On a mode of Printing enlarged and reduced Positives, etc., from Collodion
Negatives.
To explain the manner in which a photograph may be enlarged or reduced in
the process of printing, it will be necessary to refer to the remarks made
at page 20, on the _conjugate foci_ of lenses.
If a collodion negative be placed at a certain distance in front of a
camera, and (by using a tube of black cloth) the light be admitted into
the dark chamber only through the negative, a reduced image will be formed
upon the ground glass; but if the negative be advanced nearer, the image
will increase in size, until it becomes first equal to, and then larger
than, the original negative; the focus becoming more and more distant from
the lens, or _receding_, as the negative is brought nearer.
Again, if a negative portrait be placed in the camera slide, and if
the instrument be carried into a dark room, a hole be cut in the
window-shutter so as to admit light through the negative, the luminous
rays, after refraction by the lens, will form an image of the exact size
of life upon a white screen placed in the position originally occupied
by the sitter. These two planes, in fact, that of the object and of the
image, are strictly _conjugate foci_, and, as regards the result, it is
immaterial from which of the two, anterior or posterior, the rays of light
proceed.
Therefore in order to obtain a reduced or enlarged copy of a negative, it
is necessary only to form an image of the size required, and to project
the image upon a sensitive surface either of collodion or paper.
A good arrangement for this purpose may be made by taking an ordinary
portrait camera, and prolonging it in front by a deal box blackened inside
and with a double body, to admit of being lengthened out as required; or,
more simply, by adding a framework of wood covered in with black cloth. A
groove in front carries the negative, or receives the slide containing the
sensitive layer, as the case may be.
In reducing photographs, the negative is placed in front of the lens, in
the position ordinarily occupied by the object; but in making an enlarged
copy it must be fixed behind the lens, or, which is equivalent, the lens
must be turned round so that the rays of light, transmitted by the
negative, enter the back glass of the combination, and pass out at the
front. This point should be attended to in order to avoid indistinctness
of image from spherical aberration.
A portrait combination of lenses of 2-1/2 or 3-1/4 inches is the best form
to use, and the actinic and luminous foci should accurately correspond, as
any difference between them would be increased by enlarging. A stop of an
inch or an inch and a half aperture placed between the lenses obviates to
some extent the loss of sharp outline usually following enlargement of the
image.
The light may be admitted through the negative by pointing the camera
towards the sky; or direct sunlight may be used, thrown upon the negative
by a plane reflector. A common swing looking-glass, if clear and free from
specks, does very well; it should be so placed that the centre on which it
turns is on a level with the axis of the lens.
The best negatives for printing enlarged positives are those which are
distinct and clear; and it is important to use a small negative, which
strains the lens less and gives better results than one of larger size.
In printing by 2-1/4 lens for instance, prepare the negative upon a plate
about two inches square and afterwards enlarge it four diameters.
Paper containing chloride of silver is not sufficiently sensitive to
receive the image, and the print should be formed upon collodion, or on
iodized paper developed by gallic acid.
The exposure required will vary not only with the intensity of the light
and the sensibility of the surface used, but also with the degree of
reduction or enlargement of the image.
In printing upon collodion the resulting picture is positive by
transmitted light; it should be backed up with white varnish, and then
becomes positive by reflected light. The tone of the blacks is improved by
treating the plate first with bichloride of mercury, and then with ammonia.
Mr. Wenham, who has written a most practical paper on the mode of
obtaining positives of the life size, operates in the following way:--he
places the camera, with the slide containing the negative in a dark room,
and reflects the sunlight in through a hole in the shutter, so as to
pass first through the negative and then through the lens; the image is
received upon iodized paper, and developed by gallic acid.
_On Printing Collodion Transparencies for the Stereoscope._--This may
be done by using the camera to form an image of the negative in the
mode described at the last page; but more simply by the following
process:--Coat the glass, upon which the print is to be formed, with
collodio-iodide of silver in the usual way, then lay it upon a piece of
black cloth, collodion side uppermost, and place two strips of paper of
about the thickness of cardboard and one-fourth of an inch broad, along
the two opposite edges, to prevent the negative being soiled by contact
with the film. Both glasses must be perfectly flat, and even then it may
happen that the negative is unavoidably wetted; if so, wash it immediately
with water, and if it be properly varnished no harm will result.
