the part of the subject which has more particularly
attracted my attention is that which relates to prepared lard. Reference
is made by Mr. Willmott to lard prepared in different ways, and it
appears from the results of his experiments that when made according to
the process of the British Pharmacopoeia it does not keep free from
rancidity for so long a time as some of the samples do which have been
otherwise prepared. The general tendency of the discussion, as far as
related to this part of the subject, seems to have been also in the same
direction; but neither in the paper nor in the discussion was the
question of the best mode of preparing lard for use in pharmacy so
specially referred to or fully discussed as I think it deserves to be.
When, in 1860, Mr. Hills, at a meeting of the Pharmaceutical Society,
suggested a process for the preparation of lard, which consisted in
removing from the "flare" all matter soluble in water, by first
thoroughly washing it in a stream of cold water after breaking up the
tissues and afterward melting and straining the fat at a moderate heat,
this method of operating seemed to be generally approved. It was adopted
by men largely engaged in "rendering" fatty substances for use in
pharmacy and for other purposes for which the fat was required to be as
free as possible from flavor and not unduly subject to become rancid. It
became the process of the British Pharmacopoeia in 1868. In 1869 it
formed the basis of a process, which was patented in Paris and this
country by Hippolite Mege, for the production of a fat free from taste
and odor, and suitable for dietetic use as a substitute for butter.
Mege's process consists in passing the fat between revolving rollers,
together with a stream of water, and then melting at "animal heat." This
process has been used abroad in the production of the fatty substance
called oleomargarine.
But while there have been advocates for this process, of whom I have
been one, opinions have been now and then expressed to the effect that
the washing of the flare before melting the fat was rather hurtful than
beneficial. I have reason to believe that this opinion has been gaining
ground among those who have carefully inquired into the properties of
the products obtained by the various methods which have been suggested
for obtaining animal fat in its greatest state of purity.
I have had occasion during the last two or three years to make many
experiments on the rendering and purification of animal fat, and at the
same time have been brought into communication with manufacturers of
oleomargarine on the large scale; the result of which experience has
been that I have lost faith in the efficacy of the Pharmacopeia process.
I have found that in the method now generally adopted by manufacturers
of oleomargarine, which is produced in immense quantities, the use of
water, for washing the fat before melting it, is not only omitted but
specially avoided. The parts of the process to which most importance is
attached are: First, the selection of fresh and perfectly sweet natural
fat, which is hung up and freely exposed to air and light. It thus
becomes dried and freed from an odor which is present in the freshly
slaughtered carcass. It is then carefully examined, and adhering
portions of flesh or membrane as far as possible removed; after which it
is cut up and passed through a machine in which it is mashed so as to
completely break up the membraneous vesicles in which the fat is
inclosed. The magma thus produced is put into a deep jacketed pan heated
by warm water, and the fat is melted at a temperature not exceeding
130 deg.F.
If the flare has been very effectually mashed, the fat may be easily
melted away from the membraneous matter at 120 deg.F., or even below that,
and no further continuance of the heat is required beyond what is
necessary for effecting a separation of the melted fat from the
membraneous or other suspended matter. Complete separation of all
suspended matter is obviously important, and therefore nitration seems
desirable, where practicable; which however is not on the large scale.
My experiments tend to indicate that the process just described is that
best adapted for the preparation of lard for use in pharmacy. There is,
however, a point connected with this or any other method of preparing
lard which is deserving of more attention than it has, I believe,
usually received, and that is, the source from which the flare has been
derived. Everybody knows how greatly the quality of pork depends upon
the manner in which the pig has been fed, and this applies to the fat as
well as other parts of the animal. Some time ago I had some pork
submitted to me for the expression of opinion upon it, which had a
decided fishy flavor, both in taste and smell. This flavor was present
in every part, fat and lean, and it is obvious that lard prepared from
that fat would not be fit for use in pharmacy. The pig had been
prescribed a fish diet. Barley meal would, no doubt, have produced a
better variety of lard.
* * * * *
ANTI-CORROSION PAINT.
The _Neueste Erfinderung_ describes an anti-corrosion paint for iron. It
states that if 10 per cent. of burnt magnesia, or even baryta, or
strontia, is mixed (cold) with ordinary linseed-oil paint, and then
enough mineral oil to envelop the alkaline earth, the free acid of the
paint will be neutralized, while the iron will be protected by the
permanent alkaline action of the paint. Iron to be buried in damp earth
may be painted with a mixture of 100 parts of resin (colophony), 25
parts of gutta-percha, and 50 parts of paraffin, to which 20 parts of
magnesia and some mineral oil have been added.
* * * * *
CARBON IN STEEL.
At a recent meeting of the Chemical Society, London, a paper was read
entitled "Notes on the Condition in which Carbon exists in Steel," by
Sir F.A. Abel, C.B., and W.H. Deering.
Two series of experiments were made. In the first series disks of steel
2.5 inches in diameter and 0.01 inch thick were employed. They were all
cut from the same strip of metal, but some were "cold-rolled," some
"annealed," and some "hardened." The total carbon was found to be:
"cold-rolled," 1.108 per cent.; hardened, 1.128 per cent.; and annealed,
0.924 and 0.860 per cent. Some of the disks were submitted to the action
of an oxidizing solution consisting of a cold saturated solution of
potassium bichromate with 5 per cent. by volume of pure concentrated
sulphuric acid. In all cases a blackish magnetic residue was left
undissolved. These residues, calculated upon 100 parts of the disks
employed, had the following compositions: "Cold-rolled" carbon, 1.039
per cent.; iron, 5.871. Annealed, C, 0.83 per cent.; Fe, 4.74 per cent.
Hardened, C, 0.178 per cent.; Fe, 0.70 per cent. So that by treatment
with chromic acid in the cold nearly the whole of the carbon remains
undissolved with the cold-rolled and annealed disks, but only about
one-sixth of the total carbon is left undissolved in the case of the
hardened disk. The authors then give a _resume_ of previous work on the
subject. In the second part they have investigated the action of
bichromate solutions of various strengths on thin sheet-steel, about
0.098 inch thick, which was cold-rolled and contained: Carbon, 1.144 per
cent.; silica, 0.166 per cent.; manganese, 0.104 per cent. Four
solutions were used. The first contained about 10 per cent. of
bichromate and 9 per cent. of H_{2}SO_{4} by weight; the second was
eight-tenths as strong, the third about half as strong, the fourth about
one and a half times as strong. In all cases the amount of solution
employed was considerably in excess of the amount required to dissolve
the steel used. A residue was obtained as before. With solution 1, the
residue contained, C, 1.021; sol. 2, C, 0.969; sol. 3, C 1.049 the
atomic ratio of iron to carbon was Fe 2.694: C, 1; Fe, 2.65: C, 1; Fe),
2.867 C, 1): sol. 4. C, 0.266 per 100 of steel. The authors conclude
that the carbon in cold rolled steel exists not simply diffused
mechanically through the mass of steel but in the form of an iron
carbide, Fe_{3}C, a definite product, capable of resisting the action of
an oxidizing solution (if the latter is not too strong), which exerts a
rapid solvent action upon the iron through which the carbide is
distributed.
* * * * *
APPARATUS FOR EXTRACTING STARCH FROM POTATOES.
