Full text of "A manual of photography: intended as a text book for beginners and a book of reference for advanced photographers"

See other formats

ill

*•,

ivA O ^C~

MANUAL OF PHOTOGRAPHY.

L-£-

M A x r A L

PHOTOGRAPHY:

TEXT BOOK FOR BEGIN:

ID PHOTOGRAPHI

V. • . LEA.

SECOND EDITION,

REVISED AXP EX LA:

PHILADELPHIA:
PRINTED FOR THE Al'TH
1871.

Entered according to Act of Congress, in the year 1871, by

M . CAREY LEA,

( « ' < .

PHILADELPHIA i
COLLINS, PB1NTEB, 7u5 JAY.NK STKKET.

PREFACE TO THE SECOND EDITION.

In preparing a second edition of this manual, rendered necessary
by the early exhaustion of the first, the author has endeavored as
far as possible to include all the information useful to the working
Photographer. A very considerable portion of the matter in the
first edition has been cancelled and rewritten, aud over a hundred
pages have been added, so that fully one-half of the book is new.
The number of engravings has been also nearly doubled: all
have been engraved expressly for this manual, and, with two or
three exceptions only, all have been made from original drawings
of the author.

The present edition also contains the .results of several trains
of investigation by the author, hitherto unpublished. Some of
them he hopes will be found of material practical importance,
especially those relative to " permanent" printing-paper and to
water-proof negative varnishes. The arrangement adopted in the
first edition has been continued in this. The first part gives a
short and clear course of instruction for beginners. In the
subsequent parts the various subjects are treated of in detail.

June, 1871.

CONTENTS.

PAET I.
INTRODUCTION TO PHOTOGRAPHY.

PAGE

Chapter I. Selection of Materials 9

II. Making the Negative .17

III. Printing 44

IV. General Rules for Beginners 47

PAET II.

PHOTOGRAPHIC OPTICS AND THEORY OF PERSPECTIVE.

Chapter I. General Optics 52

II. Of Lenses 56

III. Faults incident to Spherical Lenses 58

IV. Focal Lengths of Lenses 66

V. Photographic Objectives .78

VI. Photographic Perspective 97

PART III.

PHOTOGRAPHIC MANIPULATIONS.

Chapter I. The Dark Room 10?

II. The Glass Room . 114

III. Pyroxyline and Collodion 126

IV. The Negative 147

V. Ambrotypes and Ferrotypes 188

VI. Portraiture 190

VII. Landscape and Architectural Photography . . . .208

Vlll

CONTENTS.

PAGE

Chap. VIII. Composition 234

IX. On Copying 251

X. The Stereoscope 256

XI. Microphotography and Microscopic Photography . . 258

XII. Development on Paper 260

XIII. Silver Printing 269

XIV. Failures in Photographic Operations 301

XV. Out-door Photography 344

XVI. Dry Plate Photography 351

XVII. Dry Processes 364

XVIII. Negative Varnishes 375

XIX. Treatment of Residues 379

XX. Photography on Glass and Enamel, and Collodio- Chloride

Printing, &c 383

XXI. Carhon Printing 398

PAET IV.

THEORETICAL CONSIDERATIONS.

Chapter I. General Observations .....
II. Action of Light on Silver Compounds
III. Action of Various Portions of the Spectrum

404
406
413

PART V

Chapter I. Photography in its Relations to Health
II. Chemical Manipulations

415
420

Addenda

431

MANUAL OF PHOTOGRAPHY.

PART I.

INTRODUCTION TO PHOTOGRAPHY.

CHAPTER I.
SELECTION OF MATERIALS.

\ 1— Selection of Photographic Lenses.

The information first wanted by the beginner will be as to his
materials, and especially as to his lenses. They are to form the
image which it will be his part to render permanent, and, unless
they are right, his work will never be satisfactory. And they
must not only be good in themselves, but expressly suited for
the work which he proposes to do.

Such a thing as a universal lens does not exist. One combi-
nation is best for one purpose, another for another.

For Landscapes the best lenses are the View Lens, the Rapid
Rectilinear, and the Steinheil Aplanatic. If architectural subjects,
or any others, are introduced, in which straight lines must be
preserved, the view lens will be unsuitable, because it slightly
distorts, and although this distortion is of no consequence when
buildings are not introduced, it will be a sufficient reason, when
such are included, for using a lens of which the stop, or dia-
phragm, is central, that is, between two lenses, as in the case of
the second and third of the above-mentioned objectives.

The view lens has also this fault, that it includes but a small
angle of view, or, in other words, but a small portion of the
scene at which it is exposed. This defect has been remedied in
Dallmeyer's wide-angle view lens, of which the writer thinks
very favorably ; it is, however, not adapted for architectural sub-
jects, for the reason already given.
2

10 INTRODUCTION TO PHOTOGRAPHY.

The lens, whether single, double, or triple, is termed an Objective.
The single lens has its stop in front, that is, on the object side,
and the concave side of the lens must always be turned also
towards the object. Sometimes, in cleaning the lens, it may hap-
pen that it is set back wrong side foremost, the effect of which is
very injurious. In all cases when any lens is taken to pieces to
clean, the utmost care must be used to replace everything exactly
as before.

For Portraits there is but one lens proper, and that is the
" portrait combination," invented by Petzval, and made by many
excellent opticians in all parts of the world. For groups the
Steinheil aplanatic is the best lens ; it is often applied also for
taking portraits, which may be obtained of large size with com-
paratively small lenses, at the expense, however, of rapidity of
action. Triplets were formerly much used for groups, but are
now superseded by the lens just named.

For copying engravings, plans, maps, &c, any lens with central
stops may be used, except the portrait combination, which, as
well as the view lens, is unsuited for such work. In copying, a
stop with small opening will be proper.

A great mistake is often made by those who interest themselves
in photography, in practising too much economy in their lenses.
One lens cannot be made to do the work of another, except at a
sacrifice of excellence of result. Every lens has a certain size of
picture for which it is suited ; if vised for a smaller size, it will
give a less angle of view, and work more slowly, than the lens
made for that size; if strained to cover a larger plate than that
which the maker intended, a sufficient sharpness of focus can
only be got by using too small a stop. And the beginner cannot
too soon learn what is too often overlooked, that, where solid
bodies are to be depicted, a stop of a fair size is essential if the
best effects are desired. It is only where flat objects, such as
maps, engravings, or plans, &c, are to be copied, that small stops
are right.

If the student intends at first to provide himself with one lens
only, that had probably better be a Steinheil aplanatic. This
and the Dallmeyer " rapid rectilinear" are the nearest approaches
to a universal lens that we have.

In commencing photographic work, the student, whether he
intends devoting himself chiefly to portraiture or to landscape

SELECTION OF MATERIALS. 11

work, whether as amateur or professional photographer, will find
it most convenient to begin by taking views, or, in other words,
he will point his camera out of the windows and practise on
whatever scene presents itself. He will endeavor in this way,
firstly, to learn to make clean work, that is, to get negatives free
from failures, such as stains, fog, comets, &c., and secondly, to
secure harmonious effects. The first will be soon accomplished,
but to obtain the latter in a good degree will require effort and
experience. The high lights must be dense enough not to print
through before the shadows are dark enough, and there must be
detail everywhere. That is, the high lights must never show a
flat white surface, but must be relieved by faint half tint, except,
perhaps, in some very minute portion. The shadows must not
show a black mass, but the shape and form of the objects in
shadow must be everywhere perceptible.

Portraiture may next be attempted, and, in default of a sitter,
a white plaster bust may be used, with different colored draperies.
A white bust with black drapery makes a very difficult subject,
and to obtain at once a well-shaded face and preserve the folds
in the drapery, will be no easy task, but will afford excellent
practice.

Care and cleanliness in the operations, and a thoughtful and
close study of results, and comparison with their cause, will ac-
complish more in a month, than rapid, careless work in two or
three.

In undertaking landscape photo <rjraphy, it is not well to begin
with views too small or too large. The smaller the pictures are.
the more easily they are taken in every respect ; difficulty in-
creases vastly with the dimensions. On the other hand, small
prints are apt to be too trifling and insignificant to repay for the
trouble expended upon them. Therefore the beginner will do
well to start with "half size" plates, and go from that to whole
size, after becoming perfectly familiar with all the manipulations.
Eventually he will probably prefer to advance to 8 x 10 and per-
haps larger work. Generally speaking, the most artistic effects
are got with plates of from 6 J X 8 \ up to 12 x 14. Larger prints
are apt to be less pleasing, however technically perfect. It is no
advantage whatever to have a lens embrace an unnecessarily wide
angle, except, indeed, where architectural objects have to be

12 INTRODUCTION" TO PHOTOGRAPHY.

taken in positions where the photographer cannot recede beyond
a certain point. An angle of 50° to 60° is generally best.

In undertaking portraiture, the beginner will naturally (after
having just practised as above explained) commence with card
portraits. For this work a " card lens" will be wanted, which is
simply a small-size portrait lens. Of these, the French " Jamins"
are the lowest in price ; they are often very fair in their perform-
ances, though not equal to the best English, American, or German
lenses.

Lenses should be kept with the greatest care — never wiped
with anything except clean, soft old linen cambric, and even with
this only ivhen necessary. The exquisite polish on the surface is
of the highest importance, and it is easily injured.

Do not begin by buying second-hand lenses, but go to respon-
sible dealers and purchase the work of makers of reputation.

In choosing amongst a number of lenses by the same maker,
view a piece of perfectly white paper through the lens, holding
the latter close to it. If the appearance shows that the glass of
which the lens is made has any color, especially if that color be
brownish, the lens should be rejected: it may be expected to be
slow. So, too, if, -when carefully examined by reflected light, it
shows any strias, or hair-like lines. "Very small bubbles, or
white spots, if not exceeding one or two, are unimportant, and
often occur in excellent lenses, though, of course, they are better
absent, and, indeed, are rarely, if ever, found in lenses of the best
makers.

These brief remarks are perhaps as much as the beginner can
advantageously act upon. Other points will be explained later.

§ 2.— Selection of Camera.

Without a thoroughly good camera, no first-rate work can be
done, and the beginner cannot make a greater mistake than that
of purchasing a cheap one. Any camera that is not thoroughly
good is absolutely worthless.

A camera is to be tested as follows: —

1. Observe if all the wood-work is sharply cut and closely
fitted.

2. Try the rack and pinion movement, to notice that it works
easily and regularly, and not by jerks.

3. Rack the back forwards until all the bellows bodv is closed

SELECTION OF MATERIALS. 13

in ; then continue to rack up till the back wood-work just comes
into contact with the front. Observe attentively if this contact
takes place everywhere at once — top, sides, and corners. If it
does not, the camera is worthless, for the sensitive plate will in
such a case not occupy a position perpendicular to the optical
axis of the instrument.

4. These points having all been found satisfactory, it remains
to ascertain whether the sensitive plate, when in place, occupies
the exact position of the focussing screen of ground glass.

This is the most essential point of all, and is precisely that in
which cameras, even of good makers, are apt to be defective.
The fault, if it exists, is easily detected with a little attention.

Take a piece of plate glass of the size which the dark slide is
intended to carry, set it in place, close the door, set the slide on
the table, door undermost, and draw out
the shutter. Lay across the middle of the
slide a perfectly flat and rigid ruler, a
draughtsman's straight edge, or a long,
thick, narrow piece of plate glass. Take
a piece of smooth hard card, rest one end
of it on the plate-glass, pressing the side
close up to the ruler, and with a sharp

.... .... , , , TheboUom ofthe car.l A rests

hard pencil draw a hair-line where the card ou „„. gla8Sj „„. side ,,,_,,
touches the ruler. Next repeat this exactly a^liust the ru,<11' /; '■'■ and ,!"'

i • i p i pencil Hoe Is drawn where the

with the focussing slide, ground side of the edge .bc touches the cam a.
glass uppermost. If the camera is well

made, the two hair-lines will exactly coincide to make but one.
If they do not, the camera will require to be fitted over again by
the maker. Care and attention are necessary to make this trial
effectual, but it is essential to make it with every new camera.

An absolute coincidence of the two lines must be insisted on.
At the same time, the experimenter must be sure that he is doing
the measuring correctly, and not producing an apparent discord-
ance by careless manipulation.

The next point requiring attention will be the inside of the door
of the slide. This is always blackened in order that the light
which passes through the sensitive plate during exposure may
not be reflected back upon it, but this blacking is often very in-
sufficiently done. It is not sufficient that the surface be perfectly
black, it must also be perfectly dead, must have no appearance

14 INTRODUCTION TO PHOTOGRAPHY.

"whatever of shining when held with the light falling upon it in
any direction.

If any reflection is visible, and the maker be accessible, he
should be required to render the surface perfectly dead. If the
owner, however, finds it necessary to attend to this himself, he
can mix

Powdered gum arabic 1 drachm.

Brown sugar £ "

Fine lampblack 2i drachms.

and rub them well together with a little hot water to a thick
paste. This is to be applied with a flannel rag, and rubbed in
well and evenly. But if the black appears to have been origi-
nally applied in the form of black varnish, it will be well to
remove this polish in a great measure by rubbing with a rag
moistened with a mixture of alcohol and ether. If the above
mixture shines when dry, there was too little lampblack. If it
soils the finger when rubbed, too much.

Carriers are small frames constructed to enable one with any
given camera and slide to take a smaller plate than the proper
plate of the camera ; large cameras are often supplied with a set
of these to enable the owner to take a whole series of sizes with
the same instrument. Thev are certainly very convenient: thev
have the objection, however, that they sometimes yield a little
to the pressure of the spring of the back of the slide, and allow
the plate to advance too near the point, by a little distance,
which may, however, displace the focus. Therefore the above
system of testing should be repeated with each carrier. This
fnethod has the advantage that the plates receive the same pres-
sure, and are under exactly the same conditions, as when receiv-
ing the image.

Of course, in testing, the plates set into the slides must be per-
fectly flat, or erroneous indications will inevitably result.

Although carriers will be often useful, yet, as far as practi-
cable, it will be better to use the slide with the size of plate
for which it was made.

Prevention of Stains. — Stains often occur from the absorption
of more or less decomposed nitrate of silver from the slide, left
there on occasions of previous use. Saturating the whole inside
of the slide with some repellant substance has been found useful
as a preventive. Paraffine or lard may be used. If paraffine be
used it must be melted and the different parts of the slide plunged

SELECTION" OF MATERIALS. 15

in successively. Lard has the advantage that it may be rubbed
in cold. Either the application should be made when the slide
is new, or it should be well washed and all old stains scraped
carefully away. If paraffine be used, each portion of the holder
should remain in it about ten -minutes, that it may be properly
absorbed.

The Cut-off. — All slides should have a cut-off, a wooden spring
inside the slit through which the shutter passes, and which closes
the opening light tight when the shutter is withdrawn.

I 3. — Selection of Stand.

For out-door work, a folding tripod is employed. For in-door
work many forms are in use. Those in which the table is sup-
ported by a single cylindrical stem are very objectionable, for
want of steadiness. The most absolute steadiness is requisite,
and a large proportion of the stands in the market fail to fulfil
this requirement. A stand cannot be judged if almost unloaded.
Place a heavy camera on it, strike it a gentle blow, and observe
if anv vibration follows.

\ 4. — Selection of Chemicals.

Few photographers have sufficient chemical knowledge to be
able to apply tests of purity to their chemicals. Perhaps the
very best advice that can be given to a beginner is to observe
who amongst his friends is most regularly and completely suc-
cessful, and then to obtain materials from the same place. In
fact, the demands of photography are now so enormous, that good
materials can be obtained almost anywhere. The substance most
likely to give trouble, in the hands of a learner, is nitrate of
silver. This last should alwa}'s be purchased prepared expressly
for photography — never from the druggist. Without the best
and purest neutral nitrate, the negative bath cannot be expected
to work well.

The same remark is to be made respecting alcohol and ether,
which are needed of the very best quality and higher grade than
usually sold by even the best druggists. The photographer will
need to have alcohol and ether always at hand to thin his collo-
dion with ; for, after coating a plate, the excess of collodion that
is poured off (into a separate bottle) is always much thicker than

INTRODUCTION TO PHOTOGRAPHY.

the stock in the bottle, and will probably need to be thinned as
well as filtered before using again. This thinning work needs to
be done chiefly with ether, sometimes with the addition of a little
alcohol.

I 5.— Selection of Glass for Negatives.

Of all matters connected with photography, the selection of the
glass is that which is most habitually overlooked.

Plate glass has some evident advantages over blown. Its sur-
face is a true plane; the material of which it is made is generally
whiter, and it is free from blebs and other faults and irregularities.
On the other hand, it is found that the artificial surface of the
plate glass, produced by polishing, does not hold the collodion
and varnish so well after a lapse of years as the natural surface
of the blown, and that with time the film is more apt to crack
and suffer. The surface of plate glass is also more porous than
the natural surface of blown glass, and holds back stains more
strongly.

In consequence of the high price of plate glass in America,
blown glass is almost exclusively used. But in this blown glass
there is great variety of quality.

1. A good surface, free from knots and blebs, is important, and
no glass that has not this characteristic should be employed. A
smooth collodion film cannot be got on an irregular surface.

2. Glass varies greatly in thickness. It is a great advantage to
have stout glass ; the loss from breakage of negatives in the
printing-frames is less, and the operator may venture to apply a
strong pressure in his frames where his glass is strong : he thereby
gets a sharper and cleaner print.

3. Blown glass varies extremely in curvature. Much of it is
very flat; much, again, greatly curved. All that is much curved
should be rejected. See also Part III., Chap. IV.

MAKING THE NEGATIVE. 17

CHAPTER II.
MAKING THE NEGATIVE.

§ 1. — Absolute Cleanliness.

All photographic work depends upon the delicate turning of
nicely-balanced affinities, which a slight alteration of the condi-
tions may completely reverse. It is necessary, therefore, that the
operator should not only follow closely the directions given, but
that he should learn to constantly maintain a perfect cleanliness.

All the vessels which he uses must be irreproachably clean ;
and, as far as practicable, each should be restricted to some par-
ticular use, so that if slight vestiges of substances escape the
attention, such may be less hurtful. The hands, especially, must
be constantly washed ; there is no way in which small portions of
material are so readily transferred as by adhesion to the fingers.
In all these respects too much precaution cannot be taken, and
many failures, perfectly unaccountable to the beginner, may be
traced to trifling neglects of this sort. Nothing will so well
repay its trouble as a systematic and invariable attention to hav-
ing the hands and all the utensils clean beyond suspicion.

§ 2. — Preparing the Glass.

Unless the glass be •perfectly clean, a regular development can-
not be hoped for. Perhaps the best method of cleaning glass is
one introduced into photography by the writer a few years ago,
and which has since been extensively used.

Provide a large glass pan, in which make a mixture in the
following proportions : —

Bichromate of potash 2 ounces.

Sulphuric acid 3 fluidomices.

Water 25 fluidounces.

Place the pieces of glass in the pan alternately, one at each end,
so that their ends shall overlap a little, and allow the free pas-
sage of fluid between them. For new glass half a day will be

18 INTRODUCTION TO PHOTOGRAPHY.

sufficient to destroy the greasiness. Old glass that has been used
before, should have a day, and, if it has been varnished, even
longer, or a mixture containing only half the above proportion
of water.

So long as this bath is yellowish-brown, it is active. When it
acquires a violet color, it is spent, and will want renewing.

After a suitable immersion in the cleaning bath, place the
glasses one by one in a pan under a water-faucet, and, as fast as
the water fills the pan, lift one end, and empty it. Repeat this
half a dozen times at least. Then take up the first plate, let the
stream of zvater run some seconds, first on one side, then on the other,
until every possible trace of the cleaning bath is removed, and
then rub dry with soft blotting-paper — not with cotton rags, as
so universally directed. Cloths always leave fluff, which has to
be carefully brushed a'way afterwards — paper does not.

It is usual to roughen the edges of the plates, and thus diminish
the chances of having the film slip off during the work, and also
to lessen the risk of cutting the fingers. A coarse file is com-
monly used, but the writer greatly prefers a coarse whetstone,
such as is used for sharpening scythes. It cuts faster and more
evenly, doing better work in less time, and is good until wholly
worn away, whereas the file quickly becomes clogged and smooth.
The whetstone, or file, is to be drawn three or four times along
each edge, holding it so that it shall rest more on the face than
on the edge. The roughing should precede the cleaning. After
cleaning the glass must be handled as little as possible ; its face
must never be touched by a finger, or there will probably be a
finger mark developed on the negative. Glass when cleaned
should be laid away, each piece in a fold of soft clean blotting-
paper, in which it may lie even for months without injury, if set
in a box kept out of the reach of dust and vapors. The writer
has used glass which, after cleaning with the bichromate bath,
had been kept eighteen montlis ; it gave good results. When
glass is to be kept for more than a few days, it should rest on its
edges, and not lie fiat, otherwise there is a jiossibilily (the writer
has seen this happen) that folds in the paper between two sheets,
may show in the development.

Nitric acid maybe used for cleaning, or caustic alkali ; but the
above is not only the easiest and most economical, but is perhaps
the only one with which an old picture never reappears in the
development of a new one.

MAKING THE NEGATIVE. 19

Plates that have been varnished are necessarily more difficult to
clean. They will need a stronger bath and a longer immersion
in it. Or the varnish may be easily and completely removed by
soaking in a bath of caustic soda. It is best to wait till a quan-
tity accumulate, and then to dissolve a pound of " concentrated
lye" in a half pailful of hot water, and put the plates in, one by
one, leaving them in till they easily rub clean ; after rinsing off,
put them into the bichromate bath for a few hours. When com-
mon photographic glass is used, varnished plates scarcely repay
for the trouble of cleaning, especially as, if the cleaning is not
done carefully, the negatives will not be satisfactory.

§ 3.— The Negative Bath.

Of all that the photographer works with, nothing exceeds in
importance the negative bath. Its preparation is exceedingly
easy, and, if thoroughly good nitrate of silver be used, it cannot
fail to work well, if no mistake or oversight has been made in
its preparation.

A vertical glass bath is to be procured ; there is none other which
is perfectly safe. In a porcelain bath, if there is the slightest
flaw in the glazing inside, the solution will penetrate it, and
gradually saturate the whole of the porous biscuit which makes
the body of the vessel, between the inside and outside glazing.
This not only involves a great loss of expensive silver solution,
but after a time the outside glazing also probably cracks, and
some clay the operator finds his bath empty. In many cases
porcelain baths last for years, but there is never a certainty about
them, as there is with glass. The "photographic ware" has been
much complained of in the same way.

A glass bath requires to be supported in some way, and the
simplest is to place it in a box sufficiently wide to give the bath
a proper inclination, laying a wooden or pasteboard cover over
it, when not in use, to exclude the dust; or boxes may be pur-
chased provided with covers, and with an iron foot at the back
to enable the box to stand at a proper inclination (see beyond,
Fig. 6, p. 24).

A "whole-size" bath, for plates 6Jx8j, will be found a con-
venient one for the beginner, as, even if much smaller plates are
worked with, it is not worth while to use a smaller bath — it holds
too little solution and changes too rapidly. The " whole-size"

20 INTRODUCTION TO PHOTOGRAPHY.

baths require about 25 ounces of solution to charge them. This
solution is to be made as follows : — ■

Dissolve 2 ounces of nitrate of silver in 25 ounces of water,
which need not be distilled water. Leave the solution in a glass
bottle in the sunlight for several hours, or in cloudy weather for
a day or two near a southerly window. Separate this into two
equal portions. Take 3 grains of iodide of potassium or iodide
of ammonium, dissolve it in a few drops of water, and pour it
into one of the halves ; stir up well and let stand half an hour,
or longer. Filter the other half into a clean bottle, and then filter
into it the second half, that to which the iodide of potassium was
added.

Observe: The two portions are not to be mixed until after they
are filtered, and the portion to which the iodide was added is to
be filtered last, if the same filter be used for both.

Next, take a clean six-ounce stoppered vial ; place in it one
fluidrachm1 of pure nitric acid, fill it up with water, and label it
" Dilute nitric acid, ten minims to the ounce." To the twenty-
five ounce bath add one fluidrachm of this dilute acid.

If this does not prevent fogging, the fault is probably in the
collodion. It will therefore be advisable to add to it enough
tincture of iodine to bring it up to a light sherry wine color.
Tincture of iodine (which must not be confounded with " Lugol's
Solution") may be purchased ready made, or be prepared by dis-
solving a quarter of an ounce of iodine in four ounces of alcohol ;
it should be prepared and kept on hand, as it does better after
standing for a time. If with a collodion of a sherry wine color,
and the acidification already mentioned, which is in the propor-
tion of about a drop of nitric acid to twenty ounces of bath, the
fogging continues, it shows that there is something very much
wrong. The operator may try the effect of a further addition
of acid, but he may be assured that either he has made some mis-
take, or is working with bad materials. More acid may force a
clean picture, but will fail to give delicately graded shadows and
half tints. (See also Chapter on Failures.)

The negative bath should always be kept covered to exclude
dust and dirt. Constant care must be taken to let no extraneous

1 The photographer should provide himself with graduated measures of one
pint, of two ounces, and a minim glass for measuring a drachm and its frac-
tions. One minim of water weighs one grain nearly, and corresponds approxi-
mately with a drop. Sixty minims make the fluidrachm.

MAKING THE NEGATIVE. 21

matter get into it, and to place it in nothing, and nothing in it,
that is not perfectly clean.

When the bath by use will no longer work well, add "bicarbo-
nate of soda till the bath just turns red litmus paper blue, boil it
down to one-half, expose it for a day to sunshine, filter, dilute,
and add just enough dilute nitric acid to get a clean picture, with
a collodion known beforehand to give good results. Of course
nitrate of silver must be added from time to time to keep up the
strength, which is rapidly diminished by sensitizing plates.

Litmus Paper is useful to indicate whether solutions are acid,
alkaline, or neutral. An acid solution turns blue litmus red ; an
alkaline turns red litmus blue; a neutral solution is without influ-
ence on either. The paper should be cut into narrow strips, and
kept in a wide-mouthed vial, corked.

§ 4. — The Developer.

Make the developer as follows: —

Proto-sulphatc of iron 400 grains.

Acetic acid, No. 8 H ounce.

Alcohol l\ "

Water 20

The developer, if kept corked, will keep for a couple of months.
It is ready for use as soon as the solution of the sulphate of iron
is complete and the whole has been filtered. As it grows older
it becomes reddish, but, so long as kept clear by nitration, the
reddening is rather beneficial than otherwise.

§ 5. — Collodionizing the Plate.

Holding the clean glass plate by pressing a finger or two of
each hand at the edges of the plate (the fingers must never touch
the face), hold it up to the light, and look along the long edge to
see which is the convex and which the concave side. The choice
between these is a matter involving a variety of considerations
which will be stated in full farther on. The beginner will find
it best to generalize as follows : for portraits and for buildings,
coat the hollow or concave side ; for landscapes, the convex side.
Next brush it off with a broad (two-inch) soft camel's hair brush,
which must be kept clean and free from dust, and be used for no
other purpose. It should not even be left in damp air, or it may

INTRODUCTION TO PHOTOGRAPHY.

Fisr. 2.

leave streaks of dampness on the plate, producing stains in de-
velopment. It is an excellent plan to have a tin box, three or
four inches deep and an inch larger in breadth and length than
the plates which thus lie in it between folds of clean blotting-
paper. Any impurity in the paper is transferred infallibly to the
glass. The writer has seen glasses between which newspapers
had been laid, take off a complete copy of the print. If the
glasses remain for a long time unused, the box should be turned
on its edge that the plates may not rest on each other. The brush
should lie in this box, ready for use. When the brush is drawn
over the surface of the glass, it should slip over with a peculiar
facility. The careful operator will occasionally notice an absence
of this facility : the difference is so slight that only experience
enables one to appreciate it, but when once observed it is unmis-
takable. This always indicates that the plate, though it may
have been well cleaned, has not been sufficiently rubbed in dry-
ing. A quick rubbing with clean dry blotting-
paper will at once remove this, and enable the
brush to pass easily and lightly over the sur-
face. But rubbing just before coating is always
objectionable : the glass becomes electrical, and
attracts and holds motes of dust that may be
floating through the air.

After brushing, gently but thoroughly, take
the plate in the left hand, three fingers sup-
porting it underneath, the thumb pressing on
the corner, and the narrow end towards you.
Fold up a piece of blotting-paper, and put it
between the bottom of the plate and the finger
ends. For want of this there will occasionally
appear curious mottled markings at the points
where the fingers touch the under side.

Take the collodion bottle in the right hand,
having previously removed the cork and wiped
the lip to remove dust or fragments of dried
collodion. {Never neglect this, and repeat it
between every plate.)

Pour the collodion slowly and steadily on,
letting it come upon the plate at a spot a little further from you
than the middle — say equi-distant from the end and the two

Hold at 3, pour on at
A, or even a little below
the dot, and off at i.

Fig. .3.

MAKING THE NEGATIVE,

Fi<*. 4.

sides (see A, Fig. 2). Pour on till the pool covers rather less
than half the plate.

Incline the plate till the pool extends itself to corner No. 2
(see also Fig. 3), then to corner No. 1 (see Fig. 4). Then bring
it down to the lower end, reaching, however,
corner No. 3, where the thumb is, before cor-
ner No. 4, at which it is to be poured off (see
Fig. 5).

This is all to be done quite coolly, and yet
without loss of time. The collodion must go
up full to the edge of the plate all round, and
with a little practice this is accomplished with
great ease and without spilling a drop. When
the operator has learned to do this with ease,
he will find it a good plan to send back the
collodion from 4 to 1 before pouring off, by raising corner 4 ; as
soon as the wave reaches 1, corner 4 is lowered again, and the
excess poured off there. This makes a more even plate.

It is best not to pour back the collodion into the bottle from
which it came, but have a separate bottle ready, uncorked.

The operation of pouring off requires the operator's best atten-
tion. The plate must be slanted but very little, otherwise the
collodion runs off too fast, and leaves too thin a film, especially
at corner No. 1. At the same time the operator 7-ocJcs the plate,
that is, turns it backwards and forwards, one quarter round,

INTRODUCTION TO PHOTOGRAPHY

without changing the inclination (see Fig. 5, in which the dotted
line shows the direction taken by the upper left-hand corner).
If this be neglected, the film will be full of crapy lines. If the
plate be properly rocked, it will dry as smooth as the glass itself.
The writer has endeavored here to give as clear a description
of the method of collodionizing a plate as possible ; at the same
time it is unquestionably one of those manipulations which it is
almost necessary to see done, in order to execute properly one's

self.

No formula for making collodion is given here. The beginner
is strenuously advised to introduce no unnecessary difficulty by
such attempts, but to procure a reliable collodion from some pro-
fessional photographer or trustworthy dealer. When he has
mastered the manipulations, he may advantageously make his
own collodion, for which a number of good formulas will be
given further on. The nitrate bath, the developer, and the fixing
solution, on the other hand, every one must learn to prepare for
himself from the outset.

§ 6. — Sensitizing.

The collodion coating quickly sets — in half a minute or less in
summer, whilst a minute may be necessary in winter. The be-
ginner may judge of its condition by gently touching it near
corner No. 4 with the tip of the finger; if the film does not wet

Fie. 6.

the finger, but receives a slight depression from it, which remains
after the finger is removed, it is called "tacky," and is now
ready for immersion in the bath. Up to this time the rocking
motion is to be steadily continued, pausing only for a second, if

MAKING THE NEGATIVE. 25

necessary, to ascertain the condition -of the film. "When this has
attained the proper state of setting, the plate is to be rested upon
the dipper firmly and steadily. The operator next lowers the
dipper, carrying the plate with it, into the bath, by a gentle, con-
tinuous, and uninterrupted motion. For if he pauses for any
fraction of time, however short, the part of the film which at that
moment corresponded with the surface of the bath will show a
distinct line, ruining the negative. No unnecessary delay should
occur in putting the plate in the bath, or the risk of marbled
stains is increased.

Dippers are made of porcelain, glass, and gutta-percha. If glass
ones could be got of a right pattern, they would be preferable,
but made of rods they are too fragile. The porcelain are good,
and the gutta-percha also, provided they are well made, and con-
sist wholly of gutta-percha, without any metallic support in the
centre. The porcelain dipper may rest in the bath when not in
use ; the gutta-percha dipper must never be left in the bath. The
porcelain is the best and safest. It has, moreover, this recom-
mendation, that if the plate slips off, and goes down to the bottom
of the bath, the porcelain dipper can be easily worked under it;
at least this can be done with glass baths, the bottoms of which
are always a little rounded and hollow.

If the plate whitens too rapidly in the bath, it is an indication
that it has waited too long between coating and immersing, has
become too dry, and its sensitiveness will be impaired. The
plate should wait only long enough to prevent splitting in
the bath, or turning mottled in the part least dry, both of which
results are liable to follow too quick an immersion. This mot-
tling must, however, not be confounded with the mottling at the
pouring-off corner, which results from a collodion too thick, or
containing too large a proportion of alcohol, or alcohol not up
to 95 per cent.

It has just been said that the collodion poured off from the
plate must be received into a different bottle. This is because it
is apt to carry with it motes and particles of dust, which appear
on the next plates. The collodion is, however, perfectly good
for subsequent use, but it will not only need to be filtered, but
thinned, because the evaporation which takes place from the
moment that the collodion is on the plate, causes the portions
poured off to be much thicker than the original stock. As the
ether evaporates more rapidly than the alcohol, the thinning is
3

2(3 INTRODUCTION TO PHOTOGRAPHY.

best done altogether with ether. Neglect to thin the collodion
will produce ridgy plates, and especially in hot weather, tend to
the production of small transparent spots, known as pin-holes,
appearing anywhere on the plate, but oftenest in the dense parts,
particularly in skies of landscapes.

(The sources of trouble in photographic operations have been
collected together by the author, and will be found in a "Chapter
on Failures," farther on, in which they have been classified for
easy reference by the photographer whenever occasion may call
for it.)

The plate having been placed in the bath will be left quiet for
a couple of minutes, and then must be moved up and down from
time to time; and a side motion is also beneficial, especially if
the plates show a tendency to form lines in the direction of the
dip, a trouble of which much complaint has been made by some
photographers, though it has never been experienced by the
writer. Until the plate has been in some minutes it should not
be raised in moving so as to be partly uncovered by the silver
solution.

The time requisite for stay in the bath cannot be fixed in
minutes with any positiveness, as it depends somewhat on the
temperature, the nature of the collodion, and the condition of the
bath. From three to five minutes is about the time. The plate
is ready when, on withdrawing from the bath, no oily lines form
on the surface, but the whole face presents a uniform moist film.
The plate should never be left longer than necessary in the bath,
as bv so doing the film tends to dissolve, thus choking the bath
with excess of iodide, and rendering the plate irregular. Worse
still, there is a great tendency in such plates to give flat and dull
images, at least in collodion containing bromides.

There is, of course, always a little latitude allowable. And it
is to be remarked that a plate removed from the bath as
soon as the oily streaks are gone is in condition to give the
cleanest plates; if left a little longer, it gains in sensitiveness, but
also there is a little more tendency to veil.

The plate is now to be removed from the bath and rested on
several thicknesses of soft blotting-paper, changing its position
every few seconds, until it no longer wets the paper. A thorough
draining in this way is very important, and cannot be neglected
without danger of streaks and other irregular action. At the
same time the back of the plate is to be carefully wiped dry with

MAKING THE NEGATIVE. 27

soft paper. This wiping and thorough draining must never be
omitted ; neglect of these precautions will tend to produce
streaks and stains. It is a very good plan to keep ready pieces
of thick soft red blotting-paper, half an inch smaller than the
plate all round ; and after it has< been wiped clean to apply one
of these pieces moistened with clean water, but not too wet, to
the back. This precaution, though recommendable, has not yet
come into general employment. Its use is to diminish internal
reflections or blurring, as will be more fully explained hereafter.

In all these operations the face of the plate must never be
touched by the fingers, and with the same precaution the plate
is to be lifted and gently set into its place in the dark side, taking
care that the shutter is in its place. The door is then closed.

From the time that the plate is lifted from the bath the same
edge must carefully be kept undermost ; that is, the side which
went undermost into the bath must be kept undermost — must be
that which rests on the blotting-paper — must be kept undermost
in the transfer to the dark slide, and the slide with its plate in it
must be carefully kept with that edge downwards, not only during
exposure, but in carrying backwards and forwards and up to the
moment of development. This is essential; neglect of it will
almost certainly result in streaky lines and irregular deposits
along the outside of the plate, running up in places some distance
into the plate. If the small size of the bath renders it necessary
to set the plate in end down, when the side is to be down in the
slide, the plate must be turned immediately on taking it from the
bath, and the draining and blotting done whilst it is in the same
position which it is to have in the slide. In this way no harm
results from the change of position.

Particular descriptions of the dark room and glass room must
be omitted for the present. Here it is sufficient to say that all
the operations of sensitizing and developing must be performed
by yellow light. A very simple way of converting an ordinary
room into a dark room for photographic work consists in pro-
curing some of the very thickest and stoutest brown paper made
for envelopes, and pasting pieces of it over the panes of the win-
dow ; a great deal of light will come through this, sufficient for
all the operations, and yet, if the paper be good and thick and of
fine grain and quality, there will be no danger of fogging. If,
however, the sun shines directly, at times of the day, upon the
window, it will be well to have a buff curtain on rollers inside the

28 INTRODUCTION TO PHOTOGRAPHY.

window, so that when the light is too strong it may be properly
tempered.

If the room used as a dark room has two windows, it will be
found preferable to cover the panes of one only, and to have
closely fitting inside shutters to the other, over the joints of which
black muslin must be pasted or tacked. In this way the room
may be lighted at any moment, and may serve for other uses than
merely as a dark room.

However the dark room be arranged, 'provision must be made for
its thorough ventilation, the fumes of collodion tending to produce
headache, nervous exhaustion, and to undermine the health.
This subject will be recurred to hereafter; it should never be
lost sight of by the photographer who values his health.

» § 7. — Focussing.

The photographer first covers the camera with a black cloth,
and places his head beneath it. The cloth should be ample to
exclude all white light ; even a few scattered rays of light will
greatly diminish the brilliancy of the image as seen on the ground
glass, and interfere with a proper judgment. The picture should
be composed and arranged with the largest opening of the lens,
and after this is done the proper stop is next substituted and the
focus carefully taken.

Few persons have unassisted sight so sharp as to enable them to
take a thoroughly good focus, although a delusion to the contrary
is very wide-spread. It is always better to examine the image on
the ground glass through a microscope, as a better focus can be
got more quickly, and with less strain upon the eyes. The
microscope should consist of two lenses in the same tube, at least
an inch in diameter. The difference of fatigue to the eyes in
using large and small lenses is enormous. A magnifier, with
lenses of one and a half to two inches in diameter is the best ; its
expense is small, as it is not absolutely necessary that the lenses
should be achromatized. The little doublets used by engravers
are good, and larger ones can be got of any optician of the same
pattern. The writer does not advise the system of focussing on
clear glass with an adjusted eye-piece.

The operator is not to take his focus on any point of the picture
indifferently, but according to the following rules : —

MAKING THE NEGATIVE.

In taking a single portrait, focus on the face as the most im-
portant point.

In taking two heads equidistant from the centre, focus on
either head, not on any more central object.

In taking a group, focus on one of the heads occupying a posi-
tion midway between the centre and the extremity of the group.

In focussing a landscape, care must be taken that the fore-
ground is in good focus, and at the same time that sufficient
sharpness is preserved all over the picture. The largest stop
with which this result can be obtained, must always be used. It
is, however, not necessary that very distant objects should be as
sharp and clean cut as the foreground must be; to accomplish
this would require the use of a stop so small as to flatten the
whole picture. Many, however, do this, and the result is that
their pictures have no effect of distance or atmospheric per-
spective. On the other hand, if the focus be not taken with
judgment, the result will be a failure. A swing hack (hereafter
to be described) aids materially in getting a whole view into
good focus with a large stop.

These directions are important, and cannot be disregarded with
impunity. Careless focussing is almost the worst fault that a
photographer can have, and will counteract every care or pre-
caution that he can take in other parts of the process.

Where buildings of any description form part of the subject,
it will be necessary to level the camera, otherwise the perpen-
dicular lines of the edifices will not be
perpendicular in the negative, but will
converge or diverge. This levelling the
camera often prevents the upper part of
the building from appearing upon the
ground glass. Material help can be gained
by raising the sliding front (see Fig. 7). This,
however, must be done with circumspec-
tion, or the upper corners of the negative
will be transparent (and print black) by
being outside the circle of light given by
the lens. It must be also remembered that
the definition is always best at the centre,
that when the lens is shifted in position by
raising the front, the upper parts of the objects will not be quite
so sharp as when the lens is in its usual place; nevertheless, the

30 INTRODUCTION TO PHOTOGRAPHY.

plan is a useful one. The swing-back is also useful, but will need
an intimate acquaintance with photography to avail one's self of
it; its operation will be explained hereafter.

§ 8. — Exposure.

The time of exposure for a wet plate may vary from a fraction
of a second to half an hour.

With a portrait combination, medium stop, and good light
from three to fifteen seconds, or even more, may be required.
"With landscapes taken by a view or a doublet lens and medium
stop, from ten seconds up to several minutes may be given, ac-
cording to the light. With a bright light, and by having the
chemicals in exact order, a picture may be got in a fraction of a
second with a short focus lens, using a large stop. The operator,
however, will do well to leave instantaneous photography until
he succeeds regularly and without difficulty in ordinary ex-
posures.

The slide should always be set into the camera steadily and
gently, not with a jerk or snap, lest any dust be set in motion and
settle on the sensitized plate, the result of which will be seen in
comets or pin-holes.

§ 9. — Development and Redevelopment.

The operator brings' back the dark slide, without loss of time,
to the dark room, never forgetting for an instant to keep that part
of the slide down which was lowest in the camera, and in all pre-
vious stages. Holding the slide with the left-hand edge in his
left hand, he opens the door with his right, places his thumb on
the upper edge of the plate, with the fingers touching it lower
down, and, by inclining the slide a little backwards, brings out
the plate. This is now transferred to the left hand, always keep-
ing the lower edge downwards. lie now turns the plate up nearly
to a horizontal position ; a proper quantity of the developer (about
an ounce for a whole-sized plate, or, for a beginner, a little more)
has previously been placed in a suitable glass vessel — Fig. 8
represents a good shape; this the operator takes in his right
hand, and holding it a little inclined, and at the upper edge of
the plate near the left hand, pours out the liquid, at the same
time drawing the vessel towards the right, so that the liquid may

MAKING THE NEGATIVE. 31

spread rapidly and evenly over the whole surface of the plate.
Some dexterity is required to do this, except with very small
plates. Just as the developer spreads over the plate
and reaches the lower edge, the plate is carried to a
horizontal position, for it is an object not to let more <C
than can be helped run over. The developer becomes
mixed on the surface of the plate with the bath solu-
tion with which the film is impregnated, and this mix-
ture provokes the development. If much is wasted
by washing over the side, the image will come out less strong,
and a redevelopment will be more likely to be necessary.

The rapidity of development under the action of the developer
will depend on what has been the exposure. If the image flashes
out instantly, the exposure has been too long, and the picture
will want contrast. If the picture comes out slowly, reluctantly,
so that after a minute or two only the strongest marked points
of the subject are visible, the exposure has been too short, and
the picture will probably be too full of contrast, wanting in
detail, and hard and blocky. If the picture soon begins to show
itself, and, instead of flashing out too suddenly, grows steadily
and even rapidly in strength, a good result may be anticipated.
As the development goes on, the operator inclines the plate a
little in different directions, so as to render the developer regular
and even in its action. When the plate has come pretty well
out the operator pours off' the developer from one corner into its
vessel again, and, as he drains the last drop, he raises the plate
perpendicularly between himself and the light, and judges of its
strength and character. If these appear satisfactory, he stops the
operation by washing off the plate ; if not, he pours on the deve-
loper again (provided this last has remained active and clear),
and keeps it on a few moments longer. But if it seems to have
ceased its effects, and still more, if the slightest tendency to fog
manifests itself, or if the developer looks in the least muddy, the
operator quickly washes the plate, and if on a further careful
inspection he finds that it still wants strength, he proceeds to
redevelop.

Care will always be needed that the developer is used in suffi-
cient quantity to cover the plate quickly and easily. Too much
is always better than too little, though with too much developer
the silver will always be too much diluted and washed away, and

32 INTRODUCTION TO PHOTOGRAPHY.

there will be more probability of a redevelopment being needed.
(Very full information in all the details of development will be
found in the second part.)

Another point will require special attention. The developer
is apt not to mix easily with the bath solution contained in the
film ; as long as the plate is level the tendency does not appear.
But when the plate is raised to judge of its strength by looking
through, and part of the surface liquid drains off, the indisposi-
tion to mix shows itself by the formation of oily lines resembling
those upon a plate removed too soon from the negative bath.
Now these oily lines that form on the plate when raised to look
through, consist of the developing liquid which collects in that
form, consequently the development of the plate goes on under
these lines, and checks elsewhere. There results a set of streaks on
the plate that wholly ruin it. There is no more fruitful origin
of trouble to beginners than this, and its source is often wholly
unsuspected. Nor is it easily avoided. If the negative bath
have been a good deal used, the addition of alcohol to the deve-
loper to the proportion of an ounce or two to the pint will some-
times help.

Redevelopment may be done either before or after fixing, the
difference is but slight in the final result ; as far as it goes, it
may be stated as follows : If the contrasts are likely to be a little
too great, or tend that way, redevelop before fixing ; if the con-
trasts are scarcely sufficient, fix first and redevelop afterwards.
Not much, however, in the way of a curative agency can be ex-
pected in this way, and pictures which are either too harsh or too
uniform, are best wiped out at once and taken over.

The operator will always bear in mind, in deciding when his
development or redevelopment is carried far enough, that the
apparent strength of the picture, as he then sees it, will be con-
siderably reduced in the operation of fixing, and for this he must
make due allowance.