A little ingenuity will suggest a simple framework of wood, on which the
negative and sensitive plate are retained, separated only by the thickness
of a sheet of paper; and the use of this will be better than holding the
combination in the hand.
The printing is conducted by the light of gas or of a camphine or
moderator lamp, diffused daylight would be too powerful.
The employment of a concave reflector, which maybe purchased for a few
shillings, ensures parallelism of rays, and is a great improvement.
The lamp is placed in the focus of the mirror, which may at once be
ascertained by moving it backwards and forwards until an _evenly
illuminated circle_ is thrown upon a white screen held in front. This in
fact is one of the disadvantages of printing by a naked flame--that the
light falls most powerfully upon the central part; and less so upon the
edges, of the negative.
* * * * *
(From Humphrey's Journal, No. 17, Vol. 8.)
On the Use of Alcohol for Sensitizing Paper.
[Sidenote: TO SENSITIZE PAPER.]
I have practised for some time the following simple method, which appears
to me to be very superior for cleanliness and celerity in working, for
depth of tone, and especially for purity of white in its results. By means
of it T have produced very satisfactory results upon paper which was
otherwise nearly worthless.
To your sensitizing solution (which should be not less than 60 grains to
the ounce), whether simple nitrate or ammonio-nitrate, add 50 per cent, of
alcohol. Float the paper upon the solution for 40 seconds.
This method answers equally well for albumenized or plain paper.
You will find that the solution penetrates the paper which flattens
_instantaneously_ upon it. It becomes as transparent as though it were
oiled, and every minute air-bubble or defect in the paper is rendered
visible. Remove the air-bubbles by pressing upon the paper about an inch
from the bubble, and thus driving it out under the paper. In doing this,
if the solution flows partially over the back of the paper, shake it
until the paper is wholly immersed, which will prevent any unevenness
in printing. The paper reassumes its transparency in the toning bath,
but it will dry a pure white. The sensitising solution will not become
materially discolored even after frequent applications of albumenized
paper. Should it become so much discolored as to give a dark hue to the
paper, shake it in a bottle with two drachms Of animal charcoal and leave
it a night to settle. It will filter clear. A very small portion of your
solution may be made available in sensitizing a sheet of paper by pouring
it upon a clean glass, the size of the paper or a little larger, which
is carefully levelled and nicely laying down the paper upon it. This is
useful when your solution is too small to float in your trays. The alcohol
causes it to flow and be absorbed with perfect evenness.
To remove the papers from the solution and dry them:--Provide a dozen
or more clothes-pins, of the kind that are supplied with a ring of
india-rubber for a spring. Into the top drive a pin firmly and bend it
to a hook. Lift a corner of the paper by passing under it the point of a
quill tooth-pick, and attach to it one of the clothes-pins; lift the edge
out by this, and attach another to the other corner. You may thus carry
the sheet by the pins and hang it upon a line to dry without touching it
with the fingers, a matter of some importance to Amateurs of the art, who
must have unstained hands for their day's _business_.
It may be worth while here to add the following simple and economical
method of printing, which I have found to surpass in convenience and
afford all the advantages of the most expensive printing frames. Four
common clothes-pins, such as work with a _wire_ spring supply pressure
enough for a 4/4-plate. Lay your prepared paper upon the negative, and
next to it about twenty _separate leaves_ of thin common wrapping paper
cut to the size of the negative; next a sheet of tolerably stiff and
smooth writing paper, and lastly, a piece of glass as a back to the whole.
Let the glass back be pushed from the lower edge of the papers about 1/20
of an inch, or just so far as to enable you to pinch the negative and
papers with the thumb-nail and forefinger. Attach a pin to each corner
and your negative is prepared for exposure. Now, to examine your picture
without endangering its displacement:--remove the pins from one end, and
place it, face downwards, on a table, the other end with pins attached
projecting an inch beyond the edge. Hold down the back glass with the left
hand, while with the right you remove the pins and pinch the papers and
negative together between the forefinger and thumb-nail. Upon the smooth
sheet of paper you can easily slide the back glass an inch from the edge.