In the apparatus of Mr. Angele, of Berlin, shown in the annexed cuts
(Figs. 1 and 2), the potatoes, after being cleaned in the washer, C,
slide through the chute, v, into a rasp, D, which reduces them to a fine
pulp under the action of a continuous current of water led in by the
pipe, d. The liquid pulp flows into the iron reservoir, B, from whence a
pump, P, forces it through the pipe, w, to a sieve, g, which is
suspended by four bars and has a backward and forward motion. By means
of a rose, c, water is sprinkled over the entire surface of the sieve
and separates the fecula from the fibrous matter. The water, charged
with fine particles of fecula, and forming a sort of milk, flows through
the tube, z, into the lower part, N, of the washing apparatus, F, while
the pulp runs over the sieve and falls into the grinding-mill, H. This
latter divides all those cellular portions of the fecula that have not
been opened by the rasp, and allows them to run, through the tube, h,
into the washing apparatus, F, where the fecula is completely separated
from woody fibers. The fluid pulp is carried by means of a helix, i, to
a revolving perforated drum at e. From this, the milky starch flows into
the jacket, N, while the pulp (ligneous fibers) makes its exit from the
apparatus through the aperture, n, and falls into the reservoir, o.
[Illustration: ANGELE'S POTATO-STARCH APPARATUS.]
The liquid from the jacket, N, passes to a refining sieve, K, which,
like the one before mentioned, has a backward and forward motion, and
which is covered with very fine silk gauze in order to separate the very
finest impurities from the milky starch. The refined liquid then flows
into the reservoir, m, and the impure mass of sediment runs into the
pulp-reservoir, o. The pump, l, forces the milky liquid from the
reservoir, m, to the settling back, while the pulp is forced by a pump,
u, from the receptacle, o, into a large pulp-reservoir.
The water necessary for the manufacture is forced by the pump, a, into
the reservoir, W, from whence it flows, through the pipes, r, into the
different machines. All the apparatus are set in motion by two
shaftings, q. The principal shaft makes two hundred revolutions per
minute, but the velocity of that of the pumps is but fifty
revolutions.--_Polytech. Journ., and Bull. Musee de l'Indust_.
* * * * *
A SIMPLE APPARATUS FOR DESCRIBING ELLIPSES.
By Prof. E.J. HALLOCK.
A very simple apparatus for describing an oval or ellipse may be
constructed by any apprentice or school boy as follows: Procure a
straight piece of wood about 1/4 inch wide by 1/8 inch thick and 13 inches
long. Beginning 1/2 inch from the end, bore a row of small holes only
large enough for a darning needle to pass through and half an inch
apart. Mark the first one (at A) 0, the third 1, the fifth 2, and so on
to 12, so that the numbers represent the distance from O in inches. A
small slit may be made in the end of the ruler or strip of wood near A,
but a better plan is to attach a small clip on one side.
[Illustration: ELLIPSE INSTRUMENT.]
Next procure a strong piece of linen thread about four feet long; pass
it through the eye of a coarse needle, wax and twist it until it forms a
single cord. Pass the needle _upward_ through the hole marked 0, and tie
a knot in the end of the thread to prevent its slipping through. The
apparatus is now ready for immediate use. It only remains to set it to
the size of the oval desired.
Suppose it is required to describe an ellipse the longer diameter of
which is 8 inches, and the distance between the foci 5 inches. Insert a
pin or small tack loosely in the hole between 6 and 7, which is distant
6-1/2 inches from O. Pass the needle through hole 5, allowing the thread
to pass around the tack or pin; draw it tightly and fasten it in the
slit or clip at the end. Lay the apparatus on a smooth sheet of paper,
place the point of a pencil at E, and keeping the string tight pass it
around and describe the curve, just in the same manner as when the two
ends of the string are fastened to the paper at the foci. The chief
advantage claimed over the usual method is that it may be applied to
metal and stone, where it is difficult to attach a string. On drawings
it avoids the necessity of perforating the paper with pins.
As the pencil point is liable to slip out of the loop formed by the
string, it should have a nick cut or filed in one side, like a crochet
needle.
As the mechanic frequently wants to make an oval having a given width
and length, but does not know what the distance between the foci must be
to produce this effect, a few directions on this point may be useful:
It is a fact well known to mathematicians that if the distance between
the foci and the shorter diameter of an ellipse be made the sides of a
right angled triangle, its hypothenuse will equal the greater diameter.
Hence in order to find the distance between the foci, when the length
and width of the ellipse are known, these two are squared and the lesser
square subtracted from the greater, when the square root of the
difference will be the quantity sought. For example, if it be required
to describe an ellipse that shall have a length of 5 inches and a width
of 3 inches, the distance between the foci will be found as follows:
(5 x 5) - (3 x 3) = (4 x 4)
or __
25 - 9 = 16 and \/16 = 4.
In the shop this distance may be found experimentally by laying a foot
rule on a square so that one end of the former will touch the figure
marking the lesser diameter on the latter, and then bringing the figure
on the rule that represents the greater diameter to the edge of the
square; the figure on the square at this point is the distance sought.
Unfortunately they rarely represent whole numbers. We present herewith a
table giving the width to the eighth of an inch for several different
ovals when the length and distance between foci are given.
Length. Distance between foci. Width.
Inches. Inches. Inches.
2 1 13/4
2 11/2 11/4
21/2 1 21/4
21/2 11/2 2
21/2 2 11/2
3 1 11/2
3 11/2 2-7/8
3 2 2-5/8
3 21/2 21/4
31/2 1 3-3/8
31/2 11/2 3-1/8
31/2 2 2-7/8
31/2 21/2 21/2
31/2 3 13/4
4 2 31/2
4 21/2 3-1/8
4 3 2-5/8
4 31/2 2
5 3 4
5 4 3
For larger ovals multiples of these numbers may be taken; thus for 7 and
4, take from the table twice the width corresponding to 31/2 and 2, which
is twice 2-7/8, or 53/4. It will be noticed also that columns 2 and 3 are
interchangeable.
To use the apparatus in connection with the table: Find the length of
the desired oval in the first column of the table, and the width most
nearly corresponding to that desired in the third column. The
corresponding number in the middle column tells which hole the needle
must be passed through. The tack D, _around_ which the string must pass,
is so placed that the total length of the string AD + DC, or its equal
AE + EC, shall equal the greater diameter of the ellipse. In the figure
it is placed 61/2 inches from A, and 11/2 inches from C, making the total
length of string 8 inches. The oval described will then be 8 inches long
and 61/4 inches wide.
The above table will be found equally useful in describing ovals by
fastening the ends of the string to the drawing as is recommended in all
the text books on the subject. On the other hand, the instrument may be
set "by guess" when no particular accuracy is required.
* * * * *
THE MANUFACTURE OF CHARCOAL IN KILNS.
The manufacture of charcoal in kilns was declared many years ago, after
a series of experiments made in poorly constructed furnaces, to be
unprofitable, and the subject is dismissed by most writers with the
remark, that in order to use the method economically the products of
distillation, both liquid and gaseous, must be collected. T. Egleston,
Ph.D., of the School of Mines, New York, has read a paper on the subject
before the American Institute of Mining Engineers, from which we extract
as follows: As there are many SILVER DISTRICTS IN THE WEST where coke
cannot be had at such a price as will allow of its being used, and where
the ores are of such a nature that wood cannot be used in a
reverberatory furnace, the most economical method of making charcoal is
an important question.
Kilns for the manufacture of charcoal are made of almost any shape and
size, determined in most cases by the fancy of the builder or by the
necessities of the shape of the ground selected. They do not differ from
each other in any principle of manufacture, nor does there seem to be
any appreciable difference in the quality of the fuel they produce, when
the process is conducted with equal care in the different varieties; but
there is a considerable difference in the yield and in the cost of the
process in favor of small over large kilns. The different varieties have
come into and gone out of use mainly on account of the cost of
construction and of repairs. The object of a kiln is to replace the
cover of a meiler by a permanent structure. Intermediate between the
meiler and the kiln is the Foucauld system, the object of which is to
replace the cover by a structure more or less permanent, which has all
the disadvantages of both systems, with no advantages peculiar to
itself.