A close watch must be kept on the plate, and if the slightest
tendency to form oily lines shows itself, the plate must be in-
stantly held under the tap, or better, be plunged into a pan of
clean water ready for the purpose. And if it proves on careful
examination to want density, this must be got by redevelopment.

Negatives that come out of the right strength by the first de-
velopment are the best. If under-exposed, they are apt to become

MAKING THE NEGATIVE. 33

hard and crude in the process of redevelopment ; and if over-
exposed, the evil is incurable. A brilliant print can only be got
from a brilliant negative. Much will depend upon the collodion,
or, rather, the pyroxyline from which it is made. Highly sensi-
tive collodions, and those newly prepared, are more likely to
need redevelopment : more intense pyroxylines and older collo-
dion less likely.

Eedevelopment may be effected in various ways. The most
usual is with pyrogallic acid, and that is the plan which I shall
here describe.

To redevelop with pyrogallic acid, the operator keeps in a
stoppered vial the following solution: —

Nitrate of silver 60 grains.

Citric acid 120 "

Water 6 ounces.

And in a well-corked vial: —

Pyrogallic acid h ounce

Alcohol 4 ounces.

Both these solutions will need filtering ; both keep for months.

When the iron development has done what it can, and before
any disposition to fog sets in, the plate is to be thoroughly well
washed off. In a convenient developing vessel the operator puts
water, about an ounce or a little less for a Q}2 x 8 J plate, and pro-
portionately for other sizes. He next adds a little pyrogallic
solution, about twelve or fifteen drops for the ounce of water,
with which it immediately mixes. He then adds a few drops,
say fifteen or twenty, of the silver and citric acid solution to the
ounce of water, mixes well, and pours the mixture over the plate.
The image immediately begins to grow in strength, and, by keep-
ing the silver and pyro on, any desired degree of strength can be
obtained. The redeveloper soon darkens to a wine color, and in
that condition its action is still powerful. But if it becomes in
the least muddy, it must be rapidly washed off the plate. So
long as the solution remains transparent and bright, even if port-
wine color, it is not easy to fog the picture. Still, even the pyro-
gallic developer is not to be trusted too far, or fog may set in in
brown spots. When redeveloping is done after fixing, the hypo-
sulphite must first be washed off most thoroughly, back as well
as front.

34 INTRODUCTION TO PHOTOGRAPHY.

When it is intended to redevelop plates that have been fixed
and dried, a little more care is necessary. It is best to redevelop
in a pan. And as there is here more danger of spotting and
staining, it is best to add a little acetic acid besides the citric.
The operator watches the operation, keeps the developing bath
continually moving by tilting the pan, and examines the progress
of the work at intervals. Plates after drying take density more
slowly than when redeveloped immediately after the first develop-
ment. When plates have been allowed to dry, and are afterwards
found to need redeveloping with pyro, they are apt to show a ten-
dency to split in drying after the redevelopment ; it is therefore
a good plan to flow them over with the following solution: —

Clean gum arabic 2 ounces.

Water 20

Carbolic acid 5 drachm.

The carbolic acid enables the gum solution to be kept indefi-
nitely without moulding or souring. A little of the solution is
poured over the plate, worked in by moving the plate so that it
shall spread over the whole surface, which can easily be judged
of by catching the light upon it. This is drained off by holding
up the plate, and the operation repeated with a fresh portion of
solution, after which the plate is reared up to dry. Different
collodions vary very much as to tendency to split in drying, and
to their need for this protection. (This operation does not take
the place of varnishing ; plates that have been gummed must be
varnished the same as Others.)

A pyrogallic development may be used in the first place instead
of the iron. In this case the pyrogallic acid solution is added to
water, about eight drops to the ounce, a little acetic acid is added,
and the mixture is poured over the plate as it leaves the frame.
This is a very easy development, and gives bright, strong pic-
tures. But the iron development is preferable, because softer
pictures are got, more full of detail, and shorter exposures are
sufficient.

The vessels used for developing must be kept scrupulously
clean. If the remains of the developer be left in them a few
minutes, it becomes turbid, and a gray-black precipitate of metal-
lic silver collects round the sides and bottom. Any of this left
in will tend to render the next lot of developer muddy, and
therefore must be completely removed.

MAKING THE NEGATIVE. 35

I am in the habit of keeping beside me the following solution
in a beaker or wide-mouthed bottle : —

Concent, solution bichromate of potash . . .1 fluidounce.
Sulphuric, or better, hydrochloric acid . . • i "

Water 3 fluidounces.

Tt is only necessary to pour this solution into the dirtiest de-
veloping vessel, and then immediately out again, when it will
be found perfectly bright and clean, It is scarcely necessary to
say that it must be well rinsed.

The same solution is very useful for removing, silver stains
from the fingers. If got into cuts or abrasions of the skin, it is
to some violently irritating, to others quite indifferent, except a
momentary smarting. It is much preferable to the use of cyanide
of potassium, a most dangerous chemical, and the indiscreet use
of which is injurious to health, and may become destructive to
life. Or they may be rubbed with strong tincture of iodine
(alcohol 1 oz., iodine 40 grs.); and when the stain has become
yellow (not before), it will dissolve in a strong solution of hypo-
sulphite of soda.

Of these methods, the first will generally prove the most effi-
cacious; it should be followed by washing with hyposulphite.
All silver stains, however, should be attacked before they are set
by exposure to light, otherwise the difficulty of getting rid of
them is greatly increased.

§ 10. — Fixing, Washing, and Drying.

The negative fixing-bath consists of a strong solution of hypo-
sulphite of soda, in the proportion of five or six ounces to the
pint of water. Some pour the solution over the plate until it is
clear. But this involves a loss of time. It is better to keep the
fixing-bath in a horizontal pan, and carefully to slide the nega-
tive into it. When the yellow opaque appearance of the iodide
and bromide has completely disappeared, the plate is fixed. The
same bath may be used for a number of negatives, but should
not be kept too long. A yellowish feathery appearance through
the film indicates insufficient fixing, and may be removed by
another immersion in the fixing-bath.

The plate thus fixed is to be set under a tap and thoroughly
washed by allowing a stream of water to fall upon it, whilst the

86 INTRODUCTION TO PHOTOGRAPHY.

plate is supported at such an angle that the ripple is seen to
spread in all directions, and keep the water in continual motion
over the whole surface of the plate. To accomplish this, the
plate must be kept in such a position that the stream of water

which falls upon it will flow off in every di-
rection. The writer finds the most conve-
nient mode of accomplishing this to consist
in having two cones of zinc, as represented
in the margin. The lower and larger is six
inches in diameter at bottom, and five at top;
stands seven inches high. The upper is six
inches diameter at top, three at bottom, and
five inches high. Both are open at top and
bottom, and small notches are cut at the base
of the larger. The negative rests on the upper rim; it will
be found easy to give it any slant in any direction, and with the
advantage that it will retain that position with entire steadiness.
After setting the plate upon this or any other support during the
washing, the operator must never fail to catch a reflection of light
upon the surface of the plate to assure himself positively that
the water is in motion all over the surface, otherwise the washing
will not be well done. The above dimensions will answer for
all sizes of plates up to 8 x 10 and even 10 x 12.

Ten to fifteen minutes is the right time for washing a negative,
although much less is often given by hasty operators. It is
almost as important to wash the back as the face, although the
latter requires only simple rinsing off. If this be neglected, por-
tions of the hyposulphite bath will remain there, and, when the
plate is set up to dry, will run down to the edge, and thence be
drawn up by capillary attraction into the film, preparing the way
for spots and stains at some future time.

The plates are next allowed to dry, either reared up corner-
wise in a drying-frame, or simply supported in a vertical posi-
tion, resting on several thicknesses of blotting-paper. Fig. 10
represents a very convenient rack made by simply attaching
upright pieces to a flat board. Backs can be purchased of the
dealers to hold a much larger number of negatives ; the form in
the figure is, however, very convenient, and safer.

From the time that the plate enters the fixing-bath the plate
may be exposed to the light without injury.

If it is intended to redevelop the plate after instead of before

MAKING THE NEGATIVE.
Fig. 10.

fixing, the washing must be equally careful after the fixing solu-
tion is applied, or the application of the redeveloping solution
will cause brown stains.

Sore hands produced by contact with chemicals sometimes give
a good deal of trouble. Where a tendency of the sort exists, the
photographer should endeavor to keep his hands as much as pos-
sible out of contact with chemical solution, and should thoroughly
wash them immediately after any such contact. At the close of
the day's work the hands should be well scrubbed with soap and
a nail brush, and then be moistened with cologne-water to which
one-eighth of its bulk of glycerine has been added. This will
strengthen the skin, and at the same time retain its softness and
pliability. Carbolic acid, five drops to the ounce of water, has
been found useful.

§ 11. — Varnishing the Negative.

To varnish a negative well will require both care and attention
on the part of the beginner, until by habit and practice a com-
plete control over the operation is obtained.

Choice of Varnish. — First as to the selection of varnish. The
beginner should never attempt to make his own, but always pro-
cure a reliable commercial varnish. The experienced photogra-
pher should always make, never buy ; not so much for economy,
though the saving is material, but in order to be certain that he
has exactly what he wants — a hard, tough varnish, made out of
the very best materials. Suitable directions will be found in the
latter part of this manual for preparing negative varnishes.

The commercial varnishes may be divided into two classes — the

38 INTRODUCTION TO PHOTOGRAPHY.

benzine and the spirit varnishes. The former will sometimes
dry clear, even if used cold; the latter always require the aid of
heat. On the other hand, the benzine varnishes (so far as the
writer's experience goes) always reduce the strength of the nega-
tive considerably, whilst -the spirit varnishes do not; and the
latter are every way more reliable. Either sort that the ope-
rator becomes accustomed to he will consider the more easy,
and it is best to adopt some particular varnish, and use it always.
The writer prefers the spirit varnishes. The two different sorts
can always be distinguished by the odor.

Applying the Varnish. — First dust off' the plate, either very gently
with a very soft, broad camel's-hair brush, or by blowing with a
bellows. AVith plates developed with iron, or redeveloped, the
latter is the better plan. To apply a spirit varnish, warm the
plate gently ; in winter a coal stove will be convenient, in summer
a gas stove is most commonly employed. Try the temperature
by holding it at one corner with the left hand, and moving the
right hand under it and applying the side of the hand and back
of thumb to various places to see if the heat be uniform. To be
right, the temperature should be quite warm, but not in the least
hot; there should be a distinct, pleasant sensation of warmth, but
no more. If too hot, set aside a few minutes to cool. If used
too hot, there is danger of getting lines, as will be presently de-
scribed. If used too. cool, the varnish will probably " dry dead."
A benzine varnish requires rather less heat than a spirit varnish.
Some use it cold when the weather is clear and dry. The writer
prefers to use heat with all varnishes. Taking a convenient posi-
tion in front of a window so as to watch by the reflection all the
movements of the varnish, pour it on precisely in the same way
as with collodion. Having put on a liberal supply, slant the plate
towards you and bring the pool of varnish towards you, in a J nil,
slow wave, keep its border as square as p>ossible, making it advance
slowly and quietly; if one edge gets a little the advance, incline
the plate the other way to bring it up. With too little varnish
or too much tilt to the plate, long arms will start out, and whilst
you are slanting the plate this way and that to get it covered on
some part of the border, the wave will stop moving, and a line
may result.

Having now got the whole plate covered, keep it quite level
or even tilt it backward, so as to send a returning wave clear up
to the far end of the plate. The varnish should rest on the whole

MAKING THE NEGATIVE. 39

plate some seconds before beginning to pour off, otherwise it will
not soak in sufficiently, and so dry dead.

The length of time necessary for the varnish to rest on the plate
varies a good deal. The more a plate has been redeveloped the
longer it will need the varnish to remain upon it ; the thicker
the varnish, the less time is required. A thick varnish with a
close film will need only seven to ten seconds. A very thin var-
nish with a spongy film may need fifteen to twenty. Generally
speaking, eight or ten seconds will be a proper time ; a few
trials on rejected negatives will show what is needed. The time
here spoken of is to elapse after the negative has been completely
covered.

Having let it soak in sufficiently, incline it very little, so that it
will run of!' at the right-hand near corner into the " pouring off
bottle" held there to receive it. After it has run slowlv for a
couple of seconds, the plate being of course nearly level, bring it
suddenly up by a quick movement till it is vertical, and there hold it
for half a minute or more that it may drain and set. Eock it
from right to left precisely as in the case of a collodion plate.
Let it drain until it almost ceases to drop, and then hold it pretty
close to a hot stove until perfectly hard, but not longer than
necessary for this. The heat of the stove should be about as
great as the hand can bear in holding the plate.

The varnish must of course not be returned into the same bottle
as that from which it was poured off, otherwise it will soon have
bits of collodion, dust, etc., on it. The writer invariably manages
as follows : Take two clean six-ounce vials, fill one with filtered
varnish, put on the neck of the other a funnel of about two and
one-half inches in diameter, with a paper filter in it. Pour off
from the plate into this filter ; in this way there will be less
varnish lost, and less trouble in getting the stream from the plate
into the bottle. The varnish having run through the filter, is of
course clean, and when the first bottle is empty, the funnel is
transferred to it, and the operation reversed. The funnel with
the filter in it may stand permanently in the neck of the bottle,
to which it supplies the place of a cork, and so is always ready.

The varnish which has been poured off from plates has of
course lost alcohol by evaporation, and is thicker than at first.
Therefore before the pouring-off bottle is used for varnishing
with, a little alcohol must be added — one-sixth or one-eighth its
bulk, in round numbers, but this is a point of which the operator

40 INTRODUCTION TO PHOTOGRAPHY.

must learn as quickly as possible to judge for himself. If varnish
is too thin it is apt to dry dead, and does not properly protect the
plate. A negative film varnished with a very thin varnish can
be easily rubbed up by the finger. Such negatives are of course
very perishable, and are soon destroyed in printing. If too thick
it is less easy to work with, and removes the film too far from
the paper in printing, thus (especially in shade-printing) diminish-
ing the sharpness of the print.

Some varnishes require heat only before their application;
generally, however, they should be dried by heat, as well as be
applied on a warm plate. The drying by heat expels the vola-
tile portions more thoroughly, and renders the varnish less liable
to become soft and sticky in printing.

The main points are to get the corners covered immediately
after you begin to pour, to put on enough, and to bring it down as
above explained to a full, slow, square wave. The learner cannot
pay too close an attention to these directions. By doing so he
will get a smooth, even plate. Neglecting them, he will find :—

Ridges. — These start from some point at the edge of the plate
and extend some distance over the face of, or even all across the
negative. If strong enough to be likely to show in the printing,
the plate must be flowed with alcohol, drained, and revarnished.

Lines result from a momentary stopping of the wave of var-
nish. The varnish dries a little on the hot plate during the
pause, and the result is a line exactly marking the position it
then had. The hotter the plate, the more apt lines will be to
appear. If a line has been made and is seen before you begin to
pour off, it may be lessened, and sometimes entirely removed, by
keeping on the varnish a few seconds longer than usual before
beginning to pour off. Fine parallel lines may come from omitting
to rock the plate.

Drying Dead.— This results in the production of a film looking
like ground glass — sometimes fine, sometimes coarse. If fine, it
may not show at all in the printing ; if coarse, it will. This may
arise from several sources : —

From Dampness of the Film. — After the film is surface dry, it
takes a long time to dry through, and the drying must be thorough
before the varnish is applied. So, too, the film is very absorbent
of atmospheric moisture, and even after thorough drying and
standing for weeks, may easily in damp weather absorb enough to

MAKING THE NEGATIVE. 41

affect the varnishing. It is therefore better, so far as convenient,
to varnish in clear dry weather, or at least after the plate has
remained some time in a warm dry room.

Too thin a varnish may also cause drying dead, or too little ap-
plied. If, as soon as the plate is covered, the varnish be poured
off again, it will almost certainly dry dead, because the surface
only was moistened ; this presently soaks in and leaves the film
only half saturated with varnish. This is perhaps the commonest
of all causes of drying dead, and often (by the beginner) the last
suspected. Therefore the writer advises, if the operator is
troubled by this difficulty, to proceed as follows : Put on an
abundant supply of varnish after covering the plate, send back a
wave to the far end, and then hold the plate quite level and
motionless for at least twelve seconds quietly counted. At the
end of this time, incline the near right-hand corner until a steady
stream runs into the bottle, and then, as before directed, bring
the end up with a quick motion.

Negatives will be found to vary; some will dry smooth with the
very same treatment that gives, perhaps with the very next one
varnished, a dead film. This depends upon the amoimt of re-
development they have received ; the more redeveloped, the more
apt to dry dead, because there is more silver powder to soak in
the varnish. If found necessary, the varnish may be kept on
even for fifteen or twenty seconds, to penetrate thoroughly.

Special care should always be taken not to allow the varnish
to get over the edges upon the back of the plate, not only
because it is troublesome to clean it off, but because if a stream
of varnish runs across the back of the plate, it will often happen
that the corresponding part of the face will dry dead, the evapo-
ration going on at the back keeps the corresponding portion of
the face cool, and thus prevents the drying smooth.

Breathing on the plate may at times, and under some circum-
stances, lead to spots of deadness.

Often a deadness of the surface will not affect the printing.
An experienced operator will be able to distinguish at once
whether the evil is great enough to bring about this result. If,
when the plate is examined by allowing the light to fall through
it, the deadness is not at all or very slightly perceptible, the nega-
tive will probably print well.

Revarnishing. — But if the roughness is quite distinct, a remedy
must be applied. Since the first edition of this work was printed,
4

42 INTRODUCTION TO PHOTOGRAPHY.

it occurred to the writer to remove the varnish at once by hot
alcohol, and this proves to be much the best method.

The defective plate is to be warmed precisely as for varnishing,
and then instead of varnish, an abundant quantity of ninety-five
per cent, alcohol is poured on and well worked over the plate ; this
is then poured off and a second portion used to wash off residue.
The plate is then allowed a few moments to become quite dry, is
heated again, and varnished precisely as with a new plate. This
operation, when carefully performed, leaves nothing to be de-
sired in its results.

Ridges, that is, lines of greater thickness extending across the
plate, may be easily got rid of in the same way.

When it is intended to print a very large number of positives
from one negative, two coats of varnish may be applied. Mr. G.
W. Wilson always gives two coats, touching out defects between
the two. In this case, the varnish should be thinner than when
one coat only is applied.

It is a good plan, as soon as the face of the varnished plate is
dry, to draw a piece of blotting-paper along the lower edge of the
glass; this prevents the production of a thick ridge there, which
would have a tendency to lift up the paper in printing, and pre-
vent a close contact with the adjoining parts.

•

§ 12. — Ambrotypes and Ferrotypes.

If the development of a negative be stopped as soon as all the
details are out and considerably before printing density is reached,
we have a picture called an Ambro(//j>c when made on glass, and
u Ferrotype when made on a thin plate of varnished iron. The
high lights appear white by reflected light, because of the white-
ness of the silver deposit of which they are made; the transparent
portions are rendered black by black varnish applied on the back,
in the case of the ambrotype, and by the black lace of the metal
in tin- ease of the ferrotype.

All negatives, therefore, in an early stage of their develop-
ment, are ambrotypes. But to get the best effects, it is found ad-
vantageoua to use in the negative bath a little more acid, and to
employ an old and ripe collodion, for it is necessary to keep the
shadows perfectly transparent and free from the least tendency to
yeil, which wouM destroy their depth and richne

An ordinary negative collodion may be used if it is thoroughly

MAKING THE NEGATIVE. 43

ripe ; if not, tincture of iodine may be added till it is sherry wine
colored. (Tincture of iodine may be purchased, or may be made
by dissolving iodine in alcohol. Thirty grains of iodine to the
ounce of alcohol is a convenient strength.)

Some photographers prefer a special collodion containing iodide
of potassium, now rarely used in negative collodions. Mr. Thomas,
of New York, uses the following proportions : —

Iodide of potassium 50 grains.

Bromide of potassium 30 "

Dissolve these salts, with the aid of heat, in 8 ounces of alcohol,
Take 60 grains of pyroxyline, dissolve it in 5 ounces of ether and
2 of alcohol. Then add the above while still hot.

The developer is to be the same as for negatives, taking care
that it be sufficiently acidified, for which purpose one-half more
acetic acid may be added, than for negatives.

§ 13. — General Remarks.

Avoid doing anything which may cause dust in the dark room.
Keep the dark slide clean and well wiped.

Notice the camera from time to time to assure yourself that the
wood work is close and tight.

See that the focussing slide sits tight and close up. The spring
that holds it to the body of the camera will sometimes get out of
order and affect the two slides differently, so that one comes up
more closely than the other. The result of this will be that the
focussing surface no longer corresponds with the sensitive film,
and no matter how carefully the focussing be done, the pictures
will not be accurately sharp.

Make sure that the camera-stand is absolutely steady and not
given to trembling.

See that the dark room is thoroughly ventilated, so that whilst
at work you are not inhaling noxious vapors, and as little as
possible of the fumes of collodion.

Removing stains from hands.— Fresh stains come away much more
easily than those that have been exposed to light. Dilute hydro-
chloric acid, to which a little solution of bichromate of potash is
added, is very effectual. It should be followed by an applica-
tion of a vegetable acid, tartaric, citric, or better yet, binoxalate
of potash, which last is also convenient for removing ink stains.
One or more of these substances should be kept at hand in solu-

INTRODUCTION TO PHOTOGRAPHY.

tion to use after the bichromate solution, which otherwise leaves
behind a yellow stain and disagreeable odor; the injurious effect
upon the skin is also diminished. Perchloride of iron, which has
been recommended, the writer has not found to answer. Cyanide
of potassium should not be used. /Silver stains on clothes are best
removed by solution of corrosive sublimate, which destroys them
effectually and without injuring either the texture or the color.

CHAPTER III.
PRINTING.

§ 1. — Sensitizing.

As albumenized paper is now almost exclusively used in positive
printing, it will be the only method described in this introduction ;
others will be hereafter given.

Those who operate upon a large scale sensitize their sheets
whole, others divide them into halves or quarters, and one corner

is to be folded backwards for
half an inch or three-quarters.
The piece is then held at its
two ends, is folded into a loop
by bringing the hands some-
what together so that the cen-
tre will be lowest, and the
albumenized surface under-
most. The centre of the sheet
is made to touch the bath first,
and then, by opening the hands
and lowering them, the whole
surface is regularly opened out on the bath. In this way air-
bubbles are avoided. Should an air-bubble remain under the
paper, its place will be marked by a white spot in the print.

Laying the sheet un the printing bath.

Positive Bath.

Water

Nitrate of silver

22 ounces.
3 "

The paper remains on it about four minutes in winter, and two
in summer. It is then lifted off by the corner turned up, and

PRINTING,

pinned to a rod or string to dry. A convenient method is to take
a long strip of avoocI, and glue on it at spaces corks, into which
to stick the pins.

"When the bath turns dark, shake it up with half an ounce of
kaolin. Let it stand some hours, with occasional shaking, and
filter.

Examine the bath from time to time with red and blue litmus
paper, and keep it as nearly neutral as possible. If the blue
litmus turns red, the bath is too acid, and may be neutralized
with a grain or two of bicarbonate of sodium. If red litmus
paper turns blue, the bath is alkaline, and a little dilute nitric
acid must be carefully added. It is best to have the solution an
inch deep in the glass or porcelain bath. Too shallow a bath
tends to irregular action.

See that the paper is thoroughly dry before printing it. A
dense negative prints best in the sun, a thin one in the shade.
That is, it is to be exposed at a window to a good light, but not
to sunshine. A negative too thin to give a good result in any
other way, may often be successfully printed by laying a sheet
of tissue paper over it.

Printing frames are made in many different patterns. The
writer recommends the bar frame (Fig. 12) to the exclusion of all
so-called improvements on it, which
generally fail to bring the paper
closely up to the negative, unles the
pressure is dangerously increased.
The padding behind the paper should
be of soft woollen material, felt, or,
best of all, 2)iano-cloth.

Print till the highest lights just
begin to color. By this time the
dark shadows ought to show the
greenish, almost metallic, look
known as " bronzing."

Examine the print from time to
time, taking; the frame to a darker
part of the room, open the back

gently, taking care not to shift the print, bend it back, and judge
of the degree to which the printing has gone.

As fast as the exposure is finished, throw the prints into a dark
drawer.

Fig. 12.

46 INTRODUCTION TO PHOTOGRAPHY.

When all are ready, proceed to wash them by putting them
one by one into a basin of water, where they lie ten minutes.
This water is to be carefully added to the residues, as it is rich
in silver. Change the water two or three times, then tone.

As the printing-bath will continually lose in strength, it should,
be kept up by adding crystals of nitrate of silver, remembering
that each sheet of 18x22 will remove about a drachm and a
quarter of nitrate of silver.

§ 2.— Toning Bath.

Water 10 ounces.

Chloride of gold 4 grains.

Acetate of sodium 1 ounce.

If mixed with warm water, it will in two or three hours be
ready for use, otherwise it is best kept till next day. In very
cold weather, a little more gold must be used ; and the bath,
except in hot weather, should be warmed till it is tepid.

Pat in only a few prints at a time, and keep them constantly
moving about. When they reach the shade desired, let them
remain a little longer, as they will afterwards recede a little in
color; then take them out, pass them through clean water, and
proceed to fixing. This bath will give rich warm tones, but not
black ones, for which, if desired, the carbonate bath, or better,
the chloride of lime bath (see beyond), must be used.

Prints that look blue when finished, have been over-toned by too
long an immersion.

§ 3.— Fixing Bath.

Water 32 ounces.

Hyposulphite of sodium 4 "

Keep the prints moving about in this, and leave them in fifteen
minutes. The above bath will suffice for two whole sheets, and
must be increased in proportion if more are to be toned. N
vse on any suhs&iuent day a balk that has had, even only one single
print fixed in it, or the print so toned will surely fade in time.

§ 4.— Washing.

A very thorough washing is needed to prevent fading. Prints
thrown into a tank into which a tolerable stream of moving water

tails, will be sufficiently washed in six to ten hours, provided
there arc not too many of them. When the number is large, the
tank must be continually emptied of water and refilled.

A FEW GENERAL RULES FOR BEGIXXERS. 47

CHAPTER IV.
A FEW GENERAL RULES FOR BEGIXXERS.1

1. Ixvariably wash the fingers under the tap immediately
after they have been in any solution, but most particularly after
hyposulphite. Neglect of this will transfer portions of one solu-
tion to another, and lay the foundation for long series of failures,
which may prove utterly distressing and perplexing.

2. Do not be actuated by an ambition to commence with diffi-
cult work. Point the camera out of the window, and take the
view, such as it is, until it is done with certainty and success.
After that will be time enough to try portraiture — last of all,
copying.

3. Begin with small plates, and do not try large ones until
the smaller are mastered. Half-size will be the largest proper to
begin with.

4. Do not undertake to make collodion before its use is learned.
Be satisfied to purchase that which some experienced friend re-
commends.

5. Do not tend towards intensifying thin pictures by after-treat-
ments. "When photography was less understood this was oftener
necessary. It is better to wash off and begin again, and generally
less trouble to get a better result.

6. The quickest way to learn is this: take any simple object
as above, a brick house, for example, and try it again and again,
varying the length of exposure and the length of development,
until a negative is got that prints exactly right. This will teach
more in a few mornings than as many weeks of random work.

7. Successes that come by chance are worthless, and prove
nothing as to ability. Try to know exactly the causes of success
and of failure.

8. The right exposure may often be got the first time, but not

1 At the end of this volume will he found descriptions of those simple chemical
manipulations which are used in photography, and with which the beginner
will do well to make himself early familiar.

48 INTRODUCTION TO PHOTOGRAPHY.

certainly ; yet a careful examination of the first trial ought to
enable one to make sure of the second.

9. If the camera needs to be placed in the sunshine, throw the
focussing cloth over it before the shutter is drawn out to make
the exposure. The direct light of the sun may find its way
through cracks too small to admit diffused light.

10. Once in a while wipe out the camera with a damp cloth to
remove dust, which by settling on the plate may cause pin-holes
or comets.

11. Treat the lenses with the utmost care. Never leave them
about ; never wipe them with anything but the softest old linen
cambric, perfectly clean, and not even so except when needed.

12. Do not unscrew the tubes unnecessarily to wipe the inside
surfaces of the lenses, or for any other purpose, and always do
this in dry weather, or damp air will be admitted, which will be
apt later to leave a dew on the lenses. If any of the lenses are
set loosely in the tube, be sure they are replaced with the same
side front as before.

13. Do not let either the lenses or the camera stand in the sun,
the result will be warping and splitting of the wood, and discolo-
ration of the lens.

14. Be sure that the camera stand is free from vibration. Un-
cover the lens very gently so as not to shake the camera in the
least, or the definition will be impaired.

15. Unless the ground glass is of the best, the focus cannot be
taken with accuracy. Much of the ground glass in cameras made
for sale is very poor. The glass should, in fact, not be ground at
all, but only "grayed," that is, have its surface removed by
rubbing with fine emery powder. Focus a brick house 200 feet
off with a short focus lens, and if the white lines of the mortar
cannot be seen, either with the naked eye or with a magnifier,
the glass is too coarsely ground ; and it is to be expected that all
the work done with it will be inferior.

16. Focussing with a microscope is less trying to the eyes, and
gives sharper work. The larger the lens of the microscope used,
the less the eye is strained. An engraver's glass set in horn
is good, but a similar one, an inch and a half or two inches in
diameter, tires the eye still less.

17. Learn exactly how to make a negative bath, and then avoid
doctoring. For the most part it will only be injured. Add a
very little carbonate of soda, and sun it, if out of order, for some

A FEW GENERAL RULES FOR BEGINNERS. 49

hours in direct sunlight, then filter and acidulate as directed for
a new bath. Filter first, then acidulate.

18. Decaying organic matter, foul smells, sulphuretted hydro-
gen, and fumes of ammonia may be expected to produce fog.

19. Do not think it necessary to have the dark room too dark.
There may be light enough to work with perfect comfort, and
the strain on the eyes in going backwards and forwards will be
so much the less : an important consideration.

20. Have nothing to do with cyanide of potassium. It is a
substance of which the photographer has no real need. If used at
all, it should be left to those who have learned their experience
on less dangerous materials.

21. Eemember that most chemicals are poisons, and that if the
fingers are not washed immediately after being plunged in them,
or if, even with this precaution, they are kept long in the solu-
tions, mischief may ensue. What this mischief may be is of so
gradual and insidious a nature, as to be ascribed to any other
cause than the right one.

22. Eemember also that most fumes are injurious. Vapors of
ammonia disorganize and paralyze the blood corpuscles. Yapor
of ether is very injurious to the nervous system, produces head-
ache, and depresses the whole tone of the body. Nitric acid is
highly poisonous ; its fames, when inhaled for a sufficient length
of time, will cause death.

23. Therefore make every provision for thorough and complete
ventilation. And do not fancy (as many most unwisely do) that
because the senses become habituated to such fumes, and cease
to be inconvenienced by them, that the system is therefore not
suffering.

24. Adopt invariably the maxim, that whatever is worth doing
is worth doing well. Practice never makes perfect without care,
and thoughtful and intelligent observation. Some will do a thing
all their lives, and always badly.

25. Acquire the habit of rinsing out all the vessels as soon as
emptied, and of not leaving the adhering portions to dry on the
bottom and sides, when it will take five times the trouble to get
it out.

26. Make it a rule to wash every vessel before you put it away,
and again before using it. Never trust to anything being clean,
but make it so. If there is any one thing that is essential in
photography, it is care of this sort. The delicate reactions on

50 INTRODUCTION" TO PHOTOGRAPHY.

which photographic processes depend are sufficiently exacting,
without further embarrassing the processes by introducing foreign
matter of unknown nature.

27. Never forget that no vessel is rendered clean (even if what
it has contained has been merely an aqueous solution) by simply
pouring water in and throwing it out.

Hold therefore the vessel, whether beaker, bowl, bottle, or
whatever it may be, under the tap, so that the water may run
over every part, inside and out. Outside, because it is never
certain that a glass vessel is clean inside unless it has also been
made so outside. Eemember that if a vessel be hastilv rinsed
out, there may be left drops of the old solution adhering to the
sides above the part washed, and that a single drop so left may
spoil the following operation. This direction may be thought so
much a matter of course as to be superfluous; it is not so.

In all cases, except where the old contents are very easily
removable by water, employ the bichromate cleaning solution,
which for this purpose may be made of double or treble strength,
so as to work more energetically.

28. In the field, before making the first exposure, take pains
to make sure that everything is right. (See especially sections 3
and 4 in chapter on Landscape Photography.)

29. Make it a fixed rule that every failure shall be made the
stepping-stone to some new advance. If by accident any work is
destroyed or injured, make it a rule that it shall be replaced with
better. The result will be that, instead of feeling that time has
been lost in merely remedying an accident, there will be a feeling
of congratulation that that very mischance was converted to an
advantage.

Again, instead of falling into a routine of work from time to
time, consider whether there may not be some better mode of
operating, and if a probable improvement suggest itself, or is
suggested by others, give it a fair trial.

On the other hand, beware of capriciously changing about from
one process to another. There are often several good ways of
doing some one thing, any one of which well done is better than
any other unskilfully carried out. It is best, therefore, to acquire
a thorough knowledge of some good means of managing each
operation — this gives firm foothold. Experiments in other di-
rections then will be compared carefully with the regular plan,

A FEW GENERAL RULES FOR BEGINNERS. 51

which will never be abandoned until by repeated trial the new
method has shown itself distinctly superior.

30. Success will very often depend upon the willingness to
make another trial, for want of which many barely fail.

31. Finally, the beginner in Landscape Photography is earnestly
recommended to act upon a definite system. For example, let
him not run from one lens to another, but rather, having provided
himself with one thoroughly good one, let him study out its capa-
bilities and learn exactly how to use it. Different lenses work
so differently, that, to the beginner, they are very confusing, and
tend to conceal from him the sources of the mistakes and faults
that he must necessarily make. Only in one way can he usefully
employ himself with several lenses, and that is by using them in
succession to take the same view, and observing and studying
closely the differences in the results.

The secret of success lies in taking up separately each different
portion of the work and mastering it by careful study. First
take the view from any convenient window until you can do it
with regular and complete success. Next select some attractive
landscape, and try it upon different points, and with varying
lights, and longer and shorter exposures, until you have done
with it the best that it admits of, and until you know why such a
result is the best that can be attained. One such piece of nega-
tive-making, worked thoroughly out, will teach as much as thrice
the time spent in random view-taking. The student should bear
steadily in mind that whilst a thoroughly good negative is very
valuable, there is nothing more worthless than a tolerable one.
A tolerable negative is not worth the trouble of printing, and is
consequently worth nothing at all.

PART II.

PHOTOGRAPHIC OPTICS AND THEORY OF

PERSPECTIVE.

CHAPTER I.

GENERAL OPTICS.

Fis. 13.

§ 1. — Reflection and Refraction.

When a ray of light (this expression will be more convenient,
although wave of light would be more correct) falls upon any
surface, a part is reflected and a part transmitted.

Let the ray A 0 (Fig. 13) pass from the rarer medium on one
side of the surface E F into the denser on the other ; for example,

out of air into glass. Part of the
ray will be reflected and part re-
fracted. In order to study these
phenomena, we draw a line per-
pendicular to the surface E F at
the point of incidence 0. This
line NO is the normal, and the
angle A 0 Arbetween the incident
ray and the normal is the angle
of incidence.

We find that the reflected ray makes the angle of reflection BON
equal to the angle of incidence A 0 N.

The refracted ray is bent out of its course towards the normal.
In place of continuing on in its direction A 0 /, it is deflected
towards the normal NNf, in some direction 0 li, and the quan-
tity of deflection depends upon the character of the substance.
The greater the deflection, the higher the refractive power is said

to be.

In the foregoing we have considered the case of a ray passing

REFRACTION". 53

from a rarer medium into a denser. In the converse case the
converse result takes place. If in the above figure we suppose
the directions to be reversed, and that the ray R 0 passes at 0
from the denser medium into the rarer above it, then the ray R 0
will be bent away from the normal to precisely the same extent,
and will follow the path 0 A.

It therefore follows from this that when a ray passes from a
rarer medium into a denser, and then through the denser again
into the rarer, it will emerge in a direction parallel to that in which
it entered, provided that the denser medium has parallel sides.

The ray A I) (Fig. 14), in passing through the denser medium,
takes the course D B, being deflected towards the normal, and,
on emerging, again assumes a direction B C parallel to A D.

Fi«r. 14.

But if the sides of the denser medium are not parallel, the ray
will not emerge from the second surface parallel to its first direc-
tion. Thus the sides OF, B F (Fig. 15) of the denser medium
not being parallel, the ray A 0, in passing through the surface
B F, takes a different direction B C.

Different substances refract the rays of light very differently,
and are therefore said to differ in refractive power.

We have a very convenient method of measuring refractive
power, which is as follows: —

In Fig. 16 let Sf S" be the boundary line between an upper and
rarer substance and a lower and denser one. Let any ray of light
R 0 pass at 0 out of the rarer into the denser, and let the line
0 R' represent its deflected direction.

With any distance 0 A as a radius, draw the curve A N' R'.
Draw at the point 0 the normal iV W, and from the intersection
A let drop the perpendicular A S, similarly from R' the perpen-
dicular R' S.

A S will be the sine of the angle of incidence and R' S the sine

GENERAL OPTICS.

FiS- 16. of the angle of refraction. Each

of these angles will be conve-
niently measured by its sine.

Now it is found that when any
two given substances constitute
the rarer and the denser me-
dium, the proportion between
the lengths of A S and R' S is
invariable, whatever be the an-
gle of incidence. If the upper
medium be air and the lower a
certain quality of glass, the sine of refraction R' S will always be
exactly two-thirds the sine of incidence A #, let the ray fall upon
the dividing line *S" S" at what angle it may.

The ratio of the sines is then invariable for any given substance,
and this ratio is called the index of refraction. In the case just
mentioned A S being to R' S always as 3 to 2, the index of re-
fraction of such glass is said to be | or 1.5.

The path which will be taken by any ray in passing from one
medium into another can easily he traced as follows : Let the ray
R 0 pass out of air (or rather out of a vacuum, but the difference
is unimportant here) into glass of refractive power 1.5. Draw
the normal N Nr through the point of incidence and perpendicu-
lar to the surface. Set off any distance 0 Sf, and, taking this as
unity, make 0 S" equal to the index of refraction. In this case
0 S" will stand to 0 Sr in the proportion of 1.5 to 1. Draw the
perpendiculars Sr R', S'r A. Putting one leg of a compass at 0
and the other at A (the intersection of S" A with 0 R) draw the
curve A R', the intersection of this curve with S' R' when con-
nected with 0 gives the path of the refracted ray.

§ 2. — Dispersion.

In the foregoing section we have reasoned as if light were
homogeneous. But white light is made up of rays of very differ-
ent refrangibility, so that when a ray of white light A D (Fig. 17)
passes at 1) into the denser medium bounded by the line B C,
these rays are differently affected. The more refrangible rays
arc bent more out of their course, following the direction D F;
the less take the direction D E.

On reaching the second surface B D, if this surface is not

DISPERSION.

parallel to the first, but inclined to it, these different rays will
have their divergence greatly increased, and will be spread out
as there represented.

Fig. 17.

We find that a difference of color accompanies a difference of
refrangibility, the most refrangible being violet, and so proceeding
in the order, violet, indigo, blue, green, yellow, orange, and red.
Under very favorable circumstances, and with well-exercised eyes,
a commencing disposition to repeat this gamut, like octaves in
musical sounds, is observable, far beyond the red a crimson tint
has been seen, and beyond the violet, a lavender.

But, independently of these, the existence of non-luminous
influences beyond the limits of the visible spectrum is easily
detected. Beyond the red rays, rays of dark heat are made
evident by the thermometer, and beyond the violet there exists
rays also invisible, but having a powerful chemical effect, so that
in a portion of space completely dark, sensitive paper is rapidly
impressed.

Whilst rays, invisible to our eyes, are thus capable of exerting
powerful actinic action, other rays, plainly and even brilliantly
visible, exercise little or no actinic influence. The yellow and
red rays, in which the chief illuminating power of light resides,
scarcely act upon sensitive substances. The green rays exert an
influence on some and not on others.

It is not a little remarkable that sulphate of quinine possesses
the power of lowering the refrangibility of the rays beyond the
violet, and thus rendering them visible to our eyes. If sulphate
of quinine be dissolved in water acidulated by sulphuric acid, and
the solution be placed in the dark rays beyond the violet, these
become visibly blue.

GENERAL OPTICS,

CllAPTKK II.

OF LENSES.

§ 1. — Nature of Lenses.

A LENS may be plane on one side and convex on the other —
plano-convex. (Fig. IS.") Plane on one side ami concave on the
oilier — plano-concave. (Fig. L9.) Convex on both sides — double
convex. (Fig. 20;) Concave on both sides- — double concave.

Pig. 18. 1!». 00. 81.

Fig. 04.

(Fig. 21.) Concave on one side and convex on the other — menis-
cus. The meniscus may be of two sorts. It' the radius of the
convex side is the shorter, the lens is thickest in the middle, and
is called a positive meniscus. (Fig. 22.) If the concave curve has
the shorter radius, the meniscus is thickest at the edges, aud is
termed a negative meniscus. (Fig. 23.)

To understand the action ot'a lens on rays of light, let us select

a plano-convex lens and con-
sider its properties.

W hen a ray of light L A falls
upon any curved surface at any
point .1. we draw a tangent /> G
at the point .1, and we may
then consider the solid body
.1 (,'. as far as the ray L A is
considered, not as a body hav-
a curved surface, but as a prism
/>' Q <\ for it will act towards the ray /. .1 precisely as if it were
such a prism. The ray /. .1 passing out ol' it will be sent away
from the normal in the direction .1 //. and will intersect the axis
D 7/ at a point II.

L < ^

D y' \ --^

C J C ~*

O V L EC N S E S .

Let as now consider several rays of light L //, &c. (Fig. 25.;
/, strikes at the centre of the curve, where the tangent is pari
to the plane side A /i, and is therefore influenced precisely as if

Pig. 25.

T
A

\\\

x-^^a^

T T

it passed through a pn-cc of plane glass, and emerges in the same
right line. U is bent on leaving the curved surface, and tends
towards F. Other rays strike the curve still higher from the axis,
where the tangents are still more inclined, and are therefore still
more deflected. This greater deflection makes up for the fact
that the original path of that ray was farther from the central
ray, and thus all the rays approximately tend to gather together
at a point h\ called the focus.

What is true of the plano-convex lens, is true of all lenses that
are thickest in the centre, of double convex and of positive
meniscus lenses. Those lenses which are thinnest at the centre
are called negative. They do not collect parallel rays to a focal
point, but cause them to diverge. They have no real focus, but
only a virtual one. Such lenses t.'iken alone would be of no use
in photography, but they are often employed in connection with
others.

If matters passed exactly in the manner above described, the
construction of photographic objectives would be far more simple
than it, is. But the spherical lenses which we use are liable to
faults, which will next be considered.
5

58 GENERAL OPTICS.

CHAPTER III.

FAULTS INCIDENT TO SPHERICAL LENSES.

There are five distinct sources of inaccuracy in the image
formed by a spherical lens. These are, Spherical Aberration,
Chromatic Aberration, Astigmation, Curvature of the
Field, and Distortion.

\ 1. — Spherical Aberration and the Modes of Remedying it.

All lenses in use at the present day have their curves, parts of
spheres. Now it is a property of all spherical curves A B, Fig.
26, that they do not bring the rays exactly to a point at F. Just
in proportion as the parallel ray L' is further from the central
axis X, so is that ray, after passing through the lens, brought
down to the central axis at a point nearer to the lens. The focal
length F' for the ray L' is shorter than the length of F for the
ray L, and so on.

It will be seen, then, that for the spherically curved lens A B
there is no real focus, but a succession of foci all the way from
jPto Fr, and although the fault is intentionally exaggerated in the
figure, it is still so great as imperatively to require attention.

Fig. 2G.

Spherical aberration may be destroyed, or at least diminished,
in two ways. Either lenses may be so combined that their aber-
rations will be in opposite directions, and so compensate and
destroy each other, or else diaphragms may be employed.

Correction by Diaphragms. — The ray It" A which would come

FAULTS INCIDENT TO SPHERICAL LENSES. 59

to a focus at a point F' nearer to the lens than F (see Figs. 26
and 27) is cut off by the diaphragm CD. We thus greatly in-

Fig. 27.

/?' F

1 — ^S

K G

crease the sharpness of definition by the use of a stop, though of
course at a great sacrifice of light. Thus, if the lens is two inches
in diameter, and the aperture of the diaphragm is a quarter of an
inch, then, as the areas of circles are at the squares of their dia-
meters, the loss of light is §§, or only one sixty-fourth part of
the whole light which would reach the sensitive film, if a full
aperture could be employed, is left available.

Although this loss of light is a most serious evil, it is necessa-
rily submitted to, and we gain that the image, before dull and
hazy, becomes at once sharp and crisp. Before, the lens seemed
to have no true focus ; now, for any given object, the focus can
be found with exactitude.

§ 2.— Chromatic Aberration and Mode of Correction.

Spherical aberration is independent of the nature of the light
employed ; it results wholly from the form of the lens, and occurs
even with homogeneous light. We have next to consider a sort
of aberration arising from the different indices of refraction of
the different rays of which white light is composed.

When considering the subject of dispersion, we saw that when
light fell upon a prism, it was spread out into a spectrum, in
which its different constituents were arranged in the order of
their refrangibility. And as a lens may be taken to represent a
number of small prisms, it follows that the same spreading of
the colors will there take place.