Hold it there, and on the uncovered margin attach _three_ of the pins with
as deep a bite as they will take. You may now examine your picture to
within an inch of its margin, as you would turn over the leaves of a book.
To replace the back, lay it again on the table and slide the back glass up
to the pins before you remove them. The rest of the process is obvious.
The minutiæ of my communication may excite a smile with some, but I shall
always act upon the principle, that nothing is more out of place than an
apology for minuteness in describing manipulations.
G. B. C.
* * * * *
Recovery of Silver from waste Solutions,--from the black Deposit of Hypo
Baths, etc.
[Sidenote: RECOVERY OF WASTE SILVER, ETC.]
The manner for separating metallic silver from waste solutions varies
according to the presence or absence of alkaline hyposulphite and cyanides.
a. _Separation of metallic Silver from old Nitrate Baths._--The silver
contained in solutions of the nitrate, acetate, etc.; may easily be
precipitated by suspending a strip of sheet copper in the liquid; the
action is completed in two or three days, the whole of the nitric acid and
oxygen passing to the copper, and forming a blue solution of the nitrate
of copper. The metallic silver however separated in this manner, always
contains a portion of copper, and gives a blue solution when dissolved in
nitric acid.
A better process is to commence by precipitating the silver entirely in
the form of _chloride of silver_, by adding common salt until no further
milkiness can be produced. If the liquid is well stirred, the chloride of
silver sinks to the bottom, and may be washed by repeatedly filling the
vessel with common water, and pouring off the upper clear portion when
the clots have again settled down. The chloride of silver thus formed may
afterwards be reduced to metallic silver by a process which will presently
be described.
b. _Separation of Silver from solutions containing alkaline Hyposulphites,
Cyanides or Iodides._--In this case the silver cannot be precipitated by
adding chloride of sodium, since the chloride of silver is _soluble_ in
such liquids. Therefore it is necessary to use the sulphuretted hydrogen,
or the hydrosulphate of ammonia, and to separate the silver in the form of
_sulphuret_.
Sulphuretted hydrogen gas is readily prepared, by fitting a cork and
flexible tubing to the neck of a pint bottle, and having introduced
_sulphuret of iron_ (sold by operative chemists for the purpose), about as
much as will stand in the palm of the hand, pouring upon it 1-1/2 fluid
ounces of oil of vitriol diluted with 10 ounces of water. The gas is
generated gradually without the application of heat; and must be allowed
to bubble up through the liquid from which the silver is to be separated.
The smell of sulphuretted hydrogen being offensive, and highly poisonous
if inhaled in a concentrated form, the operation must be carried on in the
open air, or in a place where the fumes may escape without doing injury.
When the liquid begins to acquire a strong and persistent odor of
sulphuretted hydrogen, the precipitation of sulphuret is completed. The
black mass must therefore be collected upon a filter, and washed by
pouring water over it, until the liquid which runs through gives little or
no precipitation with a drop of nitrate of silver.
The silver may also be separated in the form of sulphuret from old hypo
baths, by adding oil of vitriol in quantity sufficient to decompose the
hyposulphite of soda; and burning off the free sulphur from the brown
deposit.
_Conversion of Sulphuret of Silver into Metallic Silver._--The black
sulphuret of silver may be reduced to the state of metal by roasting and
subsequent fusion with carbonate of soda; but it is more convenient, in
operating on a small scale, to proceed in the following manner:--first
convert the sulphuret into nitrate of silver, by boiling with nitric acid
diluted with two parts of water; when all evolution of red fumes has
ceased, the liquid may be diluted, allowed to cool, and filtered from
the insoluble portion, which consists principally of sulphur, but also
contains a mixture of chloride and sulphuret of silver, unless the nitric
acid employed was free from chlorine; this precipitate may be heated in
order to volatilize the sulphur, and then digested with hyposulphite of
soda, or added to the hypo bath.
The solution of nitrate of silver obtained by dissolving sulphuret of
silver is always strongly acid with nitric acid, and also contains
_sulphate_ of silver. It may be crystallized by evaporation; but unless
the quantity of material operated on is large, it will be better to
precipitate the silver in the form of chloride, by adding common salt, as
already recommended.
* * * * *
On the Use of Test Papers.