The kilns which are used may be divided into the rectangular, the round,
and the conical, but the first two seem to be disappearing before the
last, which is as readily built and much more easily managed.
ALL VARIETIES OF KILNS
Are usually built of red brick, or, rarely, of brick and stone together.
Occasionally, refractory brick is used, but it is not necessary. The
foundations are usually made of stone. There are several precautions
necessary in constructing the walls. The brick should be sufficiently
hard to resist the fire, and should therefore be tested before using. It
is an unnecessary expense to use either second or third quality
fire-brick. As the pyroligneous acid which results from the distillation
of the wood attacks lime mortar, it is best to lay up the brick with
fire-clay mortar, to which a little salt has been added; sometimes loam
mixed with coal-tar, to which a little salt is also added, is used. As
the principal office of this mortar is to fill the joints, special care
must be taken in laying the bricks that every joint is broken, and
frequent headers put in to tie the bricks together. It is especially
necessary that all the joints should be carefully filled, as any small
open spaces would admit air, and would materially decrease the yield of
the kiln. The floor of the kiln was formerly made of two rows of brick
set edgewise and carefully laid, but latterly it is found to be best
made of clay. Any material, however, that will pack hard may be used. It
must be well beaten down with paving mauls. The center must be about six
inches higher than the sides, which are brought up to the bottom of the
lower vents. Most kilns are carefully pointed, and are then painted on
the outside with a wash of clay suspended in water, and covered with a
coating of coal-tar, which makes them waterproof, and does not require
to be renewed for several years.
[Illustration: RECTANGULAR KILNS FOR THE MANUFACTURE OF CHARCOAL.]
The kilns were formerly roofed over with rough boards to protect the
masonry from the weather, but as no special advantage was found to
result from so doing, since of late years they have been made
water-proof, the practice has been discontinued.
The wood used is cut about one and a fifth meters long. The diameter is
not considered of much importance, except in so far as it is desirable
to have it as nearly uniform as possible. When most of the wood is
small, and only a small part of it is large, the large pieces are
usually split, to make it pack well. It has been found most satisfactory
to have three rows of vents around the kiln, which should be provided
with a cast-iron frame reaching to the inside of the furnace. The vents
near the ground are generally five inches high--the size of two
bricks--and four inches wide--the width of one--and the holes are closed
by inserting one or two bricks in them. They are usually the size of one
brick, and larger on the outside than on the inside. These holes are
usually from 0.45 m. to 0.60 m. apart vertically, and from 0.80 m. to
0.90 m. apart horizontally. The lower vents start on the second row of
the brickwork above the foundation, and are placed on the level with the
floor, so that the fire can draw to the bottom. There is sometimes an
additional opening near the top to allow of the rapid escape of the
smoke and gas at the time of firing, which is then closed, and kept
closed until the kiln is discharged. This applies mostly to the best
types of conical kilns. In the circular and conical ones the top
charging door is sometimes used for this purpose. Hard and soft woods
are burned indifferently in the kilns. Hard-wood coal weighs more than
soft, and the hard variety of charcoal is usually preferred for blast
furnaces, and for such purposes there is an advantage of fully 33-1/3
per cent. or even more in using hard woods. For the direct process in
the bloomaries, soft-wood charcoal is preferred. It is found that it is
not usually advantageous to build kilns of over 160 to 180 cubic meters
in capacity. Larger furnaces have been used, and give as good a yield,
but they are much more cumbersome to manage. The largest yield got from
kilns is from 50 to 60 bushels for hard wood to 50 for soft wood. The
average yield, however, is about 45 bushels. In meilers, two and a half
to three cords of wood are required for 100 bushels, or 30 to 40 bushels
to the cord. The kiln charcoal is very large, so that the loss in fine
coal is very much diminished. The pieces usually come out the whole
size, and sometimes the whole length of the wood.
The rectangular kilns were those which were formerly exclusively in use.
They are generally built to contain from 30 to 90 cords of wood. The
usual sizes are given in the table below:
1 2 3 4
Length 50 40 40 48
Width 12 15 14 17
Height 12 15 18 18
Capacity, in cords 55 70 75 90
1 and 2. Used in New England. 3. Type of those used in Mexico. 4. Kiln
at Lauton, Mich.
The arch is usually an arc of a circle. A kiln of the size of No. 4, as
constructed at the Michigan Central Iron Works, with a good burn, will
yield 4,000 bushels of charcoal.
The vertical walls in the best constructions are 12 to 13 feet high, and
1-1/2 brick thick, containing from 20 to 52 bricks to the cubic foot of
wall. To insure sufficient strength to resist the expansion and
contraction due to the heating and cooling, they should be provided with
buttresses which are 1 brick thick and 2 wide, as at Wassaic, New York;
but many of them are built without them, as at Lauton, Michigan, as
shown in the engraving. In both cases they are supported with strong
braces, from 3 to 4 feet apart, made of round or hewn wood, or of cast
iron, which are buried in the ground below, and are tied above and below
with iron rods, as in the engraving, and the lower end passing beneath
the floor of the kiln. When made of wood they are usually 8 inches
square or round, or sometimes by 8 inches placed edgewise. They are
sometimes tied at the top with wooden braces of the same size, which are
securely fastened by iron rods running through the corners, as shown.
When a number of kilns are built together, as at the Michigan Central
Iron Works, at Lauton, Michigan, shown in the plan view, only the end
kilns are braced in this way. The intermediate ones are supported below
by wooden braces, securely fastened at the bottom. The roof is always
arched, is one brick, or eight inches, thick, and is laid in headers,
fourteen being used in each superficial foot. Many of the kilns have in
the center a round hole, from sixteen to eighteen inches in diameter,
which is closed by a cast iron plate. It requires from 35 M. to 40 M.
brick for a kiln of 45 cords, and 60 M. to 65 M. for one of 90 cords.
* * * * *
The belief that population in the West Indies is stationary is so far
from accurate that, as Sir Anthony Musgrave points out, it is increasing
more rapidly than the population of the United Kingdom. The statistics
of population show an increase of 16 per cent. on the last decennial
period, while the increase in the United Kingdom in the ten years
preceding the last census was under 11 per cent. This increase appears
to be general, and is only slightly influenced by immigration. "The
population of the West Indies," adds Sir A. Musgrave, "is now greater
than that of any of the larger Australian colonies, and three times that
of New Zealand."
* * * * *
HEAT DEVELOPED IN FORGING.
M. Tresca has lately presented to the Academy of Sciences some very
interesting experiments on the development and distribution of heat
produced by a blow of the steam hammer in the process of forging. The
method used was as follows: The bar was carefully polished on both
sides, and this polished part covered with a thin layer of wax. It was
then placed on an anvil and struck by a monkey of known weight, P,
falling from a height, H. The faces of the monkey and anvil were exactly
alike, and care was taken that the whole work, T = PH, should be
expended upon the bar. A single blow was enough to melt the wax over a
certain zone; and this indicated clearly how much of the lateral faces
had been raised by the shock to the temperature of melting wax. The form
of this melted part could be made to differ considerably, but
approximated to that of an equilateral hyperbola. Let A be the area of
this zone, b the width of the bar, d the density, C the heat capacity,
and t-t0 the excess of temperature of melting wax over the temperature
of the air. Then, assuming that the area, A, is the base of a horizontal
prism, which is everywhere heated to the temperature, t, the heating
effect produced will be expressed by
Ab x d x C(t-t0)
Multiplying this by 425, or Joule's equivalent for the metrical system,
the energy developed in heat is given by
T1 = 425 AbdC(t-t0).