If, as in Fig. 28, a perpendicular ray of light strikes a plano-
convex lens at A, it passes into it unchanged; but at B the dis-
persion of the rays takes place according to their refrangibility,
and the focus of the violet rays is nearer to the lens than that of
the less refrangible rays at the red end of the spectrum. The

GENERAL OPTICS.

distance between these two foci Fand E is called the chromatic
aberration, which in the figure is necessarily exaggerated for
clearness.

Fig. 28.

This fact may be easily rendered visible by holding such a lens
in the sunlight. Rays of white light L L (Fig. 29) are divided,

Fig. 29.

and the violet rays find their focus at V, the red at P. If a
white screen be interposed anywhere between the lens and the
point I, there will be a circular image of the sun with a red
border ; beyond /, where the violet rays cross the red and pass
outside, the image will have a violet border. The distance VP
along the axis between the foci of the red and violet is termed
the longitudinal aberration, and that at // the lateral aberration.
II is the place at which the least circle encloses the whole of the
rays, it is therefore the best focus.

To understand clearly how the chromatic aberration is cor-
rected, it is necessary to bear in mind that the refractive power of
substances and their dispersive power arc not proportionate to each
other. For substances may exist of equal refractive power, and
different dispersive, and conversely.

Let us, then, take two sorts of glasses, and construct a double
convex lens of that sort that has the least dispersive power. Next
let us form a negative lens (*'. e. one thinnest in the middle) of a
sort of glass having a much greater dispersive power, and let us

FAULTS INCIDENT TO SPHERICAL LENSES.

so regulate its curves that it shall exactly compensate and de-
stroy the dispersion of the first lens (by introducing an equal dis-
persion in an opposite direction). As the
negative lens had a higher dispersive power
than the double convex, it will, whilst re-
moving wholly the dispersion of the latter,
leave it a residue of refraction. So that the
compound lens (Fig. 30), although its disper-
sive power has been destroyed, is still capa-
ble of converging rays to the focus. This is now an achromatic lens.
It is not necessary that the negative lens should be double concave,
as in Fig. 30. It may be plano-concave, and may be combined
with a plano-convex (Fig. 31), or a double convex (Fig. 32).

§ 3. — Astigmation.

Astigmation is produced in those pencils of light that fall
obliquely upon the lens.

Let G D E F represent the face of a lens, not a section as
usually shown in the figures. Let R R, R' is?', R" be rays of

Fig. 33.

light coming from an object so distant that they are parallel.
Let the central ray R" pass through the optical centre of the
lens; it will emerge parallel to its original direction; its prolonga-
tion in the direction p will constitute a secondary axis. Let E F

62 GENERAL OPTICS.

be a diameter of the lens, perpendicular to the axial ray R",
and CD another diameter at right angles with the first. Now
the rays R' R' ', which reach the lens at E and F, strike it under
absolutely the same conditions. They will, therefore, undergo
equal refraction, and will meet the secondary axis at some
point P'.

But this is not at all the case with the rays R R, which fall on
the ends of the other diameter CD. They will strike the curved
surface of the lens under very unequal angles, and will be very
differently refracted. R D will reach the axis at some point P,
R C at some point p.1

But the use of a diaphragm cuts off R D and the neighboring
rays. Of the rays that are left, R C and the neighboring rays
have their focus at p, whilst R' E, R' F have their focus at p'.

It follows, therefore, that oblique pencils have no true focus.
For if p be taken as the focus, then the rays Rr F, R' F will have
crossed at p', and at^> they will have widened out again, and the
image of the radiant point, instead of being a point, will be an
ellipse, having its major diameter in the direction E F. Con-
versely, if_p' be taken as the focus, R C and the neighboring rays
will not have converged to a focus, and their section on the focus-
sing screen will form an ellipse, having its major diameter in
the direction CD. In neither case will the point have its image
as a point, hence the name astigmation (a, no, and atiy^, point).
The image of the point will appear as an ellipse, whose greatest
diameter will change its direction according as the focussing
screen is farther or nearer to the lens.

Eays incident perpendicularly upon the lens, do not produce
astigmation. If, then, we examine the case of a pair of lenses
having convex surfaces outside, and a stop between them, we
shall see that if this stop be placed at the centre of curvature of
the outside surfaces, then only rays of incidence nearly perpen-
dicular to the surfaces of the lenses will be permitted to pass
through the stop. Lenses with central stops, will have less or
more astigmation, according as their central stop corresponds
more or less nearly with the centre of curvature, and as its open-
ing is smaller.

1 The unequal refraction of Jl C, E D is the cause of coma, -which will be
presently treated of.

FAULTS INCIDENT TO SPHERICAL LENSES,

In the single meniscus view lens, the astigmation will be less
in proportion to the depth of concavity of the front surface. It
will also be controlled by the position of the front stop. The
nearer this is placed to the centre of curvature of the front con-
cave surface, the more nearly will the incidences be perpendicu-
lar, and consequently

the less the astigma- FlS- 34-

tion.

Coma. — Spherical
aberration is much
more easily removed
for direct rays than
for those that strike
the lens in an oblique
direction. Let the
rays R R' R" strike
the plano-convex lens
in an oblique direc-
tion. One ray, R',

which, after refraction at the first surface of the lens, passes
through the optic centre C, emerges in a direction parallel to
that which it originally took. This line OP' is the axis of the
refracted pencil. The ray R" meets the axis at P, whereas the
ray R meets it at P' farther on. Thus whilst the rays
corresponding with R are gathered at the point P\
those corresponding with R" are spread out below it
constituting coma. (Fig. 35.)

This incorrectness, like so many others, is kept
within bounds by the use of the diaphragm, which in
the above case would cut off the ray R, and permit only such
to pass as would converge on the axis OP to a single point, P,
or to a sufficiently near approximation.

Fig. 35.

§ 4. — Curvature of the Field.

If we suppose an object of some size placed before a lens, we
shall find that its extremities do not come to focus on the same
plane as its centre.

The arrow 0 is supposed to be so distant that its ends and
centre may be regarded as equally far removed from the lens.
Now if the centre of the arrow 0 has focus at (7, its extremities
will have their focus not in a plane perpendicular to the axis of

GENERAL OPTICS.

Fig. 36. the lens, but at points nearer to the

lens.- The whole image, therefore,
will not fall upon a plane, but upon
a concave surface. As it is necessary
that it should be rendered flat, we
shall consider the means of doing
this by the conjoint operation of the
diaphragm and the correction of the lens.

Diaphragms. — If a diaphragm or stop were placed immediately
in contact with a lens, it would virtually reduce the lens to one
the size of the diaphragm. But the diaphragm is always placed
some distance away, and then every part of the lens concurs in
forming the picture, but each part is only permitted to act upon
those rays for which it is intended.

Fig. 37.

By the interposition of the diaphragm, the dotted oblique ray,
for example, which would reach its focus at a much nearer point,
is cut off, and only those rays are permitted to pass which meet
at a focus as nearly as possible in the plane in which the central
rays find their focus at F. Here is at once a valuable approxima-
tion towards a plane field.

Moreover, by virtue of the stop the rays which form the image
meet with a very small angle, and it is evident that the focussing
screen may be brought into such a position that all parts of the
image will be very good focus at the same time.

This is flattening the field by use of the diaphragm.

Correction. — But the field may also be flattened in the same
manner that the correction for chromatic aberration is applied.

FAULTS INCIDENT TO SPHERICAL LENSES. 65

In the simple lens the field is very curved. If we now add the
correcting negative lens to remove the color, we shall lengthen
out the oblique pencils more than the central.

This is flatten in g the field by correction of the lens.

\ 5. — Distortion.

The mathematical conception of a lens regards it as consisting
merely of its bounding planes, and destitute of thickness. If
lenses actually possessed this form, the images produced by them
would correspond strictly with the principles already laid down.
But all lenses necessarily possessing a definite thickness, the image
is thereby deformed, unless special measures be taken to correct
such distortion.

Every right line, no matter what be its inclination, if it be
directly in front of the lens, so that the prolongation of the axis
of the lens passes through it, is imaged on the screen as a right
line, whether perpendicular, horizontal, or inclined, because of its
symmetrical position with respect to the different parts of the lens.

But if the line be not symmetrically placed, that is, if the pro-
longation of the axis of the lens do not pass through it, then the
image of such a right line will be curved, with its concavity
turned towards the axis of the lens, and a square,
for example, will be represented as in Fig. 38.

This is termed barrel distortion, and is seen in
the single view lens.

The position of the diaphragm has necessarily
a strong; influence on distortion. When the dia-
phragm is in front of the lens, as in the case
of the view lens, the crossing of the rays takes
place in front of the lens, and the lower part of the lens receives
the rays from the upper part of the object, and the distortion is
barrel-shaped. If the diaphragm be placed behind the lens, the
crossing of the rays takes place behind the lens, and the lower
part of the lens receives the rays from the lower part of the ob-
ject. If now we take the case of two lenses with a stop between,
as in photographic doublets, the one compensates the other, and
the distortion disappears completely if the lenses be exactly
similar and the stop be placed equidistant from each.

Falling off of Intensity at Edges. — In addition to the foregoing
faults incident to lenses there is the defect introduced by the dia-

GENERAL OPTICS,

<- rk *

FiS- 39- phragm that the light is strongest at the

centre, and falls oft* at the edges instead
of the illumination being everywhere
equal.

For if D D be a diaphragm, it is evi-
dent that the pencil of rajs that enter it
at right angles will be much larger than
the pencils that take an inclined posi-
tion, as represented by the dotted rays.
The diminution of light in the pencils
from the skv, is rather an advantage
than otherwise ; but the contrary is the
case with the pencils from the fore-
ground.

Several ingenious contrivances have
been made to counteract this tendency.
Thus a conical piece is arranged to
set in the opening of the diaphragm
D D, within it is an inclined diaphragm.
This evidently allows a larger pencil to
pass from the foreground than the centre,
and the pencil admitted from the sky is still smaller. With
badly illuminated foregrounds this arrangement is advantageous,
but in ordinary landscapes the distribution of light is found to
be sufficiently good in the regular image.

CHAPTER IV.

FOCAL LENGTHS OF LENSES.

§ 1. — Images of External Objects.

If an opening be made in a shutter A of a dark room, there
will be formed on the opposite wall an image of external objects.
The rays of light coming from an object B C will cross each other
at the opening A ; will form an image E D on the opposite wall,
which image will have the following characteristics: —

It ivill be reversed, because the rays cross at A, and that which
was lowest (C) in the object, becomes uppermost (E) in the image.

FOCAL LENGTHS OF LENSES.

Fig. 41.

If the opening A be small the image
will be very faint, but moderately
sharp.

If the opening he large, the image
will be better lighted, but will be
confused.

There ivill be no focus. E D may
be at any distance from A.

The fact that the confusion of the image can only be removed
by an excessive diminution1 of the opening, and consequent re-
duction of the light, renders it useless for photography. The
cause of this confusion is shown in Fig. 42. Let P be any point

v"^

Fig. 42.

of any distant object, as the point 0 of the arrow in the preced-
ing figure. The rays that emerge from it, after passing through
the opening A B, are spread out upon the wall at A' B', whereas
they should be collected at the point P'.

This collecting of the rays and conveying them to the point
P' is effected by placing a lens at the opening AB.

But now a new condition comes in with the lens. Without it
images were formed though the wall were at any distance from
the opening. But with the lens the surface that receives the
image must be at a fixed distance from the lens. This distance
is its focal length. Measured from the back surface of the lens,
it is called the " back focus," an extremely rough and erroneous
mode of measurement. Measured from the true point (the centre
•of emission, hereafter explained) it is the absolute focus, also
called the principal focus or equivalent focus.

1 With an excessive diminution of the opening, another difficulty presents
itself, that of diffraction. The lines of light are bent by the edges of the
opening.

GENERAL OPTICS.

If rays from an external object
fall upon the lens L, Fig. 43, and
an image is formed at F, the focal
length would be the distance from
F to the lens at L, supposing the
lens to have no thickness. But
as all lenses have thickness, the

question immediately arises, from what point or part of the lens

or lenses is the measurement to be taken ?

To answer this question it is necessary that we should get a

clear idea of certain remarkable points belonging to lenses, single

or compound.

Fig. 44.

§ 2. — Optical Centre.

All lenses have a remarkable point, to which the above name
has been given. All lines that pass through the lens and also

through this point, are termed
transversals, and have the remarka-
ble property that all rays which
pass through the lens along their
path, emerge from the lens parallel
to the direction in which they en-
tered it.

If Che the optic centre, any line

G T passing through it will be a

transversal. If now a ray of light strike the lens at T at such

an angle that it follows the path T T it will, on emerging at T',

follow the direction T P parallel to its original course.

The optical centre of any lens is easily found. It is only ne-
cessary to draw parallel radii from the two centres of curvature,
to connect the points at which these radii meet the curves, and
to prolong this line till it intersects the axis.

From the centre G of the one curve draw any radius G R.
From the centre C of the other curve draw another radius C R',
parallel to the first. Connect the points R R', prolonging, if
necessary, the line of connection R R', till it intersects the axis
G C. The point of intersection 0 will be the optical centre of
the curve. In a double convex lens (Fig. 45) the optical centre
falls Inside the lens, in the meniscus (Fig. 4G) outside of it. In a

FOCAL LENGTHS OF LENSES,

Fig. 45.

Fig. 46.

double convex lens, whose surfaces are of equal curvature, the
optical centre will coincide with the centre of the lens.

Fig. 47.

§ 3. — Centres of Admission and Emission.

These centres play too important a part in photography to be
here passed over.

Let 0 be the optical centre, as before, of a double convex lens;
then any lines drawn through it, as
T T, T' 7", are transversals, and any
rays that strike the points T T' at such
angles of incidence as to follow the
course of the transversals, will, as be-
fore explained, emerge at T T', on the
other side of the lens, and follow paths
parallel to their original direction.

If, now, all the entering rays be pro-
longed in their original directions, they
will converge to a point P on the axis
of the lens. This is the centre of admis-
sion. If the emerging rays be likewise
prolonged, they will meet at a point P'.
This is the centre of emission.

This statement is rigorously true only for rays very nearly
parallel with the axis, for others it is simply an approximation.

Now, if in Fig. 48 we have a bi-
convex lens, and A B be an object
before it, CD its image, the focal
length of that lens must be mea-
sured from P, its centre of emission,
that being the point to which all
the rays, G P, F P, D P, converge.
And similarly, if we wish to take

Fig. 48.

GENERAL OPTICS.

Fiff. 49.

into account the distance of the object from the lens, it is to be
computed neither from the exterior of the lens, nor from its
centre, but from the centre of admission P\ Consequently,
when we speak of the conjugate foci belonging to the lens for an
object A B, and its image CD, these focal lengths are the lines
F' Pf,FP.

In the following figure of a meniscus lens, the transversals are
seen centering at 0, the optical centre of the lens. The respective

rays R R R R are those that
undergoing refraction at the
surface A B, follow the
courses of the transversals
through the lens. Emerg-
ing they take directions T
R', &c, parallel to those
which they originally had,
and all cut the axis at P,
the centre of emission.

The focal distance of any

object in front of this lens

will therefore be measured

to the centre of admission

P' . And the focal distance of any image will be measured from

that image to the centre of emission P.

If the first surface of the lens A B be plane, the lens becomes
a plano-convex, and the points 0 and P both recede to the inter-
section of the curve CD with the axis 0 P', where they coincide.

§ 4. — To Determine Focal Lengths by Actual Measurement.

Equivalent Focus. — This term is constantly misapplied, and
most of the popular explanations of it are erroneous. The
whole matter is, however, very simple, and may be explained as
follows : —

In a plano-convex with its plane side to the object, the focal
length is the distance between the ground glass B' (Fig. 50) and
the back surface of the lens, therefore A' IV. This distance is
easy to measure, and offers a valuable aid towards determining
the focal lengths of other forms of lens.

Suppose now that we have a doublet M N, O P, and that a very
distant object is focussed correctly when the ground glass is in

FOCUS LENGTHS OF LENSES.

the position C D. The question
arises, are we to measure from the
ground glass at B to what point ?
the back lens, the front lens, or
what point between ?

Let us suppose that we find a
plano-convex lens B, S, which,
when placed in the same position
as the doublet, and focussed on
the same distant object, makes its
image C D' exactly the same size
as the image C D of the same object
given by the doublet. Then these lenses have the same equivalent
focus, and the easily measured focal length A' B' of the plano-
convex is also the true (equivalent or absolute) focal length of
the doublet. The rays A C, A D, which form the image in the
case of the doublet, diverge as if they came from a point A, which
point is the centre of emission.

It follows from the foregoing that all lenses that have the same
equivalent focus, will, when focussed on some distant object,
produce images of it that have the same size, the one as the others.
And further, which is important, that lenses of different focal
lengths will, when focussed on the same distant object, produce
images of it whose size is proportionate to the respective focal
lengths.

If A B, Fig. 51, be any distant object : different lenses placed
at L will give images of it having different sizes, but these sizes
will always be proportional to
the focal length P' F, P' F', &c,
and will be larger or smaller
in the exact proportion of the
focal length of the lens that
forms them. A leiis having
twice the focal length of ano-
ther, will, when placed in the
same spot, and focussed upon
the same distant object, produce an image having twice the linear
dimensions of the image given by the first. If, therefore, in
order to find the focal length of a doublet, we compare it with
a plano-convex as in Fig. 50, it is not essential that the two
should give images of the same size, -which might in practice

GENERAL OPTICS.

be difficult to attain. But having easily measured the focal
length of the plano-convex, we simply compare the size of the
two images, the proportion between which establishes the focal
length of the doublet. If the image given by the doublet is
one-fourth longer, we know that its focal length is necessarily
one-fourth longer, and so on. And having thus determined the
exact focal length of one doublet, we may use it (just as well as
the plano-convex) to determine the focal length of any other de-
scription of lens, by the same system of comparing the linear
dimensions of the image formed.

Another practical method of determining the focal length of
any form of photographic objective has been indicated by Mr.
Grubb.

Mark the centre of the focussing screen by drawing diagonals
from opposite corners. Set the camera on a large sheet of
white paper; place the camera so that the images of two well-
marked distant points shall be equally distant, one on each
side of the centre. Measure the distance of these two points
from each other on the screen. Now turn the camera so that
one of these points shall fall exactly upon the centre. Having
done this, run a pencil along the side of the camera, ruling a

lineon the paper underneath. Now
turn the camera around again, till
the other point falls on the centre
of the focussing screen, and draw
another line on the paper.

Let A B and G D be the lines
so drawn ; continue them till they
meet at E. Bisect the angle AEG
by the line E E. At any point F
erect the perpendicular E G equal
to half the length of the space measured on the ground glass be-
tween the points. From G draw G II parallel to A B. The
distance on F II of its intersection H from F will be the abso-
lute focal length of the objective used.

This having been once correctly done for any one lens, it will
serve as a standard for the easy determination of others by the
method above described.1

x. 02.

1 Another method is the following: Focus two objects, so that their images
will fall upon the ground glass equally distant from the centre, as before de-
scribed ; then measure with a theodolite the angle which these objects subtend.

FOCAL LENGTHS OF LENSES. 73

It is remarkable that the method of determining the focal
length of a lens by focussing an object so that the size of its
image shall be equal to its own, and then taking one-fourth of
the distance between the object and its image for the focal length,
after having been repeatedly shown to be inaccurate, has been
constantly brought forward again. The error lies in the misap-
plication of the formula j = — h - by which it is attempted to

afford a proof. This formula neglects the thickness of the lens,
which, in compound lenses (i. e. doublets, &c), is often very con-
siderable, and thereby introduces an error. Nor can this error
be avoided by computing these focal distances from the optical
centre of the lens, since they must be. computed from the centres
of admission and emission to render the formula applicable.1

§ 5. — To Calculate the Focal Length of a Lens from its Dimensions.

In the following formula}, it will be taken for granted that the
lens is made of glass, having its refractive power equal to 1.5.
The more general expressions will be given in foot-notes. The
focus in all cases is determined for sunlight or parallel rays fall-
ing parallel with the axis of the lens.2

In the case of a glass sphere the focal length is 1| times the
radius, measured from the centre of the sphere. It falls there-
fore beyond the sphere at the distance of half the radius from
the surface.3

Calling this angle «, and d the distance measured on the ground glass, the focal
length will be found by the expression —

f=~—a

2tan-
o

1 If it were required to make a correct determination by the method of fo-
cussing equal size, it would be necessary to determine for any lens the distance
which separates its centres of admission and of emission. Calling this J and

the distance between object and image, D, we have /= — - — , the positive sign

applies when the centres cross each other, the negative when they do not, as in
the photographic objectives.

2 These calculations are all based (except when otherwise specified) accord-
ing to custom, and for simplicity, upon the supposition that the lens has no
thickness.

3 The general expression is as follows : Let r equal index of refraction, B the

r
radius, / the focal length, then f=R„. _ny

74 GENERAL OPTICS.

Double Convex Lens} — If the curves on both sides are equal,
the focal length will be equal to the radius.

If unequal, multiply the radii together, and divide by half
their sura. If the radii are respectively 5 and 7 inches, the focal
length will be V5 inches or 5§ inches.

Plano-convex Lens. — Where the plane side is exposed, the focus
will be twice the radius, measured from the convex side. Where
the rays fall on the convex surface -§- the thickness of the lens
must be deducted from twice the radius, and this will be mea-
sured from the plane side.

Meniscus Lens. — Multiply the radii, and divide the result by
half the distance of the radii. For example, if a meniscus has
its positive curve with a radius of 5 and its negative 7 inches, its

focal length will be T-fn — *\ or 35 inches.

If the concave surface had a radius of 5 and the convex of 7,

the focus would be the same, but
Fig. 53. it would be a virtual focus, an im-

aginary one in front of the lens.
So in Fig. 53, the parallel rays
R R R are spread out by the
negative meniscus, so that if their
direction were continued back-
wards, they would meet at F, the
virtual focus.
Although this focus has only an imaginary existence, it be-
comes important in computing the effect of introducing a negative
lens, as in several forms of photographic objectives.

§6.— Focal Lengths of Combined Lenses Computed from their

Elements.

Where two lenses of known focal length are combined to-
gether, it is easy to determine the focal length of the combina-
tion. It becomes here necessary, however, to take into account
the distance at which the two lenses are separated, as the focal
length always increases as this separation increases.

' The general expression for the focal length of any lens in terms of its radii, is
%^L, the positive sign belonging to the biconvex lens, the negative to the
meuiscus.

FOCAL LENGTHS OF LENSES,

Add the two focal lengths together, and subtract the distance
of separation. Multiply the two focal lengths together, and di-
vide this last quantity by the first, which gives the focal length.1
This formula, which, like the preceding, depends on the suppo-
sition that glass with a refractive power of 1.5 forms the material
of the lenses, is that which is employed by opticians in their
calculations.

Two lenses of 6 and 10 inches focal length respectively, sepa-

, 6xl°
rated one inch, will have their combined focal length -.^ ,

or 4 inches.

If these lenses when combined are to have a focal length of 5
inches, this can be effected by giving them a separation of <±

inches, because 1fi , is 5 inches.

§ 7. — Conjugate Foci.

Up to the present point we have considered parallel rays only.
But when divergent or convergent rays fall upon a lens, its focal
length is thereby necessarily altered.

Thus the lens A B having its focus at F for parallel rays, may
have it at D for diverging, and at E for converging rays.

Ficr. 54.

If D' be a point from which diverging rays emanate and these
converge again after passing through the lens, at D, these two
points D and D', are termed conjugate foci. If D' be an object,
it will have its focus at D. These points are interchangeable,
so that if the object be placed at Z), its focus will be at D' .

1 If/ and/' are the respective focal lengths, and d the distance of separa-

tion, then the combined focus -will be

f+f'-*

GENERAL OPTICS,

Fig. 55.

To observe this better, let us take
a plano-convex lens, with its plane
side to the object. ■

The object D' has its focus at D.
If the principal focus (that for paral-
lel rays) be called/, and the distance
D' C, u and G D, v, then we shall
have this relation : —

= - +

- or v =

V-

-f

This equation will permit, if the principal focal length is
known, to determine the position of the image D of any object
situated at any point D'. If, for example, the lens have a focus
of 6 inches, and the object D' is 10 feet or 120 inches off, we shall
have —

6x120 720

120—6 " ' 114

= 6.815.

The focus of such a lens will, therefore, be a little over three-
tenths of an inch longer for an object at the distance of ten feet,
than for a very distant object, that is to say, for parallel rays.

It will be seen that this formula gives a very simple rule for
calculating focal lengths. If the principal or absolute focal dis-
tance of a lens be known, and we place an object nearer to the
lens, and require to know what will be the focal length of the
lens for such an object, we have only to take these two quanti-
ties— the absolute focal length and the distance of the object.
First multiply them and then subtract them, and divide the first
number by the second, as in the example where 120 was multi-
plied by 6, and divided by 120 less 6.

It is a very important point, and one that has been too often
overlooked in treating the subject elementarily, that the formula

t. = + neglects the thickness of the lens. In practice it
j u v °

is necessary either to introduce a correction for this quantity,1 or

1 The most general form of expression for conjugate foci is

v=-

i TOrr/_(?l_i) tr'\ + t

r r

u in (/i — 1) (r-f r')— (n— l)2 1 \ + (n— 1) t r—n r v'

There t is the thickness of the lens, rr' the radii, and n the index of refraction.
— Secretan, Sysfemes Ojjtiques Convergents, 54.

FOCAL LENGTHS OF LENSES. 77

else to consider the various focal lengths as measured from the
centres of admission and emission already described (p. 69). In
the case of a plano-convex lens, these centres fall together at the
centre of the convex curve, and the focal lengths are correctly
measured from the point G in the figure.

Although, exactly speaking, the focal length of the image
always varies with its distance from the lens, yet there is practi-
cally a distance for each lens beyond which all objects are simul-
taneously in focus. If, for example, we say that a difference of
focal length not exceeding -^ of an inch may be neglected, then
we may fix for every focal length of lens the distance beyond
which all objects are practically at once in focus.

fu
We had on the last page the formula v = ——. Now, if the

u j.

limit of u is that it shall not be more than $\ of an inch longer

than the principal focus, put u = / + ^-A, and we have

' _ _ v = 50f*+f

As/ is inconsiderable in comparison with the other members
of the equation, it may practically be neglected, and it may be
said that all objects that are distant over fifty times the square
of the focus, are simultaneously in focus.

Consequently : —

For lenses of

inches focal length

the distance

37£ feet.

150 "

300 "

((

417 "

• (

600 "

1fi

((

mr..^ "

Objects at these distances may be said to have practically the
same focal length as those at any greater distance. To get objects
at these distances into focus simultaneously with those at less
distance, we must depend upon the " depth of focus'1'' of the lens, a
very precious quality possessed by different lenses in very various
degrees.

When the image is formed by rays which meet at a very small
angle, as at F, Fig. 37, it is evident that the focussing screen can
be racked a little in or out without much injury to the definition,
and thus a good uniform average focus is obtained.

GENERAL OPTICS.

CHAPTER Y.
PHOTOGRAPHIC OBJECTIVES.

In this chapter will be briefly considered the various forms of
photographic objectives now chiefly used.

Fig. 56.

§ 1. — The View Lens.

By a view lens is understood a single achromatic combination,
■usually consisting of two pieces, forming a meniscus or a plano-
convex lens, with the concave or plane face, as the case may be,
turned to the light. This form of lens is figured at page 61, Figs.
30, 31, 32. The combination of a double convex of crown and a
double concave of flint glass is the usual method employed.

Latterly Dallmeyer has produced a wide angle view lens, con-
structed of three pieces, as shown in the margin (Fig. 56).

A flint negative meniscus is inclosed between two menisci of

crown glass. In these two latter
the crown glass is not of equal
refractive power, the rear lens
having a somewhat less index of
refraction than the front.

In this way a most excellent
lens is formed. It has, of course,
the fault common to all lenses not
centrally stopped, that straight
lines are more or less curved on
the image. It is therefore only
suited for landscapes in which
architectural subjects are not in-
serted, or where these are small
and inconspicuous. But for all
cases in which it can be properly used, and these are very nume-
rous, the writer thinks very highly of it. If this lens be criti-
cally compared with the Steinheil aplanatic, it will be found that,
in respect of that very important quality, depth of focus, the wide
angle view lens has a distinct advantage. It also covers satisfac-

F F. Flint negativo meniscus.
c c. Two positive menisci of crown glass.
d. Diaphragm.

PHOTOGRAPHIC OBJECTIVES.

torily a wider angle. Thus the 8| wide angle covers a 6|x8i
plate, whereas with the aplanatic the 9£-inch is. required. It is
true that the seven-inch is sold for this purpose, which, however,
it does not properly accomplish. The 9|-inch Steinheil used
on a 6Jx8i plate gives, of course, a rather less angle of view
than the 8| view lens, but, on the other hand, gives a better mar-
ginal definition and straight lines.

The wide angle view lenses more than cover the plates for
which they are advertised, and admit of a little pushing up or
down of the camera front, without producing black corners. The
writer has not found any more serviceable lens for view-making.

§ 2. — The Portrait Lens.

The form of objective represented at Fig. 57 is that at the pre-
sent time exclusively used for portraiture. It was the result of

Fig. 57.

C, C. Double convex crown glass lenses.

F, F. Negative flint lenses ; the front, plano-concave, the back, negative meniscus.
/,/. Flange.
D. Diaphragm.

the labors of Petzval, of Vienna, who calculated this combina-
tion, and by its immense improvement over the systems pre-
viously in use for portraiture gave a vast impetus to that branch
of photographic art. A glance at the figure will at once explain
the nature of the arrangement.

As the portrait is most natural and effective when the sitter

80 GENERAL OPTICS.

has riot been compelled for a length of time to retain his position,
and as the chances of moving are greatly increased with the
length of the exposure, the great object of the portrait combina-
tion is to throw as strong a body of light into the camera as
possible. Considerations of depth of focus, correction for sphe-
rical aberration, &c, have been necessarily, to some extent, sub-
ordinated to the one great need.

It follows that, instead of having many planes in excellent
focus simultaneously, as in the case of the view lens, the portrait
lens is very restricted in this respect, and hence cannot be
appropriately used except for the purpose for which it is
intended.

Some portrait lenses, especially the Jamin (Darlot) lenses, are
arranged to permit of the front portion, consisting of the double
convex and plano-concave, to be unscrewed, and after reversing,
be screwed into the same flange for use as a view lens*. This is a
very convenient system ; it is, however, liable to the objection
that the front surface of the view lens thus made is plane, instead
of concave. Now, to get the best results, not only the front sur-
face should be concave, but this concavity should be consider-
able. Such a view lens cannot, therefore, be expected to give
strictly first-rate results, though it may do good work. It can-
not be too clearly understood by the student, that the whole
system of photographic objectives is a system of compromises
between conflicting troubles; that these compromises can always
be best adjusted for some definite end, and that consequently
when one sort ot objective is made to do another's work, such
work is always done at a disadvantage.

Mr. Dallmeyer gives the following information relative to the
character of portrait lens best suited for given sizes of plates,
supposing the camera to be placed at a distance of 18 to 20 feet
from the sitter, as he advises.

The equivalent focal length of the lens for a given sized plate
should be about double its largest side ; that is for card size,
4£ x 3|, the focal length should be 8 to 9 inches ; for cabinet
size, 6x5, 12 inches; for 8x10 plates, 20 inches. Salomon's
success confirms these views; his 8x10 plates are made with a
lens of 20 inch focus.

Next arises the question as to what diameters these lenses
should have. It is useless to expect that the highest degrees of
rapidity, flatness of field, and depth of focus can be combined,

PHOTOGRAPHIC OBJECTIVES.

because these qualities are essentially antagonistic. So that two
lenses, both perfectly corrected for spherical aberration, and of
the same focus, the one of two inches diameter, will have double
the depth of focus of the other, whilst the latter, on the other
hand, is four times more rapid.

Or again, comparing two lenses, both having the same ratio of
diameter to focal length, consequently of equal (or nearly equal)
rapidity, the greater the length of focus the less the "depth" of
focus. Thus, for example, a card lens of 9 inches equivalent
focus and 2f diameter, producing a card picture at 20 feet, will
sufficiently define accessories at eighteen inches in front of, and
behind the principal object having thus a " depth" of 3 feet,
whereas a lens of twice the focal length placed at the same distance
of 20 feet, will have but half the " depth," viz., 9 inches before
and behind the object, but will produce an image four times, i.e.
twice linear, the size.

These lenses were first manufactured by the well-known firm
of the Voigtlrenders. Now they are made by opticians generally.

§ 3.— Steinheil's " Aplanatic" and Dallmeyer's "Rapid Rectilinear."

Several years ago two lenses were invented, the one in Eng-
land, the other in Germany, which are remarkable in their per-
formances, and in a certain similarity to each other.

Fig. 58.

82 GENERAL OPTICS.

Steinheil's aplanatic, of which a figure is given below, for which
the writer is indebted to Dr. Liesegang's Archiv, has already
become a great favorite in this country. It is a " symmetrical
doublet," that is, the front and back lenses are alike. Each con-
sists wholly of flint glass, but the respective portions being com-
posed of flint glass of different refractive powers, correct each
other, so that the lenses are achromatized ; in this is an essential
difference from any other lens hitherto constructed.

It is an advantage in the Steinheil lens that when used with a
large diaphragm, although the exterior portions of the image
lose their sharpness, the central portions are still tolerably good.
As the rapidity of a lens increases greatly with the increase of
the diaphragm, we may thus employ the aplanatic as a portrait
lens, if we reject all but the central portions. It does not, how-
ever, in this way attain the rapidity of a good portrait lens. For
groups, it and the Dallmeyer rapid rectilinear are probably the
best of all lenses.

The Dallmeyer rapid rectilinear greatly resembles the Stein-
heil aplanatic in its form. Its symmetrical lenses are not, how-
ever, made of flint glass only, but of flint and crown achroma-
tized in the usual manner. Although less known in this country,
they are equal to the Steinheil; indeed, there is, as far as the
writer's experience goes, no choice between them.

One important point in the comparison should be noted. Simi-
lar as these lenses are, their makers have taken different views as
to their powers, and the Steinheil lenses are advertised to cover
a plate one size larger than the Dallmeyer. Thus the Steinheil
having about 9 inches focal length, is advertised for use for
8x10 plates, whilst the corresponding lens of Dallmeyer is
advertised for 6Jx8J plates. This might naturally lead to mis-
conception, in the supposition that the lenses covered different
angles and had different powers. The fact is that the nine inch
lens will with a little straining cover (in either case) an 8x10
plate, and may be used with it, but generally will be found best
suited for a 6|x8|. In other words, the nine inch focus lens,
when worked with a fair-sized stop, has hardly power enough
for the 8 x 10, and rather more than power enough for the
6ix8i.

These lenses fall off a good deal in illumination towards the
edges. At the centre, the definition cannot, in the writer's opinion

PHOTOGRAPHIC OBJECTIVES. 83

be easily surpassed, but as we pass from the centre, it rapidly
falls off, unless sharply stopped down.

For architectural work both these lenses have no superiors, and
the same may be said as to groups. They are useful for instan-
taneous work, though not so rapid as a first-class portrait lens,
and the same is true of portraiture. For copying they are ex-
cellent. When width of angle of view is important, they are
exceeded by several lenses, by Zentmayer's
lens, by Dallmeyer's wide-angle rectilinear, by FiS- 59-

Steinheil's pantoscope, &c.

SteinheiVs Uncorrected Lens. — Previous to
the discovery of the lens above described,
Prof. Steinheil devised a lens consisting of
two uncorrected menisci, which were remark-
able for the great size of plate covered by so
small a lens. The adjoining figure gives an
idea of its construction. It is now superseded
by his achromatized doublet or aplanatic.

A useful maxim, familiar to experienced photographers, is
never to strain a lens. Some who purchase a lens intended to
cover a given size of plate, and who find that by using a very
small stop, good definition can be got over a materially larger
plate than that for which the lens was advertised, think they
have made a useful discovery, and perhaps avail themselves of it
habitually. The work so produced will never have the boldness,
atmospheric effect, gradation of distance, and transparency of
shadow given by a lens used with a larger opening.

On the other hand, it is a mistake to use a lens intended for
larger views, in taking small ones. Lenses for large views are
unavoidably slower, and the extent of angle included in a small
view, taken by a longer focus lens, is too small. An exception
to this is when a lens, like the triplet, is used for instantaneous
effect, and where it is worked with a large stop, rejecting all but
the centre of the image.

§ 4.— The Triplet.

The triplet lens consists of two large achromatized menisci,
between which is placed a small negative lens as near as possible

GENERAL OPTICS.

to the diaphragm. The length of the focus is thereby increased,
but at the same time marginal definition is obtained.

The triplet is a lens which, although possessing great merits,
has been somewhat over-praised. It is a useful lens undoubt-

Fig. 60.

O, C. Double convex crown glass lenses.

F, F. Double concave flint.

C". Double concave crown.

F'. Double convex flint.

D. Diaphragm with its opening at F'.

/,/. Flange.

edly, but since critically examining its power, the writer finds
himself led to the following comparison : —

For architectural objects it is surpassed by the Steinheil, the
Dallmeyer rapid rectilinear, and by Zentmayer's lens, the last
mentioned of which gives lines equally straight, and includes a
very much larger angle. Where angle is no object, where we
have free open space in the desired direction about the archi-
tectural object, there only the triplet may be conveniently em-
ployed.

For copying, it is surpassed by the same lens.

For views not embracing architectural objects, or where these
are not near the margin, and are inconspicuous, it is undoubtedly
surpassed by the view lens, especially by Dallmeyer's wide angle
view lens.

PHOTOGRAPHIC OBJECTIVES,

Fie. 61.

For portraiture, it is inferior to the portrait lens, being much
slower. By removing the central negative lens, however, its
action is increased ; but the centre of the image only is sharp
enough for use, as in the case of portraits to be vignetted.

§ 5.— The Globe Lens.

The globe form of lens was devised in this country by Mr.
Schnitzer, and was manufactured by him in connection with the
late Mr. Harrison. Its character-
istic feature lies in this, that the
exterior curves, back and front,
form part of one and the same
sphere, the diaphragm being
placed at the centre of that
sphere. Consequently it follows
that the incident ray i?, Fig. 62,
which passes through the centre,
has a nearly perpendicular inci-
dence upon the outside surface.
It therefore undergoes but little
deviation at either of the four
surfaces, but necessarily encoun-
tsrs some, and is bent from its
original direction R P down to
D. A grave objection to this lens
lies in its tendency to form a

C, C. Positive menisci of crown glass.
F, F. Negative menisci of flint glass

D. Diaphragm.
/, /. Flange.

Fig. 62.

thicker spot at the centre of the image, called flare, or ghost, the
cause of which will be explained further on (see p. 91).

GENERAL OPTICS.

§ 6. — The Zentmayer Lens.

Mr. Joseph Zentmayer, of this city, has succeeded in making a
photographic objective of a single sort of glass, his lenses being
both uncorrected menisci. Nevertheless, in these objectives the
chemical and visual foci are practically coincident. This single
fact would be enough to invest the lens with interest, but its
performances are sufficiently remarkable to indicate that this

lens will be adopted for all those
FiS- 63. descriptions of work to which it is

especially suited.

Fig. 63 will give a clear idea of
the system of construction. The
front and back curves of each lens
stand to each other in the relation
of 12 to 13, and the two lenses to
each other in the ratio of 2 to 3.
The stop is advanced a little nearer
to the front lens than the centre of
curvature of the exterior surface of
the larger lens.

It is evident that by having a
series of lenses of different sizes, the
larger lens of one pair may serve
as the smaller lens for the next larger pair. On this principle
these lenses are manufactured. The complete sets embrace six
lenses, capable of forming five pairs, having a great range of
focal lengths. Smaller sets are made, in which four lenses form
three pairs.

These lenses include a wonderful angle — fully as much as can
ever be advantageously used, and much more than covered by
the globe lens. The architectural effects attained are good, and
bolder than would be expected from the small size of the stop
that must be used. The reflecting surfaces which the ray meets
in this lens are fewer than in any other centrally stopped objec-
tive, and this gives brilliancy as well as diminishes the propor-
tion of light lost. For copying these Jenses are at least as good
as any. They are, in the opinion of the writer, unsuitable for
landscape work, by reason of the small stop required.

D. Diaphragm. /, /. Flange.

PHOTOGRAPHIC OBJECTIVES,

\ 7 —Ross's Doublet.

Mr. Eoss's form of doublet, Fig.
64, has been favorably spoken of.
It is intended for views and archi-
tecture, of which last it preserves
the straight lines, and for copying.
A material convenience is afforded
with this lens, an internal shutter,
sliding across the opening of the
diaphragm, instead of covering and
uncovering the lens in the usual
way with a cap. This feature has
been also introduced into Zentmayer's
lenses.

Eoss's lenses may be separated,
and each can be used as a single
landscape lens.

Fig. 64.

L, L. Positive menisci, corrected.
D. Diaphragm.

\ 8— Other Forms of Photographic LenBes.

Orthoscopic Lens. — This form which, like the portrait lens, we
owe to Petzval, has been extensively used, especially in this
country. Harrison manufactured many good objectives of this
form ; but on introducing the globe lens, he stopped making the
orthoscopic, and this lens is now but little used here. In Ger-
many it seems to have kept its place better.

The orthoscopic is an excellent copying lens, but slow, owing
to its long focus, and the small stop generally used with it in
copying. For taking views, a stop of considerable size may be
employed ; and, as it has a considerable depth of focus, it is by
some much prized for landscape work; though this is rather in
Germany than here. Small pictures of landscape scenery are
well taken by the smaller orthoscopic lenses, because in them
the focal length is not far from corresponding with that of the
eye. But large pictures made with the orthoscopic require a lens
of very long focus; and it results that planes of distance are not
well rendered, the foregrounds become indistinct and inconspic-
uous, and distant objects look unnaturally near. The remarkable
influence exerted by the focal length of a lens upon the resulting
image will be fully explained a few pages further on.

GENERAL OPTICS.

Fiar. 65.

Buscli's Pantoscope consists of two corrected lenses with a cen-
tral stop. It includes a very large angle of view, and has been
highly spoken of. A very carefully constructed camera appears
to be necessary for it.

Blunts Hemispherical Lens. — Mr. Blunt, of New York, con-
structs a lens of this name, which is spoken of in very high
terms by Mr. Hull and other competent judges. Mr. Hull affirms
it to be equal to any other lens for landscape purposes, without
exception. It is also suited for architecture and for copying,

Dalhneyer's Rectilinear. — This lens is less rapid than the
"Kapid" and the Steinheil aplanatic, but covers a very large
angle, about 100°. It gives straight lines.

Panoramic Cameras. — The theory of this very ingenious instru-
ment, by which such beautiful results have been obtained, is as
follows : —

Let J be the centre of emission of the cone of rays coining out

from any objective, single, double,
or triple, which finds its focus on
the screen S Sf.

If now the lens be made to rotate
horizontally, on J as a centre, the
position of objects in the image
formed on the focussing screen will
not change. If the image of any ex-
terior object, for example, falls at
the centre F, the rotation of the lens
will not cause the image of that
body to move, but it will remain accurately at F until the lens
rotates so much that it passes out of the field of view.

Now, to avail ourselves of this property, we must remember
that when the lens is rotated so that its axis passes from the di-
rection J A to the direction J A'7 its image is no longer in focus
on the screen at yl', but at the point F' ; because the central ray
is now in the direction J A, and its focal length will be the same
it originally was, viz., J F or J F' .

The first idea for applying these principles would evidently be
to use a sensitive plate of a cylindrical form, corresponding with
the curve F" F Ff, and by means of a mask with a vertical slit,
to conceal all the plate but a high narrow strip at the centre ;
then if the plate F" FF' remained stationary, and the lens rotated

PHOTOGRAPHIC OBJECTIVES. 89

carrying the mask with it, every part of the plate would be ex-
posed successively.

But in the instrument now in use, this is otherwise managed.
The sensitive plate occupies the position S S', and is flat. It is
masked, with a narrow opening at F, extending from top to bottom.
As the lens rotates, the plate S Sf is shifted sideways by a system
of clockwork, which makes its movement exactly correspond
with that of the lens, whether it be slow or fast, as the light may
require.

As a curved plate, F' F F" would receive a perfect image from
the rotating lens, masked as above explained, all that is necessary
is that the flat plate S S' should be shifted in such a way that
when, for instance, the lens has moved so that its axis is in the
direction J F', then the plate shall have been brought up to F',
there to receive its image at its correct focus. And, evidently,
if the plate be long enough, and the camera be rotated to a full
circle, an entire panorama may be obtained.

This picture will be found to differ materially from one obtained
in the ordinary camera. It will be in panoramic, instead of plane
projection. The picture will not be an harmonious whole, which
the eye sees whilst regarding its perspective centre, but as if the
eye were directed always opposite to it, in whatever direction it
chanced to look, or, to speak more exactly, as if the eyes were
directed in succession at all the vertical lines in the picture.

Another difference will be, that from end to end (but not from
top to bottom) the picture, no matter how large, will be in equally
good focus. At the right and left extremities the picture will
be as sharp as the middle. This is because the central part of
the image only is used. Each part becomes successively the
centre.

Again, the vertical slit at F may be made narrow at bottom
and wide at top, so that the foreground will get a larger exposure
than the sky ; and this difference may be regulated at will, giving,
if desired, to the sky an exposure of one-tenth or less than that
which the foreground receives. It is this which has enabled
Braun to produce such wonderful cloud pictures in his Swiss
scenery, and to get good definition of snow mountains against
the sky and clouds.

The most successful application of this principle is at present
Johnson's panoramic camera. It is patented, but the patent can-
not cover the principle, which was understood many years before
7

90 GENERAL OPTICS.

his application of it, and was applied to the construction of pano-
ramic cameras.1

§ 9. — General Remarks on Lenses.