[Sidenote: ON THE USE OF TEST PAPERS.]
The nature of the coloring matter which is employed in the preparation of
litmus-paper has already been described at page 98.
In testing for the alkalies and basic oxides generally, the blue
litmus-paper which has been reddened by an acid may be used, or, in place
of it, the turmeric paper. Turmeric is a yellow vegetable substance which
possesses the property of becoming brown when treated with an alkali;
it is however decidedly less sensitive than the reddened litmus, and is
scarcely affected by the weaker bases, such as oxide of silver.
In using test papers observe the following precautions:--they should be
kept in a dark place, and protected from the action of the air, or they
soon become purple from carbonic acid, always present in the atmosphere in
small quantity. By immersion in water containing about one drop of liquor
potassæ in four ounces, the blue color is restored.
Test-papers prepared with porous paper show the red color better than
those upon glazed or strongly sized paper. If the quantity of acid present
however is small, it is not sufficient in any case simply to dip the paper
in the liquid; a small strip should be thrown in, and allowed to remain
for ten minutes or a quarter of an hour.
If the paper, on immersion, assumes a _wine-red_ or purple tint, in place
of a decided red, it is probably caused by carbonic aid gas: in that case
the blue color returns when the paper is washed and held to the fire.
Blue litmus-papers may be changed to the red papers used for alkalies by
soaking in water acidified with sulphuric acid, one drop to half a pint.
* * * * *
The Salting and Albumenizing Paper.
[Sidenote: SALTING PAPER, ETC.]
Take of
Chloride of ammonium, or pure chloride of sodium 200 grains.
Water 10 fluid oz.
Albumen 10 fluid oz.
If distilled water cannot be procured, rain water or even common spring
water[L] will answer the purpose. To obtain the albumen, use new-laid
eggs, and be careful that in opening the shell the yelk is not broken;
each egg will yield about one fluid ounce of albumen.
[Footnote L: If the water contained much sulphate of lime, it is likely
that the sensitiveness of the paper would be impaired (?).]
When the ingredients are mixed, take a bundle of quills or a fork, and
beat the whole into a perfect froth. As the froth forms, it is to be
skimmed off and placed in a flat dish to subside. The success of the
operation depends entirely upon the manner in which this part of the
process is conducted; if the albumen is not thoroughly beaten, flakes of
animal membrane will be left in the liquid, and will cause streaks upon
the paper. When the froth has partially subsided, transfer it to a tall
and narrow jar, and allow to stand for several hours, that the membranous
shreds may settle to the bottom. Pour off the upper clear portion, which
is fit for use. Albumenous liquids are too glutinous to run well through a
paper filter, and are better cleared by subsidence.
A more simple plan than the above, and one equally efficacious, is to
fill a bottle to about three parts with the salted mixture of albumen and
water, and to shake it well for ten minutes or a quarter of an hour, until
it loses its glutinosity and can be poured out smoothly from the neck of
the bottle. It is then to be transferred to an open jar, and allowed to
settle as before.
The solution, prepared by the above directions, will contain exactly ten
grains of salt to the ounce, dissolved in an equal bulk of albumen and
water. Some operators employ the albumen alone without an addition of
water, but the paper in that case has a very highly varnished appearance,
which is thought by most to be objectionable.
The principal difficulty in albumenizing paper is to avoid the occurrence
of streaky lines, which, when the paper is rendered sensitive, bronze
strongly under the influence of the light. The writer believes these to
be caused by a commencing decomposition of the animal matter composing
the cells in which the albumen is retained and the best remedy appears to
be to use the eggs quite fresh; the same object may sometimes (but not
invariably) be attained by allowing the albumen to stand for several weeks
until it has become sour; after which it will be sufficiently limpid to
run through a filter.
In salting and albumenizing photographic paper by the formula above given,
it was found that each quarter sheet, measuring eleven by nine inches,
removed one fluid drachm and a half from the bath; equivalent to about
one grain and three quarters of salt (including droppings). In salting
plain paper, each quarter sheet took up only one drachm; so that the
glutinous nature of the albumen causes a third part more of the salt to be
retained by the paper.