Dividing T1 by T, we obtain the ratio which the energy developed in heat
bears to the total energy of the blow.
With regard to the form of the zone of melting, it was found always to
extend round the edges of the indent produced in the bar by the blow. We
are speaking for the present of cases where the faces of the monkey and
anvil were sharp. On the sides of the bar the zone took the form of a
sort of cross with curved arms, the arms being thinner or thicker
according to the greater or less energy of the shock. These forms are
shown in Figs. 1 to 6. It will be seen that these zones correspond to
the zones of greatest sliding in the deformation of a bar forged with a
sharp edged hammer, showing in fact that it is the mechanical work done
in this sliding which is afterward transformed into heat.
[Illustration]
With regard to the ratio, above mentioned, between the heat developed
and the energy of the blow, it is very much greater than had been
expected when the other sources of loss were taken into consideration.
In some cases it reached 80 per cent., and in a table given the limits
vary for an iron bar between 68.4 per cent. with an energy of 40
kilogram-meters, and 83.6 per cent. with an energy of 90
kilogram-meters. With copper the energy is nearly constant at 70 per
cent. It will be seen that the proportion is less when the energy is
less, and it also diminishes with the section of the bar. This is no
doubt due to the fact that the heat is then conducted away more rapidly.
On the whole, the results are summed up by M. Tresca as follows:
(1) The development of heat depends on the form of the faces and the
energy of the blow.
(2) In the case of faces with sharp edges, the process described allows
this heat to be clearly indicated.
(3) The development of heat is greatest where the shearing of the
material is strongest. This shearing is therefore the mechanical cause
which produces the heating effect.
(4) With a blow of sufficient energy and a bar of sufficient size, about
80 per cent. of the energy reappears in the heat.
(5) The figures formed by the melted wax give a sort of diagram, showing
the distribution of the heat and the character of the deformation in the
bar.
(6) Where the energy is small the calculation of the percentage is not
reliable.
So far we have spoken only of cases where the anvil and monkey have
sharp faces. Where the faces are rounded the phenomena are somewhat
different. Figs. 7 to 12 give the area of melted wax in the case of bars
struck with blows gradually increasing in energy. It will be seen that,
instead of commencing at the edges of the indent, the fusion begins near
the middle, and appears in small triangular figures, which gradually
increase in width and depth until at last they meet at the apex, as in
Fig. 12. The explanation is that with the rounded edges the compression
at first takes place only in the outer layers of the bar, the inner
remaining comparatively unaffected. Hence the development of heat is
concentrated on these outer layers, so long as the blows are moderate in
intensity. The same thing had already been remarked in cases of holes
punched with a rounded punch, where the burr, when examined, was found
to have suffered the greatest compression just below the punch. With
regard to the percentage of energy developed as heat, it was about the
same as in the previous experiments, reaching in one case, with an iron
bar and with an energy of 110 kilogram-meters, the exceedingly high
figure of 91 per cent. With copper, the same figure varied between 50
and 60 per cent.--_Iron_.
* * * * *
A NOVEL PROPELLER ENGINE.
By Prof. C.W. MacCord.
The accompanying engravings illustrate the arrangement of a propeller
engine of 20 inch bore and 22 inch stroke, whose cylinder and valve gear
were recently designed by the writer, and are in process of construction
by Messrs. Valk & Murdoch, of Charleston, S.C.
In the principal features of the engine, taken as a whole, as will be
perceived, there is no new departure. The main slide valve, following
nearly full stroke, is of the ordinary form, and reversed by a shifting
link actuated by two eccentrics, in the usual manner; and the expansion
valves are of the well known Meyer type, consisting of two plates on the
back of the main valve, driven by a third eccentric, and connected by a
right and left handed screw, the turning of which alters the distance
between the plates and the point of cutting off.
The details of this mechanism, however, present several novel features,
of which the following description will be understood by reference to
the detached cuts, which are drawn upon a larger scale than the general
plan shown in Figs. 1 and 2.
[Illustration: Figs. 1-2 IMPROVED STEAM ENGINE.--BY PROF MACCORD.]
The first of these relates to the arrangement of the right and left
handed screw, above mentioned, and of the device by which it is rotated.
Usually, the threads, both right handed and left handed, are cut upon
the cut-off valve stem itself, which must be so connected with the
eccentric rod as to admit of being turned; and in most cases the valve
stem extends through both ends of the steam chest, so that it must both
slide endwise and turn upon its axis in two stuffing boxes, necessarily
of comparatively large size.
All this involves considerable friction, and in the engine under
consideration an attempt has been made to reduce the amount of this
friction, and to make the whole of this part of the gear neater and more
compact, in the following manner:
Two small valve stems are used, which are connected at their lower ends
by a crosstail actuated directly by the eccentric rod, and at their
upper ends by a transverse yoke. This yoke, filling snugly between two
collars formed upon a sleeve which it embraces, imparts a longitudinal
motion to the latter, while at the same time leaving it free to rotate.
This sleeve has cut upon it the right and left handed screws for
adjusting the cut-off valves; and it slides freely upon a central
spindle which has no longitudinal motion, but, projecting through the
upper end of the valve chest, can be turned at pleasure by means of a
bevel wheel and pinion. The rotation of the spindle is communicated to
the sleeve by means of two steel keys fixed in the body of the latter
and projecting inwardly so as to slide in corresponding longitudinal
grooves in the spindle.
Thus the point of cutting off is varied at will while the engine is
running, by means of the hand wheel on the horizontal axis of the bevel
pinion, and a small worm on the same axis turns the index, which points
out upon the dial the distance followed. These details are shown in
Figs. 3, 4, and 5; in further explanation of which it may be added that
Fig. 3 is a front view of the valve chest and its contents, the cover,
and also the balance plate for relieving the pressure on the back of the
main valve (in the arrangement of which there is nothing new), being
removed in order to show the valve stems, transverse yoke, sleeve, and
spindle above described. Fig. 4 is a longitudinal section, and Fig. 5 is
a transverse section, the right hand side showing the cylinder cut by a
plane through the middle of the exhaust port, the left hand side being a
section by a plane above, for the purpose of exhibiting more clearly the
manner in which the steam is admitted to the valve chest; the latter
having no pipes for this service, the steam enters below the valve, at
each end of the chest, just as it escapes in the center.
The second noteworthy feature consists in this: that the cut-off
eccentric is not keyed fast, as is customary when valve gear of this
kind is employed, but is loose upon the shaft, the angular position in
relation to the crank being changed when the engine is reversed; two
strong lugs are bolted on the shaft, one driving the eccentric in one
direction, the other in the opposite, by acting against the reverse
faces of a projection from the side of The eccentric pulley.
The loose eccentric is of course a familiar arrangement in connection
with poppet valves, as well as for the purpose of reversing an engine
when driving a single slide valve. Its use in connection with the Meyer
cut-off valves, however, is believed to be new; and the reason for its
employment will be understood by the aid of Fig. 6.
For the purposes of this explanation we may neglect the angular
vibrations of the connecting rod and eccentric rod, considering them
both as of infinite length. Let O be the center of the shaft; let L O M
represent the face of the main valve seat, in which is shown the port
leading to the cylinder; and let A be the edge of the main valve, at the
beginning of a stroke of the piston. It will then be apparent that the
center of the eccentric must at that instant be at the point, C, if the
engine turn to the left, as shown by the arrow, and at G, if the
rotation be in the opposite direction; C and G then may be taken as the
centers of the "go-ahead" and the "backing" eccentrics respectively,
which operate the main valve through the intervention of the link.