Portraiture. — The portrait lens is so far superior to all others
for this purpose that none other is habitually used. The Stein-
heil aplanatic is the form that comes nearest in efficiency ; it is
now occasionally used for portraits, and is probably unsurpassed
for taking groups.

For card portraits the focal length needed for the lens will
depend upon how much is to be included. For full lengths, very
short focus lenses are commonly employed. For such as show
part of the body, and even including the hands, lenses of six to
eight or nine inches focal length will be proper. For "cabinet
size" lenses of eight to twelve inches focal length will be needed.
For 6Jx 8 J plates and half-length portraits, a lens of from ten to
sixteen inches will be suitable. For very short exposures, espe-
cially in taking children, "extra rapid" lenses are made, with
very short focal lengths. Some makers make a difference in their
lenses according as they are wanted for full lengths and for vig-
netted heads. In the latter case every effort is made for perfect
definition at the centre ; in the former a good definition all over
the plate is aimed at.

Generally, the shorter the focal length, the less exposure will
be needed, and the facility of getting all portions of the image
into focus will be greater; but the longer the focal length, the
less exaggeration there will be in those parts that project, the
hands especially.

Very ingenious arrangements have been adapted to the portrait
lens, with the object of changing the focus during exposure, in
the effort to get a diffusion of focus, and, instead of having one
part sharp to the exclusion of the rest, to maintain a certain
average of sharpness over the whole. Even lenses have been
made in which a certain amount of spherical aberration has been
left uncorrected, in order to diffuse the sharpness. The late Mr.
Claudet brought this whole matter prominently forward shortly
before his death, and opinions are very much divided on the
subject.

1 See Secretan, De la distance focale des Systhnes Optiques convergents. Paris,
1805.

PHOTOGRAPHIC OBJECTIVES.

Landscapes. — As already said, for such cases where it is appli-
cable, the single view lens, especially the wide-angle form, is
exceedingly satisfactory. The small angle included by the com-
mon view lens is often a great objection. The rapid rectilinear
of Dallmeyer, and the aplanatic of Steinheil, are exceedingly use-
ful in landscape work, are quick, clean, free from flare, and cover
a very satisfactory and sufficient angle. Between the two there
is little choice. In using the aplanatic, the photographer is advised
to employ a lens of one size larger than that advertised for the
size of plate which he has in view. With the other this is not
necessary.

There seems to exist a curious distinction between the effects
of these forms of lenses which has been little noticed. The wide
angle view lens produces a remarkable amount of detail — every
stone in a wall, every pebble on a shore, seem individually
brought out, distinct from the rest. The aplanatic gives less of
this individualization, but perhaps more general harmony. These
effects have nothing to do with the sharpness of the image, for
the distinction exists with lenses of equal focal length, equally
stopped down, and producing equally sharp definition. If any
difference exists, the image of the aplanatic is the sharper of the
two, at the centre. In depth of focus the view lens has the ad-

vantage.

Flare or ghost in the camera is an indistinct image of the dia-
phragm. Let C be the centre of curvature of the second surface

Fig. 66.

of the lens, whose thickness is here intentionally exaggerated, in
order to make the lines visibly distinct. A ray B, passing through
the diaphragm, strikes the first surface, is refracted, and passes
to the second at A. Here it is divided — most passing onwards in
a direction R' to form the true image, but a part suffering reflec-
tion and returning to the first surface. Here most is transmitted,
but a part is reflected again and returns to the second surface.
Here again the greater part is transmitted, after passing three

92 SPECIAL OPTICS.

times through the thickness of the lens, and, undergoing refrac-
tion, is bent down to the axis at some point F', producing the
flare.

Comparing Lenses. — A great deal of unintentional injustice is
done by photographers in comparing lenses, for want of taking
the necessary precautions to make the test a just one.

It should invariably be borne in mind that llie performance of
a lens depends entirely upon its slopping down. Of two lenses com-
pared, the inferior one may easily be made to seem the better, if
it be used with a smaller stop, and no account be taken of the
time of exposure.

It may be taken for granted that the sharpness, depth of focus,
and size of good picture obtained will always increase as the size
of the stop is diminished. This has led many landscapists to the
use of extremely small stops habitually, esteeming it of little
consequence to wait longer for the impression to be made. Several
evils result from this practice.

1. It may be taken as an invariable rule that the larger the
stop used, the more detail in the shadows will be obtained, always
supposing that each trial has* been made with a correctly timed
exposure. Let us say that, with a half-inch stop, fifteen seconds
have been found exactly right. Now, using a quarter-inch stop,
we must expose for one minute or rather more.1 The exposure
will be correct; the picture will be the best obtainable with that
size of stop, but the detail in the shadows will not be so good as
in the former case.

2. A large stop gives a bolder picture and spaces it out better.
The planes of distance are better made out. A small stop tends
to produce a map-like effect. One-thirtieth of an inch is about
the limit for the diameter of the stop for landscape work, and
one twenty-fifth is much better, and ought to be generally used.
That is, if the lens have a 10-inch focus, the stop should not be
less than § inch, or at farthest not less than £ inch. A small stop
tends to produce pictures destitute of atmosphere, the distant
objects look too near.

3. A long exposure in the case of portraiture is a serious evil.
Even with landscapes it is not unimportant, for, although the

1 Theoretically the exposure should always be inversely proportioned to the
area of the stop, and this area is proportional to the square of the diameter of
the stop. But in practice, it is found that the increase of exposure must be
considerably more than in this proportion.

PHOTOGRAPHIC OBJECTIVES. 93

contrary has been affirmed, the difficult}7 of catching foliage still
always increases with the length of the exposure.

The comparison, therefore, between lenses of equal focal length
must always be made with stops of equal opening. Between
lenses of different focal lengths no true or just comparison can
be made at all. Some approximation may be reached by trying
them with stops whose diameter is exactly proportionate to the
focal length, but even then, the smaller lens will always work
the quickest and otherwise appear to be the best. The truth is
that the difficulties both of the optician in making, and of the
photographer in using, increase so rapidly with the size of the
picture, that between different sizes a just comparison is all but
impossible. A photographer who has for a long time worked
with any one size of plate, and then changes to a larger size and
corresponding lens, becomes at once aware of the increased dif-
ficulties in his way. He must exclude more foreground, or he
cannot get his whole picture well in focus. He must use a smaller
stop also to the same end. His image on the ground glass is not
nearly so brilliant, and his exposures must be materially pro-
longed to get a harmonious negative.

Selection of Lenses. — The color of a lens is always important.
Place the lens on a perfectly white sheet of paper — any brown-
ness of tint is a serious objection. In an old lens this may arise
from the Canada Balsam, with which the separate portions are
cemented together, turning yellow. If this be thought to be the
case, the lens should be taken to an optician to be separated,
cleaned, and re-attached. The photographer is not advised to
attempt this himself.

Bubbles in the glass are objectionable, because they tend to
throw rays in abnormal directions, and to impair the brilliancy
of the image. One or two small ones are not important, nor a
sufficient cause for rejecting an otherwise satisfactory lens. But
it indicates carelessness in the maker, as these bubbles are always
visible in the disk from which the lens is made, and such disks
should be rejected.

Strise, hair-like or thready transparent lines, are very objec-
tionable, and at once a sufficient cause for rejection.

Scratches. — Lenses will sometimes come from the maker with
scratches, the result of careless handling of tools in setting, or
of bad packing. Such of course are returned.

Centering. — To every lens there belongs an optical axis, a line

94 SPECIAL OPTICS.

perpendicular to the surface of the lens, and passing through its
centre of curvature. Every achromatized lens consists of at
least two portions, and it is necessary that these should be so
arranged when attached together by the balsam used for that
purpose, that the optical axis of each should exactly correspond.
When two lenses or more are united to form an objective, not
only must the parts of each be properly disposed, but the front
lens must have its axis coincident with that of the back lens.
This will depend upon correct mounting.

The usual way in which opticians test the correctness of the
centering, is by making the tube containing the lenses revolve in
an upright position, that is, with the lenses horizontal. If, now,
a candle be placed at a little distance, and the eye be placed at a
convenient position, the candle will be seen reflected from the
surface as a bright point. Every surface of every piece of glass
in the tube will send back a reflection. Next the tube is caused
to rotate. Each lens that is correctly centered will continue to
send its reflection back perfectly fixed and immovable ; but any
surface that is out of centre will cause its reflection to deviate
more or less, according to the amount of error. It is evidently
not necessary that all the reflections should be seen at once, but
they may be observed successively. This method of observing
evidently renders it easy to fix which, if any, of the surfaces is
erroneously placed, and in which direction is its error.

Another mode of observation is more convenient for the pho-
tographer, as not requiring the apparatus needed for the method
just described.

The observer places himself in a dark room with a single can-
dle. Standing five or six feet from it, he looks at it through the
objective, inclining the latter a little until he sees a series of
bright points, which are the images of the candle, produced by
successive reflections from the different surfaces of the lens.
AVhen a lens has four pieces of glass in its construction, as in the
case of the portrait, globe, orthoscopic, and some other lenses,
the number of possible images is very considerable. These can-
not generally be all found at once, but eight, ten, or more can be
counted; a little practice, and altering the inclination of the lens
materially aids in increasing the number.

If now the centering is perfect, it will be found that, by care-
fully adjusting the position of the lens, all of these reflections
can be made to range themselves in a straight line. But if any

PHOTOGKAPHIC OBJECTIVES. 95

one or more of the component parts is out of centre, this will be
found impracticable. One or more of the bright points will re-
main obstinately out of line ; and, when a little movement is
made which brings them in, it will be found that some other
image, previously in line, has slid out of it. When the observer,
after very careful trial, finds that it is positively impossible to
make all the images range, he will be justified in concluding that
there is a fault in the centering.

Whilst this test is so easy that any intelligent observer can
apply it at once, there is no doubt that it is a very severe one.
A lens may perform quite fairly, and yet such an examination as
this may reveal a defect. But there is no doubt that first-rate
excellence is incompatible with such defectiveness.

It is also evident that the fewer the pieces of which a lens is
composed, the less difficulty the optician will find in getting them
all in correct line.

Quickness. — When lenses of equal focal lengths are tested
with equal stops, their comparative quickness will depend upon
the whiteness of the glass, the fewer number of surfaces that
enter into their formation, and on the curves given by the op-
tician : careful testing, and this alone, can settle the point.

Chemical Focus. — The correction for chromatic aberration is now
greatly better made than formerly. To test whether a lens is
properly corrected, select a newspaper printed with sharp-cut
type, and paste a piece a foot or fifteen inches square upon a
smooth piece of board. Set this up before the camera, with the
columns vertical, but inclined in a slanting direction, so that one
side, the right, for example, shall be a couple of inches nearer
the camera than the left, keeping the board, however, exactly up-
right. Focus carefully along the central upright line, and copy
it full size, or thereabouts.

Next examine the hair-strokes of the letters on the negative
with a microscope. If the lens is properly corrected, the central
line should be in the sharpest focus. If, however, it be found
that a portion to the right or left of the central line is in better
focus than the centre, then the correction has evidently been
faulty. If the sharpest image is of a part nearer to the lens than
the centre, the lens is under -corrected ; if of a part further from
the centre, the lens is over-corrected. In either case, it is said to
have a "chemical focus" that is, its chemical and visual focus

96 SPECIAL OPTICS.

does not correspond, a fault of the first magnitude, and sufficient
cause for rejecting the lens entirely.

Flanges. — The flange is the brass circle, which is permanently
attached to the camera front, and into which the lenses screw.
It is greatly to be desired that opticians should adopt a regular
set of sizes and threads for flanges, so that all the lenses habit-
ually used with one camera should screw into one flange, and
thus one camera front only be necessary. This has long been
done in the case of microscopic objectives, which, no matter
where made, screw at once into any instrument, though the
latter have been made thousands of miles awav. A similar
system is greatly needed in photographic objectives. Dallmeyer
has made some approximation to it, his lenses of different sorts
all screw into the same flange, except where the lenses are of
widely different focal length. But a universal adoption of this
system is what is wanted.

§ 10. — Care of Lenses.

A few words on the preservation and care of these beautiful
products of science and art will not be inappropriate here.

When lenses have been out of use for some time, or have been
carried to a distance, they should be carefully unscrewed and
wiped out with a soft old linen handkerchief, or a piece of chamois
leather. Nothing else should be used.

If the lenses have stood only for a short time, they ma}' only
require wiping on the exterior surfaces. They should first be
examined, and if free from dust, it is better not to wipe them.
Too much wiping is as bad as too little, and it may be set down
as a general principle, that the less lenses are touched with any-
tiling the better ; especially the fingers should never touch them.

With many forms of lenses, convenient caps of morocco lined
with velvet are now furnished. This is an excellent arrange-
ment, as dust is excluded, and the amount of wiping is diminished.
These caps are also very convenient for covering and uncovering
the lens. Such should be made and furnished with all photo-
graphic objectives. Something similar, or a light brass cap, to
protect the back lens, would also be very useful with all lenses
intended for field use.

It is a disadvantage to keep the lens in a cold place, and then?
perhaps, suddenly remove it to a warm one. A dew may form

PHOTOGRAPHIC PERSPECTIVE. 97

on the lens while the image is being impressed, or before, and
may escape observation. This may even happen by a mere
change of position in taking views, by the photographer remov-
ing his apparatus from a cool position to a warmer and damper
one.

Lenses should never be left lying where the sun, or even a
bright light, can fall upon them, as strong light has a tendency
to darken the color of the glass and increase the exposure ne-
cessary. For this reason, where steoroscopic lenses are occasion-
ally used separately, this use should be divided between the two.
If one of the pair is always used on such occasions, it will tend
gradually to work more slowly than the other, so that the two
can no longer be used advantageously together.

The care of the lens should also be extended to the brass
mounting. If this is allowed to become dented, or is in any way
roughly treated, there is danger that the centering may be inter-
fered with, ancl the working of the objective thereby impaired.
Second-hand objectives should always be severely tested before
purchasing, and no one should be induced to acquire a lens in
this way, unless he feels fully capable of judging the objective on
its own merits by a careful trial.

CHAPTER VI.
PHOTOGRAPHIC PERSPECTIVE.

\ 1. — Nature of the Image formed by a Lens.

When it was first found that the image of the camera could
be fixed, and that thus representations of natural objects could
be produced with critical exactness, the enthusiasm that resulted
was unbounded. Gradually this was mixed with severe disap-
pointment. The representations produced were, for the most
part, destitute of beauty even where the subjects themselves
were very beautiful. Everything was present in the picture, the
delineations were correct, or nearly so, and yet the result was
most unsatisfactory.

It soon appeared that good apparatus and a competent know-
ledge of the process constituted only a very small part of what

98 SPECIAL OPTICS.

was needed for obtaining a pleasing picture. A natural sense of
the beautiful, and a sufficient acquaintance with the rules of art,
proved to be at least equally necessary. Without these last, the
best point of view at which to place the camera could not be
selected, the time of day for securing the best aspects of light
and shadow could not be known, nor how much to include on
the plate, nor where to place the horizon line, &c. &c. The more
intelligent photographers gave earnest attention to these points,
and in proportion as they mastered them, their works found
favor. Those who disregarded them quickly sunk out of sight.

Even the nature of the image formed by a lens cannot be well
understood without some knowledge of perspective. It will well
repay any earnest landscape photographer to study this science
in the text-books specially devoted to it. Here, the limit assigned
by the author to this manual will permit of a very brief descrip-
tion only.

Perspective is the science of representing solid objects upon
a flat surface.

If between the object to be represented and the eye, we inter-
pose a plate of glass, and keeping the eye steadily fixed in position,
we draw lines upon the glass corresponding with the objects, we
shall obtain a representation of these objects in correct per-
spective.

Let us select a building for example, and on the plate of glass
mark the point at which we see all the corners and intersections
of the lines of the building. Then connecting these by drawing
lines on the plate we shall obtain a representation such that when
held up in its proper position between the eye and the building,
every line on the glass shall cover the corresponding line of the
building. This will be one drawing of the building in correct
perspective.

But we shall immediately notice that if we change in the least
the distance of the eye from the plate, the correspondence of lines
instantly ceases. Still keeping the eye exactly opposite the
centre of the pane, let us draw back, so as to he farther from the
window ; at once every line of the building has started out,
beyond the corresponding line of the original drawing, and we
obtain a larger picture than before.

By altering the position of the eye, any number of different
pictures will be obtained of the same object, and these correspond

PHOTOGRAPHIC PERSPECTIVE.

with the pictures obtained from lenses whose absolute focal lengths are
equal to the distance of the eye, in each case, from the pane of glass.
If the arrow A B, Fig. 67, represent the edifice, P' P' the pane

Fis. 07.

Fiff. 68.

of glass, and E the eye, the edifice as represented on the pane
will have the height P P. If the eye be withdrawn to E', the
image will be enlarged to P' P' .

Now, if the eye be replaced by a lens whose focal length is
the same as the distance of the eye from the pane, the image
formed by that lens will be precisely the same as seen by the
eye — reversed, of course.

The lens L forms on the screen an image V (Fig- 68) of the
arrow precisely as large as the image I seen by the eye when
placed at L, upon the pane at 7, the
distance of the eye to the pane being
the same as the focal length of the
lens ; that is, the distance from L to
the centre of the arrow.

If now, keeping the eye at X, we
move the plane i, backwards and for-
wards, we shall obtain any number of
images of the object A B. By drawing lines from L to all parts
of A B, it will be seen that the triangles are always similar; that
is, any triangle E A B (Fig. 67) will always be similar to the
corresponding triangle E P P. All parts of the image P P will
therefore have the same proportion to the corresponding parts of
the object A B. If any one dimension be altered, or if P P be
increased to P' P' by drawing back the eye to E', all others will
be proportionately changed. It follows, therefore (and this is
very important), that all these images of the object will vary in
size only; that is, they will be magnified or reduced images of
each other ; and as these images are identical with those formed

100

SPECIAL OPTICS,

by lenses placed at Z(Fig. 68), having focal lengths respectively-
equal to any distance from the eye to the pane, we draw the
conclusion that similar lenses of different focal lengths, placed at
the same spot, give representations which differ from each other in
size only. If the picture given by a small lens be magnified (for
example, in a solar camera) to the size of the picture given by a
large lens, the resulting picture will be identical with it, sup-
posing the lenses to be perfect instruments. The perspective
angles will be the same. But this is only true when the lenses
have been placed all successively on the same spot.

On the other hand, changing the position of the lens, or of the
eye, makes a complete difference in the nature of the image
formed. If A B G D be the side of a house seen obliquely, the

top and bottom lines, if continued,
will meet at a vanishing point I7,
and the perspective angle B V A
will be greater or smaller, ac-
cording as we place ourselves
nearer to or farther from the
building. The nearer we ap-
proach, the nearer the point V
comes in, and the more abruptly the apparent size diminishes
from A B to CD. As any good photographic lens placed in the
same position as the eye gives the same result, it follows that the
nearer we go with our lens to the edifice, the sharper will be the
perspective angle at B.

As the influence of these two conditions, viz., the focal lengths
of lenses, and the distance at which they are removed from the

Fig. 69.

objects should be very clearly understood, the writer has endea-
vored to further illustrate it by the accompanying diagrams.
Fig. 70 he has drawn in exact proportion, so that it exemplifies
exactly, and not merely approximately, the mode of rendering

PHOTOGRAPHIC PERSPECTIVE. 101

of two given objects by each of two lenses of very different focal

lengths.

Let us imagine two trees of equal height standing the one
somewhat farther than the other, and considerably to one side.
Let us assign to both the height of 50 feet, and let us first place
our camera so that the nearer tree is distant 600 feet. Let us
first take a lens of twelve inches focus. The tree will have the
exact height A B, or one inch, upon the ground glass.

Let us now suppose that the second tree is distant 1000 feet,
or 400 more than the first.1 Its image on the ground glass will
measure six-tenths of an inch in height, and it will occupy the
precise position CD, as shown in the figure.

Next let us for comparison substitute a lens of very much
longer focus, thirty inches. And let us recede to such a distance
that the image of the nearer tree shall occupy precisely the same height
A B as it did before. To accomplish this we shall be obliged to
recede to the distance of 1500 feet. How will now the second
equal tree be represented ?

Instead of measuring six-tenths of an inch, as in the previous
case, it will be found to be .79 inch, or very nearly eight-tenths.
It neither stands in the same relation of height, nor does it occupy
the same position, but is represented at E F.

Let us next substitute a lens of four inches focal length. In
order to produce an image of the first tree of the same height as
in the first case, we shall be obliged to advance to within 200
feet of the first tree. And then the second tree will be found to
have a height on the ground glass of only .33 inch, or one-third of
an inch. Its place will also be totally changed ; and it will be
found at G J, showing only that apparent height which it has in
the figure.

If now we consider the equal height and the relative position
of these trees, we shall see that the image formed by the first lens
of twelve inch focus preserves a truthful relation between these
objects, and conveys it to the eye.

On the contrary, the long focus lens brings the second tree so
far forward, and gives it so nearly the height of the first, that we
do not at all realize that it is so much farther away. The eye is
completely deceived. And this fault is incident to all lenses of

1 These distances are always measured upon the line of sight E G, Fig. 76,
and will he presently explained, and the mode of determining apparent sizes
explained.

102

PHOTOGRAPHIC PERSPECTIVE,

very long focus, that they do not preserve the relative planes of
distance, but drag objects that belong to the middle distance, into
the foreground.

The fault of the very short focus lens is in an exactly opposite
direction. The second tree is so excessively reduced in size that
the eye to account for this is driven into one or other of two
errors, either it misconceives the height of the second tree, and
imagines it to be smaller, or it misconceives the distance, and
imagines the object to be much farther.

So the vanishing point which in a correct representation is at
the point V, is, in the short focus lens, drawn in to V, and, with
the long focus lens, carried far beyond the limits of the diagram.

The author has chosen trees to illustrate this point, but the
principle is of course universally true. So the side of a house,
seen at a suitable distance, and with a lens of moderate focal length,
may present the appearance A B CD, Fig. 71. When we approach
nearer, and, as before, substitute a lens of smaller focal length,

Fi«r. 71.

so as to keep some one line A B of the same height as before,
the image assumes the appearance ABcb.

There is a certain subtlety in applying these principles to prac-
tice, which requires close attention. Although the character of
the image, as distinguished from its mere size, depends upon the
distance to which we go from the object, and not upon the lens,
yet, nevertheless, lenses of small focal lengths give almost always
very incorrect pictures, because such lenses are brought too near
to the objects, and the sharp perspective angle c B A results,
which is always offensive, and may legitimately be termed incor-
rect, because it gives incorrect conceptions of the object deli-
neated. In some cases where an excessively sharp perspective
angle is introduced, the building will actually seem to be falling
forwards, and this may happen just as easily with a draughts-
man's sketch as with a photographic view. In the latter case a
longer focus lens should be used, and taken to a greater distance.

PHOTOGRAPHIC PERSPECTIVE,

103

If, for example, it be required to photograph a large edifice, so
that the image shall be only three inches high, and we take a
four-inch lens and go to such a distance as will secure the size
required, we shall get a picture with the sharp angle G B A ; but
if we take a lens of eight to ten inch focus, and go to such a dis-
tance that the image is reduced to the same height, three inches,
we shall get a natural angle G B A, the actual apparent height
A B remaining the same in both cases, precisely as exemplified in
the cases already considered.

As the principles here involved are of much importance in ob-
taining satisfactory representations of buildings of all descriptions,
the author subjoins some illustrations that will exemplify them
strikingly. Fig. 72 gives a view of Girard College as repre-

Ficr. 72.

Girard College.— View exemplifying the exaggerated perspective produced by very short focus

lenses.

sented by a very short focus lens. The sharpness of the upper
angle will be remarked, and also the unnatural effect given to the
building in consequence of the vanishing points being so much
drawn in.

On the other hand, Fig. 73 shows the same building as repre-
sented by a much longer focus lens, not planted on the same spot,

Fig. 73.

Girard College.— View showiDg the correct perspective produced by loDger focus lenses.

10-i

PHOTOGRAPHIC PERSPECTIVE

for then the result would have been a much larger picture, with
the same angles as the former. But when the longer focus lens
is made to produce a picture of about the same size as the other
by removing it to a greater distance, we then get the effect shown
in Fig. 73, in which the perspective is natural and agreeable to
the eye.

In order to illustrate the principle more fully, the author sub-
joins two oblique views of a Gothic front, the one (Fig. 74) show-
Fig. 74.

West Front of St. Mark's Church, Philadelphia.— Exaggerated perspective of short focus lens.

the exaggerated and unpleasing effect of the short focus, by
ivhich the correct relation between the nearer and farther por-
tions is destroyed.

Fie. 7.-,.

St. Mark's. — Correct perspective of longer focus lens.

On the other hand, Fig. 75 shows the same front seen from the
same direction, but as represented by a longer focus lens placed
at a greater distance.

PHOTOGRAPHIC PERSPECTIVE. 105

The practical application of these rules is farther somewhat
complicated by the fact that it is necessary to take into consider-
ation the actual size of the picture; for it is an unquestionable
fact that the eye will support perspective angles in a large picture,
that it will not in a small one.

If, for example, we take a small picture C B A (Fig. 69), and
magnify it considerably, we shall find that the perspective angles,
too sharp before, lose this effect, and seem more natural. (The
experiment is a surprising one, and must be tried to be appreciated.)
This is one reason why the small photographs taken with very
short focus lenses are so much improved by magnifying them.
Their caricatured, or, as it is technically termed, violent, perspec-
tive, intolerable in such small pictures, becomes more endurable
in the large one. On the other hand, a large picture, in which
the perspective is appropriate and suitable for its size, cannot be
reduced without injury. Even if the reduction be absolutely
perfect, as when executed by a copying camera, the character of
the design is destroyed. Engravers know this, and know that a
large architectural drawing cannot be reduced with advantage;
and the same truth is recognized by all artists. Ruskin remarks
that true perspective is infinite and unreducible in its nature.
To every size of representation there is a certain size of perspec-
tive angle appropriate, or rather the appropriate size lies within
certain limits, and these are only to be fixed by judgment and
cultivated taste.

Farther, it is to be remarked, that as in every photographic
image the focal length of the lens corresponds with the distance
of the eye from the section on the window-pane before spoken
of, it follows that every photographic picture, to give a correct
impression, should be held from the eye at a distance equal to
the focal length of the lens with which it was taken. It will be
at once apparent that a view taken with a lens of four or five
inches focus, cannot be held that near to the eye of a person with
ordinary sight. It follows, therefore, that such lenses never can
give truthful delineations of scenery. They may make pretty
pictures, but these are wholly incorrect, as many must have
noticed. A garden becomes a park. The farther part of a house
is represented on so much smaller a scale than the nearer part,
that the eye, accustomed to correct representations, is deceived
and imagines the farther part, by reason of its smallness, to be
much farther away than it is. And thus the farther part beina
8

106 PHOTOGRAPHIC PERSPECTIVE.

dragged away, the house appears to stretch much farther back
than it does in reality, and consequently to be much larger.
Distant objects are dwarfed down, mountains become hills, if they
but stand clear of the foreground.

As we see objects best at about 10 or 12 inches from the eye,
this would appear to be about the best focal length for a lens.
Still, as the eye does not discriminate closely in these matters, and
is very tolerant within limits, lenses of all focal lengths, from 7
to 15 or 16 inches, may be employed with advantage. Beyond
this, the pictures become flat and tame, and the impression of
solidity is insufficient. The round pillar looks like a flat pilaster.

In these cases the defect is, to some extent, corrected by remov-
ing the picture considerably farther from the eye. We can here
alleviate the evil in a way that we could not with the pictures of
the short focus lens. Still, the effects are not good.

Portraiture. — Perspective is not without its bearing upon por-
traiture. All portraits taken with short focus lenses are incor-
rect. The nose is represented upon too large a scale for the rest
of the face, because it is nearer the lens. And it is still worse
with the hands and feet, if visible. If two or more persons be
included, their relative sizes are not properly preserved, unless
they stand exactly in line side by side. This incorrectness be-
comes quite striking where one person stands behind the other,
and a lens of 4 or 5 inch focus is employed. The fault in all
such cases depends upon the use of lenses of too short focal
length, in order to work in a short gallery, and work very
quickly. By using a lens of 7 or 8 inch focal length, and going
sufficiently far from the sitter to get the reduction desired, all
parts of the person will be harmoniously rendered, and the
different persons composing a group will be represented in correct
perspective proportion, whether near to, or at some distance from
the foremost figure.

§ 2. — Plane Projection and Apparent Size.

Plane Projection. — In the foregoing we have always considered
the perspective as referred to ordinary or plane projection, that
is, the surface of the image is perpendicular to the line of vision.
The eye looks in the direction E Cat the view A C B, which, as
delineated, is supposed to be projected on the screen or paper
A' Br, held perpendicularly to the line of sight E C.

PLANE PROJECTION AND APPARENT SIZE. 107

This enables us at once to fix the apparent size, that any object
will have in a plane projection, whether it be drawn or photo-
graphed. For suppose the paper
to be held at one foot from the Fig. 76.

eye, that is, that E C is one k^ ^ s

foot. If the tree 6' is a hundred \
feet from the eye, that is, one \
hundred times E C, which is \

now our scale, it will be dimin- \

ished one hundred times. There- aK—^P—/b'

fore, if it is fifty feet high, it will N^

be represented on A' B' as half / I \

a foot. Precisely the same is ^ T

true of a photographic represen-
tation. If the lens is at E, and has a focal length E Fof one foot,
the tree fifty feet high and one hundred feet distant, will appear
in the negative six inches in height.

If another tree of exactly the same height be situated at A, then,
although that tree may be distant half as far again, it will be
represented at A' of the same size as C. It appears at first anoma-
lous that two objects of the same size, at very different distances,
should have an equal size in the image or picture ; but this ano-
maly disappears by reflecting that, as the image is supposed to
be held square before the eye, the image of the tree A at A' is
farther from the eye than the image of the tree Cat C, so that
E A' stands in the same relation to E A as E C to E C, and,
therefore, if a sketch of a given size held at C would exactly
cover the real tree C, then a sketch of the same size held at A'
would exactly cover the real tree A.

It follows, therefore, that all objects of an equal size upon a line
A B, perpendicular to the line of sight E C, are represented of equal
size in the plane projection A' B', tchatever be their distances from
the eye.

An instance of this occurs in all drawings of fronts of build-
ings or rows of houses of equal heights, when the observer is
supposed to stand exactly in front. In the picture the houses
have the same actual height at the ends of the row, as in the
middle, although they may be much more distant. So in the de-
lineation of the front of the building, seen directly in front, the
roof line is parallel to the base line, and shows no tendency to
meet it.

103

PHOTOGRAPHIC PERSPECTIVE.

§ 3. — Panoramic Projection.

This form of projection is never used in architectural delinea-
tions, and has only lately attracted attention in photography,
from the introduction of the revolving camera.

In plane projection the image is projected upon a plane sur-
face, as the name indicates ; in the panoramic it is thrown upon
one that is cylindrical.

The curved surface A' C B' receives the image, and as the point
A' is no farther from the eye than (7, it follows that of the two
equal objects A and (7, A is represented smaller just in propor-
tion to the actual distance, so
that if the distance E A be
half as long again as F C, the
tree A will have only two-
thirds the apparent height of
the equal tree C.

The representations afforded
by panoramic perspective are
correct only when they are
received on a curved surface and so viewed. If printed on
paper, the paper must be curved into the arc A' C B' of a circle,
whose radius is the focal length of the lens with which they were
taken. If such prints be laid flat (as they always are in practice),
everything is distorted. With landscapes this may be tolerated,
that is, the eye, if unfamiliar with the scene, may not detect the
falsification, and the general effect maybe pleasing. But as soon
as this mode of representation is applied to architecture, its
faults become strikingly apparent. If the front of a building
be represented, the horizontal right line of the roof or cornice
becomes a curve with the ends pointing downwards. The base
line of the building becomes another curve, with the ends point-
ing upwards. All horizontal lines become curves, but vertical
lines still remain straight, because the projection plane was
curved only in a horizontal direction; it was cylindrical, and the
vertical right lines in nature were all represented by vertical
right lines on the cylindrical surface.

PART III.

PHOTOGRAPHIC MANIPULATIONS.

CHAPTER I.
THE DARK ROOM.

§ 1. — Regulation of Light.

The dark room in which the operations of sensitizing and
development are to be conducted, is most commonly made by
partitioning off a portion of a larger room for this purpose. It
consequently happens not unfrequently that this room is lighted
only by an opening into the larger room, and has no window
communicating with the exterior. This is a serious evil, and
one to be avoided if possible. No sufficient ventilation can be
obtained except from a window upon the street or yard, and
for want of this, the operator's health is exposed to suffer severe
injury.

The Window. — When access can be had to the open air, it is
desirable that the window of the dark room shall not be so
situated as to receive the direct rays of the sun. If this can-
not be wholly avoided, it is better to have the sun fall obliquely,
and later in the day, rather than perpendicularly, or in the
morning ; therefore a northwest exposure will be best, if it can
be arranged.

It is much better to have a good light in the dark room than
to work by a faint one, and this can always be accomplished by
using proper precautions. The window need not be small, if it
is properly protected.

There are two methods in common use: the use of yellow glass,
and the coloring, or otherwise guarding of common glass.

The yellow glass sold in the shops, even when the darkest
shades are used, is not in itself a sufficient protection. Even
when direct sunlight does not fall upon the window, light enough

110 PHOTOGRAPHIC MANIPULATIONS.

will enter to impress a plate ; this the writer can assert from
experience. As an additional protection, a shade of brown hol-
land is useful, which in- dark weather can be rolled up.

Pasting yellow paper, such as is made for common yellow en-
velopes, gives an excellent protection if the paper is stout, and if
the sun does not fall directly on the window, this will, in many
cases, be sufficient. The paper should be cut to the exact size of
the panes, and attached by a border of paste. In this way the
free open and shutting of the sash is not interfered with. The
yellow glass is of course preferable.

For a long time past, the writer has substituted green glass for
yellow. The orange-yellow shade of color imparted to light by
the glass in ordinary use is very trying to the eyes of many
persons. The green light, on the contrary, is pleasant both for
the operation of preparing the plates and for developing. A
tolerably dark, but not too dark, shade will be proper.

The light used may be (whether green or yellow glass be em-
ployed) either ordinary daylight, or artificial light. The latter
has the advantage that it may be had always of equal power,
which is of great use in judging of the density of a negative
during development. In employing daylight through colored
glass, more mistakes will be made as to the density of the nega-
tive than when an artificial light of uniform strength is used.

If a window is used for illumination, it should not be too
small, so that the light, after being thoroughly divested of its
actinic elements, may still be sufficiently abundant
Fig. 78. to render all operations easy. Ordinary print

should be read with ease in the dark room, and
this is not inconsistent with absolute immunity
from fogging, if the precautions just mentioned
have been suitably taken.

But a window for occasional opening, is not in
itself, by any means, a sufficient mode of ventila-
tion. In the roof of the room, a five or six-inch
pipe should be set, the exterior part of which is
bent twice at right angles, so as to point down-
wards; in this way neither light nor rain can enter.
An opening communicating with the outer air,
near the floor, for the admission of air, is also very desirable.
A slanting board is nailed against it, which freely lets pass the
air, but excludes the light.

THE DARK ROOM.

Ill

Fig. 79.

Or a Ventilating Box may be employed. Such a box is repre-
sented in Fig. 79. It is easily put together out of a few boards,
A hole is cut into the partition of
the dark room, corresponding in
size to the opening G at the right
hand end of the box, from which
one side A B C D, is here supposed
to be removed, in order to show the
interior arrangement, and then the
box is fastened close over the hole.
The air enters at the opening H, in
the bottom of the box, and passes
through the partition, whilst the

light is effectually excluded by the cross pieces E and F. Two
such boxes should be used, one for the ingress, the other for the
egress of the air. The former is better placed so as to commu-
nicate with the outside air. If this cannot be done, and both
must be placed inside, one should be near the floor, the other
near the ceiling.

§ 2. — Arrangement.

The arrangement of the room will depend so much upon its
size and shape, that it is difficult to give any general directions.
But it may be said, that the place for developing should be in
front of the window, and that near by it should be a sink with a
tap for washing. The tap, in fact, should be so at hand that
water can be made to flow over the negative at any instant to
stop its development. This is very urgent, and any arrangement
that does not accomplish this is exceedingly defective.

A good plan is to have a shelf eighteen inches wide round
three sides of the room. The height of the shelf will depend
upon whether the operator develops sitting or standing. If the
former, the shelf should be just high enough to put the knees
under, and no more. If standing, it should have a somewhat
greater height.

If vertical baths are used for sensitizing, they should not
stand on this shelf, but should be let into it, so that the top of
the bath will be level with the shelf; at least this is advisable if
it is intended to do this part of the work seated.

If the fixing is done in the dark room, the fixing bath and all
utensils connected with this part of the work, should be as far as

112

PHOTOGRAPHIC MANIPULATIONS.

possible from the sensitizing baths, and the utmost care should
be taken to avoid the introduction of the minutest portion of the
hyposulphite into the silver bath, to which it would be fatal.

The figure below represents an arrangement adopted by the
author, where it was a great object to save space. A wide shelf

Fig. 80.

to be used as a table, runs round three sides. At A are the
sensitizing baths, and near A is a small window of yellow glass,
to coat the collodion and manage the sensitizing by. (This win-
dow is by no means essential.) Opposite to B is the principal
window, looking north, and opening to the open air. In front of
it at B, is the tray or sink over which the developing is done.
This window comes down so that the bottom of the lowest pane
is level with the top of the table. A window with a high sill in
a dark room is a great nuisance. At C is the sink with a tap of
water over it. At D is the fixing bath of hyposulphite.

A double-kneed pipe is set into the roof, and fresh air is in-
troduced at the floor from the outside, as before described.

The dark room should be kept clean and free from dust. The
chemicals that emit fumes should be kept elsewhere, and care be
taken to avoid spilling hyposulphite solutions about, because
whatever substances are scattered over the floor in solution soon
dry, and are ground off into dust by the feet. This dust may
rise and settle again in vessels and solutions. All such foreign
matter is injurious, and nothing more so than hyposulphite.

Too much shelf space in the dark room is undesirable ; it is an
invitation to leave things there that are better away. No worse
mistake can be made than that of keeping chemicals in the dark
room. It happens that most of the substances used for after-
intensifying emit vapors that tend strongly to produce fogging,
and especially sulphide of potassium (liver of sulphur) and
Schlippe's salt. Old solutions containing vegetable or other or-

THE DARK ROOM. 113

ganic matter liable to turn sour or putrefy, are very injurious.
A long succession of failures was once traced by a professional
photographer to a bottle of sulphocyanide of ammonium, either
originally impure, or into which something had been dropped
that had set up a decomposition. In a word, there are so many
suspicious substances, and injury when it comes is so intensely
vexatious and so difficult to trace out, that it is best to be on the
safe side, and to absolutely interdict the presence of anything in
the dark room that is not needed for the coating, sensitizing, and
developing, to the exclusion of all other operations.

It is still worse when the dark room is used as a work room
for chemical operations, and when torrents of gases are gene-
rated that permeate the wood work and plastering, and slowl)r
ooze out again for weeks.

Foul drains, or pipes communicating with sewers may intro-
duce gases that will interfere with the work. The presence of
turpentine and of fresh paint have been affirmed to interfere with
negative work very seriously.

But the simple exclusion of these sources of trouble is not in
itself sufficient. A complete ventilation is required, and a
copious admission of pure air into the dark room is a matter
upon which the photographer's health, possibly even his life, may
depend. The recklessness shown by many in these respects is
incredible, and can only be explained by an entire want of know-
ledge of the dangers incurred. It is a fact familiar to physicians
that a daily exposure, even for a limited time, to an atmosphere
impregnated with noxious fumes will do serious mischief, even
when no inconvenience is felt at the time. Our senses rapidly
familiarize themselves with injurious emanations, and cease to
give us notice of them, even when they are silently and steadily
doing their work of destruction.

Nor should any photographer require an assistant or person
employed to do work which he would avoid himself by reason
of its insalubrity. This, however, is often done, and is always
thoroughly unjustifiable. Frequently the person so exposed is
ignorant of his own danger.

It is desirable that the temperature of the dark room should not
differ very materially from that of the glass room.

114 PHOTOGRAPHIC MANIPULATIONS.

CHAPTER It.

THE GLASS ROOM.

§ 1. — General Remarks.

No subject concerns the professional photographer more deeply
than the glass room. Chemicals, lenses, and cameras he can
always obtain of excellent quality from dealers of reputation,
but in the construction of the glass room he must depend to a
large extent upon himself, acting under such information and in-
struction as he can obtain. It is certain that a very clever ope-
rator will occasionally obtain good pictures in almost any glass
room ; this is not, however, what is wanted. The disposition of
light should be such as to facilitate to the utmost the really diffi-
cult task of regular success.

If any intelligent observer will place himself in a room lighted
from several different directions, and taking a looking-glass in his
hand, will observe his own face, as he stands in very different
parts of the room, with very different illuminations, he will see
a wonderful change as regards feature, character, and expression.
Now, the object of the glass room is to obtain from each face its
best, and at the same time, also, its characteristic expression.

If the observer with his hand-glass carefully notices the effects
of different lights upon his features, he will be especially struck
with the three following facts : —

1. That a level light, coming directly in front, flattens all the
features.

2. That a light directly from above produces an opposite effect,
exaggerating the projection of the brows and nose, rendering
the eyes cavernous, and drawing out the cheek bones.

3. That a level light from one side produces a most unpleasant
effect, causing what is known as a " hatchet" expression of face.

Pursuing his trials further, he will find that the right light to
use consists in a combination of the three into a front upper-side
light. To produce this light is the great object of the disposition
of the glass room; bearing in mind that for different sitters a
variation of light must be at command, and that as the position,
strength, and character of the light vary at different hours of the
day, the means of compensating for, and correcting these changes,
must be at hand.

THE GLASS ROOM.

115

Selection of Glass for Glazing. — The experiments of Mr. Gaf-
field and others have shown that very pure white specimens of
glass are more apt to change color by the continued action of
sunlight, than those that are a little colored. The explanation
appears to be that the freedom from color is obtained by the
addition of manganese in the making of the glass, and that glass
to which manganese has been added is apt to change by sunlight
to a color which is sometimes purple, sometimes golden; in
either case greatly obstructing the passage of the active rays.
It was found that fine white plate glass was the most liable to
change of all the sorts examined. A light bluish-green window-
glass is that which is most suitable for glazing the glass room.
It would be desirable if glass manufacturers would furnish glass
expressly for glazing photographic rooms, guaranteed free from

manganese.

§ 2. — Ridge Roof Construction.
By far the best light for the portraitist is the pure, soft, diffusive
light that comes from a northern exposure. An abundant supply
of this light is of the highest value. It is best, therefore, that
the length of the glass room should be east or west, and that the
north light should be received on one side. The best photo-
graphers all over the world are now pretty generally agreed in
preferring what is known as the Ridge Roof System of Construc-
tion, a section of which in various forms is shown in the figures.

Fig. 81.

Fig. 82.

Fig. 83.

The single line represents the glazed parts; the double line, ordi-
nary walls, ceiling, &c.

Of these forms A is the preferable one. Great differences of
opinion exist as to the best pitch to give the light side of the
roof. Two different inclinations are shown in Fig. 81 by the line
above, and that below, G. Some, however, make it still flatter

116

PHOTOGRAPHIC MANIPULATIONS.

Fig. 84.

than the flattest of these, even as little slope as two inches to the
foot. Others again will give it a pitch of thirty degrees or more.
Fig. 84 shows a perspective view of the interior of this con-
struction. The principal length
from front to back is, of course,
east and west, the glazed side
being towards the north. The
glazing is carried half way or
thereabouts; at least it is better
that it should not go farther,
in order that the camera may
be well protected from the light.
It will be necessary, or, at least,
far better, to have a screen so
interposed as to shut off useless
and injurious light from strik-
ing the camera from the glazed
portions. It is, indeed, a most
excellent canon, that the eye, if placed in the position which the lens is
to occupy, shall not see any uncovered glass. It should never be for-
gotten that neglect of this will diminish the brilliancy of the image.
The relation between the dimensions of the glass house will
be better understood by the perspective drawing of its exterior

Fig. 85.

view, Fig. 85. If a perpendicular be dropped from the top line
of the glass to the floor, its height, A B, represents the extreme
height of the glass. A line C D is drawn at right angles to it,
and the angle C D B is that of the inclination of the roof. The
glazing begins at the height E II from the floor. H D is the
height from the floor at which the top light commences.

The pitch of the upper skylight is usually measured by giving
the angle B D C. But as few carpenters are able to lay off a roof

THE GLASS ROOM.

117

at a given angle, the following table will be found useful. It
gives the actual height B C for any desired angle, taking the
breadth D C as 10, from which the height is easily found for any
other breadth, greater or less.

TABLES OF INCLINATION IN FEET FOR A GIVEN ANGLE OF PITCH.

Table I.

Angle

of pitch

of roof = 10°

if depth

= 10,

height B C

= 1.76.

Angle

" = 12°

= 2.13.

Angle

= 15°

= 2.G8.

Angle

" = 20°

= 3.64.

Angle

" = 25°

= 4.66.

Angle

= 30°

= 5.77.

Angle

= 35°

= 7.00.

Angle

" = 40°

= 8.40.

That is, with a pitch of 10°, the roof will rise 1.76 (If nearly)
feet in ten, and so on for other inclinations. To exemplify the
use of this table: Suppose it be intended that the skylight shall
have a pitch of 20°, that the room is 22 feet wide, and that the
skylight shall come perpendicularly over 12 feet of these 22,
what perpendicular height must the carpenter give the upper
edge B of the skylight above its lower edge D G ? or, in other
words, if C D is to be 12 feet, what height must B C have that
the roof rmiy pitch 20°?