_Selection of the Paper._--The English papers are not good for
albumenizing; they are too dense to take the albumen properly, and curl
up when laid upon the liquid; the process of toning the prints is also
slow and tedious. The thin negative paper of Canson, the Papier Rieve, and
Papier Saxe, have succeeded with the writer better than Canson's positive
paper, which is usually recommended; they have a finer texture and give
more smoothness of grain.
To apply the albumen; pour a portion of the solution into a flat dish to
the depth of half an inch. Then, having previously cut the paper to the
proper size, take a sheet by the two corners, bend it into a curved form,
convexity downwards, and lay it upon the albumen, the centre part first
touching the liquid and the corners being lowered gradually. In this way
all bubbles of air will be pushed forwards and excluded. One side only of
the paper is wetted: the other remains dry. Allow the sheet to rest upon
the solution for one minute and a half, and then raise it off, and up by
two corners. If any circular spots, free from albumen, are seen, caused by
bubbles of air, replace the sheet for the same length of time as at first.
The paper must not allowed to remain upon the salting bath much longer
than the time specified, because the solution of albumen being _alkaline_
(as is shown by the strong smell of ammonia evolved on the addition of the
chloride of ammonium), tends to remove the size from the paper and sink in
too deeply; thus losing its surface gloss.
Albumenized paper will keep a long time in a dry place. Some have
recommended to press it with a heated iron, in order to coagulate the
layer of albumen upon the surface; but this precaution is unnecessary,
since the coagulation is perfectly affected by the nitrate of silver used
in the sensitizing; and it is doubtful whether a layer of dry albumen
would admit of coagulation by the simple application of a heated iron.
_To render the paper sensitive._--This operation must be conducted by the
light of a candle, or by yellow light. Take of
Nitrate of Silver 60 grains.
Distilled Water 1 ounce.
Prepare a sufficient quantity of this solution, and lay the sheet upon it
in the same manner as before. Three minutes' contact will be sufficient
with the thin negative paper, but if the Canson positive paper is used,
lour or five minutes must be allowed for the decomposition. The papers are
raised from this solution by a pair of bone forceps or common tweezers
tipped with sealing-wax; or a pin may be used to lift up the corner, which
is then taken by the finger and thumb and allowed to drain a little before
again putting in the pin, otherwise a white mark will be produced upon the
paper, from decomposition of the nitrate of silver. When the sheet is hung
up, a small strip of blotting-paper suspended from the lower edge of the
paper will serve to drain off the last drop of liquid.
The solution of nitrate of silver becomes after a time discolored by the
albumen, but may be used for sensitizing until it is nearly black. The
color can be removed by animal charcoal,[M] but a better plan is to use
the "kaolin" or pure white china clay. The writer has also tried the
common "pipe-clay," which answered perfectly, but appeared to injure the
sensitiveness of paper subsequently floated upon the bath (?).
[Footnote M: Common animal charcoal contains carbonate and phosphate
of lime the former of which renders the nitrate of silver _alkaline_;
purified animal charcoal is usually acid from hydrochloric acid.]
Sensitive albumenized paper, prepared as above, will usually keep for
several days, if protected from the light, but afterwards turns yellow
from partial decomposition.
=Comparison of British and French Weights and Measures.=
[Sidenote: WEIGHTS AND MEASURES.]
WEIGHTS.
Grain, Apothecaries' = 0·0648 grammes, French.
Ounce " = 31·102 "
" Avoirdupois = 28·346 "
Drachm, Apothecaries' = 3·888 "
----
Gramme = 15·4310 grains, Apoth.
Decigramme = 1·5434 " "
Centigramme = 0·1543 " "
----
MEASURES OF CAPACITY.
_Cubic Inches._ _Fluid Ounces._
Litre = 61·028 = 35·79
Decilitre = 6·02 = 3·57
Centilitre = 0·610 = 0·35
Millilitre = 0·061 = 0·03
----
_Lb._ _Oz._
Killogramme = 2 3-1/4 Avoirdupois.
----
MEASURES OF LENGTH.
Metre = 39·37 inches.
Decimetre = 3·93 "
Centimetre = 0·39 "
Millimetre = 0·03 "
----
Cubic inch of water at 32° = 252·45 grains.