Now, in each revolution of the engine, the cut-off eccentric in effect
revolves in the same direction about the center of the main eccentric.
Consequently, we may let R C S, parallel to L O M, represent the face of
the cut-off valve seat, or, in other words, the back of the main valve,
in which the port, C N, corresponds to one of those shown in Fig. 4; and
the motion of the cut-off valve over this seat will be precisely, the
same as though it were driven directly by an eccentric revolving around
the center, C.
In determining the position of this eccentric, we proceed upon the
assumption that the best results will be effected by such an arrangement
that when cutting off at the earliest point required, the cut-off valve
shall, at the instant of closing the port, be moving over it at its
highest speed. And this requires that the center of the eccentric shall
at the instant in question lie in the vertical line through C.
[Illustration: Figs. 3-12 IMPROVED STEAM ENGINE.--BY PROF MACCORD.]
Next, the least distance to be followed being assigned, the angle
through which the crank will turn while the piston is traveling that
distance is readily found; then, drawing an indefinite line C T, making
with the vertical line, G O, an angle, G C T. equal to the one thus
determined, any point upon that line may be assumed as the position of
the required center of the cut-off eccentric, at the beginning of the
stroke.
But again, in order that the cut-off may operate in the same manner when
backing as when going ahead, this eccentric must be symmetrically
situated with respect to both C and G; and since L O M bisects and is
perpendicular to G C, it follows that if the cut-off eccentric be fixed
on the shaft, its center must be located at H, the intersection of C T
with L M. This would require the edge of the cut-off valve at the given
instant to be at Q, perpendicularly over H; and the travel over the main
valve would be equal to twice C H, the virtual lever arm of the
eccentric, the actual traverse in the valve chest being twice O H, the
real eccentricity.
This being clearly excessive, let us next see what will occur if the
lever arm, CH, be reduced as in the diagram to CK. The edge of the
cut-off valve will then be at N; it instantly begins to close the port.
CN, but not so rapidly as the main valve opens the port, AB.
The former motion increases in rapidity, while the latter decreases;
therefore at some point they will become equal in velocity, and the
openings of the two ports will be the same; and the question is, Will
this maximum effective port area give a sufficient supply of steam?
This diagram is the same as the one actually used in the engine under
consideration, in which it was required to follow a minimum distance of
5 inches in the stroke of 22. Under these conditions it is found that
the actual port opening for that point of cutting off is three-fifths of
that allowed when following full stroke, whereas the speed of the piston
at the time when this maximum opening occurs is less than half its
greatest speed.
This, it would seem, is ample; but we now find the eccentric, K, no
longer in the right position for backing; when the engine is reversed it
ought to be at, P, the angle, POL, being equal to the angle, KOL. By
leaving it free, therefore, to move upon the shaft, by the means above
described, through the angle, KOP, the desired object is accomplished.
The real eccentricity is now reduced in the proportion of OK to OH,
while the lengths of the cut-off valves, and what is equally important,
their travel over the back of the main valve, are reduced in the
proportion of CK to CH, in this instance nearly one-half; a gain quite
sufficient to warrant the adoption of the expedient.
The third, and perhaps the most notable, peculiarity is the manner of
suspending and operating the main link. As before stated, this link is
used only for reversing, and is therefore always in "full gear" in one
direction or the other; and the striking feature of the arrangement here
used is that, whether going ahead or backing, there is _no slipping of
the link upon the link block_.
The link itself is of the simplest form, being merely a curved flat bar,
L, in which are two holes, A and B (Fig. 7), by which the link is hung
upon the pins, which project from the sides of the eccentric rods at
their upper ends.
This is most clearly shown in Fig. 8, which is a top view of the
reversing gear. The link block is a socket, open on the side next to the
eccentric rods, but closed on the side opposite, from which projects the
journal, J, as shown in Fig. 9, which is a vertical section by the
plane, XY. This journal turns freely in the outer end of a lever, M,
which transmits the reciprocating motion to the valve, through the
rock-shaft, O, and another lever, N. Connected with the lever, M, by the
bridge-piece, K, and facing it, is a slotted arm, G, as shown in the end
view, Fig. 10. The center line of this slot lies in the plane which
contains the axes of the journal, J, and of the shaft, O.
A block, E, is fitted to slide in the slotted arm, G; and in this block
is fixed a pin, P. A bridle-rod, R, connects P with the pin, A, of one
of the eccentric-rods, prolonged for that purpose as shown in Fig. 8;
and a suspension-rod, S, connects the same pin, P, with the upper end of
the reversing lever, T, which is operated by the worm and sector. The
distance, JO, in Fig. 10, or in other words the length of the lever, M,
is precisely equal to the distance, AB, in Fig. 7, measured in a right
line; and the rods, R and S, from center to center of the eyes, are also
each of precisely this same length. Further, the axis about which the
reversing lever, T, vibrates is so situated that when that lever, as in
Fig 11, is thrown full to the left, the pin in its upper end is exactly
in line with the rock-shaft, O.
When the parts are in this position, the suspension-rod, S, the arm, G,
and the lever, M, will be as one piece, and their motions will be
identical, consisting simply of vibration about the axis of the
rock-shaft, O. The motion of the lever, M, is then due solely to the
pin, B, which is in this case exactly in line with the journal, J, so
that the result is the same as though this eccentric rod were connected
directly to the lever; and the pin, P, being also in line with B and J,
and kept so by the suspension-rod, S, it will be seen that the
bridle-rod, R, will move with the link, L, as though the two were
rigidly fastened together.
When the reversing lever, T, is thrown full to the right, as in Fig. 12,
the pin, P, is drawn to the inner end of the slot in the arm, G, and is
thus exactly in line with the rock-shaft, O. The suspension-rod, S,
will, therefore, be at rest; but the pin, A, will have been drawn, by
the bridle-rod, R, into line with the journal, J, and the bridle-rod
itself will now vibrate with the lever, M, whose sole motion will be
derived from the pin, A.
There is, then, no block slip whatever when the link thus suspended and
operated is run in "full gear," either forward or backward.
If this arrangement be used in cases where the link is used as an
expansion device, there will be, of course, some block slip while
running in the intermediate gears. But even then, it is to be observed
that the motion of the pin, A, relatively to the rocker arm is one of
vibration about the moving center, J; and its motion relatively to the
sliding block, E, is one of vibration about the center, P, whose motion
relatively to E is a small amount of sliding in the direction of the
slot, due to the fact that the rocker arm itself, which virtually
carries the block, E, vibrates about O, while the suspension-rod, S,
vibrates about another fixed center. It will thus be seen that, finally,
the block slip will be determined by the difference in curvature of arcs
_which curve in the same direction_, whether the engine be running
forward or backward; whereas in the common modes of suspension the block
slip in one direction is substantially the half sum of the curvatures of
two arcs curving in opposite directions.
Consequently it would appear that the average action of the new
arrangement would be at least equal to that of the old in respect to
reducing the block slip when running in the intermediate gears, while in
the full gears it entirely obviates that objectionable feature.
* * * * *
THE NEW RUSSIAN TORPEDO BOAT, THE POTI.
The Russian government has just had built at the shipyards of Mr.