Eeferring to the table, we get for 20° the height corresponding
to 10 feet of base, viz. ....... 3.64

For each additional foot we add one-tenth of this, viz., for

*_ I Qi ' I • • • • • • • • • • • i o

And find 4 iVo feet> or 4 feet 4| inches nearly . . 4.37
The following table shows the perpendicular height for differ-
ent angles when the length of slant line B D is given : —

Table II.

Angle of pitch

= 10°, slant line B D = 10, the height B C

= 1.73.

Angle

= 12° " " " " "

= 2.08.

Angle

= 15° " " " " "

= 2.59.

Angle

OQO It It tt tt tt

= 3.42.

Angle

Os;o tt tt tt tt tt

= 4.22.

Angle

1 1

_ 30o tt tt tt tt tt

= 5.00.

Angle

_ 35o tt tt tt tt tt

= 5.73.

Angle

= 40° " " " " "

= 6.43.

118

PHOTOGRAPHIC MANIPULATIONS,

As an example, suppose it be intended to build a skylight
fourteen feet square, and to give it a pitch of 15°, what perpen-
dicular elevation must be given to the top ridge?

Consulting Table II. we find for 10 feet and angle of 15° 2.59
For the four additional feet of the 14 we add four-tenths of

3.63

And find 3T603o feet, or 3 feet 7| inches nearly

The form A, Fig. 81, may be still otherwise varied. A " lean
to" roof may be substituted, that is, the glass G may be continued
all the way with the same pitch till it reaches the side wall,
which is then much higher, and the roof R is thus superseded.

Mr. Fennemore's glass room is arranged upon a different plan,
as will be seen by the adjoining figure. Its dimensions are : —

Top light, width
" length
Side light, width
Greatest height .
Lowest "

The pitch of the top light

19 feet.
12 "

12 "
12 "

7 "

is five feet in twelve, or five inches
to the foot. Keference to Table II., p. 117, will show that this
corresponds to an angle of between twenty-four and twenty-five
degrees.

Fig. 86.

Mr. Wenderoth's skylight is in form somewhat like that of
Mr. Fennemore's, that is, it is A, Fig. 81, widened out. But the
sitter has his back to the west wall, and the line from the camera
to the sitter has the usual east and west direction. lie has, in

THE GLASS ROOM. 119

addition, arrangements for admitting light at the ends, and also
a narrow line of opening just at the top of the south wall. This
last, without the most careful management, must lead to cross
lights, and is probably of no real use.

Sarony uses a longer room, with glass at each end, in order to
carry on two sets of operations at once. Both ends have light
from the northward. The roof-light is 13 feet long, and 13 feet
along the slides slanting upwards, which have an angle of thirty
decrees. The side light commences at a distance of five feet
from the floor, and meets the roof three feet above this ; it has
the same length, thirteen feet, as the roof-light that joins it. The
construction is, therefore, very similar to Fig. 85, if we .sup-
pose another glazed portion added to the farther end. The
height B H is five feet, the glazed side has a height D E of three
feet. The upper skylight is square, the lengths, B D, D K, being
each thirteen feet. The pitch or angle B D C is thirty degrees.
It is easy, by Table II., p. 117, to find the perpendicular height
of the top of the skylight from the floor. The table gives for the
absolute height, C B, of the sash, 6 feet 6 inches, and as D II is
here 8 feet, the whole height, A B, is 14 feet G inches.

Gurney's new studio is 18x30, with a top light 15xlo, the
side light 15 feet long and 7 high, beginning at a height of 2|
feet from floor. The top light is at its junction with the side
light 9 feet 6 inches from floor; at its highest point 11 feet 8
inches. Its inclination is, therefore, 2 feet 2 inches in 13, or 2
inches to the foot. This is 1.67 feet in 10 feet of slant line. Re-
ferring to Table II., p. 117, we see that this corresponds with an
inclination a little under ten degrees, or not quite one-third as
much as that of the last-mentioned studio.

In a new studio, recently completed, Loescher and Petzch, of
Berlin, continue to use the ridge roof form, but built in somewhat
different proportions from their former studio, described in the
first edition of this manual. Their light fronts north, and the
skylight is protected from the direct sunlight by higher build-
ings south of it. The glass room is 35 X 17 — the lower side of
the skylight is 10 feet from the floor, the higher 14, the inclina-
tion is, therefore, 4 feet in 17. The whole side of the room, and
about three-quarters of the roof, are glazed. This plan involved
so great an exposure of side light, that especial means were found
necessary to exclude perfectly all that was not needed.1

1 For fuller details and figures see Phila. Photog., 1870, pp. 89 and 117.

120 PHOTOGRAPHIC MANIPULATIONS.

The particulars of the construction of the glass room of a cele-
brated Parisian photographer, Eeutlinger, have been given to the
public. On the north side there is a perpendicular glazed por-
tion, 22 feet long and 12 high. The glass roof has only 14 feet
of width, protected by an awning controlled by pulleys inside,
to cut off direct sunlight. The glass overhead is ground glass,
and so are the sides as high as the eyes. The entire length of
the room is about 44 feet.1

Salomon, of Paris, uses a system corresponding for the most
part with Fig. 85. But as one of his essential peculiarities lies in
the use of a diagonal background, a sketch of the interior of his
glass room will be given in the section on backgrounds.

Any one of the forms of glass room which have been here par-
ticularly described, will, in good hands, give good work. The
whole system used by Loescher and Petzch seems that most in
accordance with sound principles, and without meaning in the
least to detract from the excellence of the others, is that which
is most strongly recommended here.

"Whatever system is adopted, the following precautions will be
found useful : Keep the end at which the camera is placed dark,
and avoid having much illumination in the space between the
camera and the sitter, because the slight dust that always floats
in the air of a room reflects back a portion of any light that falls
upon it, and so takes from the clearness and brilliancy of the
work. As to the power of dust to do this, any one may convince
himself by observing how visible the path of a sunbeam in a
dark room is rendered by the dust that floats in the air, and it is
a general rule that whatever is capable of sending back light to the
eye will also send it to the camera. Dust in the glass room is in
every respect a serious evil, and should be carefully prevented.

Closely allied to this principle is that the direction of the light
that is admitted should be towards the sitter and not towards (he

camera.

It cannot be expected that any one system of illumination
should be best for all purposes. Groups are best taken in a well-
diffused light, affording to all parts an equable illumination,
whereas for many sorts of portraits, such a light is unmanage-
able: in fact, many skilful operators, in making single portraits,
try to suppress all strong light except that which falls directly

1 Photograj>Msche Mittheilungen, No. 41, p. 130.

THE GLASS ROOM. 121

on the bead. Groups also are best managed in a tolerably large
room, whereas experience seems to show that single heads are
best taken in rather small glass rooms, and there is no doubt that
in a small room the pose is more rapid than in a large one ; light
becomes more diluted in a large room, and the sitter is farther
from the glass.

Length of the Glass Room. — This will be determined by the
character of the work to be done. The shortest length in which
a full-length card portrait can be taken is 21 feet, full-length
cabinet 24, full-length whole size 40. These requirements are
those that will fix the length, because heads and half-lengths can
always be taken within a shorter space. The breadth of the
room will need to be approximately half its length.

The quality of the glass needed for the skylight has already
been discussed. As to its management, it may be either the
simple, clear glass, ground glass, or blue frosted. Some persons
are under the belief that the blue color increases the actinic
power of the light. This is a complete error : any skylight will
work faster without than with such an application. The ad-
vantage of the frosting lies in very greatly diminishing the glare,
so that a larger amount of active light may be admitted without
inconveniencing the sitter. Ground glass is little used here, it
greatly softens the light, but also greatly diminishes it strength.
It has been found that whilst ordinary (clean) glass holds back
but about five per cent, of the light, ground glass stops one-half.
Nevertheless ground glass is largely used in France, and with
great success. The blue stippling is the favorite method here,
and is extending to Germany.

To apply it, blue frosting is first brushed on with any ordinary
flat brush. Then a thick round painter's brush is tied up with twine
to about an inch of the end, and is tapped against the moist
frosting until the effect is obtained.

Ventilation. — Some portion of the glass side should be arranged
to slide, or there should be somewhere a window that can be
raised. It is true that its use will be somewhat limited: the
photographer cannot of course run the risk of having a puff of
wind derange drapery, and even when opened between exposures
there is danger of the introduction of dust. But in weather in
which there is no dust in the atmosphere, it is highly desirable
to get the benefit of the freshness of the exterior air. Nothing
9

122

PHOTOGRAPHIC MANIPULATIONS.

tends more to give a portrait an old and faded expression than a
hot close atmosphere, the depressing effects of which are apt to
tell quickly upon the expression.

I 3. — Control of Sunlight.

An important consideration presents itself with respect to all
the forms of roof and glazing just shown in section. Even if
the roof looks directly to the north, it is impracticable to give it
so high a pitch that the sun shall not shine over the rid we at
midday, and it must also shine over the ends morning and even-
ing, unless higher walls abut against them. Various efforts have
been made by different photographers to obviate this difficulty.
Some select a position where the walls of adjoining houses afford
a screen, some use awnings moved by pulleys, others trust to
excluding the sun by curtains and shades inside. These, indeed,
are of course always necessary to regulate the amount and direc-
tion of light, independently
FiS- 87- of direct sunbeams. An

effectual course, in the ab-
sence of protection from
other parts of the build-
ing, or of adjoining build-
ings, is to construct a frame-
work of boards, as shown
in Fig. 87. This is valu-
able not only as respects
light, but checks the over-
heating of the glass room.
The same figure is intended to show a system of construction
sometimes adopted in this city ; it is easy to make and cheap, but
less advantageous than some others.

Some, however, trust so entirely to inside shades to exclude the
sun, as to prefer a southern exposure, softening the sunlight by
shades, and getting it under management as best they may. The
solitary advantage that this system possesses is, that in dull
weather the southern light is stronger than the northern.

Some, in order to get every variety of light, use a ridge roof,
with equal slopes north and south, both glazed, so that the prin-
cipal light may be taken from either side, as may be found best
suited to the weather and the sitter. But this has a most serious

THE GLASS ROOM.

123

objection in the intense heat caused by it. The glass room be-
comes in hot weather a veritable hot-house. The sitters suffer —
the chemicals do not work well.

To maintain a moderate temperature in the glass room is at
best a difficult matter, even when not complicated by a southern
exposure. A brick wall on the south side is a great protection,
and there should be, if possible, a space between the southern
slope of the ridge and the ceiling on that side. An excellent
arrangement on all these grounds is represented in Fig. 88. At
the upper augle of the ceiling A, a girder supports a wooden
studding B. This allows an interspace D on the south pitch of

Fig. 88.

Fig. 89.

the roof — very effectual in diminishing the heat. The wall B
tending to keep off the noon sun from the glazing A C.

It is evident that if the south wall supports a higher building
adjoining, as shown in Fig. 89, somewhat the same result is at-
tained. Such a form of construction requires especial care to
render it water-tight at the junction of the roof and wall. The
gutter in the angle must have a rapid pitch from back to front
(which cannot be shown in the section), and must be thoroughly
tinned by a good workman.

It will be important to keep the glass, especially its outer sur-
face, clean, and an arrangement for scattering water over the
top light will have the double advantage of affording an easy
means of washing, and a method of cooling the room in hot
weather.

Keeping the glass clean has an importance even greater than
might be supposed. It has been ascertained by careful trial that
the best and newest colorless glass stops one-twentieth of the light;

124- PHOTOGRAPHIC MANIPULATIONS.

a moderate accumulation of dust, perhaps spread and splashed
by rain and dew, may increase this source of loss five or tenfold.

§ 4. — Secondary Lights.

In all these sections the sitter is supposed to be at the far end,
and looking towards the spectator. He will thus receive on his
left side a powerful light from the glass roof, whilst his right
side will be comparatively dark.

Now, a difference in light on the two sides is desirable, and
even necessary, but this difference must not exceed a certain
moderate measure. And the dark side of the face requires a
secondary light, to give transparency to the shadows upon it.
Three different methods are used for this end.

First, and most common, reflectors are used. Generally, a large
screen covered with white paper, or white cloth, is placed on the
side of the sitter, opposite the light. Some have used screens
covered with silver paper ; others, large mirrors.

Secondlv, some have opened a window on the south side, arid
let in light directly on the dark side.

Thirdly, some object that these methods give false lights, es-
pecially affecting the expression of the eye, and, therefore, prefer
to keep the south side of the room of a sufficiently light color to
throw back a volume of soft white light, adequate to light up
the shadows.

The brilliancy of the picture is always aided by excluding all
extraneous light. The camera, therefore, should always be under
an unglazed portion of the roof, and screens should be so ar-
ranged that, if the eye be placed where the lens is to be, it shall
see no uncurtained glass. Too much glass is very objectionable,
especially toward the direction of the camera. The air of a room
always contains dust. The more strongly the dust between the
sitter and the lens is illuminated, the more it will affect the pic-
ture, and always by taking from its brilliancy.

The Tunnel System is not to be recommended, though it is
certain that good work has been done in this form of house, still
the system is every way inferior to the ridge roof. In it, one
end of the room, that in which the camera is placed, is lower than
the other, and the vertical space between the two ceilings is
glazed. Thus the strongest light is full in the sitter's eyes, at

THE GLASS ROOM.

125

the same time that its quantity is almost always deficient, seri-
ously incommoding the operator in dull weather, and producing
effects inferior to the ridge roof, in good.

It has been said that few photographers succeed in their first
attempts at building a glass house; that they require the expe-
rience of a first failure to attain subsequent success. Failures of
this kind are expensive, and infinitely vexatious. They are best
avoided by obtaining beforehand a clear conception of what are
the conditions essential to success, and then carefully and thought-
fully applying them to the position which their glass room is to
occupy. Sometimes splendid success comes by mere chance.
Mr. Hughes gives an instance in which the portraits produced
by a photographer in a country town in England were so excel-
lent as to induce, him to travel a long distance to see the maker.
He proved to be a man of limited intelligence, who, however,
had chanced to erect an excellent room, where an abundance of
soft, pure light from the north was received to the exclusion of
cross lights. The photographer knew that his work was excel-
lent, and ascribed it all to his personal skill, neither understand-
ing nor appreciating the merits of his room. Encouraged by
success, he erected a new gallery in another town, intended to be
far better than his old one, but was confounded to find that in it
he could not make anything worth having.

One material difference that will be found between a well and
ill-planned glass room is, that in the former work can be con-
tinued till a late hour in the afternoon, and, even then, brilliant
and well-modelled portraits can be got. It is, therefore (and this
cannot be too clearly understood), no proof of a good construction
that the operator can show a piece of first-rate work made in it. A
glass room can hardly be so badly planned but that in some sort
of weather, and at some hour of the day, good work may be done
in it. The well-planned room is one that is always in a condition
to meet the operator's needs.

126 PHOTOGRAPHIC MANIPULATIONS.

CHAPTER III.
PYROXYLINE AND COLLODION.

g 1. — Pyroxyline.

The manufacture of this substance has passed so much, in fact,
so completely into the hands of those who make it their business,
and who employ special methods, that it scarcely requires atten-
tion here, except in a brief way.

When any form of cellulose, such as cotton, paper, linen, &c,
is exposed to the action of mixed nitric and sulphuric acid, a
substitution takes place by which one or more molecules of N04,
hyponitric acid, are taken up by the cellulose. Several different
compounds are thus formed, and often simultaneously. When
the acid mixture is too weak, the cellulose is dissolved with
abundant disengagement of red fumes. When it is somewhat
stronger, and used before the heat generated by the mixture of
the acids escapes, pyroxylines suitable for photography are pro-
duced, thoroughly soluble in mixed alcohol and ether. With
lower temperatures and stronger acids, the more explosive form
of pyroxline is produced, which does not dissolve well in the
usual solvents.

The proportions most commonly employed in these later years,
are to take equal bulks of the two acids, using sulphuric acid of
full commercial strength (1.83 to 1.84), and nitric acid, sp. gr.
1.42. For each ounce of cotton, about twelve fluidounces1 of
each acid will be required. When this relative proportion of
acids is varied from, it is more usual to increase the sulphuric
acid than the nitric. The proportion of 12 sulphuric to 10 nitric
is often used, and indeed the sulphuric may be increased until it

1 As it is more convenient to measure liquids than to weigh them, it is com-
mon to take them in " fluidounces"— that is, a quantity equal to a measured
ounce of water. Of course, mth heavy acids, the quantity may largely exceed
an ounce in weight. A fluidounce of sulphuric acid will weigh not far short
of two ounces, one of nitric acid 1.42, nearly an ounce and a half. So in collo-
dion formulae the ounce of alcohol or ether means always a measured ounce,
and consequently much less than an ounce in weight.

PYROXYLINE AND COLLODION. 127

is threefold the bulk of the nitric. Some hold that this excess
of sulphuric acid tends to increase the intensity of the pyroxyline
produced. The mixing of the acids produces considerable heat.
If the thermometer plunged into them rises above 150°, the mix-
ture is allowed to cool ; if it stands below, heat is applied. When
the temperature is right the cotton is immersed in tufts, is pushed
quickly under the liquid so as to become soaked immediately
(otherwise red fumes may burst out from it, which, however, will
be checked by a complete immersion). The whole cotton is got
in as rapidly as possible, and is well worked round to insure
equality of action. After eight or ten minutes of immersion, the
cotton is drawn up with two stout glass rods, pressed against the
sides, and then thrown into a bucket of water. Without a mo-
ment's delay the operator separates it out so that the water may
penetrate it instantly. This can only be well done with the
fingers, and as they would be corroded and stained yellow by the
acids, it is best to use India-rubber gloves.

The pyroxyline then receives a very thorough washing in run-
ning water, is squeezed out and dried at ordinary temperatures
and not near a stove or other source of heat. The washing must
be sufficient to remove every trace of acid. Some, therefore,
wash it with very dilute ammonia or solution of carbonate of
soda, one ounce to the gallon, which must itself be washed out
of the cotton with clean water.

As commercial nitric acid varies very much in strength, it is
often found convenient to substitute nitrate of potash, and to
increase the quantity of sulphuric acid, inasmuch as part goes to
separate the nitric acid from the potash. It is also affirmed that
pyroxyline made with nitrate of potash dissolves more easily,
and gives a clearer solution, than that made with nitric acid.

Mix 200 parts of sulphuric acid of 1.8-1 (the full commercial
strength) with 100 parts of dried and pulverized nitrate of potash,
and keep them at a temperature of 1-17° to 150° F., which must
be maintained during the operation. Stir with a glass rod till
the lumps disappear. Then add six to eight parts of perfectly dry
carded cotton. Agitate the mixture from time to time with a
glass rod. After the action has continued for from ten to forty-
five minutes, empty suddenly into a large pan of water. Wash
thoroughly and rapidly with plenty of water ; finally with boil-
ing distilled water.

During the whole operation the temperature must remain over

128 PHOTOGRAPHIC MANIPULATIONS.

147° or the pyroxyline is of inferior quality, and if over 160°
the cotton is partly dissolved, and becomes shorter in fibre.1

But, as already said, the manufacture of pyroxyline as a busi-
ness is now so thoroughly understood, that it is no longer neces-
sary for the photographer to prepare it for himself in order to
have it good. On the contrary, it is probable that it would cost
him much labor and some experience, to get it of as good quality
as that which he can readily purchase.

It has been found that the quality of the original cotton used
has much to do with the resulting pyroxyline, and that in general
the best cottons make the best pyroxyline — especially the Ameri-
can Sea-Island. Also, that different cottons require different
treatment ; the same mixtures of nitric and sulphuric acids, or of
nitre and sulphuric acid, which give the best results with one
description of cotton, will give inferior results, or perhaps fail,
with another. It seems to be well attested that a small quantity
of chlorine in the nitric acid adds considerably to the intensity of
the cotton, but diminishes its adhesiveness to the glass. The
writer has observed that the introduction of a chloride into the
collodion is attended with the same results, increased strength in
the picture, accompanied with a tendency of the film to slip from
the plate.

As to the keeping properties of pyroxyline, especially at tem-
peratures above the common, there exists a great difference of
opinion. It has been affirmed that pyroxyline exposed for several
days to a temperature of 150° F. became uniformly decomposed,
and that at the temperature of boiling water, some specimens
explode. On the other hand, another experimenter declares, that
pyroxyline was sealed up in a glass bottle and exposed in his
garden for a year, the temperature of the interior of the bottle
having frequently exceeded 150° F., and was found at the expira-
tion of the time to be unaltered.

That pyroxyline does easily decompose there can be no doubt.
And. also, that that decomposition is greatly aided by light —
even by diffuse light. The writer prepared at one time several
different pyroxy lines, which were placed in glass bottles and
corked. One of these bottles was partly used just before leaving
town for the summer, and was by oversight left on the table,
where it remained for nearly three months. The room received

• Belitzky, Br. J. XII, 4.

PYROXYLIN'S AND COLLODION. 129

a north light only, and no sunlight. At the expiration of the
time just mentioned, the pyroxyline was converted into a moist,
sticky, spongy substance, not one-fifth the bulk of the original
cotton; the vial was filled with red vapors of hyponitric acid,
and the cork much eaten away. Other bottles left in a closed
closet had not suffered.

For this reason pyroxyline should always be kept in opaque
cases. It is also found that it keeps better when not too closely
kept from the air. Pasteboard boxes are the most suitable, and
the most usually employed.

M. Blondeau has published some interesting views on the
subject of pyroxylines, which may be briefly expressed as
follows : —

He considers pyroxyline to be a definite compound of fulmi-
nose, a substance isomeric with cellulose, and nitric acid. Of this
fulminose little is stated except that it is decomposed at 140° F.
into vapor of water and carbon. In the case of pyroxyline, the
nitric acid which is in combination with the fulminose oxidizes
the carbon to carbonic oxide, so that the products of explosion
are carbonic oxide, nitrogen, and vapor of water.

M. Camuzat affirms that when collodion is poured into water it
separates into three portions, a powder which sinks, a flaky
portion that swims, and a third, which dissolves. In his opinion,
the flaky portion is the only one which is essential or useful in
photography. It seems almost certain, however, that the nature
of the image must depend also upon any soluble organic matter
present. In one hundred parts he found —

Best cotton
Ordinary
Powdery
Papyroxyl

Dr. Leisegang- strongly recommends the substitution of tissue
paper for cotton in preparing pyroxyline. The tissue paper is
cut into strips and plunged into the acid mixture, which per-
meates it more rapidly and evenly. There is, therefore, less
tendency to decomposition, and, it is affirmed, the product is
more regular and uniform in its character. It is also claimed
that it gives a remarkably smooth and uniform film when poured
out upon the glass. Of this papyroxyline 4 to 5 grains only are
dissolved in the ounce of solvent.

Flaky part.

Powdery part.

Soluble part

130 PHOTOGRAPHIC MANIPULATIONS.

A variety of pyroxyline, called " alcoholic," has been intro-
duced, but has been found of little use, even in our hottest sum-
mer weather, with the thermometer ranging from 90° to 100°.
The ordinary pyroxylines, made up with perhaps a little more
alcohol than in cooler weather, are preferred.

Xyloidine is a substance analogous to pyroxyline, produced by
the same mixed acids, when made to act upon starch. It dries
from its solutions as a dead, and not as a transparent film. Nitro-
glucose will be discussed in Chapter XII.

The careful study which every department of photography has
received during the past years has taught us the almost unlimited
influence exercised upon photographic operations by the nature
of the pyroxyline used. And especially that this affects the image
obtained even more than the salts dissolved in the collodion. So
that it is impossible to say that any particular salting is best for
any particular photographic process. All we can say is, that a
particular salting does best with some particular pyroxyline.

It has not been found practicable in cottons made for the wet
process, to combine great sensitiveness and great intensity. The
most sensitive cottons mostly give rather thin soft images, de-
ficient in intensity, needing re-developrnent, whilst those that
give easily a full and bold image need a longer exposure.

These tendencies of the cotton necessarily affect the salting.
A very intense cotton will do best with a good deal of bromide,
a treatment very inappropriate for one tending to give a thin
soft image.

Nothing but actual trial will determine the quality of a cotton :
the indications which some rely on are mostly fallacious. A
yellowish color has been supposed to indicate intensity, but in
reality depends upon the wash water having contained traces of
muddiness. Some think that a short fibre indicates intensity ;
this is likewise a mistake, as is the supposition that a powdery
cotton is intense. These indications may, or may not, accompany
intensity.

Nor can manufacturers produce at will, with any exactness,
any particular quality of cotton, or even re-produce one that
they have already made. The best that they can do is to avoid
any wide variation.

PYROXYLTNE AND COLLODION". 131

\ 2.— Collodion.

When pyroxyline is dissolved in acetic ether, it makes a per-
fect solution, but dries opaque. The solution of good negative
cotton in a mixture of alcohol and ether has the inestimable
quality of leaving behind it in drying an absolutely transparent
film, not to be distinguished from the glass on which it lies.1 It
is, moreover, acted upon in some way by nitrate of silver, with
the effect of adding greatly to the ordinary sensibility of iodide
and bromide of silver, so that in the " wet collodion process" a
fraction of a second is sufficient, under favorable circumstances,
to impress a latent image, full of gradation and detail, in the
camera.

Formerly, the plain collodion was generally prepared sepa-
rately, the salts were dissolved apart in a portion of the alcohol,
and added subsequently. But as more care was taken in the
manufacture of pure materials, and as the proper constitution of
collodions came to be better understood, it became possible to
prepare them so much more stable, that now it is more usual to
prepare at once the collodion in the condition in which it is to be
used. A good sound collodion, placed in a cool cellar, will keep
two years, and is then by many preferred to fresh.

Influence, of Alcohol, Fther, and Water on Collodion. — Alcohol
and ether have been used in very different proportions in collo-
dion. Water is present in quantity depending upon the strength
or weakness of the other two substances.

The tendency of ether is to make a close, skinny, and tough
film. Therefore, where it is intended to transfer a film, it is use-
ful to employ a collodion with an abundance of ether.

Alcohol loosens the film and renders it porous. By rendering
the permeation of the developer easy, the development is more
rapid, and intensity is gained.

The action of water, or in other words, of alcohol and ether of
low grade, is mostly injurious, except that when there is much
tendency to make silver stains, water in the collodion seems to
check them. With too much water there is a tendency to crapy
lines, to form ridges, and especially to make a peculiar mottled
appearance at the corner at which the collodion is poured off.

1 Some varieties leave a "dead" film, which is rendered transparent in the
varnishing, and this is by some operators preferred. It is doubtful if such a
film is as strong as a clear one.

132 PHOTOGRAPHIC MANIPULATIONS.

Proportions. — Formerly ether was used to excess, about 3 parts
ether to 2 of alcohol. For some time past the practice of em-
ploying equal parts of each has gained ground.

Washing with, or steeping in, Alkalies. — Pyroxyline is often
treated with ammonia, which has the effect of destroying any
acid that may either have been left in it by the maker, or have
been generated by a disposition to decompose. A more regular
action is thereby obtained, and a certainty of avoiding the in-
sensitiveness which acidity of the cotton inevitably causes.

The ammonia treatment is applied by diluting ordinary liquid
ammonia with four times its bulk of water. Into this the cotton
is plunged, and the solution well worked through it by alternate
soaking and squeezing. The cotton is then to be well washed,
squeezed, and dried, at ordinary temperature, or by a furnace
flue, but not near a stove or open fire.

It is desirable that the drying should be complete to avoid in-
troducing water into the collodion. The plan used by some of
getting the cotton ready at once by moistening with alcohol,
squeezing out, and repeating this several times, is not to be re-
commended, partly because the water is not thus completely re-
moved as supposed, but principally because some sorts of cotton
are somewhat soluble in alcohol. The writer has himself seen
alcohol that has been used for this purpose gelatinize in drying,
so much cotton had been taken up by it.

The proportion of pyroxyline to that of solvent varies, accord-
ing to the character of the pyroxyline itself, from 4 to 8 grains ;
5 to 6 is the most usual with average pyroxylines. Some cottons,
however, make a collodion so dense that the proportion must be
lessened ; others make it so thin that 6 grains are insufficient.
Something will depend upon the character of the work to be
c]one — for instance, negatives require a denser collodion than
positives (ambrotypes).

Relation of Salting to Development.— -The very important influ-
ence exerted by the nature of the pyroxyline has been already
dwelt on. The tendency of photographers at the present day is
not to accept pyroxylines on the authority of the makers, but to
try specimens and see what can be done with them, before mix-
ing quantities of collodion with which it may prove impracti-
cable to get the very best results.

It consequently becomes important with any particular cotton
to ascertain exactly what it will do, and this cannot be found by

PYROXYLINE AND COLLODION. 133

mixing it according to any routine formula to be followed by a
routine development: this will only ascertain the suitableness of
the cotton for such treatment, and not its real value.

The question is not to find a routine formula, but what salting
will do best with the particular specimen. Some will yield with
h grain of bromide as much softness and detail as others with 2|.
It is a good plan to make up a new sample in several portions,
with varying quantities of bromide, until that which is best has
been determined. And then having found the best salting, we
must depend upon a proper development to get the best combina-
tion of half-tone and intensity.

A collodion giving a very weak image with plenty of detail is
generally very sensitive, and will bear a very weak developer
which deposits silver slowly and heightens contrasts, especially
if the plate is kept in motion during development. This will
be the proper treatment for a collodion tending to give weak
negatives.

A collodion giving strong contrasts should have a strong de-
veloper which (as the writer long since pointed out) tends to
soften the picture by a more equal deposit of silver. This action
may be heightened by using so much developer as to wash off
the plate a certain portion of the bath solution with which it is
soaked.

Although a developer of 15 to 30 grains of sulphate of iron
to the ounce will do very well for regular use and suit most cases,
it will be a great mistake to assume that it will suit all collo-
dions, or to persist in using it when the character of the image
indicates the need of a different treatment. To avoid the trouble
of keeping many developers on hand, one may keep besides the
regular mixture, one of double strength. When a stronger de-
velopment is called for, part of this may be added, or when a
weaker, the regular developer may be diluted with water, and
must at the same time have an addition of acetic acid propor-
tionate to the water added.

The object of the worker with the wet process will always be
to secure a very sensitive collodion with a reasonable amount,
but not an excess, of intensity, and having found a cotton which
with some appropriate salting, will answer this need, he will
regulate the development so as to make up for whatever defi-
ciencies the character of his images may tend to show.

134 PHOTOGRAPHIC MANIPULATIONS.

| 3. — Selection of Bases.

The selection of bases to which the iodine and bromine shall
be united, is a matter of very great interest to the photographer.
And this has been so well recognized that even exaggerated im-
portance has been ascribed to it. The following will, it is be-
lieved, be found to be the sum of what is actually known on the
subject.

It appears that the most permanent collodions are obtained
when the iodine and bromine are combined with only a mode-
rately powerful base. The alkalies tend to provoke decompo-
sition, perhaps by attacking the hyponitric acid contained in the
pyroxyline, whereby iodine is liberated, or at least enters into
other forms of combination. Of the moderately strong bases,
cadmium has been found to give such excellent results that it is
very extensively used.

On the other hand, freshly-mixed collodion does not give as
good results as that in which certain reactions, little understood
as yet, have taken place between the constituents; and these re-
actions take place much more rapidly when an alkaline base is
present. For this purpose ammonia is greatly preferred. Po-
tassium is liable to the objection that its bromide is comparatively
insoluble in the mixture of alcohol and ether used as a solvent.
And even if the potassium appears in the form of iodide, yet as
a bromide must be employed also, it follows, according to the
well-known chemical law, that if the constituents present are
capable of forming a combination insoluble in the solvent used,
that combination will be formed. Therefore, if with bromide of
cadmium we mix iodide of potassium in such proportion that if
by the combination of all the potassium with its proportional
amount of bromine, there will be more bromide than the liquid
present can dissolve, then that excess will inevitably be formed
and precipitated.

A grain, or possibly two, to the ounce of bromide of potas-
sium can, however, be kept in solution in an ordinary collodion.
To get it dissolved, all the salts should be placed together in a
large test-tube or a flask, alcohol be poured over them, and the
whole boiled for some minutes. Fresh alcohol is then to be
added to the undissolved part, and the operation repeated till
complete solution is effected. It should be clearly understood
that the bromides of potassium and ammonia are more soluble in

PYROXYLINE AND COLLODION. 135

a solution of bromide or of iodide of cadmium than in plain
alcohol. They form double salts of greater solubility than the
unmixed alkaline bromide. This fact explains why some ope-
rators can prepare a collodion partly with potassium, and some
cannot : all depends upon the manner of operating.

Much also depends upon the solvents. The less high the
grades of the ether and alcohol, the more easily will the bromide
of potassium be kept in solution. The writer is much disposed
to think that when two grains of this salt are used to the ounce
of good solvents, a portion of it is sooner or later precipitated,
and if the collodion be used whilst this precipitate is tending to
form, pin-holes will result.

Sodium forms a more soluble bromide than potassium, and the
use of bromide of sodium, or of iodide of sodium, in the presence
of bromide of cadmium, has been highly praised, but has never
attained general acceptance.

Lithium forms a very soluble bromide, and its use in collodion
has been very highly spoken of. Its higher price prevents its
being more extensivelv used. Its action is similar to that of
potassium.

A curious difference exists between the actions of alkaline salts
and of cadmium compounds in this: that the alkaline iodides
and the bromides tend to render collodion thin and fluid, whilst
the corresponding cadmium compounds render it thick and
viscid.

For the various reasons here given, it is almost invariably
customary to combine in collodion and alkaline and a metallic
base.

Collodions made for sale must have good keeping properties,
therefore in such the proportion of cadmium largely prepon-
derates. Those mixed by photographers for their own imme-
diate use, bear a larger proportion of ammonia, and this compo-
sition is generally preferred by portraitists.

Before touching upon the influence of iodine and bromine,
which will form the subject of the next section, I must remark
here that it is by no means indifferent in what form we add the
respective substances to the collodion. It is a general law in
chemistry, that when different salts are all completely dissolved
in a solvent, the resulting combination will be independent of the
form in which the substances were added. For example, if an
equivalent of nitrate of potassium and one of chloride of sodium

136 PHOTOGRAPHIC MANIPULATIONS.

be dissolved in water, the result will be absolutely the same as if
one equivalent of chloride of potassium and one of nitrate of
sodium had been used. In each case the affinities are independ-
ent of the original form of the compounds.

It would be a great mistake to apply this principle to the
preparation of collodion, as some might be disposed to do. The
admixture of one equivalent of iodide of ammonium and one of
bromide of cadmium would produce a quite different collodion
from that afforded by the mixture of one equivalent of bromide
of ammonium and one of iodide of cadmium. This is a point
that cannot be too well understood.

The explanation is, that bromide of ammonium is a very stable
salt, so, likewise, are bromide and iodide of cadmium ; but iodide
of ammonium is not. As received from the manufacturer it is
apt to be yellowish, and to have a penetrating smell, apparently
of iodine. It reacts quickly on the collodion and brings it soon
to an orange shade, as is observable in collodions made with
iodideof ammonium and iodide and bromide of cadmium. Whereas
collodions made with bromide of ammonium and iodide of cad-
mium retain a pale straw-yellow color (if the pyroxyline has
been quite neutral) easily for a year, and even more.

Mr. Blanchard has published some remarkable experiments
which show the difference of the action of alkaline and metallic
bases. He found that in some cases a bath rendered alkaline and
exposed to the sun, fogged, and that acidifying only made it
worse. If such a bath, showing a decided alkaline reaction, was
used to sensitize a film in which ammonium salts predominated,
each plate showed less fog, until presently perfectly clean ones
were obtained. Under the same circumstances, cadmium collo-
dions gave dense fog, without a trace of an image.

This probably has something to do with the fact that the ten-
dency of late years has been to use less and less cadmium, some
even omitting it entirely (see formula 5).

To resume, then. For all practical purposes, ammonium and
cadmium are the great resources of photography as bases. Where
the bromine is combined with the ammonium, and especially
when the proportion of ammonium compound is not over the
fourth parts of that of the cadmium, a collodion is obtained which
ripens within ten days or a fortnight, and then continues of excel-
lent quality for many months, or, in a cool place, for years.

PYROXYLINE AND COLLODION. 137

When the iodine is combined with the ammonium, and espe-
cially when this is used in larger proportions than above men-
tioned, collodions are obtained that ripen rapidly, and are fit for
use in two or three days, or even in a few hours; but which
become dark colored and insensitive, and give harsh pictures
when kept. Whilst these are in their best condition, they are
by some considered as giving the best possible results, and supe-
rior to those of the other class. It is only, however, when there
is a regular and uniform consumption of collodion that this form
can be employed without waste, or the risk of having a quantity
of material on hand that has passed its best condition.

Collodion which contains an iodide assumes in a few days,
often in a few hours, an amber color, whereas collodion made
with bromides only (for certain dry processes) remains as color-
less as water, or rarely takes a perceptible yellowish shade.

Where it is desired that new collodion shall ripen rapidly so
as to be fit for use as soon as possible, it should be kept in a
warm room and in a strong light. On the contrary, when it is
intended to keep it for a length of time, it should remain in the
dark, and in a cold room, best in a cellar.

§ 4. — Effects of Iodine and Bromine.

At first iodides were used alone in connection with collodion.
But as photographers were familiar with the influence of bromine,
bromides were shortly after used with collodion. Experience led
(by surprisingly slow degrees, however) to the recognition of the
fact that they were invaluable.

The manner in which bromides act is, however, still a point
not thoroughly settled. It is a familiar fact that iodide of silver
solarizes very easily, that is, the maximum effect of light is quickly
reached, after which its action is reversed. So that with a certain
degree of exposure, for example, the brightest lights may produce
less impression, and come out in the development less strongly
than others of inferior intensity. Bromide of silver has much
less of this tendency, and a collodion containing bromide has
much less tendency to solarize.

It has also been generally held that the use of iodides was
favorable to the effects of force and contrast, whilst bromide
tended to softness and the correct rendering of half tone.

Some careful experiments made by the writer brought him to
10

138 PHOTOGRAPHIC MANIPULATIONS.

the conclusion that this view requires a certain limitation, for
that when bromides were added to collodion in large excess, that
collodion used in the wet process, gave harsh pictures, so that
softness of effect and correct rendering of half tone depend upon
the judicious combination of the two. For example, two grains
of bromide and four of iodide gave a soft and well-modelled
picture. More bromide was found to make the picture too soft
and deficient in contrast, up to a certain point. Then the con-
trary effect set in, and when four grains of bromide were used to
two of iodide, the picture was harsh.

Another important function of bromide of silver is that of
keeping the plate clean. It is certain that a bath which will no
longer work with a pure iodide collodion, will give good pictures
with one containing bromide. So with careless manipulation and
impure chemicals, clean pictures may be got with a collodion
containing bromide, when this would be impossible with a simple
iodide collodion.

In the older formulas employed for collodions, a great variety
of substances were employed, and in some not only iodides and
bromides, but also chlorides and fluorides. Then came a tendency
to reject everything but iodides. Next this was modified by in-
troducing bromides, and it is by no means impossible that we may
yet find it advantageous to introduce a portion of chloride into
our collodions.

The writer expresses this opinion, not with any positiveness,
but as an idea which we may yet see realized. He has made
many experiments on the development of positive prints on
paper, and has been much struck with the superiority of chloride
for this purpose. He believes that, at least when he first pub-
lished this view, it was contrary to the prevailing opinions,
according to which mixtures of iodides and bromides were pre-
ferred. But he found chloride of silver, though less sensitive
and needing a rather longer exposure, to work far more evenly
and regularly than the others, and he has little doubt that a grain,
or perhaps half a grain to the ounce of chloride of copper, would
be found an improvement. A collodion containing three grains
of chloride of copper, ten of bromide of ammonium, and twenty-
five of iodide of cadmium, to two and a half ounces each of
alcohol and ether, and twenty-five grains of pyroxyline, would
constitute a collodion which would probably be found to have
superior qualities.

PYROXYLINE AND COLLODION. 139

(Since the foregoing was written, the writer has shown that a
perfectly invisible image upon chloride paper can be perfectly
developed with as full detail as one upon bromo-iodized paper.
And that, the use of chloride of silver in connection with bromide
in a particular form of dry process (chloro-bromide process)
gives most excellent results.)

Experiments made by the writer with collodion containing a
chloride and a bromide in equivalent proportions, resulted in
showing that such a collodion gave faint images and foggy plates,
with a bath working well with ordinary collodions. He con-
cluded, therefore, that an iodide is an essential constituent of col-
lodion for the wet process, at least with baths as used at present.
Herein is a remarkable distinction between wet and dry processes.
On the other hand, neither chlorides nor bromides are essential
to the wet process, but good plates may be obtained with iodide
of silver alone, or in connection with either bromide or chloride
of silver.

By some it has been argued, that the beneficial effects of the
addition of bromide of silver are due to the fact that, as has been
stated, bromide of silver is sensitive to less refrangible rays than
iodide. That whilst iodide of silver was affected by only the
violet and bluish-violet rays, the bromide was sensitive to the
blue, and even, to some extent, to the green.

The writer pointed out, as far back as 1865, that the action of
the green color of leaves upon the collodion film was very
trifling and of little importance, and that leaves impressed them-
selves upon the film, not by the agency of their green, but of
their white light.

In bodies generally we distinguish two sorts of light as ema-
nating from them. One reflected from the surface, which is white,
whatever be the color of the body, and the other emanating from
the interior of the body, which is characterized by color. In
some cases one of these may predominate almost to the exclusion
of the other. Perfectly black objects send us only surface light,
and in perfectly white objects the interior color is white as well
as the surface color.

Now this surface light, which we scarcely take into account at
all in our ordinary observation of bodies around it, so completely
is it masked by the colored light, is, in fact, as the writer has else-
where pointed out,1 all that is really effective to the photographer,

1 Philadelphia Photographer, July, 1867.

140 PHOTOGKAPHIC MANIPULATIONS.

with the exception only of blue or violet-colored bodies. All
bodies of blue-green, green, yellow, orange, and red colors im-
press themselves on the collodion film solely by virtue of the
white surface light that accompanies, unperceived to us, the
colored emanations which they give forth.

It follows from this that there is little use in endeavoring to
find collodion that has a little greater range of impressibility.
What we want is a film sensitive to the very faintest rays of
white light, so that every faintest emanation of surface light shall
act upon it by virtue of the violet rays which it includes. This
high sensitiveness is rarely accompanied with a great intensity,
so that it is precisely the most sensitive collodions that are most
apt to need a redevelopment.

Yogel has published some interesting experiments, from which
he concludes that iodide of silver is more sensitive to strong
lights, is more quickly impressed by them than bromide, but, on
the other hand, that bromide is more sensitive to weak rays.
Schrank and others have since called this view in question.
Schrank gives as the result of special experiments made by him,
that the beneficial influence of bromide depends upon its ab-
sence of tendency to solarization.

In view of this diversity of opinion, and still more, of the in-
fluence of the pyroxyline itself, it is not surprising that the rela-
tive quantity of bromide to iodide, which gives the best result,
is still unsettled. It has been positively ascertained that the
bromide should not form less than 20 nor more than 50 per cent.
of the whole salting. It may be said, however, that the propor-
tion of bromide recommended has steadily increased for several
years past, and with its increase has been a well-marked gain in
the artistic effect of the photographs produced. The addition,
moreover, of bromide has the effect of rendering the process far
more certain. The bath will continue to work with a well-bro-
mized collodion long after it has ceased to give any good result
with a simply iodized collodion. The tendency to stains, fog,
and other troubles in development is far less with a bromo-iodized
collodion. On the other hand, too much bromide leads to the
production of flat and monotonous pictures, unless, indeed, the
proportion of bromide be very much exaggerated, when the
result again becomes too harsh. Too much bromide also tends
to give a granular crystalline precipitate wanting in fineness.

PYROXYLINE AND COLLODION. 141

It now remains to give a few general directions as to the pre-
paration and management of collodion, and then will follow some
of the best formulas in use.

To make the collodion, the cotton should first be weighed and
placed in the bottle. Three-fourths of the alcohol are then to be
added, and shaken up with the cotton. Next the ether is added,
and the whole shaken till the cotton dissolves. If the cotton is
exactly right, little or no visible residue will be left — a few fila-
ments through the liquid, which, however, will not be clear.

This constitutes plain collodion, which may either be kept as
such, or at once be sensitized (which is the better plan) by dis-
solving the salting in the remaining one-fourth of alcohol.

In preparing a collodion, the photographer will always be
guided by the purpose for which it is destined. It is true that
collodions can be made which will answer well for almost any
use ; but not so thoroughly well as a collodion especially intended
for that particular employment.

Thus for portraiture there is a general preference given for
collodions containing from one to two grains of a bromide. Here
the main object is rapidity and delicacy. The light is under
almost complete control by the shifting of blinds and shutters,
and harsh contrasts can always be avoided by that control.

With landscapes the case is very different. We take the light
as we find it, and must enable ourselves to control our chemicals.
Collodions suitable for portraiture would give excellent results
in landscape work in dull weather, but in bright there might
with some be difficulty in getting harmonious effects. These we
secure by increasing the bromide, if the collodion in question be
deficient in it. Where the contrasts constitute the main diffi-
culty, as in taking interiors of buildings, or copying old paint-
ings, the proportion of bromide may be increased to one-half.
The writer proved some time ago that if we go beyond this point,
in place of obtaining a still farther increase of softness, a contrary
effect sets in, and we get increase of contrast.

A difference will also be made in the formula, according as the
collodion is needed for immediate use, or can be put aside for
some time to ripen.

142 PHOTOGRAPHIC MANIPULATIONS.

Formula 1. Portrait Collodion.

For immediate use.

Alcohol and ether, equal parts 1 ounce.1

Iodide of ammonium 5 grains.

Bromide of cadmium lJtoS "

Pyroxyline . . . . . . . . . 6 "

This collodion can be used as soon as it assumes a straw-color,
or immediately, if a little tincture of iodine be added.

Formula 2. Portrait Collodion.

To be kept for several months before using.

Alcohol and ether in equal parts 1 ounce.