" " mercury " = 3425·35 "
Fluid oz. of water = 437·50 "
" " measures = 1·73 cub. in.
1 f. drachm = 54·68 grains.
1 pint (New York) = 27·68 cub. in.
1 oz. bromine = 2-1/2 f. drachms.
1 grain, Troy or Apoth. = 1·097 gr. Avoir.
1 lb. Avoir. = 7000 Troy grs.
1 " = 7680 of its own grs.
The drachm Avoirdupois is never used except in weighing silk.
Pendulum vibrating seconds at New York = 39·102 inches.
In weighing solids, few weights are really necessary if they are properly
assorted; nothing less than half a grain is likely to be useful, and
the series following will weigh any quantity from the half grain to two
thousand one hundred and ten and a half grains, by differences of only a
single grain.
The numbers are in grains, but the same principle may be carried out with
any other denomination, whether ounces, pounds, or tons.
1/2, 1, 2, 3, 4, 10, 20, 30, 40, 100, 200, 300, 400, 1000, &c.
The artist should be provided with not less than three glass measures--one
of a pint, graduated to ounces--one of two ounces, graduated to
drachms--and one of two drachms, graduated to minims.
* * * * *
=Lewis's Patent Glass Baths= for Nitrate of Silver Solutions.--Since the
foregoing pages have been in print this new article of Baths has been
introduced, and will probably supersede all others now in market. They
are encased in a box made expressly to hold them, and form a valuable
and important improvement in the apparatus used in the various Glass
processes.
INDEX.
Aberration, chromatic, 23;
spherical, 22.
Acetic acid, 66.
Albumen, 63;
preparation of positive paper with, 206.
Alcohol, 70;
used in sensitizing paper, 201.
Ammonia, 71.
Ammonio-nitrate of silver, preparation and use of, 152.
Animal charcoal, 74.
Barium, chloride of, 77.
Baths, glass, 211;
gutta-percha, 34.
Bichloride of mercury for whitening positives, 159.
Bromide and iodide of potassium and silver, 60.
Bromide of potassium, 73.
Bromine, properties of, 72.
Bromo-iodized collodion for positives, (ambrotypes), 58, 59;
for negatives, 60.
Camera boxes, 28.
Camera, construction of, 28.
Camera stands, 31.
Carbonate of soda, 73.
Chemical and visual focus, 21.
China clay, 75.
Chloride of ammonium, 77.
Chloride of barium, 77.
Chloride of gold, preparation of, 83;
for toning, 155
Chloride of sodium, 78.
Chlorine, 75.
Chromatic aberration, 22.
Citric acid, 78.
Cleaning glass plates, 129.
Coating large glasses with collodion, 160.
Collodion, manufacture of, 53;
iodized for positives, 58, 59;
for negatives, 60;
mode of coating glasses with, 131;
vials, 38.
Collodio-Albumen process, Dr. Taupenot, 190.
Color-boxes, 38.
Cutting's patents and correspondence, 173.
Cyanide of potassium, 79;
use of, 63.
Decomposition of light, 16.
Developing solution for positives, 62;
for negatives, 144, 145.
Dippers, glass and gutta-percha, 34.
Double iodide of potassium and silver, 61.
Ether, preparation of, 79.
Fixing positives on glass, 134;
negatives on glass, 146;
positives on paper, 155.
Fluoride of potassium, 81.
Fogging of collodion positives, 137.
Formic acid, 81.
Fulminating gold, 84.
Gelatine, properties of, 82;
for mounting photographs, 157.
Glass, cementing, 158.
Glass plates, cleaning of, 129;
coating with collodion, 131;
coating with albumen, 193.
Glass rods, bending of, 158.
Glycerine, its properties, 82.
Gold, chloride of, preparation of, 85;
for toning, 155.
Grape sugar, 86.
Hadow, Mr., Researches and Formula for making soluble cotton, 46;
on iodizing collodion, 54.
Head rests, 33.
Helio, collodion process for positives and negatives, 164.
Honey, 86.
Humphrey's collodion gilding, 63.
Hydrochloric acid, 87.
Hydriodic acid, 87.
Hydrosulphuric acid, 88.
Hypo bath, 203.
Hyposulphite of gold, 85.