Normand, the celebrated Havre engineer, a torpedo boat called the Poti,
which we herewith illustrate. This vessel perceptibly differs from all
others of her class, at least as regards her model. Her extremities,
which are strongly depressed in the upperworks, and the excessive
inclination of her sides, give the boat as a whole a certain resemblance
to the rams of our navy, such as the Taureau and Tigre.
[Illustration: THE NEW RUSSIAN TORPEDO BOAT, THE "POTI".]
A transverse section of the Poti approaches an ellipse in shape. Her
water lines are exceedingly fine, and, in point of elegance, in no wise
cede to those of the most renowned yachts. The vessel is entirely of
steel, and her dimensions are as follows: Length, 28 meters; extreme
breadth, 3.6 meters; depth, 2.5 meters; draught, 1.9 meters;
displacement, 66 tons. The engine, which is a compound one, is of 600
H.P. The minimum speed required is 18 knots, or 33-34 meters, per hour,
and it will probably reach 40 kilometers.
The vessel will be armed with 4 Whitehead torpedoes of 5.8 m., and 2
Hotchkiss guns of 40 cm. Her supply of coal will be sufficient for a
voyage of 1000 nautical miles at a speed of 11 knots.--_L'Illustration_.
* * * * *
A NEW STEAMER PROPELLED BY HYDRAULIC REACTION.
The oar, the helix, and the paddle-wheel constitute at present the means
of propulsion that are exclusively employed when one has recourse to a
motive power for effecting the propulsion of a boat. The sail
constitutes an entirely different mode, and should not figure in our
enumeration, considering the essentially variable character of the force
utilized.
In all these propellers, we have only an imitation, very often a rude
one, of the processes which nature puts in play in fishes and mollusks,
and the mode that we now wish to make known is without contradiction
that which imitates these the best.
Hydraulic propulsion by reaction consists, in principle, in effecting a
movement of boats, by sucking in water at the bow and forcing it out at
the stern. This is a very old idea. Naturalists cite whole families of
mollusks that move about in this way with great rapidity. It is probable
that such was the origin of the first idea of this mode of operating.
However this may be, as long ago as 1661 a patent was taken out in
England, on this principle, by Toogood & Hayes. After this we find the
patents of Allen (1729) and Rumsay (1788). In France, Daniel Bernouilli
presented to the Academic des Sciences a similar project during the last
century.
Mr. Seydell was the first to build a vessel on this principle. This
ship, which was called the Enterprise, was of 100 tons burden, and was
constructed at Edinburgh for marine fishery. The success of this was
incomplete, but it was sufficient to show all the advantage that could
be got from the idea. Another boat, the Albert, was built at Stettin,
after the same type and at about the same epoch; and the question was
considered of placing a reaction propeller upon the Great Eastern.
About 1860 the question was taken up again by the house of Cokerill de
Seraing, which built the Seraing No. 2, that did service as an excursion
boat between Liege and Seraing. The propeller of this consisted of a
strong centrifugal pump, with vertical axis, actuated by a low pressure
engine. This pump sucked water into a perforated channel at the bottom
of the boat, and forced it through a spiral pipe to the propelling
tubes. These latter consisted of two elbowed pipes issuing from the
sides of the vessel and capable of pivoting in the exhaust ports in such
a way as to each turn its mouth downward at will, backward or forward.
The water expelled by the elbowed pipes reacted through pressure, as in
the hydraulic tourniquet of cabinets of physics, and effected the
propulsion of the vessel. Upon turning the two mouths of the propelling
tubes backward, the boat was thrust forward, and, when they were turned
toward the front, she was thrust backward. When one was turned toward
the front and the other toward the stern, the boat swung around.
Finally, when the two mouths were placed vertically the boat remained
immovable. All the evolutions were easy, even without the help of the
rudder, and the ways in which the propelling tubes could be placed were
capable of being varied _ad infinitum_ by a system of levers.
The Seraing No. 2 had an engine of a nominal power of 40 horses, and
took on an average 30 minutes to make the trip, backward and forward, of
85 kilometers, with four stoppages.
The success obtained was perfect, and the running was most satisfactory.
It was remarked, only, that from the standpoint of effective duty it
would have been desirable to reduce the velocity of the water at its
exit from the propellers.
Mr. Poillon attributes the small effective performance to the system
employed for putting the water in motion. At time of Mr. Seraing's
experiments, only centrifugal force pumps were known, and the theoretic
effective duty of these, whatever be the peculiar system of
construction, cannot exceed 66 per cent., and, in practice, falls to 40
or 50 per cent. in the majority of cases.
It is probable, then, that in making use of those new rotary pumps where
effective duty reaches and often exceeds 80 per cent., we might obtain
much better results, and it is this that justifies the new researches
that have been undertaken by Messrs. Maginot & Pinette, whose first
experiments we are about to make known.
In order to have it understood what interest attaches to these
researches, let us state the principal advantages that this mode of
propulsion will have over the helix and paddle wheel: The width of
side-wheel boats will be reduced by from 20 to 30 per cent., and the
draught of water will be diminished in screw steamers to that of the
hull itself; the maneuver in which the power of the engine might be
directly employed will be simplified; a machine will be had of a
sensibly constant speed, and without change in its running; the
production of waves capable of injuring the banks of canals will be
avoided; the propeller will be capable of being utilized as a bilge
pump; all vibration will be suppressed; the boat will be able to run at
any speed under good conditions, while the helix works well only when
the speed of the vessel corresponds to its pitch; it will be possible to
put the propelling apparatus under water; and, finally, it will be
possible to run the pump directly by the shaft of the high speed engine,
without intermediate gearing, which is something that would prove a very
great advantage in the case of electric pleasure boats actuated by piles
and accumulators and dynamo-electric machines.
[Illustration: NEW STEAMER PROPELLED BY HYDRAULIC REACTION.]
We now arrive at Messrs. Maginot & Pinette's system, the description of
which will be greatly facilitated by the diagram that accompanies this
article. The inventors have employed a boat 14 meters in length by 1.8
m. in width, and 65 centimeters draught behind and 32 in front. The
section of the midship beam is 70 square decimeters, and that of the
exhaust port is 4. At a speed of 2.2 meters per second the tractive
stress, K, is from 10 to 11 kilogrammes. At a speed of 13.5 kilometers
per hour, or 3.75 meters per second, the engine develops a power of 12
horses. The piston is 19 centimeters in diameter, and has a stroke of 15
centimeters. The shaft, in common, of the pump and engine makes 410
revolutions per minute. It will be seen from the figure that suction
occurs at the lower part of the hull, at A, and that the water is forced
out at B, to impel the vessel forward. C and C' are the tubes for
putting the vessel about, and DD' the tubes for causing her to run
backward. Owing to the tubes, C, C', the rudder has but small dimensions
and is only used for _directing_ the boat. The vessel may be turned
about _in situ_ by opening one of the receiving tubes, according to the
side toward which it is desired to turn.
This boat is as yet only in an experimental state, and the first trials
of her that have recently been made upon the Saone have shown the
necessity of certain modifications that the inventors are now at work
upon.--_La Nature_.
* * * * *
A NEW FORM OF FLEXIBLE BAND DYNAMOMETER.
[Footnote: Read before Section G of British Association.]
By Professor W.C. UNWIN.
[Illustration: Fig. 1.]