Bromide of ammonium 1£ to 2 grains.

Iodide of cadmium 5

Pyroxyline 6

Formula 3. Portrait Collodion.

To be kept six months in a cellar before using.

Alcohol and ether, equal parts 1 ounce.

Bromide of cadmium H to 2 grains.

Iodide of cadmium 5

Pyroxyline 6 "

The tendency to the use of the more rapidly ripening collodions
made chiefly with ammonium (Formulas 1, 4, 5, 6) rather than the
slower ones in which cadmium preponderates (Formulas 2, 3, 8),
seems to be on the increase, though, many good workers still prefer
the more stable sorts. Collodions, like No. 3, if kept in a cool
place, are good in six months, better at a year, and still good at
eighteen months.

In addition to the foregoing the writer gives the collodions of
some of the most successful portraitists in various countries.

Formula 4.2 Reutlinger (Paris).

Ether 6 ounces.

Alcohol 4 "

Cotton 50 to GO grains.

Iodide ammonium 30 "

" cadmium 20 "

Bromide of ammonium 5 "

1 It is important to understand that in these and all other photographic for-
mula' the ounce means a Jhiidounce as measured in a graduate, and never a
weighed ounce. The expression is evidently an incorrect one, but its use is
universal. See also foot-note to p. 120.

* This formula calls for the addition of " a little pure sodium."

PYROXYLIXE AND COLLODION'. 14

Formula 5. Sarony.

Ether and alcohol, equal parts.

Iodide of ammonium, to ounce 4^ grains.

Bromide of potassium " 2

Pyroxyline 5 to 7

The pyroxyline to be treated with ammonia. (See Sec. 2 of
this chapter.)

Formula 6. Gurney.

Ether and alcohol, equal parts.

Iodide of ammonium, to ounce 5 grains.

Bromide of cadmium " li "

Bromide of ammonium 1^

Pyroxyline 5 to 7

Nos. 1, 4, 5, and 6 work best when from ten to thirty days old.

Formula 7. Landscape Collodion.

Alcohol 15 ounces.

Ether 15 "

Bromide cadmium 35 grains.

Iodide " 80 "

Bromide ammonium 30 "

Iodide " 60 "

Pyroxyline 180

This ripens more rapidly than the following, in consequence of
containing iodide of ammonium.

If softer effects are desired, the bromide may be moderately
increased, but too much of it will result in flat pictures and a
coarsely grained deposit.

Formula 8. Landscape Collodion.

To be kept some weeks, or else mixed with other ripe collodion.
Alcohol and ether, equal parts.

Bromide of ammonium 2 grains.

Iodide of cadmium . 4A

The sensitizing is done by placing the weighed salts in a test-
tube for small quantities, or a flask for larger, and pouring over
them the remaining fourth of the alcohol, not at once, bat in
successive portions, allowing each to take up what it will before
pouring it off. It is generally expedient to employ the heat of a

14-i PHOTOGRAPHIC MANIPULATIONS.

Bunsen burner or spirit lamp to get the bromide into solution.
It is not worth while to filter the solution — the simplest plan is
to pour it into the plain collodion, shake well, and filter or de-
cant afterwards.

Bromide of cadmium dissolves very easily in alcohol; bromide
of potassium and of ammonium, with much difficulty. But these
alkaline bromides dissolve much more easily in a solution con-
taining already bromide of cadmium (because double salts are
formed, whose solubility is greater than that of the alkaline salt).
Therefore it will always be found easiest to place all the salts
together in the test-tube or flagk and dissolve them together.

Great care must be taken of fire, in all operations with
ether which may readily ignite from a flame at a considerable
distance. Ether evaporates very easily, and its vapor rapidly
spreads through the atmosphere — this vapor may easily become
dense enough to carry the flame. For this reason the utmost care
is needful, and accidents with the heedless are very common.
The danger is all the greater that as ether has little affinity for
water, water does not easily extinguish it, the ether floats on the
surface and continues to burn. Wet sand is the best application.
If a quantity of ether is spilled by the breaking of a large vessel,
the first care should be to extinguish every light and fire in the
building. The next to provide buckets of wet sand, in case of
kindling. If happily this is avoided, no fire or match should be
lighted until the whole house has been so thoroughly ventilated
that the smell of ether has disappeared.

Many operators regularly add a little solution of iodine to all
their collodion, and there is no doubt that that svstem is the
one that obviates the most completely all danger of fogging.
Others prefer to depend upon the aging or ripening of the
collodion.

Those who adopt the former plan of adding iodine to the col-
lodion, should be extremely careful about acidifying the nitric bath-
Perfectly neutral nitrate of silver should alone be employed, and
before adding any acid to the bath, a plate should be tried with
the collodion intended to be used, and if it works cleanly, then
no acid must be introduced into the bath, or the sensitiveness of
the film will be materially diminished. This point will also be
adverted to in the remarks on fogging.

A collodion that gives a thin image will often be cured of this

PYROXYLINE AND COLLODION.

145

•defect by adding to it pyroxyline in the proportion of a grain or
two to the ounce. On the other hand, coarseness indicates the
presence of too much pyroxyline.

Fin. 90.

§ 5. — Clearing Collodion.

When time can be given, the simplest and much the best
method of clearing collodion is by subsidence and decantation.
The collodion is set aside for any time not
less than a month, and the clear part
poured off. It will be found, however,
that the operation of pouring quickly stirs
up the sediment at the bottom, consequently
the method of transferring represented in
Fig. 90 should invariably be employed.
Two holes are pierced through a cork, one
carries a short bent tube A, and through
the other is passed the shorter leg of the
siphon S. By blowing gently into the
tube A, the siphon is started, and then
continues to empty the bottle to the level
of the bottom of the shorter leg. This
last should be pushed down to within a
quarter of an inch of the layer of sediment.

At B is represented the size and weight
of glass tube which will be proper. The siphon is easily made
by bending the glass tube over a bat-wing gas-burner : heavy tube,
though slower in heating, is much more manageable than light.
The cork should be very conical, in order that it may fit any size
of neck for which it may be wanted.

If filtering be resorted to, then instead of the filtering appa-
ratus commonly employed, in which the collodion is filtered
through sponge, the writer has found it far preferable to select a
piece of fine strong close-woven linen. This is thrown into
boiling water and left to soak for some hours to get rid of the
dressing; it is then well shaken in cold water and dried. A
round piece about four inches in diameter is cut. As the collo-
dion runs through in a rapid stream, this will be large enough.

By preparing a yard or two of linen in this way, the pho-
tographer will be supplied for an indefinite time ; for one piece

116

P If O T O G U A P II I C MANIPULATIONS.

Fi«\ 91.

answers over and over again. Although it

may appear to have its meshes completely
stopped by the solidified collodion, still it filters
as well as ever.

Sponge is also excellent for filtering collodion.
The writer takes " surgeons' sponge," or even
a fine quality of carriage sponge, and soaks it
for two or three days in hydrochloric acid di-
luted with eight times its bulk of water, using
plenty of the dilute acid. This removes the
calcareous matter, and renders the whole tex-
ture of the sponge weak and soft. It is then
tlwrougldy washed out with water, dried, and is
fit for use.

Whichever is used, the funnel should be
covered with a plate of glass, as shown in Fig. 91. With this
precaution the evaporation becomes inconsiderable.

\ 6. — Keeping Collodion.

The ripening of collodion depends upon temperature, and, pro-
bably, to some extent upon light. If, therefore, it is desired to
ripen collodion rapidly, it should be kept in a warm light room.
On the other hand, if a quantity is prepared to be used over a
long period, it should be placed in a cool dark cellar. Collodion
chiefly salted with cadmium salts keeps well and improves for a
long time.

It is well to understand that with time all collodions tend to
produce a substance having a peculiarly irritating odor, which
sometimes causes personal suffering to those that use it. Espe-
cially it attacks the eyes, and cases have been known of persons
obliged to give up photography for six months or a year, so ob-
stinate is the soreness produced in this way.

THE CAMERA. 147

CHAPTER IV.
THE NEGATIVE.

§ 1.— The Camera.

The photographic camera should be made of mahogany or
cherry, not of walnut, should be neatly fitted, and strongly put
together. Small cameras are often fitted up with a removable
partition, so that they can be used either with two lenses for
stereos, or with a single lens. The front of the camera should
permit of a movement up and down, and sideways, in either case
to be arrested and the front held firm, by a mill-head screw. This
is known as a Sliding Front. The focus is regulated in two
different ways, the camera front is racked in and out by a long
screw moved by a mill-head at the back, or the back is moved in
and out by a mill-head that turns a pinion working in a rack. In
the latter construction a " pinching screw" serves to secure the
position firmly when the focus has been taken. Every camera
should have a " universal level" set in, to enable the operator
with certainty to level his instrument. The universal level is
about an inch and a quarter in diameter, and contains a piece of
glass ground to a slight curvature somewhat like a watch-glass.
A single bubble of air in the spirit underneath, indicates a true
level by resting in the centre of the glass. This level is in-
serted in the camera at the back, just behind the ground glass.
Those who have cameras unprovided with them, can procure
them at a small cost from makers of surveying instruments (the
writer's were made by Mr. Zentmayer, Fourth St. and Harmony
Court, Philadelphia). To insert them a board must first be fixed
in a perfectly level position. A hole \ inch deep must previously
have been made in the camera for the level. The camera is set
upon the accurately levelled board, the level is then so set into
its cavity that the bubble will be in the centre. A little cap
cement or bottle wax serves to secure it permanently.

The landscape camera should be lightly but strongly made of
the best seasoned mahogany, walnut being too apt to crack, and

143

THE NEGATIVE

should combine lightness for carrying, with solidity. Brass
bindings will be useful, by permitting the wood to be lighter.

Although most views require that the greatest dimension of
the plate should be horizontal, still there are very many cases
where this condition can be advantageously reversed, and, there-
fore, it is essential that the camera shall be arranged to screw on
to the tripod in either position. There is only one way in which this
can he properly done, that is, by having a wood or metal cross-
piece, as represented in the figure. That shown in Fig. 92 is
of wood. When brass is used, it may be much narrower, but
needs a third arm extending from the screw-hole A to the front
part of the base at C. (See Fig. 94.)

Sheet brass is wholly unsuitable. A careful brass casting is
needed, which must be stout and stiff.

Fig. 92.

If wood be employed, nothing will be suitable except the best
mahogany. The screw-plate must be set on the inside, if set on
the outside it will soon be pulled off.

After having given both a fair trial, the writer prefers the
wood, especially for large cameras.

In cameras made for sale, there will often be found, instead of
a cross-piece a simple screw-hole at B. It is evident that the
strain resulting from actual use will be so great as either to soon
pull the camera to pieces, or force it out of shape. On the con-
trary, the arrangement here described adds materially to the
solidity of the instrument.

The Siving -back and Swinging Lens. — The swing-back is the most
capital improvement to the camera that has ever been made. Its
object and mode of use should be fully understood, and when
once mastered, this contrivance will be accepted at once as an
indispensable adjunct to both landscape work and portraiture.

THE CAMERA

149

The swing-back has two objects perfectly distinct from each
other. The first is —

To render it possible to tilt the camera and yet avoid distortion of
vertical lines. — In making a view of any building, we are apt to
find that we get too much foreground, whilst the upper part of
the building is apt to be beyond the edge of the plate. To some
extent we can remedy this by pushing upwards the sliding front
of the camera. But this is insufficient, and is open to the serious
objection that as the axis of the lens no longer coincides with
the centre of our picture, we no longer get the best definition of
the lens. So that only a little adjustment is allowable in this
way. And if we tilt the camera upwards all the vertical lines of
the building are intolerably distorted.

The remedy is as follows : Let E F represent a vertical line in
any building. If we tilt the camera
so as to get the whole of it upon
the plate, the plate will occupy the
inclined portion AB, and the lines
will be distorted. But if we can
shift the back so that whilst the
camera is tilted, the plate can be
kept in the vertical position C D
and remain parallel to E F, then
there will be no distortion, however
much we may tilt the camera.

This result is obtained by saw-
ing through the back of the camera and interposing a few bellows
folds. At a point about half way between the top and bottom

Fig.

93.

Fi«?. 94.

150 THE NEGATIVE.

there is a pivot on each side, on which the back swings, and on the
top there is a brass slot and a mill-head which secures the swing-
back firmly into any position that has been given it.

This arrangement is, however, incomplete without a second
piece exactly similar, but with its pivots at top and bottom, and
slot and mill-head at sides. As the first described permits the
plate to be adjusted vertically, it will be called for distinction the
vertical swing-hack. And as the second, that with its pivots at
top and bottom, moves horizontally, it will be called the horizon-
tal swing-back. The two together constitute the " double swing-
back," and is represented in Fig. 94.

The second and perhaps the most important function of the
swing-back isto aid in getting different parts of a subject simultaneously
into focus. It is evident that with a double swing-back, the
different portions of the plate may be made to assume a great
variety of positions. Either the top, the bottom, or either side
may be brought nearer to the lens, or farther from it than the
centre.

Use of Swing-lack in Portraiture. — Often the camera needs to
be depressed in front to make it conveniently include the whole
of a standing figure. Here the first-mentioned application of
the swing-back comes in, and vertical lines, as columns, windows,
&c, are preserved from distortion. The second application of
the swing-back finds its use with sitting figures, in which the
feet are always too near for the rest of the body, and with lenses
of long focus it will not be easy to get them into focus with the
face. Being nearer to the lens, they will have a longer focus.
We have, therefore, only to move the vertical swing on its pivot
so as to draw the top of the plate back a little, and the difficulty
disappears. For this purpose the pivot A should be below the
middle, in order to be opposite to the head, it being an object in
adjusting the swing-back not to disturb the focus on the principal
object, but this point is apt to be overlooked by the makers.
(For landscapes, the pivot is best exactly in the middle.)

The horizontal swing-back will be useful in taking groups, and
permit of varying the grouping in a way otherwise impossible
with a portrait lens. With its aid, the members of the group at
one side may be nearer or more distant than those at the other :
may be more distant than the central ones, and yet may be got
into focus by bringing the end of the plate upon which they fall
nearer to the lens.

THE CAMERA. 151

Landscape Work. — For landscape work the swing-back is very
valuable in several ways. In almost all views the foreground is
the nearest portion to the camera. Its conjugate focus is longer,
consequently if the focus is taken so as to embrace satisfactorily
the rest of the picture, the foreground is apt to be wrong.
And if the focussing slide be racked back to bring the foreground
into correct focus, the rest of the picture suffers materially. The
evil here spoken of is often considerably alleviated by curvature
of the field, but yet not often sufficiently, and in lenses possessing
a flat or nearly flat field, even this assistance is wanting. It is
therefore an immense aid to be able to move the top of the plate
a little away from the lens.

There is yet another use for this valuable contrivance. It will
occasionally happen in landscapes that one side of the view is mate-
rially nearer to the camera than the other. Here the horizontal
swing-back comes into play. The side on which the nearer
objects fall is pulled a little out from the lens, and that part
of the picture comes into focus without material injury to the
centre.

The combination of these two movements, vertical and hori-
zontal, will sometimes be valuable, and it is moreover to be ob-
served that as the camera is used sometimes on its base and
sometimes on its side, the functions of the two swing-backs
change with this change. When the camera is turned upon its
side, that which was before the horizontal swing-back now serves
to regulate the foreground. So that whatever value is placed on
the two modes of adjustment, neither can be dispensed with ex-
changing functions as they do. It is, therefore, a serious mistake
to purchase a camera with a single swing-back, except, perhaps,
in the case of a camera to be used solely and exclusively for
stereoscopic work. In this case a vertical swing-back (with
pivots at the sides) is principally needed.

Swinging Lens. — A little consideration will show that results
analogous to the above may be obtained by simply so setting
the lens that it may turn freely in all directions. The writer
considers, however, that the introduction of this system as a
substitute for the swing-back, is a serious evil. Before explain-
ing this, it will be proper to exhibit the action of the swinging
lens.

Suppose that the tube of the lens L be jointed to the camera

152

THE NEGATIVE,

Fisr. 95.

so that it can be turned in any direction whilst the body of the

camera remains fixed. It is evident
that the focussing screen A B, and
consequently the sensitive plate
remains vertical, precisely as if the
lens had not moved. And remain-
ing vertical it cuts the cone of rays
from the lens, parallel to the verti-
cal lines of any building that may
stand before the lens. These are,
therefore, correctly represented on the screen A B, precisely as
if the lens L had remained in the ordinary position.

But the tilting of the lens, whilst it enabled the camera to
take in the higher parts of any building before it, at the same
time altered the position of the axis of the lens. This axis when
the lens is in its usual position, passes through the centre of the
camera, but with the tilting assumes a new position L A, and the
centre of the image no longer corresponds with the centre of the
focussing screen, but falls to A.

To remedy this the camera front, carrying with it the lens, is
raised until the axis of the lens takes the position B L (Fig. 96).

So that here we have accomplished
much the same result as by the swing-
back, viz., we have tilted the lens
so as to embrace the higher objects
and yet have kept the image per-
fectly vertical. With the swing-back
the centrality of the axis was not
disturbed, here it has been disturbed,
but readjusted.

For this object, the utility of the
swinging lens is probably equal to
that of the swing-back.
Next, as to adjusting the focus for the foreground. It is to be
remembered that the image is formed at right angles to the axis of
the lens, consequently when the lens is bent downward and the
axis takes the position L A (Fig. 97), the image is found in the
plane B C. But this image is not received on the focussing
screen at the position B C, but in that of D E. A little reflection
will show that this change corresponds with the moving back of

Fisr. 96.

THE CAMERA. 153

the swing-back. That is, that in F;„. 9^

both cases the image is received
on a plane which, at the top of
the camera, is farther from the lens.
And thus in both cases, the longer
focus of the foreground will be ac-
commodated.

It is evidently a fault in the L.
swinging lens that thus to bring
the foreground of a landscape
into focus we are obliged to tilt

the camera downwards, and so take in more foreground. But
this again can be cured by tilting the body of the camera
upwards. Let us say that we first arrange the camera in such a
position that we include just what we want, and have the horizon
line where we want it. But the foreground is not in focus. We
therefore first turn down the lens somewhat, and then tilt the
camera upwards until this tilting brings the lens into its first
position. It is therefore certain that the swinging lens can, like
the swing-back, accommodate the focus of the foreground.

But its great inferiority lies in the ivay in which this is done.
With the swing-back we arrange the camera with the largest
opening of the lens until we get the picture exactly composed,
and then changing the diaphragm as the case may need ; if the
foreground is not in focus, a slight adjustment of the top of the
plate brings it right.

With the swinging lens we have a double adjustment to make.
First, the lens must be depressed. We cannot tell, however, how
much, but can only make a trial, then the camera is to be tilted,
the horizon line readjusted, and we examine if the proper amount
of change has been hit upon. If the foreground is not yet in
focus, or if, in getting it into focus, we have seriously injured the
focus of any other part, in either case the manipulation must be
tried over again. Whereas with the swing-back, we watch the
changes and stop it exactly at the proper point. And a similar
objection holds where these contrivances are used to meet the
case of the two sides of the picture being at different distances
from the lens. Here also the adjustment with the swing-back is
the easier.
11

154 PHOTOGRAPHIC MANIPULATIONS.

§ 2.— Selecting the Glass.

None but very careless operators will use a lot of glass indis-
criminately. Every piece should be gone over and examined
previous to cleaning it. The high price of plate glass in this
country almost wholly excludes it from photographic use. If it
could be obtained at the same cost as in England, France, or Ger-
many, none other, or very little other, would be used. As it is,
photographers for the most part content themselves with a quality
of glass, usually of French manufacture, known as " photo-
graphic glass."

The best quality of the glass only should be purchased. It
comes in boxes containing fifty square feet. Opening such a
box, and sitting with his face to a well-lighted window, the ope-
rator examines every piece —

1. As to sufficient thickness. Thin plates break too easily in
the printing process.

2. As to curvature, by running the eye along the edges : a
slight curvature cannot always be avoided ; but anything over a
certain degree of bow is a sufficient cause for rejection.

3. As to blebs. In sun printing these are apt to show, and it
is generally safest to reject all plates that exhibit this defect, as
it is difficult to foresee how much injury may result from it.

4. As to scratches. Some lots of glass by careless handling will
be scratched. All pieces with scratches visible by transmitted
or reflected light are to be rejected. And to avoid farther danger
every piece after examination must have a sheet of paper laid
between it and the adjoining piece. And this precaution must
be kept up in every subsequent stage of the operations. Printed
paper should never be employed for this purpose, but some com-
mon though clean sort. If glass is left for some time in contact
with printed paper, a complete impression will be taken oft' upon
it, and the difficulty of cleaning will be proportionately increased
by the greasiness transmitted to the glass.

5. As to surface. Some pieces of glass must be rejected for
roughness of the surface.

A close attention on the part of photographers to these points
would have the effect of obliging those who manufacture photo-
graphic glass to work more carefully and deliver a better ma-
terial.

THE NEGATIVE. 155

Preparing the Glass. — The cleaning of the glass has already-
been explained in the introduction. A system has latterly gained
ground a good deal, of albumenizing the glass, and thus obviating
the necessity of being very particular in the cleaning. Some
simply take white of egg and shake it up with twenty times its
bulk of water, in a bottle with sharp fragments of glass, filter
it, and make fresh for each day's use. Others mix the white of
egg with an equal bulk of water and a little liquid ammonia, a
fluidrachm for a dozen eggs. In this condition it keeps, and can
at any time be used by diluting it with an ounce of water to
each drachm of albumen.

Some prefer to iodize the albumen, obtaining in that way
rather more brilliant points — 2 or 3 grains to the ounce of dila-
ted albumen will be sufficient. The albumen is to be extended
over the plate with a glass rod (by some a piece of pasteboard is
preferred), the excess poured off, and the plate reared up to dry.

As the cleaning of glass cannot be wholly dispensed with, the
writer does not see that any sort of cleaning involves less trouble
than the method with bichromate. And when that is done pro-
perly, anything further is altogether superfluous. The writer
has in some of his experimental trials in dry work used the same
pTates over and over until the marks made on the back with a
diamond pencil indicated that they had been used 5, 6, or 7
times each. And never on these or any other occasions has he
seen indications of imperfect cleaning or the reappearance of a
previous image.

§ 3.— The Negative Bath.

The course of proceeding recommended in the introductory
portion of this manual involved the use of a single bath of mode-
rate size. This is the best course for the beginner, because he
will inevitably spoil some of his first baths, either by introducing
foreign substances into them, or by mistaken treatment with the
view of improving them. But when he has attained a certain
familiarity with photographic operations, he will do best to adopt
the two-bath system originally proposed, I believe, by Mr. Wharton
Simpson. In this mode of operating, one bath serves to form
the sensitive film and receive the alcohol and ether ; the second
bath furnishes a nearly pure silver solution, moistening the film
and serving for development.

156 PHOTOGRAPHIC MANIPULATIONS.

The writer prefers to make these baths of widely different
strengths. The first bath is made strong, 40 grains to the ounce,
because the stronger the bath the more completely the iodide and
bromide remain in the film. The second is made comparatively
weak, 20. grains to the ounce. This furnishes an ample supply
of silver for development, and the danger of stains is materially
lessened.

Moreover, the writer advises ample baths — one size larger than
the largest size of plate habitually used, and not in any case less
than 60 ounces each.

The advantages of the system of working with two abundant
baths are so great that no one who has fairly tried it will ever
voluntarily use any other. They consist in extreme regularity
of working over a long period, so that the photographer runs
little risk in being deceived in his exposures, in unusual facility
in obtaining plates of the right density without the annoyance of
redevelopment, and in almost complete immunity from stains,
marbling, pinholes, &c. &c. The system is, moreover, an econo-
mical one. The impurities are concentrated in the first bath
for a long time, and when at last the working ceases to be satis-
factory, it is put into the residues and the second receives addi-
tional 20 grains of nitrate of silver per ounce, and takes its
place as the first bath with a new second bath.

The mode of making a bath, and of curing a propensity to
fog has been explained in the introduction. It remains to be
said here, that although the introduction of iodine into the bath,
by working with a collodion to which it has been added, tends
to acidify the bath, yet the effect of the two treatments upon
the working is entirely different. The writer has known a case
of fogging, which could not be cured by any amount of acidifi-
cation of the bath, give way immediately under the addition of
a little iodine to the collodion. It appears from experiments of
Weltzien that iodine liberates hyponitric acid (not nitric) from
nitrate of silver, and Eeynolds ingeniously remarks that as
hyponitric acid by action of water splits up into nitrous and
nitric acid, it is probably to the production of the nitrous acid
that the curative influence of the iodine is due.

Be this as it may, it is certain that if, after a very slight ad-
dition of nitric acid to the bath (1 drop to 20 ounces of bath),
there appears a disposition to fog, it is far better to add iodine to

THE NEGATIVE. 157

the collodion than to go on acidifying the bath. This it is im-
portant for the photographer to bear steadily in mind. Also
that a bath that fogs badly with collodion in which cadmium
salts predominate may not improbably do well with a collodion
chiefly salted with ammonium salts.

The nitrate of silver should be perfectly neutral. Most per-
sons prefer the crystallized ; the writer has generally used the
fused in preference. Crystallized nitrate1 can be converted into
fused by melting it in a Berlin porcelain basin over a Bunsen's
burner ; it should be kept in fusion for a time proportionate to
the quantity — five minutes for several ounces, and for quantities
of one or several pounds, ten minutes. It is allowed to cool in
the basin, and removed by inverting the basin upon a sheet of
letter paper placed on a board, the board is then tapped on the
back of a chair, and the jarring loosens the cake without break-
ing the basin.

A negative bath may by careful treatment be used for a won-
derfully long time. The writer has been informed by a profes-
sional photographer that he had made considerably over 2000
negatives, many of them 10 x 12 size, in two 4-gallon baths, and
had them both still in excellent order. When they ceased to
give good results he added carbonate of silver, boiled down,
filtered, sunned well, filtered again, acidulated and strengthened.

When the bath gives }rinholes it must be poured into its own
bulk of water, filtered, and after filtering, be evaporated down
to its original bulk.

The writer, in working the wet process, has generally adopted
the principle of not wasting time and patience in trying to bring
faulty baths into working order, but had made it a rule to sub-
stitute a new bath, putting the old one aside until a proper quan-
tity collected. These are then to be evaporated down in a large
basin, large enough to hold perhaps a fifth at a time, of the
whole quantity. As fast as the liquid goes down, more is added.
When the liquid becomes small in bulk, it is transferred to a
smaller basin of first quality Berlin or Meissen porcelain, and
heat applied until all the water goes off, and a powdery mass is
left. The heat is then carefully raised till the whole mass passes

1 One hundred and eight parts of pure 6ilver correspond to one hundred and
seventy parts of nitrate. The mint value of pure silver is $1 40 in silver,
per troy ounce. Metallic silver is sold by the troy ounce (480 grains), nitrate
of silver by the ounce avoirdupois (437^ grains).

158 PHOTOGRAPHIC M A AIPUL ATIONS.

into quiet fusion, in which condition it is kept five or ten minutes,
not longer. After cooling, the cake of nitrate is broken up and
used for new baths, acidulating with dilute nitric acid if necessary.

Some, before evaporating, dilute largely with water to throw
down the iodide. This makes an immense mass of material to
evaporate, and in the writer's experience, has not been necessary.
If when the fused cake is dissolved, hot water is used, and the
solution filtered at once, most of the iodide will remain undis-
solved. The full quantity of water needed for the bath should
be added to the cake at once, and not a strong solution first made
and then diluted.

A second bath, in first-rate order, should always be kept on
hand to avoid the need of hurriedly treating a bath that has
ceased to work well. The plan of having a second weaker bath
to redip the plates after the first, already described, cannot be
too much recommended.

Swinging Bath. — In the ordinary dipping bath, if any scum
forms on the surface of the liquid, it is apt to settle on the plate
as the latter is lifted face upward on the dipper. This may be
avoided by swinging the bath on pivots half way up. The plate
is put in, with the bath in its regular position, the bath is then
swung forwards until the plate tips over with its front upper
corners on the other side of the bath. In this way when worked
up and down, the face of the plate is continually washed, and
when drawn out, the scum attaches itself to the back of the
plate instead of the front.

§ 4.— Making the Plate.

The mode of coating the plate has been already described and
illustrated with explanatory figures. (See p. 22.) In the first
edition of this manual, the course habitually taken by photog-
raphers in coating blown glass, viz., to coat the hollow side, was
recommended. The reasons in favor of this course are, first and
principal, the curvature of the field exhibited by many lenses,
and secondly, that when the hollow side is coated the pressure of
the spring of the dark slide acts to some extent as a corrective,
flattening the plate.

Continued experience inclines the author to believe that this
system cannot always be advantageously employed, but that in
a considerable number of cases, the reverse is the proper plan.

THE NEGATIVE. 159

In most landscapes the most distant objects occupy a position
towards the centre of the plate; the objects occupying the sides
are mostly, and those occupying the lower edge are almost in-
variably, nearer to the camera than the central objects. It, there-
fore, follows that the central objects will be apt to have a focus
shorter, often considerably shorter than those occupying the mar-
gins of the plate. This fact every practical photographer will
have very often noticed. And if this is so, it is clear that what-
ever difficulty there may be in bringing these parts simulta-
neously into focus upon the ground glass, the case will be yet
worse on the sensitive plate if coated on its hollow side, whereas
if it be coated on the convex side, the centre of the plate will
approach nearer to the lens, and consequently tend to remedy
the defect.

It we apply these principles to photographic subjects generally
we shall conclude that when the different objects included in the
pictures are nearly in the same plaiie, we should coat the hollow
side. Therefore in portraits, and in views of architectural sub-
jects, the hollow face should be coated.

On the other hand, when landscapes are to be taken, with the
central objects farthest, it will be best to coat the convex side.

In some landscapes the nearest objects are at one side, and as
we pass towards the other side of the plate they continually in-
crease in distance. This is not a common case, and is to be
managed by the use of the swing-back, drawing back that part
of the ground glass upon which the nearer objects fall.

To the remarks already made in Part I., the following may be
added : —

Pneumatic Holders. — These are of two sorts; the one intended
for collodionizing with, is made entirely of rubber. If the cup
portion be wetted and pressed firmly against the glass at the
middle of the back, it adheres and affords a convenient handle.
Some have a hollow chamber below (see Fig. 98),
by squeezing the air out of which, the adhesion is Fig. 98.
improved. These holders avoid the danger of
mottled-marks produced by the warmth of the
fingers touching the under side of the glass, but
must be used with care. They must be wetted to
adhere. If set down in places soiled by spilled so-
lutions, these may be transferred to the back of the

160 PHOTOGRAPHIC MANIPULATIONS.

plate, and thence to the negative bath, to its destruction. And
occasionally the adhesion will give way during the pouring off:
the operator must be prepared for this, and if he feels the plate
slipping, must support it by the ends of the fingers till he can
get hold of the corner.

Fis. 99.

Another sort is useful for keeping the hands clean during de-
velopment. (Fig. 99.)

A good manipulator will find both these instruments useful.

As the film dries, the surface, which looked before perfectly
smooth, will frequently show minute specks, which, by capillary
attraction, cause the collodion to collect round them so that they
form slightly raised spots. These are one of the great nuisances
of- photography, and one which no carefulness of manipulation
will get rid of. The writer has even tried forcing collodion
through thick filtering paper by the pressure of a considerable
column, but the collodion so filtered produced them just as much
as that filtered through sponge. These specks, as far as he can
find, depend upon —

1. Minute filaments carried through the filter (if sponge) or
coming from the filter itself (if paper or cotton-wool).

2. Dust on the plate before pouring.

3. Dust falling during the collodionizing.

4. Dust on neck of collodion bottle.

Of course cause (1) is beyond helping, and is therefore the
most serious of all. To obviate (2) brush the plate gently with a
soft wide camel's hair brush, or rub gently and very moderately
with blotting-paper moistened with alcohol, just before collo-
dionizing. Not using too much friction, or it will very easily
become electrical and attract every mote in the atmosphere, and
retain it obstinately.

Cause (3) is best obviated by having a special closet in the
dark room for collodionizing. This is so desirable on hygienic
grounds alone, that it should never be omitted.

Often these specks may be floated off by pouring on a good
quantity of collodion, so that the excess in flowing off the plate
may carry the speck or mote with it.

THE NEGATIVE. 161

Only experience can enable the photographer to decide as to
whether a film showing some of these specks must be wiped off
again. If intended for copying, it must, invariably, be rejected ;
and, generally, if for portraiture. In landscape work, one or two
small specks are not likely to show in the negative.

This is on the supposition that the particles are filaments of
wool, or cotton, or other inert substance. Sometimes there may
be chemical dust, as of hyposulphite of sodium, in the atmos-
phere. In this case the speck, after sensitizing, will appear
darker than the rest when viewed by transmitted light, and the
plate is, of course, worthless.

Attention to the proper moment for dipping into the bath is
necessary, because, if the plate be kept too long, it is insensitive,
and tends to marbled stains ; if plunged in too soon, it may split
in the bath. But even if the film does not split, it may still not
have been dry enough, and may exhibit an appearance which no
one, without instruction, would ascribe to the right cause. Some
portion of the film will assume a peculiar appearance, not easily
described, but very observable. Perhaps a better idea can be
given by saying that it has something the appearance of wax,
the structure of a freshly-broken cake of camphor, or of fused
nitrate of silver ; neither exactly conveys the idea, but are per-
haps as good comparisons as can be found. This appearance is
rarely at, or carried to, the edges, which dry faster, but is gene-
rally to the interior of the plate, and mostly covers a few square
inches of surface. It rather gives the idea of some decomposi-
tion to the collodion, than suggests its true origin.

On the whole, it is perhaps better to remove the plate from
the bath as soon as the greasy marks disappear. At this stage
the iodides and bromides are still in excess at the bottom of the
film ; this bottom is therefore insensitive, and consequently the
sensitive portion of the film is separated by this insensitive por-
tion from contact with the glass, and thus the danger of stains
from imperfect clearing is greatly diminished.

It has seemed to the writer that short immersions in the bath
tend to produce images that rest on the film and are whitish
powdery. Longer immersion gives an image more in the film,
and a rich, creamy-looking negative. In this respect the advan-
tage seems on the side of a little longer immersion.

162 PHOTOGRAPHIC MANIPULATIONS.

§ 5. — Developers and Development.

Gallic acid, the first developing agent used, was in time super-
seded by pyrogallic acid, obtained from gallic acid by sublima-
tion. Proto-sulphate of iron was found to give a softer picture,
and needs less exposure than pyrogallic acid, and has by degrees
wholly taken its place in wet plate development.

Operators differ a good deal in their views as to the proper
strength of the iron developer for ordinary exposures, using from
ten grains of sulphate to the ounce up to forty or more. The
following proportion will be found to give good results. It will
be needful, however, to bear always in mind what has been said
on maintaining a due relation between the collodion and the de-
velopment (p. 132), and to suit the developer to the needs of the
film. A collodion containing much bromide will need a stronger
developer than one containing less, and it will also need a longer
development, because the deposit is more crystalline, and not so
close and dense ; it lets more light through, and will give a weak
print unless the development is carried farther than in the case
of a collodion containing less bromide.

No. 1. Stronger Developer.

Sulphate of iron 3 ounces.

Acetic acid 3 to 4 ounces fluid.

Water 40 ounces fluid.

No. 2. Weaker Developer.

Sulphate of iron 2 ounces.

Acetic acid 3 to 4 fluidounces.

Water 40 ounces fluid.

Aids to Development. — In developing plates, and still more in
redeveloping them with pyrogallic acid and silver, the hands are
apt to be much stained, and various contrivances have been sug-

Fiir. 100.

gested for avoiding this annoyance. The author, after trying
such as had been proposed, with no satisfaction, devised one, of
which the construction is explained in the adjoining figure.

THE NEGATIVE. 163

Two brass rods, one considerably longer than the other, are
fastened firmly into a wooden handle. At their ends the rods
lead at right angles, and have pieces of silver soldered on to
them. A rod passes through these, through one end it simply
turns, but fits into the other with a screw thread. A mill head
enables one to turn it conveniently. The plate is grasped so
tightly as to give a perfect security, without ever being broken.
An ingenious contrivance for the same purpose was communi-
cated to the author by Mr. Henderson, of Montreal. A brass

Fig. 101.

rod A C has a knob fixed at its end A, made by heating a piece
of gutta percha and kneading it into shape while hot. A notch
is made under it to receive the edge of the plate. A short piece
of lead pipe, B, slides on the rod and is held by the thumb
against the plate, which it holds in place. This plan is simpler
than the first described, but does not give equal security.

If any repellant action show itself between the developer and
the film, alcohol must be added to the developer, in such pro-
portion as will check this tendency. An ounce of alcohol to
eight, ten, or twelve of developer may be needed. This is a
matter of no small importance, because the repellant tendency
may at any moment lead to the formation of oily lines, and these,
unless the plate is instantly washed off, almost inevitably produce
streaks.

When sulphate of iron is used for developing instantaneous
pictures, no restraining acid is employed, but simply a very strong
solution of the iron, 80 or 100 grains to the ounce. Such a de-
veloper cannot, of course, be kept on more than a very short
time, and the image once forced out, recourse must be had to
redevelopment, or to after-intensification, to bring the image up
to printing strength. Conversely, when a long exposure has
been given, a good deal of restraining acid may with propriety
be added.

It has been proposed at various times to place a very great
number of various organic substances in the developer. Expe-
rience has shown that almost any organic substance may take the
place of acetic acid as a restraining agent, and sometimes writh
advantage; for some of these substances have a remarkable

164 PHOTOGRAPHIC MANIPULATIONS.

power of destroying the tendency to fog, so that the iron de-
veloper can be kept upon the plate like a pyrogallic developer.
Thus redevelopment becomes wholly superseded, and the picture
is always finished at a single operation. The substance that pos-
sesses this property in the largest degree is, as shown by the
writer, gelatine, that has been treated with sulphuric acid, with
formation of glycocine and tyrosine. The writer published several
formulas for this purpose, and the subject attracted at one time
very great attention. Many experimenters went to work at it,
and produced formulas of their own. Since publishing, some
years ago, the remarks on the subject that gave the initiative to
what has since been written, the writer has remarked that the
quantity of sulphuric acid necessary to modify the gelatine is
absolutely so small in proportion that it exercises no hurtful
agency upon the development, and consequently it does not require
to he removed by a subsequent neutralization. This brings the pre-
paration of the collo-developer to a singularly simple form, as
follows : Take

Common glue 6 ounces.

Sulphuric acid | fluidounce.

-yvater 9 fluidounces.

Boil these together for a couple of hours in a flask, replacing the
water as it evaporates. Then throw in an ounce of granulated
zinc, and boil for an hour and a half. Add water as it evapo-
rates, and, when done, dilute to twelve ounces.

This syrupy liquid has the most extraordinary restraining
power. A single drop is sufficient for three ounces of 30-grain
iron solution ; one ounce, therefore, of the above gelatine solu-
tion is sufficient for 1500 ounces of developer.

Two essential remarks remain to be made in reference to this
process. It might be alleged that the restraining power is due to
the sulphuric acid by reason of its powerfully acid nature; but
the writer has, by careful experiment, demonstrated the fact that
sulphuric acid does not tend to restrain development, but tends
to fog. It is therefore clearly not the sulphuric acid that acts.

Again, it may be alleged that by the long boiling with zinc,
the whole of the sulphuric acid must have been removed by the
excess of zinc present. But the presence of the gelatine checks
the action of the acid on the zinc so much that it was ascertained
by careful experiment that when the operation is performed as
above described, at the end of a boiling of an hour and a half,

THE NEGATIVE. 165

only one-fourth of the sulphuric acid was neutralized. This was
ascertained by weighing the zinc before and after the operation,
and determining the quantity of sulphuric acid corresponding to
its loss of weight.

The action of the gelatine in this case in checking chemical
action, prevents a very striking analogy to its action in the
development.

The collo-developer, obtained by adding one drop of the gela-
tine solution, prepared as above, to three ounces of water and 90
grains of protosulphate of iron, develops rapidly and with less
tendency to fog than the common iron developer. By somewhat
increasing the quantity, the development goes on still more
slowly, with still less tendency to fogging.

The Sugar Developer.— For the regular needs of the photog-
rapher no developer can be better than the sugar developer.
The writer uses a formula of his own which he strongly recom-
mends. It is as follows : —

In 32 ounces of hot water dissolve 7 ounces of protosulphate
of iron. This is best done by letting a portion of the hot water
stand over the crystals until it is pretty well saturated, pouring
it off, and repeating it with a second and third portion. To this
solution add 6 ounces of white sugar and 2| ounces of acetic
acid No. 8. This need not be filtered. It is the sugar developer
in a concentrated form, and keeps indefinitely. To prepare for
use take —

Above solution 7£ ounces.

Acetic acid No. 8 4 "

"Water ... .... 18 "

Filter.

•

It is perhaps an improvement to add a little sulphate of cop-
per. An ounce of it may be added to the 10 ounces of sulphate
of iron. With it, or without it, excellent results are got. The
strength above given is suitable for winter, and may be diluted
with from one-half to an equal quantity of water in summer.

Management of Development. — By close attention to the manipu-
lations of the development something may be done towards con-
trolling the nature of the image produced. Softness will be pro-
moted by keeping the plates still whilst the image is coming
out; — contrast will be increased by inclining the plate alternately
at each end and keeping the developer continually in motion,
because in this way the silver solution which impregnates the

166 PHOTOGRAPHIC MANIPULATIONS.

film is much more washed out and mixed up with the developer.
The strong parts of the image will always rapidly abstract the
silver from the solution upon their portions of the plate; thus as
the image comes out the shadows will continue to be moistened
with a solution rich in nitrate of silver, after that which bathes
the high lights has been more or less impoverished. This state
of things is changed by keeping the developer in motion ; more
silver is then carried to the high lights, and contrast is heightened.
With very large plates it will be best to develop in a pan.
The developer is poured in abundant quantity to the lower end
of the tilted pan, one end of the negative is placed in the dry
(upper) end of the pan. The pan is then brought to a horizontal
position, and at the same time the negative is let gently down
into it. In this way a wave of developer passes evenly over the
whole surface. Unless flatness of effect is dreaded, it will be
best to leave the negative at rest in the developer, and not to
work backwards and forwards.

It follows from what has been said here and elsewhere that
the operator must be governed in his development by a principle
quite different from that which guides him in exposure. For
whilst his exposure must be timed with a view to the worst illu-
minated part of the subject, the development will be guided by
the high lights. These two principles are of such capital im-
portance that they cannot be repeated too often, or mastered too
thoroughly. They may be expressed in two rules, as follows: —

Expose the plate for the dark shadows, leaving the lights to be
cared for in the development.

Develop for the high lights, keep the eye steadily fixed on the
very highest light (the densest spot) of the plate, and stop whilst
that is transparent enough to preserve its perfect moulding in the
print to be made from it. The shadows are not to be watched in
developing (except in local redevelopment, see below) ; they have
been, or should have been, cared for in the exposure. Not that
they are indifferent, far from it, but in point of fact, watching
the high lights is doing the best possible for the shadows, the
object of continuing the development as long as possible being
to get out as much detail in the shadows as possible. Not they,
however, but the high lights are to be watched, because we so
ascertain the exact moment at which the development can be

THE NEGATIVE. 167

pushed no farther, but must stop under pain of producing chalki-
ness and flat lights, which are simply ruinous.

Too much attention cannot be directed to this matter. It will
be necessary for the photographer to learn by experience the
appearance of the deposit when it has reached a point beyond
which it must not go. This cannot be expressed or described,
can only be learned by care and attention, and at the expense of
spoiled plates. It is of course to be judged of by holding the
plate up to the light; by degrees the operator will learn the
point to which he can go safely. With practice the photographer
will pick out at once the high light which he must watch ; he
will, in fact, have seen it in the subject before he uncovered his
lens, and his attention will be directed to it as soon as he raises
the plate to the light. On this portion his attention will be
fixed throughout the development, and his anxiety will be always
that it shall not reach the point at which it must stop before he
gets the desired detail in the dark shadows. It has already been
remarked that great care will always be needed in raising the
plate to observe the stage reached, lest the developing solution
break its even film into lines, producing streaks of unequal de-
velopment, a trouble that besets every photographer in his earlier
work.

Influences controlling the Character of the Negative. — "Whatever
influences in development tend to softness will, if exaggerated,
tend to fogginess, and whatever helps brilliancy will, if exagge-
rated, produce harshness, because harshness and fogginess are
the extreme terms of development.

Those, therefore, who seek for the softest effects will endeavor
to keep just inside the line of fogging, and by the use of a strong
developer will equalize the deposit of silver. Those who are
anxious for brilliancy will use a weak developer, which will in-
crease contrasts.

The anxiety for brilliancy which at one time existed has nearly
disappeared. The magnificent effects of half-tone which have
been attained by skilful photographers have produced universal
desire for imitation. In fact, if different series of photographs
be compared, it will be found that they are most pleasing in pro-
portion to the amount of half-tone that they contain, and the
recognition of this fact, both amongst photographers and the
general public, is every day becoming more widespread.

If a portrait is harsh, crude, and unpleasing, with a want ot

168 PHOTOGRAPHIC MANIPULATIONS.

relief in its various parts; if the figure seems resting against the
background, and if the eye has to examine the whole to estimate
the relative positions of the parts, the capital fault (besides what
others may exist) will be want of half-tone. A landscape that
wants half-tone will be patchy and blocky ; it will have a certain
narrow and scant effect, an absence of boldness and breadth ; the
eye will not at a glance take in the relative position and bearing
of its parts, but requires some moments of observation before it
recognizes where everything belongs, and perceives that certain
parts belong to the middle distance, so that the picture is not all
foreground and distance, as it at first appeared to be. In such
work, the leaves in the foreground will be either white, if well
illuminated, or black, if not. It is such work that has led to the
epithet of unartistic, so freely bestowed by artists upon the pro-
ductions of photography.