Hyposulphite of silver, 17.
Hyposulphite of soda, preparation and properties of, 89.
Instantaneous positives, 159.
Iodide of ammonium, preparation of, 91;
for iodizing collodion, 58, 59.
Iodide of cadmium, 92.
Iodide of iron, preparation of, 93;
its uses and acceleration, 159.
Iodide of potassium and silver, preparation of, 61;
use in sensitizing collodion, 58, 60.
Iodide of potassium, properties and preparation of, 94.
Iodide of silver, preparation and properties of, 112;
its use in the nitrate bath, 65, 147.
Iodine, preparation and properties of, 90.
Iodized collodion, 58, 59, 60, 131.
Iron, perchloride of, 98.
" protonitrate of, 97.
Jenny Lind stands, 32.
Kaolin, properties of, 75.
Lenses, double-convex, concavo-convex, double-concave, 19.
Lenses, forms of, 19, 20;
combination of, for portraits, 27;
chromatic aberration of, 23;
spherical aberration of, 22.
Leveling stands, 35.
Light, decomposition of, 16.
Litmus, 98.
Manipulations of the positive collodion process, 129;
negative process, 143.
Measures and Weights, 210.
Milk, 99.
Mounting positives on paper, 157.
Negatives for printing positives, 151, 169.
Nitrate of potash, 102.
Nitrate of silver, 116.
Nitrate of silver bath, mode of preparing for positives, 64;
for negatives, 147;
for negatives and positives in Helio's process, 164.
Nitrate of silver used in developing negatives, 145.
Nitric acid, preparation and properties of, 100;
use in nitrate bath, 65, 147;
use in making soluble cotton, 46.
Nitro-sulphuric acid used in preparing soluble cotton, 42, 51.
Oxide of silver, preparation of, 109.
Oxygen, 109.
Oxymel, preparation of, 105.
Paper, sensitive, for printing, 152;
alcohol used in, 201.
Patent for the use of camphor in combination with iodized
collodion, 176;
for sealing photographic pictures, 177;
for the use of alcohol as a desiccating agent, 178;
for the use of bromide of potassium in collodion, 178;
for the use of japanned surfaces for taking positives, 179;
for photographic pictures in oil, 181;
for making transparent borders, 183;
coloring positives, 185, 187;
for albumenized collodion, 186.
Plate-Holders, Lewis's patent, solid glass corners for, 137.
Plato vices, 64.
Portrait lenses, combination of, 27.
Positives, (ambrotypes,) process for producing, 129;
by the Helio process, 164;
printing on albumenized paper, 192, 206;
ammonio-nitrate of silver used in, 152;
use of chloride of gold in toning, 155;
fixing, 155;
fixing and brightening, (ambrotypes), Humphrey's collodion gilding
used in, 63;
printing frames for, 36; collodion for, 58, 59;
mica used for, 136.
Positives, enlarging from negatives, 199.
Potash, 105;
carbonate of, 106.
Practice of the positive collodion process, 129;
negative process. 143;
Helio's positive and negative process, 164;
printing on paper, 151.
Prism, 14;
refraction of light by, 14.
Protosulphite of iron used in developing positives. 62;
negatives, 144.
Pyrogallic acid, preparation of, 107.
Sensitizing paper, use of alcohol in, 201.
Silver, properties of, 107;
removal of stains from the nitrate of, 161;
recovery of from waste solutions, 203.
Solar spectrum, 14.
Soluble cotton, 42;
Hadow on, 46.
Spherical aberration, 22.
Spots upon positives, 139.
Stains and lines upon positives, 139.
Taupenot, M., his Collodio-albumen process, 190.
Test-paper, use of, 205.
Toning bath for positives on paper, 155.
Weights and Measures, 210.
* * * * *
CORRECTIONS.
[Transcriber Note: Corrections have been applied to text.]
On Page 61 and 16th line from the top, for "Iodide of Silver," read
_Iodide of Potassium_.
On Page 167 and 2nd line, for "32 ounces," read 64 _ounces_.
* * * * *
Transcriber Note
Minor typos may have been corrected. Images were moved so as to prevent
splitting paragraphs. All images were derived from materials made
available on The Internet Archive and are placed in the Public Domain.