In the ordinary strap dynamometer a flexible band, sometimes carrying
segments of wood blocks, is hung over a pulley rotated by the motor, the
power of which is to be measured. If the pulley turns with left-handed
rotation, the friction would carry the strap toward the left, unless the
weight, Q, were greater than P. If the belt does not slip in either
direction when the pulley rotates under it, then Q-P exactly measures
the friction on the surface of the pulley; and V being the surface
velocity of the pulley (Q-P)V, is exactly the work consumed by the
dynamometer. But the work consumed in friction can be expressed in
another way. Putting [theta] for the arc embraced by the belt, and [mu]
for the coefficient of friction,
Q/P = [epsilon]^{[mu]^{[theta]}},
or for a given arc of contact Q = [kappa]P, where [kappa] depends only
on the coefficient of friction, increasing as [mu] increases, and _vice
versa_. Hence, for the belt to remain at rest with two fixed weights, Q
and P, it is necessary that the coefficient of friction should be
exactly constant. But this constancy cannot be obtained. The coefficient
of friction varies with the condition of lubrication of the surface of
the pulley, which alters during the running and with every change in the
velocity and temperature of the rubbing surfaces. Consequently, in a
dynamometer in this simple form more or less violent oscillations of the
weights are set up, which cannot be directly controlled without
impairing the accuracy of the dynamometer. Professors Ayrton and Perry
have recently used a modification of this dynamometer, in which the part
of the cord nearest to P is larger and rougher than the part nearest to
Q. The effect of this is that when the coefficients of friction
increase, Q rises a little, and diminishes the amount of the rougher
cord in contact, and _vice versa_. Thus reducing the friction,
notwithstanding the increase of the coefficient. This is very ingenious,
and the only objection to it, if it is an objection, is that only a
purely empirical adjustment of the friction can be obtained, and that
the range of the adjustment cannot be very great. If in place of one of
the weights we use a spring balance, as in Figs. 2 and 3, we get a
dynamometer which automatically adjusts itself to changes in the
coefficient of friction.
[Illustration: FIG.2 FIG.3]
For any increase in the coefficient, the spring in Fig. 2 lengthens, Q
increases, and the frictional resistance on the surface of the pulley
increases, both in consequence of the increase of Q, which increases the
pressure on the pulley, and of the increase of the coefficient of
friction. Similarly for any increase of the coefficient of friction, the
spring in Fig. 3 shortens, P diminishes, and the friction on the surface
of the pulley diminishes so far as the diminution of P diminishes the
normal pressure, but on the whole increases in consequence of the
increase of the coefficient of friction. The value of the friction on
the surface of the pulley, however, is more constant for a given
variation of the frictional coefficient in Fig. 3 than in Fig. 2, and
the variation of the difference of tensions to be measured is less. Fig.
3, therefore, is the better form.
A numerical calculation here may be useful. Supposing the break set to a
given difference of tension, Q-P, and that in consequence of any cause
the coefficient of friction increases 20 per cent., the difference of
tensions for an ordinary value of the coefficient of friction would
increase from 1.5 P to 2 P in Fig. 2, and from 1.5 P to 1.67 P in Fig.
3. That is, the vibration of the spring, and the possible error of
measurement of the difference of tension would be much greater in Fig. 2
than in Fig. 3. It has recently occurred to the author that a further
change in the dynamometer would make the friction on the pulley still
more independent of changes in the coefficient of friction, and
consequently the measurement of the work absorbed still more accurate.
Suppose the cord taken twice over a pulley fixed on the shaft driven by
the motor and round a fixed pulley, C.
For clearness, the pulleys, A B, are shown of different sizes, but they
are more conveniently of the same size. Further, let the spring balance
be at the free end of the cord toward which the pulley runs. Then it
will be found that a variation of 20 per cent. in the friction produces
a somewhat greater variation of P than in Fig. 3. But P is now so much
smaller than before that Q-P is much less affected by any error in the
estimate of P. An alteration of 20 per cent. in the friction will only
alter the quantity Q-P from 5.25 P to 5.55 P, or an alteration of less
than 6 per cent.
[Illustration: FIG. 4]
To put it in another way, the errors in the use of dynamometer are due
to the vibration of the spring which measures P, and are caused by
variations of the coefficient of friction of the dynamometer. By making
P very much smaller than in the usual form of the dynamometer, any
errors in determining it have much less influence on the measurement of
the work absorbed. We may go further. The cord may be taken over four
pulleys; in that case a variation of 20 per cent. in the frictional
coefficient only alters the total friction on the pulleys 11/4 percent. P
is now so insignificant compared with Q that an error in determining it
is of comparatively little consequence.
[Illustration: FIG. 5]
The dynamometer is now more powerful in absorbing work than in the form
Fig. 3. As to the practical construction of the brake, the author thinks
that simple wires for the flexible bands, lying in V grooves in the
pulleys, of no great acuteness, would give the greatest resistance with
the least variation of the coefficient of friction; the heat developed
being in that case neutralized by a jet of water on the pulley. It would
be quite possible with a pulley of say 3 feet diameter, and running at
50 feet of surface velocity per second, to have a sufficiently flexible
wire, capable of carrying 100 lb. as the greater load, Q. Now with these
proportions a brake of the form in Fig. 3 would, with a probable value
of the coefficient of friction, absorb 6 horse power. With a brake in
the form Fig. 4, 8.2 horse power would be absorbed; and with a brake in
the form Fig. 5, 8.8 horse power would be absorbed. But since it would
be easy to have two, three, or more wires side by side, each carrying
its load of 100 lb., large amounts of horsepower could be conveniently
absorbed and measured.
* * * * *
SEE'S GAS STOVE.
This stove consists of two or more superposed pipes provided with
radiators. A gas burner is placed at the entrance of either the upper or
lower pipe, according to circumstances. The products of combustion are
discharged through a pipe of small diameter, which may be readily
inserted into an already existing chimney or be hidden behind the
wainscoting. The heat furnished by the gas flame is so well absorbed by
radiation from the radiator rings that the gases, on making their exit,
have no longer a temperature of more than from 35 to 40 degrees.
[Illustration: SEE'S GAS STOVE.]
The apparatus, which is simple, compact, and cheap, is surrounded on all
sides with an ornamented sheet iron casing. Being entirely of cast iron,
it will last for a long time. The joints, being of asbestos, are
absolutely tight, so as to prevent the escape of bad odors. The water
due to the condensation of the gases is led through a small pipe out of
doors or into a vessel from whence it may evaporate anew, so as not to
change the hygrometric state of the air. The consumption of gas is very
small, it taking but 250 liters per hour to heat a room of 80 cubic
meters to a temperature of 18 deg. C.--_Revue Industrielle_.
* * * * *
The number of persons killed by wild animals and snakes in India last
year was 22,125, against 21,427 in the previous year, and of cattle,
46,707, against 44,669. Of the human beings destroyed, 2,606 were killed
by wild animals, and 19,519 by snakes. Of the deaths occasioned by the
attacks of wild animals, 895 were caused by tigers, 278 by wolves, 207
by leopards, 356 by jackals, and 202 by alligators; 18,591 wild animals
and 322,421 snakes were destroyed, for which the Government paid rewards
amounting to 141,653 rupees.
* * * * *
RECTIFICATION OF ALCOHOL BY ELECTRICITY.
Some time ago, Mr. Laurent Naudin, it will be remembered,[1] devised a
method of converting the aldehydes that give a bad taste and odor to
impure spirits, into alcohol, through electrolytic hydrogen, the
apparatus first employed being a zinc-copper couple, and afterward
electrolyzers with platinum plates.
[Footnote 1: See SCIENTIFIC AMERICAN SUPPLEMENT of July 29, 1882, p.
5472.]