How then is this invaluable half-tone to be attained ? The
answer is not so easy. First, it may be premised that it is the
use of bromides in collodion that has made it possible, the .use,
not the exaggeration. Experience has shown that broad and ex-
pressive half-tones do not depend upon, and cannot be reached by
any particular composition of collodion or of developer alone,
but will depend upon a happy combination. And that in every
case the conditions necessary can only be discovered by careful
and intelligent observation. For any good specimen of pyroxy-
line there will be a certain proportion of iodide or bromide, and
a certain strength of development that will produce good results,
and these must be found by trials. (See p. 133.)

A serious difficulty is introduced into all photographic opera-
tions by the variable nature of the cotton. It seems almost im-
possible to repeat an operation for making pyroxyline twice, and
get identical results.

It will be important to bear in mind that whenever a very
considerable quantity of bromide has been used in the collodion
the tendency of the deposit is to be more crystalline. A curious
result follows, that in printing the plates show themselves to be
less dense than they appear to the eye, and consequently they
show less contrast.

It may consequently happen that such plates, whilst appearing
to a good judge to have been developed exactly right, may yet
in printing yield flat and unsatisfactory results. In changing

THE NEGATIVE. 169

from one formula of salting to another it will be important to
bear this in mind.

The whole tendency of modern photography is to full ex-
posures and slow, careful developments. It follows, from what
has been already said, that a full exposure absolutely necessitates
a slow development, otherwise the negative is flat and tame, a
fault now much commoner than it used to be when brilliancy was
more sought after than half-tone. In fact, some seek so earnestly
for masses of half-tone that they sometimes have no high lights
at all in their prints : this is a fault which, though not as bad as
the opposite error, is nevertheless a fault; no contrasts that can
be produced on paper, as shown by Mr. Euskin, can fully repre-
sent the ordinary contrasts of nature. "We are, therefore, never
justified in still farther contracting our means by substituting
half-tone for high lights. Indeed, a certain quantity of high
light is essential to give to half-tone its full value and due effect.

Washing the plates should not be hurried, but ample time be
given to get rid of the hyposulphite, especially with valuable
negatives. A simple arrangement for supporting the plate
whilst washing is figured in the introduction at p. 36, and is spe-
cially recommended as facilitating a safe and perfect washing.

§ 6. — Local Redevelopment.

It will occasionally happen that after the deposit on a negative
has reached a point such that, whilst the denser parts have re-
ceived all that they can bear consistently with giving full detail
in the high lights in the print to be hereafter taken, the thinner
portions, or some of them, might advantageously have more
strength, that is, these thinner portions, though exhibiting fine
details to the eye, may be too thin to print properly. In order,
therefore, to bring the negative into a condition to show the
greatest possible transparency of shadow, that is, a clear render-
ing of details in the least illuminated portions, it may be very
advantageous to resort to a local redevelopment.

This may be performed either before or after fixing. When
done before fixing, there is more hope of adding to the details,
when after, the operation can be performed more satisfactorily,
because the operator sees far better what he is about. In the
former case, although details not before visible may be rendered
visible, yet it is doubtful if, within the limits of this operation,
12

170 PHOTOGRAPHIC MANIPULATIONS.

detail so brought out can be got up to printing strength. The
proper hope of this operation seems, therefore, to be the bringing
of visible details, too weak to print, up to printing strength, and
this is better done upon the fixed and washed negative. I shall,
therefore, so describe it. It will be understood, however, that if
preferred, exactly the same operation may be performed upon
the unfixed negative, remembering that the same precaution as
to light must be then used as in the regular development, other-
wise fogging will ensue.

If the negative has been allowed to dry, it will be advisable
first to go round the edges with India rubber dissolved in benzole.
The film must then be well wetted, the plate is to be grasped by
the left thumb and forefinger at one of its corners, and so held
that those parts which are already fully dense shall be on the
side of the plate farthest from the operator (in a landscape nega-
tive this will generally be the sky side); the plate is to be tilted
a little, so that this far side will be a little the higher, and a solu-
tion of pyrogallic acid, silver, and citric acid, such as is usually
employed for redeveloping, is to be dropped upon those parts
where the additional deposit is needed. The plate being very
wet, this dropping of solution will produce circles that slowly
expand, and as they cease to expand wash down towards the edge
near the operator, by reason of the tilting position given as above
directed. As this takes place the operator holds the plate under
the bath and washes off the solution. If the parts nearest to the
operator will easily bear the additional deposit that they get as
the solution passes over them, the operator proceeds more delibe-
rately. If they are already pretty strong, he washes off almost
as soon as the solution spreads to them. A few seconds suffice
to wash away the solution, when the operator recommences, and
this is done as often as necessary, even up to six or a dozen
times.

By this mode of proceeding, spots and stains are avoided. If
the solution were left to rest on any one part, a circular spot
might result which would print lighter. The pjTogallic solution
can be used pretty strong, but should be kept clear and colorless.
The whole operation turns on not allowing the solution to be for
a moment stationary anywhere, but washing it off as it ceases to
spread, and recommencing. Of course, before washing, the greater
part of the solution may be first drained off into the developing
vessel.

THE NEGATIVE. 171

§ 7. — After-Intensification.

The three stages by which the utmost possible density is ac-
quired by a negative are — development, with iron, pyrogallic or
gallic acid ; redevelopment, by a second application of either of
the foregoing reducing agents, not necessarily or even generally
the same as at first employed, since iron is commonly followed
by pyrogallic acid ; and after-intensification, which, last may be
effected in a variety of different ways.

Eedeveloprnent may be resorted to either before or after fixing,
and in all cases is accompanied by an addition of silver solution.
After-intensification is always applied after fixing, and silver is
never used. The object of redevelopment is always to add more
silver, without acting in any way upon the previous deposit.
After-intensification adds no silver, but always acts chemically
upon the original image, bringing it into a new combination more
opaque to light.

When it is intended to apply an after-intensification, it is not
usual to redevelop also, but to fix after the first development.
It should be thoroughly understood by all students in photo-
graphy that after-intensification is at best the remedy either of. a
mistake in the exposure, or else is rendered necessary either by
a deficiency of illumination, or an exposure which for good
reason has been greatly curtailed. Therefore, whilst a good
knowledge of several modes of intensifying is necessary for the
photographer, he should resort to them as little as possible.
Where the exposure has proved much too short or too long, it
is generally better, when practicable, to take another negative.
It will cost but little, if any, more time ; the experience of the
first will enable the operator to time the second correctly, and
the probabilities of a fine negative are decidedly greater. The
following are the best methods of after-intensification : —

Iodine. — When only a little additional strength is wanted,
iodine may be employed. If a few drops of tincture of iodine
be dropped into a quantity of water, the latter acquires a pale
sherry wine color, and if poured over a negative gradually
blackens it, or rather brings it to an exceedingly deep violet
black. The application must be stopped at this point by washing
off the solution as its continued action brings the plate to a light
yellow color. The solution may either be flowed over the plate,

172 PHOTOGRAPHIC MANIPULATIONS.

replacing it with fresh as soon as it loses its color, or it may be
applied as a bath.

Care must be taken that there are no undissolved particles of
iodine present, as these may lodge on the film and produce yellow
spots. For this reason many prefer to add a little iodide of potas-
sium to the liquid, which enables it to keep more iodine in solu-
tion. This combination may be purchased of the druggist, under
the name of " Lugol's solution," which may be diluted with
thirty or more times its bulk of water and used.

Chlorine. — The blackening may be equally well effected by
chlorine. Make a solution of bichromate of potash, one grain to
the ounce, and add to each ounce two drops of hydrochloric acid.
This solution is applied like the preceding, stopping as soon as
a uniform dark color is obtained.

Corrosive Suhlimate. — If a saturated solution of this substance
be diluted with ten times its bulk of water, it may be applied
precisely like the preceding, and blackens the plate very effec-
tually.

The foregoing applications all give a moderate degree of addi-
tional density to the image, though the latter acts more power-
fully in this respect than the others. They also act alike in this,
that if their influence be continued too long, the images, after
having become black, become lighter again; in the first case
pass to a yellow shade, in the two latter, to white. In this con-
dition, the film is in all cases much less dense than at first. In
this stage, however, they are fit for additional treatment, which
may confer upon them a much greater density yet, as follows : —

Sulphide of potassium will not act much upon the silver film,
but if by the continued action of either of the three first methods,
the film has been brought to the yellow or white stage, and then
a dilute solution of sulphide of potassium be poured over it, the
image acquires an intense blackness, so intense, in fact, that all
middle tints may be expected to disappear. Nevertheless, there
do exist cases in which this treatment may be applied with very
useful results. Negatives of line-engravings, especially such as
are of the full size of the original, are often very successfully
obtained by developing only till an ambrotype is got, and then,
without any redevelopment, intensifying in this way. But it is
to be said that, in skilful hands, equally good and quicker print-
ing negatives of line engravings are got by the ordinary develop-

THE NEGATIVE. 173

merit and redevelopment, though they do not give prints which
so easily tone to a perfect black as those yielded by the denser
sort of negatives. Even, however, when these denser negatives
are wanted, they may be still better obtained by the following : —

Cyanide of Potassium. — When a film has been treated with cor-
rosive sublimate till the white stage is reached, there is often a
little veiling produced, scarcely visible while the print has this
light color, but visibly injurious after the blackening by sulphide
has been effected. The writer has found it, therefore, useful to
substitute cyanide of potassium for the alkaline sulphide. The
cyanide solution must be very weak, one grain, or not exceeding
two, to the ounce of water. It must be flowed over evenly, or
applied as a bath, and must be washed off as soon as an even
blackness is obtained. A continued action will cause the nega-
tive to whiten again.

This treatment gives great intensity, and, at the same time,
keeps the transparent parts of the negative beautifully clear.
For photographic operations in processes not intended to give
half tones, it is exceedingly well suited, as well as for all cases
where o-lean sharp contrast is a main object.

Schlippe's Salt — Scarlet Negatives. — This method of intensifying,
which the writer introduced to photographic notice some years
ago, has been largely used where great increase of intensity is
needed, and with excellent results. The negative is first treated
in either of the three first described methods : with iodine, chlo-
rine, or corrosive sublimate, until the light stage is reached, and
then, after washing, a dilute solution of Schlippe's salt (sulphanti-
monite of sodium) is poured over it. The negative instantly
turns bright scarlet, presenting a remarkable and very beautiful
appearance, and becoming very opaque to active rays.

The solution of Schlippe's salt should contain about ten grains
to the ounce, and should be kept tightly corked. It, however,
gradually deposits a precipitate, but if decanted from this it still
acts well. The addition of a few drops of liquid ammonia pre-
vents the precipitate and causes the solution to keep quite well.
In this condition it does not give the bright-colored negatives
before spoken of, but beautiful russet-brown ones, which are per-
haps as non-actinic as those obtained without the ammonia. The
color will also be found to vary a good deal with the extent to
which the first application (of chlorine, iodine, or sublimate solu-
tion) has been allowed to act. The full scarlet color is got by

174 PHOTOGRAPHIC MANIPULATIONS.

allowing the first action to reach the full light stage, and apply-
ing the Schlippe's salt without ammonia.

Solution of Schlippe's salt is apt to stain the fingers red. A
little weak solution of caustic potash or soda instantly removes
this.

It should always be borne fully in mind that operations with
either sulphide of potassium or Schlippe's salt should be car-
ried on away from the dark room, as the sulphuretted hydrogen,
of which a little is diffused in the atmosphere, may tend to cause
fogging. It is also injurious to the health to breathe a sulphu-
retted atmosphere, therefore a thorough draft should be provided
to carry off such vapors.

Permanganate of potassium has been highly recommended for
after-intensifying by Mr. Wharton Simpson. A dilute solution
is poured over the plate till the requisite intensity is obtained.

Uranium intensifying is now abandoned, because the nega-
tives rapidly become denser in printing till worthless; after-
intensification with sublimate is, to some extent, liable to a similar
objection.

In such cases it has been recommended to expose them to a
gentle heat for a length of time, which treatment is said to lower
the intensity. In copies of engravings without half tint (line
engravings and wood-cuts, but not mezzotints, lithographs, or
photographs) this increase of strength is of little or no disadvan-
tage ; in such cases, therefore, the mercury may be used without
hesitation.

These processes may be divided into three classes, according
to the amount of effect that they produce. For a quite moderate
increase of density chlorizing or iodizing may be used. For a
rather greater, but still moderate result, sublimate solution is
suitable. When a very decided increase is needed, chlorizing,
iodizing, or mercurializing, in each case till the light color is
reached, may be resorted to, to be followed by Schlippe's salt or
sulphide of potassium.

All the mercurial treatments weaken the film and render it
liable to split in drying. If, therefore, a valuable negative is so
treated, it is a prudent course to flood it with gum-water or solu-
tion of gelatine, the former about 30 to 35 grains to the ounce,
the latter about 20 to 25. If intensifying is much practised it is
well to have a solution of this sort on hand ; it may be made to
keep by adding either creasote or carbolic acid, one or two drops

THE NEGATIVE. 175

to the ounce. The gum solution or gelatine is flowed over the
plate for half a minute, worked in, and then poured off again,
and the plate is reared up to dry. After thorough drying it is to
be varnished. It has been affirmed that a plate so treated can be
varnished cold without the varnish drying dead. On the whole,
the gum -water answers better than the gelatine, and does not
require to be warmed to liquefy it.

This mode of operating has, however, the disadvantage that
the varnish cannot penetrate the film of gum (or gelatine) and
does not reach the back of the plate. And as the gum and gela-
tine have no very powerful adhesion to the glass, the film is
liable to scale off.

To Intensify Varnished Negatives. — The usual plan is to remove
the varnish by soaking in alcohol or benzole, whichever has been
used in the making of the varnish to be removed; then apply
any of the intensifiers already described.

The complete removal of a lac spirit varnish by alcohol is no
easy thing, portions of gum remain behind and refuse to dissolve.
Some, therefore, intensify without removing the varnish. Mr.
Alfred Hughes's method is as follows: Dissolve iodine in spirit
varnish, one grain to the ounce, and varnish the plate with this
varnish, without removing the first coat. Drain it well off, dry,
and expose to the light, when a considerable increase of intensity
takes place.

When the operation has been performed by dissolving the
varnish, the use of an alcoholic solution of iodine, two or three
grains to the ounce, is to be recommended, and acts more uni-
formly than any aqueous solution would. Care should be taken
not to leave it on too long, and it must be borne in mind that the
alcoholic solution cannot be instantaneously removed, like an
aqueous one, as it takes a few seconds for the water to moisten
the plate evenly.

According to Mr. Winter, the simple removing of the glossy
surface of the varnish by a moderately strong alcohol, so as to
give it a dead appearance, like ground glass, greatly increases
the effective density of the negative. This of course applies
only to spirit varnishes, and probably only to those made of diffi-
cultly soluble resin like lac.

176 PHOTOGRAPHIC MANIPULATIONS.

§ 8.— Reducing Over-developed Negatives.

It will occasionally happen that a negative has been over-
developed, and when examined after fixing and drying, gives
evidence that it can be expected to yield only chalky high lights.
This discovery may come too late to permit of retaking the
subject, especially with landscape negatives taken away from
home, and it should be more generally known than it is, that
such negatives can be greatly improved by the following treat-
ment, which the writer believes was first suggested by Mr.

Hughes.

A wash of very dilute solution of perchloride of iron is applied
to the film, which must, of course, be wetted beforehand. It is
also better to apply an edging of India-rubber to make sure that
the film shall not loosen, though this is not essential. The per-
chloride of iron can be got from any druggist under the name of
" muriated tincture of iron." It is sold in solution, which must
be largely diluted ; from ten to twenty times its bulk of water will
be needed. The first trial should always be made a rejected
negative. The action is extremely rapid. The film apparently
darkens, but on holding it up to the light, a welcome transpa-
rency will be found in those dense portions which previously
threatened to print without detail.

If the negative wants very little reduction it will be prudent
to use the solution still more dilute. In nine cases out of ten,
if the perchloride does not give satisfactory results it will be
from excess of strength in the iron solution.

This is the only application that has ever given the writer
satisfactory results, or that he would think of employing. Its
merit lies in that it does not eat away the image, but simply
thins it, and especially that its action seems to be greatest upon
the densest part. Thus the objectionable features of the nega-
tive are removed without material injury to the detail. Nega-
tives that must otherwise be totally rejected may in this way
become serviceable. This mode of operating is suitable for all
negatives except those taken by the bromide dry processes.

Local Reduction. — Sometimes one particular object in a nega-
tive will develop to complete opacity before the rest has attained
printing density. In such a case to apply a treatment to the
whole negative would virtually destroy it, the thinner parts being
supposed to be just thick enough. It is evident that if any re-

THE NEGATIVE. 177

ducing treatment could be applied to the single object or few
objects that are too thick, a great advantage could be gained.

Hitherto, the writer believes, this has never been attempted
successfully, in consequence of the treatment inevitably extend-
ing to the adjoining portions of the image. It occurred to the
writer lately to try the effect of sizing the film with gum and
tlaen applying the reducing agent. It was found that this treat
ment, as foreseen, resulted in making a change in the film similar
to that which blotting paper undergoes by sizing, that is, that a
solution no longer sunk into the film and spread around, but was
completely localized in its action ; and, therefore, that any single
dense object could be reduced in a quite remarkable way.

The operation is as follows: Pour over the plate (of course
before varnishing) a 50 grain solution of gam arabic, work it in,
and let the plate dry. Then take some perchloride of iron (or
muriated tincture of iron) and dilute it largely until it is of a
pale straw color only. Apply this delicately on the part to be
reduced, with a small elastic sable brush, keeping strictly inside
the limits of the object. This presently diminishes very satis-
factorily in density, and when a proper point is reached, the
solution is washed off. It is to be observed that if the object
proves not to have been sufficiently reduced, a fresh coat of gum
must precede a new application of the reducing agent, supposing
that the plate has been washed off. For washing1 quickly takes
out the gum, and then the film returns to its blotting and spread-
ing condition. This mode of treatment is really useful.

§ 9. — Negatives for Enlargement.

A negative intended to be enlarged from, should always be
taken specially for that purpose. It is undoubtedly true that
some negatives taken for ordinary printing are capable of being
used for enlarging from ; such are those that print easily in the
shade. Usually, however, it is found better to take negatives
expressly.

These must be thinner than usual, but it is not to be supposed
that that thinness is to be secured by a brief exposure. On the
contrary, because the development must be short, the exposure
must be full, a little longer than usually given, so that the picture
may flash up as soon as the developer is poured over it ; and
then, after a very few seconds, the plate is rapidly to be washed,

178 PHOTOGRAPHIC MANIPULATIONS.

lest the deposit should become too thick. Van Monckhoven, who
is excellent authority on this subject, remarks that the details in
the shadows should be scarcely visible, and the denser parts so
thin that one can read through them, and see the smallest objects
without difficulty. Also, that negatives which are too strong are
best reduced by plunging them into a bath of one grain of per-
chloride of iron to each three ounces of water ; then, after wash-
ing, apply cyanide, which will reduce the strength. The opera-
tion to be repeated if necessary.

The deepest shadows should be represented by perfectly clear
glass. Veiling that would be unimportant in an ordinary nega-
tive, will unfit one for enlarging.

Varnish is objectionable for many reasons. The best results
are got with negatives washed and dried without even a solution
of gelatine or other preservative. Some, however, do not hesi-
tate to apply protectives, but, if possible, they are to be avoided.

§ 10.— Retouching the Negative.

Of late years the retouching of the negative has acquired a
very great importance. It has been found that well retouched
negatives will give prints so superior to those from unretouched
negatives as to receive a very marked preference from the public.

It is not every one who can do this work, and it is, moreover,
found to be very exhausting to the eyes, especially when done at
night, by artificial light. It should, therefore, be always done
by daylight, on a retouching desk, or, for want of this, a large
piece of ground glass may be rested in a somewhat inclined posi-
tion, and a looking-glass placed under it, and near to a window.
The negative being laid upon the ground glass, all its details will
appear distinctly. The eyes should be protected by drawing
down a curtain so as to admit light upon the looking-glass only.
In some establishments this is more completely effected by ar-
ranging a partition in front of and near a window. In the parti-
tion an opening is cut sufficient to let the light upon the mirror

only.

Several modes of retouching are practised. A soft Faber's
pencil, B B or B B B, may be used, or water-color be applied
with a sable pencil. As the varnish does not take these applica-
tions easily, it requires a preparation. Some prefer to take off
the glazed surface by rubbing gently with turpentine. Others

THE NEGATIVE. 179

take finely powdered cuttle bone and rub it gently with the tip
of the finger until the glassy surface becomes mat and takes the
application.

Excellent results are got both from the pencil retouching and
the water color. When the pencil is used, it is found advanta-
geous to go over it with a stump, such as is sold by the dealers in
artists' materials; this softens and harmonizes the effect, and
blends it with the neighboring tints.

Water color retouching has the advantage that it is easier
altered, and that, if mistakes have been made, they are easier to
rectify. Experience shows that the best results are got by using
colors that are rather transparent to the actinic rays — blue or
neutral tint. This is to be carefully laid on until the desired
effects are attained.

Too great a smoothness is not to be sought for, as the character
of the face is removed. But as defects of complexion, freckles,
pimples, or irregularities of skin, are apt to be exaggerated in
photographic work, the removal of these by retouching improves
the picture amazingly. So that those professional portraitists,
who have judiciously retouched their negatives, have found them-
selves suddenly overrun with work.

Eetouching is especially useful in removing theblockinessand
want of moulding that results from one part of the face printing
too light or too dark in proportion to the rest. It is evident,
however, that if a negative is already too dense, retouching is
scarcely applicable, because it can only increase and not diminish
the opacity of the image.

The effect of a retouched negative is almost always more pleas-
ing and more flattering than that of one unretouched. Because
wrinkles, deep folds at the angles of the mouth, and lines under
the eyes, are all apt, in photography, to be much more conspicuous
than in the face itself; by retouching they are subdued to any
extent desired, and very pleasing and even flattering prints are
obtained from negatives otherwise unsatisfactory. Practice and
some artistic skill are necessary, however ; the rounded shape of
the cheeks must be preserved, and the face be not too much flat- *
tened. A little careful and systematic practice will give an in-
sight that no directions can. It is evident that the negative must
not be too dense to begin with.

Another method of retouching the negative is to work upon
the back. As the colors do not take well upon glass, it is usual

180 PHOTOGRAPHIC MANIPULATIONS.

to apply a thin varnish, and then to take its surface off in the
same way as directed for preparing the film side. The interpo-
sition of the glass causes the retouching to print less sharply and
more softly than when it is put upon the face; there is also no
danger of injuring the image. The same modes of operating, the
black lead pencil or the water color, may be used.

Still another method is to attach thin letter paper to the back
by pasting or gumming at the edges, and then applying color,
&c, upon the paper ; this method has been long in use for sketch-
ing clouds into the transparent skies of landscape negatives.

For stopping out small holes, Indian ink is generally used.
A color which contrasts with the negative is always desirable, as
it is easier to see what is done; therefore if a negative has been
blackened by any after-intensification, it is more advisable to
touch out holes with a red color. Vermilion is very effective,
and seems to stand the sun pretty well. The indefinite perma-
nence of Indian ink against all action of light is an argument in
its favor that is not to be overlooked.

To landscape work little can be added by retouching, except
in the way of stopping out small holes or minute defects. If it
be attempted to materially alter the lights and shades of a land-
scape negative, a peculiar and artificial character results, which
may perhaps be an improvement in the particular case, but such
work can rarely be considered first-rate. In this is an essential
difference between landscape photography and portraiture, that
the best portraits are almost always those that have been skil-
fully retouched, whereas the contrary is the case in landscape work.

The pasting of paper behind parts that are intended to be
lighter is a well-known artifice; but it only answers well when
the borders of the part to be influenced are pretty well defined.
Some curious effects of light exhibited in this city have been so
produced. A female face, for example, is raised upwards, and a
beam of sunlight falls upon it from a window, lighting it up in a
striking way. The beam and the effect upon the face are pro-
duced by pasting thin paper on the back of the negative, and
printing in the shade. It is scarcely necessary to say that the
paper must be selected with a very even grain and an absence of
the lightish dots so commonly found in thin papers.

Hard and blocky negatives can often be made to yield materially
softer prints by printing under ground glass, as will be more
fully explained in the chapter on printing.

THE NEGATIVE. * 181

§ 11. — Other Artifices Connected with the Negative.

Other ingenious operations Lave been performed on negatives,
fcher to remove blemishes or to produce particular effects. Thus
r. Notman, of Montreal, has produced prints in which the
*ect of falling snow is very well represented. A white pigment
mixed up with water moderately thick, is put on a brush and
'ted over the negative with a quick jerk, probably an " atom-
izer" would be preferable. Snow-banks in these pictures were
made in the studio of common table-salt, which also, when scat-
tered over clothes and drapery, gives a very good imitation of
the effects of snow caught in the folds. Clear ice was represented
by plate glass resting on sheet zinc : figures in skating attitudes
were posed on this. The positions of rapid skating motion were
obtained by supporting the model in the desired position with
Sarony's apparatus, the stem of which was concealed behind the
leg of the skater which touched the ice.

One peculiarity of photography lies in the opening it affords
for original devices of all sorts by the ingenious. This seems
the proper place to mention a few of them.

Ghosts. — This name has been given to prints representing a
shadowy figure through which all the objects behind it are dis-
tinctly seen. Such pictures are obtained by causing the model,
after remaining standing or in a chair for a short time, to move
suddenly away, whilst the exposure is completed without him.
In such a case it is evident that the objects at first concealed by
him will afterwards impress themselves on the film, and be
visible through his figure.

Doubles. — A model may appear twice in the same print by
having a couple of folding doors arranged inside the camera, a
little in front of the film. One of these being closed, the sitter
is taken on the other half. This then is shut, the other door
opened (the lens being covered during the change), at the same
time the sitter is transferred to the other side, and taken again in
some different attitude, as, for instance, offering a glass of wine
to his double across a small table. By accurate adjustment a
man is made to shake hands with himself. The position of the
doors causes them to be very much out of focus, so that they do
not show in the image.

Moonlight Effects. — Although a negative of the moon itself can
be easily obtained in the camera, and although it is affirmed that

1S2 » PHOTOGRAPHIC MANIPULATIONS.

a dry plate exposed under a negative for a long time to moonlight
gives signs of an image, yet nevertheless the photographing of
objects illuminated by moonlight is practically impossible. Prints,
however, from under-exposed and over-developed negatives often
have a resemblance to moonlight views. For in effect if we ob-
serve a view by moonlight we shall notice that there is almost a
complete absence of diffuse light, Objects in shadow are not
lighted at all. A tree seen by moonlight exhibits a bright mass
of light where the rays fall, with a moderate detail ; in the shaded
foliage there is absolutely no detail at all — it is a black mass.
Now these effects are those that belong to badly-made negatives,
with all their worst faults of exposure and development. But
these same faults, when intentionally introduced and artistically
managed, are capable of producing very pleasing effects. Ferrier,
in Paris, has been particularly happy in some of these. The
moon itself is produced by a piece of paper pasted on the
negative.

Mr. Baker, of Buffalo, gives the following directions : A day
of floating clouds is selected, and when the sun is low and hang-
ing over the water surface of a river or lake, or of the sea, the
camera is pointed towards it. At the moment when a cloud
passes over the sun the exposure is made. The time given is of
course short, and the result is a " moonlight effect." The clouds
near the sun throw brightly-illuminated reflections upon the
water.

Artificial Clouds. — In cases where the sky of a landscape has
become much thinned by solarization, it may admit of painting-
in clouds. This is done by the application of transparent water
colors on the back, in imitation of natural clouds. No small
skill with the brush is necessary to produce good effects. The
description of clouds known to meteorologists as the cumulus, the
cumulo -stratus, are those most successfully imitated. The photo-
grapher should bear in mind that the direction of light must cor-
respond with that of the picture, and also that unless the sun is
very low, heavy clouds are always darkest underneath.

§ 12. — Combination Prints.

This term is applied 'to the obtaining in one print of effects
that cannot be secured in any one negative, and which are, there-
fore, taken on two separate plates and combined together in

THE NEGATIVE. • 183

printing. Most commonly this is applied to the introduction of
figures into landscapes, in some cases the figure being the prin-
cipal subject and the landscape subordinate; in others it is the
reverse. The means employed are the same in both cases. On
the plate upon which the figures have been taken, everything
else is completely stopped out by overlaying it with opaque color,
so that if the negative were printed in this condition, it would
print nothing but the figures upon a perfectly white ground.
Next, upon the landscape negative, the portion of the plate
corresponding to the figures is stopped out in the same way. Of
course if this negative is printed on silvered paper it leaves a
white space corresponding to the figures,' and upon this space the
figures can be next printed from the figure negative.

The difficulty of course lies in bringing the paper into the
exact position for the second printing, that the space left for the
figures shall fall exactly under the proper portion of the nega-
tive. To do this requires a careful and experienced printer, and
the trouble must be repeated for every print. This difficulty has
very much limited the practice of composition printing, but is in
a great measure obviated by the ingenious registering frames of
Mr. Edwards and of Col. Stuart Wortley. A printing frame is
constructed in which four small square grooves A B C D, Fig.

108, are cut, extending down to the rebate on which the negative
rests. A piece of thin wood is cut with four square projections
A' B' CD', Fig. 102, exactly corresponding to these four grooves,
so that when this piece of wood is let down, the grooves act as
guides and bring it always exactly into the same position. A
wooden screw S serves to press on the negative and keep it per-
fectly steady and immovable. A piece of silvered paper has its
ends bent over the piece of wood, as shown at E and F, and
secured with a little gum. When it is intended to print, this
board is put into the frame, paper side down, the projections slide
down the grooves, bringing the paper always into its proper po-
sition. Pads and packing are put behind the board, and the back
(which is not shown in the cut) is then fastened down.

184 PHOTOGRAPHIC MANIPULATIONS.

Two frames of this sort are provided, in one of which the
figure negative is placed, in the other the landscape. Having
stopped out all hut the figures themselves in the figure negative,
a print is taken on the silvered paper that has been fastened to
the board. This is transferred to the other frame, and the por-
tion of the landscape negative corresponding to the figures is
accurately marked and stopped out. This being done, it is evi-
dent that the printing proceeds without difficulty ; instead of a
very skilful hand being needed any ordinary printer can take off
hundreds of copies with perfect accuracy. Each piece of paper
is secured over the edges of the board and is printed, first in one
frame and then in the other.

§ 13.— Printing in Cloud Skies.

The preceding method may be applied to printing in clouds,
but as the same accuracy is not required, simpler means are suffi-
cient. If the negatives have not an opaque sky, that portion is
covered with opaque paint to render it so.

A print is taken and the sky cut carefully out from it and re-
jected, following as nearly as possible, but in flowing lines, the
outline of the landscape as projected against the sky. This is
done immediately after the print is taken from the frame. Next,
expose to light, when the whole becomes perfectly black, and fix
without toning.

A good sky negative with suitable character of clouds and
direction of light is taken, and the black mask above prepared is
neatly attached to the back of the sky negative, the white side
next the glass. The sky negative is now ready for use.

Prints from the landscape negative, when removed from the
printing frame, are placed under the sky negative, and printed
again. The black mask protects all but the sky, which receives
the cloud image from the second negative.

Printing of this kind requires, of course, to be done in the
shade, otherwise the line of the mask cannot be so well concealed.
This object is best attained by having a border of sky in the
mask— that is, not cutting too close to the landscape. With
ingenuity and care beautiful results are got in this way, and
effects can be obtained that, when exhibited, puzzle even the
photographer who is not acquainted with the mode in which
they are accomplished.

THE NEGATIVE. 185

For example, if a dead tree, or a tree without foliage, as in
winter, or with but small foliage, showing the sky through as in
early spring, stand well out and detached from the sky, clouds
may be printed in behind it, showing through the branches.
This is done by cutting out all that part of the tree that is thus
open, along with the sky, so that all such part of the tree is not
masked. The clouds are then printed in, and as such a tree pre-
sents little or no aspect of light and shade in its slender branches
standing against a bright sky, the second printing does not affect
it otherwise than to make parts a little blacker, a result that is
not injuriously noticeable in the finished print.

A splendid effect is produced by printing reflected clouds in
water. It requires three printings. A scene is chosen with a
wide expanse of water and sky. The sky and water are both
masked ; the sky first printed in, and then the cloud negative
turned over so that what was before the top, becomes the bottom,
and the film or varnished side is away from the paper. The
reflection of the cloud on the water is thus obtained by printing
through the glass, which gives it just the amount of indistinctness
wanted, whilst every cloud and shade of cloud in the sky is faith-
fully rendered in the water. The deception is so complete that
it is difficult to persuade one's self at first that the whole was not
taken at once, and the reflected clouds obtained at the same time
with the real ones.

The same general methods have been used for obtaining effects
much more odd than pleasing — as, for example, a card portrait is
printed of a man standing before his own tombstone, with his
head severed from his body, and grasped by the hair with one of
his hands. The trees and objects behind the portion where his
head would properly be, are all perfectly well made out, so that
the deception is complete. This is done by masking and repeated
printing. There are several ways in which it may be thus
managed, but the subject has not sufficient importance for the
space the details would occupy.

§ 14. — Negatives by Magnesium Light.

Some successful applications have been made of the magnesium

light to photography. Thin strands, coils, or wires of that metal,

when set fire to, burn with a splendid blue light, very rich in

actinic power ; negatives may be very well taken by it. Interiors

186 PHOTOGRAPHIC MANIPULATIONS.

and parlor groups have been photographed at night by it, and
pictures taken of caves, catacombs, and other places inaccessible
to daylight.

The chief difficulty in obtaining good interiors results from the
directness of the light. If one light be used, of course the shadows
exhibit a total want of illumination. At least two are necessary,
and this immediately introduces the danger of double shadows, an
evil which is not known in the carefully adjusted light of the
ordinary glass room, and which will require special attention on
the part of the photographer. Objects must be so placed that
only one set of shadows shall be visible, and the lights them-
selves must also be regulated with this view.

Of the two lamps used, one must give the predominant light,
and the other be used to light up the shadows. The predominant
light should be, of course, like the light of the glass room, a side-
upper-front light. The other must be lower in height, and be
placed at the other side. The predominance of the first is secured
by burning twice as much magnesium in it, say three to five tapers.

The writer has elsewhere pointed out that as the light of the
magnesium diminishes rapidly as the distance from the lamp
increases, the background must be much lighter, or it will show
too dark in the picture.

Very ingenious lamps have been constructed for burning mag-
nesium, especially one in which a draught of air, kept up by a
chimney, is made to enter in front, and thus to keep the heavy
white smoke of magnesia, which is generated by the combustion,
from obscuring the light. It is affirmed by competent observers,
that the effective light produced by a given quantity of magne-
sium is nearly doubled by this simple contrivance.

Mr. Skaife substitutes a pyrotechnic mixture burning with a
very luminous flame, a mixture of magnesium filings, chlorate
of potash, and sulphur, which he suddenly inflames. The camera
has been previously focussed by gaslight, and is left open, as the
gaslight makes no impression. Then the mixture being suddenly
inflamed gives an intense light for a moment, during which the
image is obtained.

§ 15. — Storing of Negatives.

There are three ways of storing away negatives, that are in
common use — plate boxes, shelves expressly made for plates, or

THE NEGATIVE. 187

the plates are wrapped up in clean paper in bundles of ten or
twelve each.

Plate boxes are made with either single or double grooves. In
the latter, two plates are slid together into each groove, back to
back. Much trouble arises from the grooves in plate boxes not
being made deep enough. The plates vary a good deal in size,
although nominally intended to be equal, and the boxes some-
times shrink very much ; so that in some, after having been made
some time, the small plates will get loose instead of being con-
fined, and, in other boxes, the plates a fraction over size will get
fast. It has happened to the writer to be obliged to force out
the side of a box to get out a negative. All these troubles should
be avoided by making the grooves deeper. The edges of the
groove should be rounded, not square.

Plate boxes should never be used for putting wet negatives
into, both because the boxes should never be wetted, and because,
if the washing has been imperfect, hyposulphite may be intro-
duced. Nor should negatives just varnished be placed in them,
as the edges of varnished negatives remain stickv after the face
is dry. Nor should "dry" plates be dried in them; in a word,
they are for storage only.

Shelves for negatives should be built very strong, and are
better so placed that the window shall not be opposite to, but at
one end of the room, on the side of which are the shelves, so that
as they are drawn out they can be looked through to obtain the
one sought.

Negatives wrapped up in paper have been found to keep better
than in any other way. Cases are described in which some of a
lot of negatives have been stored in boxes, some wrapped in
paper and laid flat, where those in boxes have cracked, and those
in paper have stood perfectly. The reason appears to be, that
plates sliding separately into grooves are exposed to changes in
the atmosphere to a much greater extent than those securely
wrapped up and pressed closely upon each other.

It is evident that considerable care should be exercised in the
selection of paper to be interposed. Printed or soiled paper
should be rigorously excluded. Blotting paper is too porous
and hygroscopic. An ordinary quality of sized paper, not too
hard and stiff, is the most suitable.

The outside paper should be good, strong wrapping paper.

188 PHOTOGRAPHIC MANIPULATIONS.

Paper saturated with India-rubber varnish would doubtless be
better than any other. For amateurs who have but small num-
bers comparatively of negatives, the plate box is so much the
more convenient form that it will probably be always that used.

CHAPTER Y.

AMBROTYPES AND FERROTYPES.

Although ambrotypes almost belong to the past, a few brief
remarks will be made on the subject here for the benefit of those
who may desire to make them. A really fine ambrotype is a
very beautiful thing, but for the most part, they want contrast
and breadth of effect.

An ambrotype is nothing but a thin negative. When a nega-
tive is held up to the light, those portions on which the light
has acted in the camera are more or less opaque, and the lights
and shades in the original are reversed in the negatives.

But the negative is formed of grayish-white silver powder, so
that if it be viewed by reflected light, and held against a black
background, those parts which looked dark by transmitted light,
appear light by reflected, and the transparent parts, which per-
mitted the light to pass through when viewed by transmitted
light, look dark in the ambrotype, because their transparency
permits the black background to be seen through.

Formerly, a different bath was thought necessary in the two
sorts of work. Now the same is generally used, although many
prefer to acidulate it with one or two drops more of nitric acid.

A formula for collodion (if a special collodion be desired, which
is not absolutely necessary) will be found in the Introduction,
p. 43.

The developer is the same as for negatives, a little more acidi-
fied. Or, when brilliant ivliites are wanted, take —

Sulphate of iron 250 grains.

Acetic acid, No. 8 half an ounce.

Best granulated nitre 30 grains.

Water 20 ounces.

As the bath becomes older, add a little alcohol to cause the
developer to run smoothly. If there is any disposition to fog,

AMBROTYPES AND FERROTYPES. 189

increase the dose of acetic acid. Stop the development as soon
as the image comes out enough to be seen in light reflected from
the surface of the plate.

"Where dead whites are wanted, omit the nitre.

Melainotypes and ferrotypes are ambrotypes taken on plates of
thin varnished iron instead of glass. The operation is in all
respects similar. They may be said to constitute the most ordi-
nary and least artistic of photographic products.

Opinions vary very much as to the best means of getting good
results. The points are these, that a very clear, clean picture
must be got. This of course is most easily effected by the aid of
acid. The acid may be applied in various ways. For example,
the bath may be made more acid than usual with nitric or acetic
acid, and used with the ordinary collodion and development. Or
an ordinary bath may be used with a very ripe collodion, or one
to which tincture of iodine has been added ; or a very acid de-
velopment may be resorted" to. It naturally follows that whilst
very clear pictures are got in this way, there is an absence of
detail often observable. The right plan is just to carry the
acidification far enough to get clean glass in the darkest shadows
and no farther. Of course the slightest veiling is fatal to the
ambrotype.

Collodion made with alkaline iodides and bromides ripens
quickly; some therefore omit entirely the cadmium salts from
collodion intended for ambrotypes. Others employ cadmium and
ammonium and add iodine, and others, as mentioned in the In-
troduction, consider potassium essential.

Alabastrine Positives. — The body of both the negative and
ambrotype is composed of nearly pure silver, which has a gray-
ish tint, and is deficient in brilliancy. This defect injures the
light and shade of the picture, and recourse is sometimes had to
mercury in the form of corrosive sublimate to whiten them.

The following formula may be used : —

Corrosive sublimate 40 grains.

Protosulphate of iron 20 grains.

Common salt 15 grains.

Water 2 ounces.

The first effect is to make the picture grayer, but the whiten-
ing soon sets in.

190 PHOTOGRAPHIC MANIPULATIONS.

CHAPTER VI.

PORTRAITURE.

\ 1. — General Arrangement.

Having placed the sitter in an easy and natural attitude, and
with due attention to the management of light, as described in the
next section, it will not be sufficient to simply set up the camera
before him and take a picture. Care as to the point from which
the picture is taken is of the very highest importance.

If, for example, the camera is set as high as the head of a
standing figure, and is directed at him horizontally, the head will
occupy the centre of the plate, the body one-half of the plate
only. If we move the camera down so as to be opposite his
middle, we shall get the whole figure it is true, but we get the
figure as seen by an eye placed no higher than the camera. The
shape of the nose is altered and injured, the neck is shortened,
and the whole character of the face altered.

From these difficulties we are relieved by the contrivances
already explained in a previous chapter, the swing-back and the
sliding front. We raise the camera at least as high as the
shoulders. The first effect of this is to throw the head nearly
into the centre of the plate and to cut oft' the feet. This may
be remedied —

1st. By inclining the camera downwards. This tends to dis-
tort the vertical lines, and here the swing-back comes into play
and straightens them, or,

2d. By lowering the sliding front. As the front is lowered,
the image moves down the plate, and takes its proper position.

This last arrangement has this notable advantage over the first,
that the best definition, which in the portrait lens correctly
focusscd is that of the central pencils, is got for the head, pre-
cisely as if the bust only were taken. In the first arrangement
the middle of the body is formed by the central pencils and
receives the best definition. On the other hand, the lowering of
the sliding front has this disadvantage, that the feet and lower
part of the picture are then formed by pencils more excentric

PORTRAITURE. 191

than enter into any part of the picture in the other case. Each
method has its advantages and evils, and in some cases the one,
in some the other, will be proper.

The swing-back is so valuable an adjunct to portraiture that
no one who has learned how to use it will ever willingly work
without it. It is especially useful in sitting figures ; without it,
for example, the feet will always be exaggerated in size, and
clumsy looking. It gives, in fact, a new power to the operator;
the plan of revolving the lens does not, as so often affirmed, answer
equally well.

A repeating hack enables the operator to make the image of a
lens fall in succession on different parts of the sensitive film, thus
with two lenses and a repeating back, four or more card portraits
are taken on one plate.

Distance of Position. — As a large lens will produce a small
head by increasing its distance from the sitter, and conversely, a
small lens will give a large one by diminishing it, the question
naturally arises as to what are the best conditions under which
to obtain satisfactory results.

The impression of relief and rotundity is greatest with very
short focus lenses, and gradually diminishes as the size of the
lens increases, until with lenses of 30 or 40 inches focal length,
relief almost disappears (also the size of the stop has much to do
with it, a large stop giving much more relief with the same lens).

But, on the other hand, this excessive effect of rotundity and
relief is anything but pleasant in itself, and, still worse, it is
connected with an effect of " violent" perspective which draws
the middle of the face outwards, and in a full-face portrait, swells
up the nose and lips most objectionably. The effect is detestable
in those faces in which the size of the lips and nose is as large as
the rest of the face will bear, the enlargement of them introduces
a disproportion most annoying and vexatious to the sitter and
friends, whereas in another face with thin lips and small nose, no
bad result has attracted attention, simply because other circum-
stances rendered it less obvious.

It will be well, therefore, never to place the camera nearer
than twelve feet from the sitter as a minimum, and rather to ex-
ceed this by using a larger lens to make up for increased distance.
In fact, there is but little danger of getting too far from the
sitter in any ordinary glass room ; the danger is the other way.

Arrangement of Accessories. — The curvature of the field of lenses

192 PHOTOGRAPHIC MANIPULATIONS.

renders it'desirable that objects around the central figure should
also be arranged into a counteracting curve, and be brought
nearer to the camera in proportion as they are farther from the
centre of the field of view. This enables them to be brought
into focus simultaneously with main figure.

Groups are naturally governed by the same rules. Of course
a stiffly circular arrangement is to be avoided, but it will be
always advisable to arrange that in a group the most distant
head shall be central, and those that are farthest from the centre
shall be nearest to the lens. A tasteful arrangement of inter-
mediate heads and figures will bring the whole into harmonious
combination.

With groups the swing-back will be always very valuable,
especially in avoiding sameness. For with a swing on a vertical
pivot, the figures on one side of the central object may be set as
far back as the central figure, and yet be brought into good focus,
provided that those on the other side are brought considerably
nearer. The advantages of the swing-back will thus continually
make themselves apparent, and multiply as the photographer in-
creases in familiarity with its applications.

Relative Size of the Figure. — It is highly important to propor-
tion the size of the figure to the size of the whole print, and it
may be said that the size of the figure is almost always made too
small. For one error in the opposite direction, ten are made in
this, and the result is always to render the figure insignificant
and unsatisfactory. This remark applies to all sorts of photo-
graphs, from vignetted busts to full lengths. And the smaller
the figure the more conspicuous any accessories that may be
present, until, in some portraits, they fairly eclipse the figure
itself, so that the idea is conveyed that the sitter is taking care of
the large but suspiciously unreal-looking vases, tables, and carved
furniture, which, rather than the person, seem to be the actual
subjects of the picture.

It is surprising that so little criticism has been directed to this
almost universal fault. An examination of portraits by great
masters will show a very different system. The figure takes up
a very large portion of the whole surface, the accessories are
absolutely subordinate, and not noticed unless attention is expressly
directed to them.