His apparatus had been in operation for several months, in the
distillery of Mr. Boulet, at Bapeaume-les-Rouen, when a fire in
December, 1881, completely destroyed that establishment. In
reconstructing his apparatus, Mr. Naudin has availed himself of the
experience already acquired, and has necessarily had to introduce
important modifications and simplifications into the process. In the
zinc-copper couple, he had in the very first place proposed to employ
zinc in the form of clippings; but the metal in this state presents
grave inconveniences, since the subsidence of the lower part, under the
influence of the zinc's weight, soon proves an obstacle to the free
circulation of the liquids, and, besides this, the cleaning presents
insurmountable difficulties. This is why he substituted for the
clippings zinc in straight and corrugated plates such as may be easily
found in commerce. The management and cleaning of the pile thus became
very simple.
[Illustration: FIG. 1.--APPARATUS FOR HYDROGENIZING IMPURE SPIRITS.]
The apparatus that contains the zinc-copper couple now has the form
shown in Fig. 1. It may be cylindrical, as here represented, or, what is
better, rectangular, because of the square form under which the sheets
of zinc are found in commerce.
In this vessel of wood or iron plate, P, the corrugated zinc plates, b,
b', b", are placed one above the other, each alternating with a flat
one, a, a', a". These plates have previously been scoured, first with a
weak solution of caustic soda in order to remove every trace of fatty
matter derived from rolling, and then with very dilute hydrochloric
acid, and finally are washed with common water. In order to facilitate
the disengagement of hydrogen during the reaction, care must be taken to
form apertures in the zinc plates, and to incline the first lower row
with respect to the bottom of the vessel. A cubical pile of 150
hectoliters contains 105 rows of No. 16 flat and corrugated zinc plates,
whose total weight is 6,200 kilogrammes. We obtain thus a hydrogenizing
surface of 1,800 square meters, or 12 square meters per hectoliter of
impure spirits of 50 deg. to 60 deg. Gay-Lussac. The raw impure spirits enter
the apparatus through the upper pipe, E, and, after a sufficient stay
therein, are drawn off through the lower pipe, H, into a reservoir, R,
from whence, by means of a pump, they are forced to the rectifier.
The hydrogen engendered during the electrolysis is disengaged through an
aperture in the cover of the pile.
As a measure of precaution, the hydrogen saturated with alcoholic vapors
may be forced to traverse a small, cooled room. The liquefied alcohol
returns to the pile. At a mean temperature of 15 deg., the quantity of
alcohol carried along mechanically is insignificant. In order to secure
a uniformity of action in all parts of the spirits, during the period
devoted to the operation, the liquid is made to circulate from top to
bottom by means of a pump, O. The tube, N, indicates the level of the
liquid in the vessel. The zinc having been arranged, the first operation
consists in forming the couple. This is done by introducing into the
pile, by means of the pump, O, a solution of sulphate of copper so as to
completely fill it.
The adherence of the copper to the zinc is essential to a proper working
of the couple, and may be obtained by observing the following
conditions:
1. Impure spirits of 40 deg. Gay-Lussac, and not water, should be used as a
menstruum for the salt of copper.
2. The sulphatization should be operated by five successive solutions of
1/2 per cent., representing 20 kilogrammes of sulphate of copper per 100
square meters of zinc exposed, or a total of 360 kilogrammes of sulphate
for a pile of 150 hectoliters capacity.
3. A temperature of 25 deg. should not be exceeded during the
sulphatization.
The use of spirits is justified by the fact that the presence of the
alcohol notably retards the precipitation of copper. As each charging
with copper takes twenty-four hours, it requires five days to form the
pile. At the end of this time the deposit should be of a chocolate-brown
and sufficiently adherent; but the adherence becomes much greater after
a fortnight's operation.
Temperature has a marked influence upon the rapidity and continuity of
the reaction. Below +5 deg. the couple no longer works, and above +35 deg. the
reaction becomes vigorous and destroys the adherence of the copper to
such a degree that it becomes necessary to sulphatize the pile anew. The
battery is kept up by adding every eight days a few thousandths of
hydrochloric acid to a vatful of the spirits under treatment, say 5
kilos. of acid to 150 hectoliters of spirits. The object of adding this
acid is to dissolve the hydrate of oxide of zinc formed during the
electrolysis and deposited in a whitish stratum upon the surface of the
copper. The pile required no attention, and it is capable of operating
from 18 months to two years without being renewed or cleaned.
[Illustration: FIG. 2.--ELECTROLYZING APPARATUS.]
Passing them over, the zinc-copper couple does not suffice to deodorize
the impure spirits, so they must be sent directly to a rectifier. But,
in certain cases, it is necessary to follow up the treatment by the pile
with another one by electrolysis. The voltameters in which this second
operation is performed have likewise been modified. They consist now
(Fig. 2) of cylindrical glass vessels, AH, 125 mm. in diameter by 600 in
height, with polished edges. These are hermetically closed by an ebonite
cover through which pass the tubes, B' C' and B C, that allow the
liquid, E+E-E'+E', to circulate.
The current of spirits is regulated at the entrance by the cock, R,
which, through its division plate, gives the exact discharge per hour.
In addition, in order to secure great regularity in the flow, there is
placed between the voltameters and the reservoir that supplies them a
second and constant level reservoir regulated by an automatic cock.
In practice, Mr. Naudin employs 12 voltameters that discharge 12
hectoliters per hour, for a distillery that handles 300 hectoliters of
impure spirits every 24 hours. The electric current is furnished to the
voltameters by a Siemens machine (Fig. 3) having inductors in
derivation, the intensity being regulated by the aid of resistance wires
interposed in the circuit of the inductors.
The current is made to pass into the series of voltameters by means of a
commutator, and its intensity is shown by a Deprez galvanometer. The
voltameters, as shown in the diagram, are mounted in derivation in
groups of two in tension. The spirits traverse them in two parallel
currents. The Siemens machine is of the type SD2, and revolves at the
rate of 1,200 times per minute, absorbing a motive power of four horses.
[Illustration: FIG. 3.--ARRANGEMENT OF THE SIEMENS MACHINE.]
The disacidification, before entering the rectifier, is effected by the
metallic zinc. Let us now examine what economic advantages this process
presents over the old method of rectifying by pure and simple
distillation. The following are the data given by Mr. Naudin:
In ordinary processes (1) a given quantity of impure alcohol must
undergo five rectifications in order that the products composing the
mixture (pure alcohol, oils, etc.) may be separated and sold according
to their respective quality; (2) the mean yield in the first
distillation does not exceed 60 cent.; (3) the loss experienced in
distillation amounts, for each rectification, to 4 per cent.; (4) the
quantity of essential oils (mixture of the homologues of ethylic
alcohol) collected at the end of the first distillation equals, on an
average, 3.5 per cent.; (5) the cost of a rectification may be estimated
at, on an average, 4 francs per hectoliter.
All things being equal, the yield in the first operation by the electric
method is 80 per cent., and the treatment costs, on an average, 0.40
franc per hectoliter. The economy that is realized is therefore
considerable. For an establishment in which 150 hectoliters of 100 deg.
alcohol are treated per day this saving becomes evident, amounting, as
it does, to 373 francs.
We may add that the electric process permits of rectifying spirits
which, up to the present, could not be rectified by the ordinary
processes. Mr. Naudin's experiments have shown, for example, that
artichoke spirits, which could not be utilized by the old processes,
give through hydrogenation an alcohol equal to that derived from Indian
corn.--_La Nature_.
* * * * *
PLASTIC CARBON FOR BATTERIES.
Max Nitsche-Niesky recommends the following in _Neueste Erfindung_.:
Good coke is ground and mixed with coal-tar to a stiff dough and pressed
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