No error produces worse results than this of making the figure
too small. The sitter feels the unsatisfactory and insignificant

PORTRAITURE. 193

effect of the portrait offered to him, without understanding why-
it is so, and though he may be unable to say where the fault lies,
its existence is perfectly plain to him. The photographer is,
therefore, recommended to avoid this mistake most carefully.

\ 2. — Management of Light.1

The play of light upon the sitter must be regulated partly upon
certain general principles of illumination, and partly according
to the needs of the particular case.

The general principles are —

That there shall be no cross light : never shadows visibly cast in
more than one direction.

That the light on the side away from the glazing shall be main-
tained as subsidiary.

That there shall be no false light, especially no false reflection
from the eyes.

That there shall be no excess of illumination in some one or more
parts of the picture, otherwise the eye will be led away from
the face instead of led to it, as takes place in a judicious
distribution of light and shade.

That the shadows, wherever they may be, shall invariably receive
a sufficient illumination that their details may impress them-
selves with strength enough to show agreeably in the print.
There must be no dark patches destitute of detail.

That the highest lights shall not be so illuminated but what they
shall be full of detail. A bald head, for example, must not
run into a light background, as is occasionally seen. "White
hair must preserve all its details. The play of light and
shade over white garments must be thoroughly well pre-
served, and all white patchiness rigorously excluded.

Conjointly with the above, two different systems of illumination
may be used. There is that almost universally adopted, in which
the effect of the picture is made as nearly as possible to imitate
what we commonly see around us. The part of the room, for
example, in which the model sits, is made, in its play of light
and shade, to resemble ordinary rooms.

There is another and very effective system occasionally used

1 See also chapter on the "Glass Room," and that on "Light and Shadow."

19± PHOTOGRAPHIC MANIPULATIONS.

in which some of the effects generally produced by distinguished
portrait painters in their work, are imitated. The object of this
system is to allow no light, except that which stands in some
definite relation to the face. It was the dictum of a celebrated
painter that a portrait ought to be two-thirds dark.

To obtain this effect in photographic portraits, a dark back-
ground and dark hangings are used. Dark clothing is worn,
especially dark velvets, whose play of light is always exceed-
ingly effective in photography. Whatever of light is permitted
in the clothing must " lead up to the face," that is, so far as it is
permitted to catch the eye, the eye must pass directly from it to
the face. All this, of course, is more easily effected in women's
vestments than men's; still the application is not confined to the
former. The borders of the picture are all kept dark, and, in
fact, the shadows are accumulated in order that the light may
tell as effectively as possible. When well managed, this method
produces very striking and beautiful results, but it requires con-
siderable artistic knowledge and feeling on the part of the photog-
rapher. From the large use which Salomon, of Paris, has made
of this style, it is often called after him. The " Berlin Portraits"
are made by taking a piece of glass, coarsely ground upon one
side, and making the negative upon the other. In this way a
certain softness is got, somewhat resembling, but inferior to, that
which is obtained by retouching. " Crayon Portraits" are pro-
duced by printing a thin positive on glass, and laying this, film
side down, upon a lithographed sheet, shaded in imitation of
crayon work. When well done, the effect is good. The glass
positives for this purpose are often enlargements from card nega-
tives— the enlargements are made in the camera. Others modif}'-
the effects and soften their paper points by interposing a sheet of
glass, of gelatin, of mica, or of tissue paper between the negative
and the paper; in this way are made the so-called " Mezzotint
Prints." This method, brought prominently forward by Mein-
erth, gives often very pleasing pictures.

So-called Rerahrandt Effects represent the head against a dead
black surface, with a peculiar and bright illumination round the
profile, brightest on the side away from the spectator. The effect
is produced as follows : The lighting is as usual ; the sitter is
placed in the usual position. The camera is moved partly round
so that it somewhat faces the light, and thus the portrait shows
principally the side of the face that is farthest from the side light,

PORTRAITURE. 195

what shows of the other side of the face, viz., the eyebrow and

cheek, is more brightly lighted than the near side, the former

being nearest to the light. The background must send no light

ik, and is best made of black velvet, which should be rendered

clear glass. As the camera is turned partly towards the light

will need to be carefully shaded, otherwise the brilliancy of

ect, and entire blackness of the background may be impaired.

Finally, it is to be observed that the photographer must not

msfer any system of lighting from a given lens to another of

ry different focal length. If accustomed to work with a lens

a certain focal length, he finds occasion to change, it will be

cessary to study a proper arrangement for the new lens. A

us of long focus will bear a bolder lighting than one of short

3us, and for want of it may seem tame and flat.

§ 3. — Exposure.

A correct knowledge of the time of pose comes only with long
practice and through many failures. Not only does the light of
the glass room vary continually in strength, but different com-
plexions and different clothing will alter the needful time. More-
over, the photographer's task may be greatly increased in diffi-
culty if a style of clothing, unsuited to the character of the sitter,
chance to be worn by him or her. It would, in fact, be very
advantageous if the photographer could always direct in advance,
after personal observation, what description of clothes should be
worn during the pose, for it by no means follows that clothes
most becoming to the wearer under ordinary circumstances will
be most appropriate before the lens. The element of color, which
enters so largely into consideration, as to suitableness and effect,
here disappears, and the only question is as to the rendition of
light and shade on the film. A photographically suitable clothing
is, therefore, not at all one in which the colors harmonize with
the character of the wearer, but one in which the photographic
effect of the color harmonizes with the photographic character
of the face and hair. To get a clear insight into this matter it
will be necessary to begin by considering the relation between
the skin, eyes, and hair.

A clear white skin will, of course, impress its image rapidly
on the film. If the hair be fair, all will go on well and harmo-
niously. But if a white skin be combined with dark hair, the

196 PHOTOGEAPHIC MANIPULATIONS.

exposure will have to be more accurately timed, it must be con-
tinued until the details of the hair are fully out, and yet must be
stopped before the face is overdone. Conversely, where light or
white hair accompanies a red or dark complexion there is danger
of the hair being overdone and the details lost in it before the
face is duly taken. These are faults that are constantly seen in
card portraits, and constitute difficulties to be understood and
conquered.

Dress. — The clothes worn may evidently add a further com-
plication to such of these difficulties as exist, or may produce
them where they did not. Let us suppose that a lady with dark
hair and complexion presents herself to be photographed, attired
in white, or light blue or purple. It will follow that by the time
that justice has been done to the face, the fine gradations of shade
in the dress may be lost, or, if preserved, it can only be by skill
and care.

The difficulties occasioned by contrast are, however, now far
less unmanageable than they formerly were when iodide of silver
alone was used, and we see less tendency than formerly to black
spaces destitute of detail, and white ones perfectly flat: these
blemishes are now comparatively exceptional, and such work is
always destroyed by the intelligent photographer who prizes his
reputation.

Some photographers keep two kinds of collodion on hand.
One sort for regular use, the other containing more bromide, to
be employed where too much contrast is apprehended, especially
where masses of white drapery are to be taken, in which case
the proportion of bromide may rise to one-half. For regular use
such collodions are liable to the objection that they yield thinner
pictures and require more redevelopment.

Nothing is commoner than for persons to present themselves
so attired as greatly to increase the photographer's difficulties.
Harsh contrasts, the effects of which are sufficient! v bad on the
persons, become almost intolerable in a picture. Add to which
the various actinic powers of the different tints often tend yet
farther to exaggerate those contrasts which were before suffi-
ciently annoying to the eye. A portrait in which the dress is
cut up into checkers of light and dark, or divided into parallel
stripes with striking contrasts, must always be unsatisfactory in
its character.

Attempts not wanting in ingenuity have been made to exhibit

PORTRAITURE. 197

in photographic specimens the actinic value of different pigments.
But these can never be of much help, and the reason is obvious.
Taking any color, let us say Prussian blue, let a thin shade of it
be lightly washed over white paper, and then a very deep shade.
Photographing these, the first will act almost like pure white;
the second almost like black, indeed, if made thick enough, as,
for example, the cake of paint itself, it will be perfectly black.
If, then, one color is capable of impressing itself of all shades
from white to black, the assigning to it of any particular shade
of half tint, must be purely arbitrary and altogether deceptive.
So, if we attempt to compare two colors, let us say green verditer
and raw umber. If the first be put on lightly, and the second
thickly, the first will appear to be the more actinic color, and
by reversing the proportion we shall reach an opposite conclu-
sion. Precisely the same result will accompany the various
shades of material used in dress. Experience, and intelligent
observation of what takes place in the case of every portrait
taken, will soon give a pretty exact idea of what effect any
given costume will produce in the negative.

Velvet Drapery. — Salomon, the French portraitist, whose name
is always necessarily cited in speaking of photographic aesthetics,
avoids these difficulties by making appointments, and indicating
to ladies what colors will be most effective for them. He also
provides velvet drapery, with which he frequently covers and
conceals the whole of the dress worn. The velvet which he uses
is neither silk, nor is it black, but a dark purple cotton velvet,
and its effects are often magnificent.

Posing the Sitter. — When a whole sitting figure is represented
in profile, the point at which the back legs of the chair reach the
ground will invariably and absolutely need to be supported. No
rule is so commonly violated as this, and none with worse results,
for the figure will always appear to be slipping out of the chair,
because its lines want their due support. This it will not be
always easy to give ; the position is, therefore, especially for a
male figure, an objectionable one. If for any reason it is espe-
cially desired, the photographer must introduce some object, such
as a stool, best with drapery, or characteristic objects over or on
it. With the female figure the difficulty is less, for its own dra-
pery may be so disposed as to give the support required.

The position of the head of a standing figure with respect to
the top of the card, produces a very curious influence on the

198 PHOTOGRAPHIC MANIPULATIONS.

apparent height. If the print is so cut as to bring the head very
near the top edge, a great impression of height is produced ; if,
on the other hand, the card extends far above the head, the figure
is dwarfed. This effect is independent of the position of the
figure with respect to other objects in the picture, and depends
chiefly on the cutting of the card after it is printed. Therefore
this principle may be used to improve the appearance of dwarfish
or very stout figures, providing it be not carried to excess.

Want of attending to this effect produces in card portraits the
most unintentionally ludicrous results. A man of average stature
may be made to look seven feet or more high.

Mr. Petsch makes some excellent suggestions with regard to
the overcoming of difficulties. Badly formed features he subdues
by the arrangement of the head : a crooked nose is always most
striking when seen from directly in front, therefore the head
should be so turned that the side with the smaller surface is next
the camera, and the larger surface is somewhat foreshortened.
An irregular mouth, the line of which is not parallel to that of
the eyes, should be similarly managed, the straighter end of the
mouth is turned towards the camera, and the drooping end is
seen less conspicuously, and is foreshortened. Those who squint
are taken in profile. Very stout men are to be taken in three-
quarter lengths.

Arranging the clothes has likewise much influence. Buttoning
the coat adds breadth to the figure, opening it gives relief. Dark
clothes diminish the size; light, and especially white ones, increase
it. Defects in the head and face may be exaggerated by inap-
propriate ways of wearing the hair. To arrange the hair with
ribbons, etc., at the sides, makes a broad face broader, but relieves
the thinness of a long narrow one. A high head-dress exagge-
rates the length of a long neck, but relieves a broad face if kept
front, otherwise if set far back. In profiles the hair should not
be too flat on the top of the head, or a flat expression is pro-
duced.

§ 4. — Development in its Relation to Portraiture.

Some assistance can always be had in difficult cases by regu-
lating the development. The writer has attempted, in papers
written upon the subject of negative development, to demonstrate
the true character and the rules by which it is governed, and as

PORTRAITURE. 199

a correct understanding of this is of much importance to the por-
traitist, a few words may advantageously be said on the matter
here.

The stronger the developer, that is, the more sulphate of iron
it contains, and the less restraining acid, gelatine, or sugar, the
more rapid will be the precipitation of the metallic silver that
forms the picture. Just in proportion as the. silver falls more slowly
it is more subject to the attraction of the most strongly impressed parts
of the silver. In a slow precipitation the most strongly impressed
parts of the film will get a larger proportion of the deposit than
in a rapid precipitation. This fact, which has been thoroughly
established both by theory and practice, is of the highest import-
ance, and is the key to all the peculiarities of iron development
in the wet way.

If, then, danger of a flat picture is feared, either by reason
of—

1. An absence of contrast in the subject ;

2. Too uniform an illumination ;

3. A long exposure;

We should apply a weak developer, in order to increase the contrast.

On the other hand, if we have reason to dread a harsh picture
from —

1. Excess of contrast in the subject itself;

2. Insufficient light ;

3. Light badly controlled, so that it is excessive in places

and insufficient in others ;

4. Too short an exposure ;

We should apply a strong developer to diminish the contrast by favor-
ing a more equal deposit of silver.

The application of these principles to special cases is suffi-
ciently obvious. If it is evident that the main difficulty of the
work to be done will lie, for example, in getting relief and form
into a quantity of white drapery, we shall need a slow develop-
ment, in order that the faint shadows which are to give life and
form to the white mass, shall not be overwhelmed by a rapid
deposit of silver.

But if, on the contrary, it is specially desired to obtain detail
in deep shadows, a strong developer will force the depositing
silver to find all the faint impressions in these shadows and
bring them out on the sensitive film.

200 PHOTOGRAPHIC MANIPULATIONS.

A comparison of this section and the former will lead directly
to the sufficiently obvious conclusion that exposure and develop-
ment stand to each other in opposite relations.

And the general rule will be: If all the parts of the subject
are actinic and well lighted, give a moderate exposure, and use
developer No. 1, p. 162.

So, if all the parts tend to be non-actinic, or if the light is poor,
give a long exposure, and use the same developer.

But if there is considerable contrast (and this is the more com-
mon case) so that some parts seem to demand a long and others
a short exposure, and there is danger of too much contrast, then
give a full exposure and use developer No. 2, p. 162.

It is not sufficient, however, to endeavor to overcome these
difficulties, the difficulties themselves must to some extent be re-
moved. Light must be so controlled that the illumination on the
actinic surfaces must be restrained, and that on the shadows and
non-actinic portion must be increased until the two can suffi-
ciently be combined in one development.

§ 5. — Causes of Unsatisfactory Results in Portraiture.

1. Too much Front Light.

Excess of front light produces flatness. Light is too equally
distributed over the projections and depressions of the face, so
that these lose their character, and the face assumes an unmean-
ing expression, sometimes even a stupid or silly one. Such a
light also throws, as Schrank has well remarked, too much illu-
mination on the centre of the forehead, the ridge of the nose,
the chin, and the cheek bones. What is worse still, it produces
a bright reflection in the centre of the eye, precisely where the
dark pupil properly appears, thus reversing the natural aspect,
and at times giving almost the effect of blindness. Of all defects
of lighting, excess of front light produces the most inartistic
effects, and the most thoroughly displeasing pictures.

2. Too much Side Light.

Excess of side light produces a too unequal illumination of the
two sides of the face, gives an excessive projection to the nose,
and a hatchet shape to the face. The effect upon the eyes is
sometimes very curious, causing them to look utterly unlike each
other in consequence of the difference in the amount of light that

PORTRAITURE. 201

they receive. Still, the effects of an excess of such light are not
so bad as those of excess of top or of front light. The best
effects require a difference of illumination on the two sides, which
may in skilful hands be carried to a very considerable extent.
Nevertheless, it is easily overdone, and such attempts demand
good management.

3. Excess of Top Light.

This error produces effects precisely the reverse of those of
excess of front light ; all the features become hard and project-
ing; a heavy frown settles on the brow; the eyes appear deep
set and cavernous ; the nose is enlarged, and any hollows about
the mouth are greatly and unnaturally increased. A black
shadow is produced directly under the chin, sometimes almost
producing the effect of a beard.

4. Too even Illumination.

It is easy to fall into an error the reverse of all the foregoing
by diffusing the illumination too generally. This is most apt to
occur in operating under a flat, low glass roof, where the light
comes in around the sitter from a variety of angles and direc-
tions. The result is a soft, characterless picture, which finds
little favor, and deservedly so, whilst at the same time those
unacquainted with the subject cannot tell why the picture is so
unpleasing, for it is undoubtedly like the original, and there is
no prominent objection to seize upon. At the same time there
is the greatest of all objections, viz., that the portrait is totally
devoid of merit, and gives the face with its least interesting and
acceptable expression. The fault here spoken of is one that has
received too little attention, some photographers refusing even
to recognize it, and thinking, when they produce these pictures,
that they are doing creditable work ; they do not, however, find
the sitter or the sitter's friends to agree very cordially with them.

5. Insufficient Illumination beloio.

When the illumination is at the same time chiefly horizontal,
and yet is not carried low enough on the side, it may result that
whilst the upper part of a sitter is well illuminated, the lower
part is not. There results from this a want of detail in the
shadows of all the lower part of the figure, a defect which can
only be remedied by an alteration in the system of lighting.
14

202 PHOTOGRAPHIC MANIPULATIONS.

6. Insufficient Light.

As it must always be the object of the operator to work well
•with a short exposure, a deficiency of light is one of the most
serious evils to which he can be exposed. I may, for example,
cite the case of a photographer in this city, who, after putting up
a complete gallery, found his light so deficient that he was led to
adopt the after-intensification of his negatives with mercury as a
regular system — a bad and dangerous one every way, worse by
far than even an expensive alteration in his defective glass room.
His case was by no means a solitary one. It is far better, in
constructing a glass room, to err by having too much light, the
excess of which is so easily shut out, than to make the opposite
mistake. AVhen the mistake has been made, it is better for the
professional photographer to recognize it at once, and remedy it
radically by introducing more glass at any cost. In doing so,
however, he should work neither at random nor in a hurry. He
should first carefully ascertain by study in which description of
light his glass house is most wanting, and proceed with a view to
remedying that deficiency in the introduction of the additional
glass. If his glass room has abundant top light, it would be folly
for him to introduce his additional glass on the roof, and so on.
The explanations already given will enable him to detect in what
direction his glass room tends to err, and in arranging to admit
more light he will be in a position to get exactly the kind of
light which he most wants. Thus, in remedying a fault, he may,
if he takes care and study, succeed in making his room better
than if that fault had not been committed, for he may succeed in
distributing his light more scientifically than if he had at first
arranged to admit enough. It is in this, as in so many other cases
in photography, the man who thinks carefully first over what he
wants, and chooses, after reflection, that which is best fitted to
afford the desired result, will always in the end succeed. One
who can only learn through continual failures, will be weary
before he can reach success. Every failure met with should be
required to yield its fruit in the way of useful experience; and
this should be made a fixed rule by every photographer.

PORTRAITURE. 203

§ 6. — Backgrounds and Accessories.

The subject of backgrounds is one of no small importance to
the portraitist, and one often of no small difficulty. Without
care, tact, and ingenuity, his productions are apt to be exposed to
the imputation of sameness. Every one has become thoroughly
tired of the column and the balustrade, which might as well now
be banished once for all. The heavy curtain has also been a
good deal employed, but it is too useful to be definitely dispensed

with.

The end of the gallery should be colored of a soft bluish gray,
and will form a useful background for taking groups of several
persons. Special backgrounds usually consist, when plain, of
colored cloth sold by the dealers, and which is usually stretched
on a large frame furnished with feet, rolling on castors. These
are of various shades, according to the effect desired. The photog-
rapher will need at least three— dark, light, and medium. Views
are sometimes sketched on canvas stretched on similar frames.
Considerable tact and skill are necessary for the production of
really good pictorial backgrounds.

Sometimes a very beautiful effect is produced by having the
upper part of the plain background lighter than the lower. This
is especially useful in the case of three-quarter figures, or those
which include from the head to the knees ; the light part is made
to correspond with the head, gradually softened opposite the
shoulders into the dark shade of the rest. This calls attention
to the head and throws it out, with an effect which, when well
managed, is excellent.

Another useful effect which has attracted considerable attention
of late years is that of inclining the background so that either
side, right or left, shall be nearer than the other, taking care that
the screen is towards the light, not against it. This method of
proceeding has been very effectively employed by the celebrated
Salomon, of Paris, and his mode of managing it will be seen by
inspecting the adjoining sketch of his glass room. The sitter is
turned somewhat towards the light, and the camera stands in
the direction indicated by the arrow. The portion of the back-
ground nearest to the glazing receives the strongest light, which
diminishes gradually towards the other end, producing an agree-
able effect, which may be greatly varied by altering the position
of the background and screens.

204 PHOTOGRAPHIC MANIPULATIONS.

Fig. 104.

Fig. 105.

Large backgrounds should move on heavy castors made ex-
pressly for the purpose, and running on wheels of five or six
inches in diameter.

Canopy Backgrounds. — The same photographer has for some
years past employed a peculiar arrangement enabling him to
obtain a great variety of effects, and dispensing with the necessity

of employing blinds and curtains.
As Salomon's work has never been
surpassed, his modes of proceeding
excite great interest ; the writer
annexes a figure copied from one
published in the London Photogra-
phic News, after a drawing commu-
nicated by M. Salomon himself.

A is a semicircular background
about 8 feet high, 10 wide, and 5
deep, from front to back. B B are
folding wings, about 4 feet wide
each, hinged to the background.
C is a corresponding canopy, 10
feet long and 4 wide, hinged to the
top. Another canopy, D I), covers
the background itself: it is in two
parts, hinged at the middle. The post E at the back carries a
pulley at the top, over which pass cords connected with the differ-

PORTRAITURE. 205

ent canopies, and fastened at the back so as to be easily raised or
lowered.

The semicircular background A is covered with wall-paper of
a salmon color ; it has three feet, not represented in the cut, which
carry large castors. All the other parts, the wings and canopies,
are light frames covered with thin transparent white muslin, al-
lowing a good deal of light to pass, but softening any direct sun-
light. At the corners, between the wings and the canopy (7, the
muslin of the upper canopy is continued out, so as to fill up the
corner; this is not represented in the figure.

The sitter is placed in the centre of the curved part, and just
under the front canopy, by raising or lowering which any desired
amount of soft and diffused top light is obtained. So, too, the
side light is regulated by opening or closing the wings. The
illumination is farther controlled or altered by turning the whole
contrivance on its castors, and thus exposing the open portion
more directly to the light, or, on the other hand, turning it away.
The curvature of the background affords gradation, and its form
and depth tend to give relief to the figure, and even this may be
very much modified by raising or lowering the upper canopies,
D D, by which monotony and repetition of identical effects are
avoided, and every grade of effect, from the lightest to the dark-
est, is easily obtained.

When a full-length figure is to be taken, the curve line of the
background shows unpleasingly. A movable surbase or wash-
board placed behind the sitter cuts off the curve and removes the
difficulty.

The advantages of this system may be briefly summed up.
Effectiveness, as it gives every variety of light. Adaptability:
it may be either used in an ordinary glass room, or in a common
room, as in the latter case it takes the place of blinds, curtains,
and other machinery. Economy : that in use by M. Salomon
cost him fifteen dollars only. To construct it two curved pieces
of wood, for the top and bottom, are connected by thin upright
boards, tongued and grooved into each other, whilst the wings
and canopies are formed of light framework, covered as already
described.

Conical Backgrounds, about which a good deal has been said,
have scarcely answered the expectations that have been raised.
The plan, also, of a front screen, coated white, and interposed

206

PHOTOGRAPHIC MANIPULATIONS.

Fig. 10G.

between the sitter and the camera, with an opening cut into it,
has also proved unsatisfactory, in consequence of its tendency to
produce flatness of effect.

Rotating Background. — Canvas is stretched over a flat wheel,
which, for lightness, consists simply of a round rim, connected,

by wooden bars or spokes, with the
axle at the centre. This canvas is
colored of a warm gray or fawn
color, shaded from one side to the
other (see Fig. 106), so that there
is a distinct but moderate difference
of tint.

This background can be put to
several uses. It may be set with
the lightest portion uppermost, and
used as a graduated background, the
advantage of which has been already
explained, or it may represent a
lighter shade on one side of the sitter
than the other. Or, finally, it may be made to rotate during the
whole sitting, and thus produce a perfectly even background,
with a perfection of evenness obtainable in no other way.

The invention is ingenious and useful, but the writer considers
it susceptible of a great improvement. If a triangular sector be
cut out of white paper and attached in front of the circle, with
its point at the centre, and widening towards the circumference,
then, if the background be made to rotate, it is evident that the
general effects will be lightened, and that in proportion to the
width of the sector. Similar^, by using black paper the effect
will be darkened. It is evident that, by having a supply of these
black and white sectors, a single wheel may be made to produce
an endless variety of shades of backgrounds, and always exhibit-
ing a perfectly pure and even tint. All photographers know
how difficult it is to obtain a plain background to their portraits
that is absolutely free from blemish.

Distance of Background behind the Sitter. — Four or five feet is
a common distance, but the practice varies much. Salomon
makes his recede much more than most, and commonly places it
eight or ten feet back.

It is common in photography to act on the principle that with
a plain and indefinite background no furniture shall be intro-

PORTRAITURE. 207

ducecl; and that, on the other hand, if any furniture be visible,
the background shall correspond and complete the room. This
is, however, not so absolutely necessary as some suppose. For
example, if a three-quarter figure be represented standing at the
side of a small table and occupied in any way, as with papers,
letters, flowers, work, etc., the picture may be finished with a
plain, or, better, a simple shaded background, such as just de-
scribed, and thus the photographer is relieved from the incessant
use of a limited stock of combinations.

It is a most serious mistake to crowd quantities of objects, such
as vases, urns, bouquets, etc., into the picture. This only results
in distracting and confusing the attention. Certain points, where
lines of direction reach the floor, or a table, or other object, often
need imperatively to be supported by some object ; this part of
the subject will be treated of more particular^ hereafter. A fore-
ground is often relieved by characteristic objects, grouped, not
scattered. But then they require to be handled with taste and
according to rule, and must never be strewn about or huddled
together promiscuously. Particular care should be taken to
avoid brilliant reflections of light from accessories, and for this
reason such objects should have dead, and not reflecting surfaces.
Anything, in fact, that tends to make them conspicuous, distracts
the attention from the figure itself.

In some photographs the figure itself is quite a subordinate
affair, being completely subdued by dazzling furniture and by
crowds of vases, bouquets, and other objects, placed in the most
unnatural and improper positions. Sometimes the very first
thing that catches the eye is the pattern of the carpet, composed
of ill-assorted figures and inharmonious lines. Such mistakes as
this last are doubly unfortunate, as they tend to repeat themselves
through a large part of the photographer's work. Generally
speaking, any object that must appear in many pictures should
be extremely inconspicuous, and this holds with nothing more
than with the carpet, if there is one.

A vignetted bust undoubtedly possesses advantages over any
other description of photographic portraiture : it is that form in
which the shortcomings of our methods are best overcome. It
may, therefore, be doubted whether, in the introduction of the
cabinet size, it has been wise to endeavor to exclude the vignette.
The whole plate vignette heads which were formerly made, and

208 PHOTOGRAPHIC MANIPULATIONS.

are now so rarely seen, were far more effective than the little
card heads that have taken their place.

When pictorial backgrounds are employed, it is necessary that
the lens should be directed at the point of sight, that is, at the
point to which, in the drawing of the background, the spectator's
eye was supposed to be directed, namely, the point at which the
line of vision cuts the horizon. If, as may happen, this point is
not very easily distinguishable, the lens should at least be di-
rected at the horizon line of the picture. Or, what is still better,
the horizon line should be completely concealed by a skilfully
arranged design. If neither of these precautions be adopted, there
will be no illusion whatever, and this is why the effect of fanciful
backgrounds is so rarely good.

Good effects may be obtained by using a background of brown
paper, shading it off with white crayon in a light and sketchy
way. If it be desired that the print shall show parallel strokes
of shading over the shoulders and round the head, in imitation
of crayon drawing, it is evident that this result can be attained
by marking on the background a central spot for the head, and
sketching large, coarse shading around it. In this case black
crayon or charcoal should be used on a light buff ground. Such
backgrounds will need to be in sliding frames, balanced with
weights, that they may be raised or lowered to bring the centre
into exact correspondence with the head.

The appearance of the grain of drawing-paper is sometimes
given to the finished and mounted photograph by passing it,
before quite dry, through a press, together with a piece of coarsely
grained paper laid on the surface of the print.

CHAPTER VII.
LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY.

§ 1. — General Remarks.

Landscape photography is a very fascinating pursuit ; and
when once undertaken in good earnest, and pursued to successful
and satisfactory results, is not often or easily abandoned.

The first need will be to possess a good camera and good lenses.

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 209

The subject of lenses having been already discussed, the writer
will here simply repeat his conviction that for views which do
not include architectural subjects, the view lens is not easily
excelled, at least when its too small angle of view is remedied
as in Dallmeyer's wide-angle view lenses. Used with equal
stops, these lenses have greater depth of focus than any others
that the writer has tried. The Steinheil aplanatic gives very
harmonious landscapes and renders architectural lines correctly.

It is important to repeat here that the best effects will never
be obtained with lenses of too small focus. Under their influence,
landscapes become so altered as to be unrecognizable. Buildings,
in place of seeming to stand upon a firm foundation, seem to totter
forwards. Rectangular corners are made to assume the appear-
ance of sharp angles, so that the building no longer appears
square, but lozenge-shaped. The upper corners of the roof look
high and peaked, and the real character of the edifice is lost.

Levelling the Camera. — When architectural subjects constitute
the picture or are included in it, the camera must always be
levelled, or the lines of the building will not be straight in the
image. The level may be either rested on the camera, or, what
is better, it may be countersunk into the camera, and so remain
permanently attached to it. To make this arrangement, the
camera should be placed on a perfectly level surface, ascertained
to be such by careful levelling. The "universal level," which is
round, and about an inch or an inch and a quarter in diameter,
is then permanently fastened into its opening with shellac cement,
and so placed in it that the bubble shall be central.

Of course, where a building is so unfortunately situated that a
view cannot be obtained except with a very short focus lens, its
use will be excusable, but the result will never be satisfactory.

It sometimes happens, also, that buildings in narrow streets
cannot be photographed except from the second or third stories
of opposite houses. Such pictures are inferior to those obtained
from the ground, and always give the idea of being taken from
some unnatural point of view. It is unfortunate that buildings
in cities are generally so situated that no first-class photograph
can be obtained of them, owing to the narrowness of streets and
crowding of houses.

With landscapes this levelling is less necessary. To obtain a
perfectly truthful representation, it is essential, and therefore no
view can be accepted as giving an accurate delineation of scenery

210 PHOTOGRAPHIC MANIPULATIONS.

unless the camera was levelled when it was taken. But in taking
views simply as beautiful objects, more latitude may be allowed.

§ 2. — Choice of Conditions.

As landscapes are always seen with disadvantage under a noon-
day sun, so photographs taken under similar circumstances are
mostly unpleasing ; and as photography tends to exaggerated
contrasts of light and shade, the result is all the worse. Many
experienced landscape photographers therefore avoid bright days,
and like best of all those times when the sky is covered with
white clouds through which the sun occasionally breaks. If a
glimpse of sun can be secured at the end of an exposure, the
best of all effects is got, and this may be compared to the effect
in nature of the softened sun late in the afternoon, and we all
know the magical influence of such light even upon the tamest
of scenery. It is therefore a good plan, if there is hope of a
burst of sun, to cover the lens a little before the proper exposure
has been given, and then, when the sun comes, to expose for a
moment, and so light up the picture without getting harsh con-
trasts. These last may, in extremely bright weather, give an effect
of snowiness in the high lights, which is in the highest degree
displeasing.

The time during which the lens may be covered to wait for
this sun will depend upon the weather. In moist or cool weather
much more time may be prudently allowed than in hot or dry.
Great care should be taken not to disturb the camera in opening
and closing. For this, the morocco lined with velvet caps, now
furnished with all the best lenses, are very recommendable, and
work better than the common brass caps.

As the sky is apt to be over-exposed, it may often be advan-
tageously shaded during part of the exposure. This may be done
by holding the hand or other object in front of the upper part
of the lens, and near to it, moving it continually. To accomplish
the same object, sky-shutters are often made to the lens or to
the camera, but it is difficult to use them without disturbing the
camera. In landscape taking, the photographer will avoid the
use of the two smaller stops. The object of the stop should be
clearly understood. In the case of the view lens, it is to obtain
depth of focus, to have the distant and the moderately near
objects simultaneously in focus. With the doublets and the

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 211

view lens, diminishing the size of the stop improves the defini-
tion and crispness at the margin. "When these objects have been
sufficiently attained, no further diminution of the stop is advisable,
as the image loses in character and boldness, in addition to which
the time of exposure is of course increased.

All the most experienced photographers are agreed that a view
should invariably be taken with the largest stop that the condi-
tions of the case will permit. As soon as a satisfactory definition
is obtained, further reduction of the stop should be avoided with
the utmost care. A small stop produces a flat picture, without
gradation of distance or atmosphere. A large one gives a bold,
clear view, with the objects in the respective planes of distance
well made out. Objects that with a small stop seem pressed
together, with a large one stand well out and show what they are.
The photographer cannot be too strongly enjoined not, in order to
obtain a microscopic sharpness, to sacrifice the general character
and expression of his view. Of course, good definition cannot be
dispensed with. But when the operator finds that he cannot get
this without a very small stop in using any of the ordinary forms
of lenses, he may be sure that he is straining the lens, making it
do work for which it is unsuited, and therefore that he cannot
expect the best results.

A photographer may visit scenes of great natural beauty, and
may be deeply impressed by them. He may labor very hard to
reproduce them in his negatives, and yet, after much effort, he
may obtain but unsatisfactory results. Some will, under these
circumstances, lay the blame on photography, and affirm that the
indifferent results spring from the incapacit}' of the method to
yield what is wanted. Others will not perceive the deficiencies of
their own pictures, and think they have all that can be expected;
whilst others, again, with a truer sense of the beautiful, will be
disheartened by the difference between what they have seen in
nature and what they have been able to carry away. But this
is in reality the first step towards ultimate success. A keen
appreciation of errors and imperfections gradually helps to avoid
them, but not without many failures and much persistent effort.

In viewing a landscape in nature, the eye is apt to seize and
rest upon the characteristic features, overlooking those that are
secondary. A lens cannot do this, and, singularly enough, the
eye will not do that with a picture which it will with real objects.

212 PHOTOGRAPHIC MANIPULATIONS.

but insists, as it were, that the picture should represent them as
they should be. This fact is so conspicuously true, that examples
are scarcely necessary. They will, however, continually present
themselves to the photographer. Perhaps the view lies in a wild
valley in the midst of hills, and the scene is not marred by the
presence of a rustic cottage. But perhaps beside it are lines
hanging full of clothes drying. This the eye passes over and
excuses in the scene itself, but the same feature introduced into
any picture, photographic or otherwise, provokes inextinguishable
laughter.

So with the hideous telegraph poles that line all our roads and
railroads, and intrude into almost all our scenery. The eye con-
sents reluctantly to forget them by an effort, and to consider the
scene without reference to them, and to some extent succeeds.
But in the photograph they come out straight, stiff, and promi-
nent. Even the wire is perfectly made out. It results that often
a scene cannot be taken from its best points by reason of these
detestable adjuncts, and that, because of their continued repe-
tition at short intervals, the effort to wholly exclude them be-
comes totally unavailing. Telegraphs are necessary things, but
there is no reason that they should be permitted to intrude
through scenery of recognized natural beauty. This is carrying
utilitarianism too far, and would be tolerated in no country less
corporation-ridden than ours. Six miles of the scenery of the
beautiful Wissahickon are in this way marred by the poles that
carry a wire apparently for individual convenience, which might
better dispense with it, or choose another route.

As the camera has not the painter's power of excluding or
subduing intrusive objects, all that the photographer can do is
to endeavor so to select his point of view as to avoid them. This
is a matter that deserves more pains to be taken than it mostly
receives. After the view has been taken, it will sometimes
be found that a change of position of even a few yards only
would have made a material improvement ; a discovery morti-
fying and annoying, and better avoided by a careful search be-
forehand.

A question will often present itself as to whether any particu-
lar view will give the best effect if taken on a plate with its
longest side vertical or horizontal. The writer has elsewhere
pointed out that this question is best answered by observing what

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 213

is the direction of the principal ohject in the landscape, and making
the greatest dimension of the plate correspond with it.

Thus, a dam will for the most part look best in a wide picture,
Avhilst for a narrow and high waterfall the greatest length of the
plate should be up and down. So, too, where the chief object is
a tree or a group of trees ; whereas with a bridge the principal
dimensions should be right and left. But no such rules can be
an absolute guide, it will only aid in deciding, and if any doubt
is felt, an excellent plan is to try it both ways ; on inspecting
the prints no doubt will remain as to'which was the best position,
and the comparison will aid in forming a correct judgment on
subsequent occasions.

In a landscape, the best effects are to be secured by contrast. In
photography, as we have no effects of color, our contrasts are
limited to those of line and those of light.

Contrasts of line or form are always relished by the eye. The
effect of the mountain is enhanced by the levelness of the plain
at its base. A picture that should represent a plain with no
elevation, or simply an elevation with no plain to contrast with
it, will always be deficient. Other and beautiful contrasts of
line are often seen in a rolling country, even where there is no
plain and no great elevation.

Contrasts of light and shade, technically called chiaroscuro, are
the life of all pictorial representations. They give us, in a great
measure, our ideas of the form and relative position of bodies.
Negatives taken in dull weather are necessarily deficient in this
quality, whilst those taken in clear sunshine often present con-
trasts too harsh. A weak sun often gives beautiful effects, and
as the sun is less powerful when low, this, as well as many other
advantages, is obtained by working at such times.

Whilst contrast is all-important in photography, it is to be
carefully remembered that too much of it is even worse than too
little.

If a negative be taken with insufficient exposure, and then this
be attempted to be made up in the development, it will most
frequently happen that the silver, instead of being deposited so
as to keep the regular graduation of tone, falls too much upon
the lights. Thus the picture becomes hard, and if the fault has
been great, it becomes snowy.

In some classes of subjects, snowiness is not easily avoided.

21-4 PHOTOGRAPHIC MANIPULATIONS.

If a landscape be in part very brightly, and in others very badly,
lighted, the photographer finds himself in the dilemma that
either he exposes and develops too long for the one part, or too
briefly for the other. In printing his negative, he may find an
absence of detail, accordingly, either in the lights or shadows.
This difficulty is inherent to the nature of the subject, and may
be too great to be overcome. The best advice that can be given
is to give a full exposure, compensating for this by using a rather
weak developer, and letting it lie quietly on the surface of the
plate, without sending it to and fro. The collodion should con-
tain a rather full proportion of bromides. This checks contrast,
so much, indeed, as to render such collodion unsuitable for views
in which the contrasts are less striking. Some careful operators
carry with them two sorts of collodion, using the most highly
bromided for mastering contrasts. Those who are not willing
to take this trouble, find themselves obliged to avoid such com-
binations, and to return to them in sunless weather. Where
much bromide is used, it should always be borne in mind that
the negatives will prove in printing more transparent than they
appear to the eye.

In taking views along streams with high banks, and in ravines,
the contrasts of light and shade will always be really greater
than they appear to be, and due allowance must always be made
for this. In such places the shadows are apt to be very dark,
because so much of the sky is cut off, and it is always the diffuse
light from the sky that lights up the shadows. In such places it
will be found difficult to combine darkly shaded foliage with
sunlight in the same picture; this result can only be obtained by
prolonged exposure, and slow and careful development ; gene-
rally it will be best not to attempt it, if it can be avoided.

The development must always be graduated not merely with
respect to the character of the scene, but to the amount of ex-
posure that has been given. In order to combine exposure and
development, and so to get the best possible results in difficult
cases, the following observations may be useful.

A view that is strongly illuminated all over, with few con-
trasts, will demand a moderately short exposure and a long de-
velopment with a weak developer, the object being to preserve
detail, and yet at the same time to retain contrast enough to give
life to the whole.

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 215

When the illumination is uniform and not good, or where all
the objects are non-actinic, and the light not very good, we shall
want a very prolonged exposure to get them well impressed.
And then we shall need a long development with a weak de-
veloper, otherwise the result will be tame and flat.

In this country the character of the light varies between ex-
tremely wide limits. In cloudy weather there is apt to be, of
course, everywhere, a deficiency of contrast. Such light, how-
ever, is often very favorable for taking near foliage. On the
other hand, when the sun shines, the light is apt to be very
powerful, and as the air with us in clear weather is apt to be very
transparent, it results that the shadows are dark and wanting in
detail. In clear, cloudless weather the shadows are very dark,
and in such weather it requires great experience and very good
management to get first-rate effects. Attention must be paid to
the influence both of the season and of the time of day.

Seasons. — The landscape begins in this latitude to show suffi-
cient foliage to commence photographic work towards the first of
June, though the forest trees are not well in leaf till a fortnight
later. At this time of year the light is exceedingly powerful,
and exposures must be shortened.

A slight excess of exposure, generally unimportant, will some-
times give rise to solarization. A good deal of care and circum-
spection will be required. Sometimes, when the sky is covered
with low white clouds with the sun just breaking through them,
the power of the light is truly amazing.

Throughout the spring and summer, the days when the leaves
are still are far from frequent. In September, and even towards
the end of August, the air is much quieter, and it is far less
difficult to find favorable days ; the light is also softer. On the
other hand, there is more dust, and streams are apt to be low, so
that waterfalls show but scanty streams, and mill-dams, often
very beautiful at other times, are frequently quite dry.

A serious trouble at all seasons, in our climate, is the want of
softened light. We have but a few of those partly overcast yet
luminous days which give such beautiful effects of illumination
and such soft foliage ; our light is mostly too abundant and
piercing.

Snow Landscapes should receive a medium exposure and a
full development, for, to obtain clean, bright snow scenes, all the

216 PHOTOGRAPHIC MANIPULATIONS.

most fully lighted snow must be developed to absolute opacity,
shading off, however, to give it relief.

Time of Day. — Two or three hours after sunrise the light is
very powerful ; it goes on to increase till about 11 o'clock, then
remains stationary till 12, after which it diminishes till sunset.
The afternoon light is always weaker than the corresponding
part of the morning. Thus, the light two hours (for example)
before sunset is not half as powerful as two hours after sunrise,
though the sun in both cases is equally high. This is said to be
caused by the greater quantity of moisture dissolved in the air,
though the explanation is doubtful.

Cloudless weather is always unfavorable. Clouds act as re-
flectors to light up the shadows. In cloudless weather the shadows
are always very dark, and are apt to want detail in the image.
In such weather, the middle of the day is, in the writer's opinion,
very unsatisfactory for work. In the early morning, and in the
afternoon, the evil of want of clouds is less felt. At these times,
also, the effects of scenery are more agreeable, the shadows are
longer and give more relief, the air is generally stiller. Longer
exposures are necessary, of course, but the results are better. In
overcast weather, the middle of the day is apt to be the best
time.

Cast Shadows are such as retain more or less of the form of the
object that casts them, as distinguished from the more indefinite
shadow that comes from some less distinct source. Such shadows
are often the source of exquisite beauty in landscapes. A level
foreground of grass is apt to be flat and unmeaning ; the shadow
of a tree cast across it, gives it at once life, character, relief. The
landscapist cannot pay too much attention to such effects of fore-
ground.

Generally, the more that shadow is diversified the finer its
effect. A large dark shadow of a tree is far less beautiful than
one in which the sun penetrates the leaves, and falls in irregular,
broken forms upon the ground.

When it is required that a house shall appear in the foreground,
a diversified shadow upon its walls has an extremely good effect.
In neither case, however, must the lights and shadows be too
much broken, or the effect will lack breadth. And the greatest
care must be taken to avoid spottiness of effect. As this is a

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 217

common and fatal fault, the writer will endeavor to point out its
source.

Shadows of branches and boughs through which the sun pene-
trates partly, and which retain indistinctly the forms of leaves
and sprays, are very beautiful. A level sun will often throw
shadows of such sprays upon the trunks of trees, with an exquisite
effect. So shadows of leaves and boughs on walls, houses, roads,
and grass, are often very beautiful. But it is an essential con-
dition that the shadows must be transparent, and shall present only
a moderate degree of contrast with the lights. If, however, we place
the camera in a grove and take a picture, we shall probably get
black shadows on the ground, interspersed with white patches of
sunlight, and these effects, instead of being of a wholly subordi-
nate character, will strike the eye before anything else in the
view. Such an effect is indescribably bad, and to be avoided
with the utmost care.

Parallel patches of shadow are especially ugly. These are apt
to occur when trees present themselves in rows, with sunshine
penetrating between each two trees.

The tree, the great beauty of the landscape, offers peculiar
difficulties in photography, owing to the non-actinic color of its
leaves. For this reason it has been thought advisable to use
much bromide in collodion intended for landscape photography;
the true explanation of its utility has been already given. There
is a remarkable difference between leaves of different trees, which
it will be necessary to bear in mind. Some have a brilliant sur-
face, as if they had been varnished; such are the sour-gum, black-
oak, and others. From this we descend through every degree to
those leaves which scarcely return any light, such as the white-
oak, &c. The first sort, if in direct sunshine, are apt to produce
a particularly disagreeable effect; they send back so much light,
that they develop to full opacity by the time the rest of the
picture has come up to printing strength, and so print quite
white. This is unnatural and unpleasing, and, as far as pos-
sible, to be avoided. In cloudy weather such leaves photograph
exceedingly well. Ivy-leaves on buildings easily give a very
beautiful effect. They send back a good amount of light and not
too much, and, as they are apt to look all in the same direction,
each leaf is bordered by a shadow. Thus each leaf is well made
out, and the effect is particularly pleasing and exceedingly easy
to catch, more so, perhaps, than with any other sort of foliage.
15

213 PHOTOGRAPHIC MANIPULATIONS.

It has been often advised in photography to have the. sun well
behind the camera. This, however, is a rule of very doubtful
validity. When the sun shines full upon a group of trees in the
middle distance, the forms of the individual trees are never well
made out, and the result is apt to be a mere mass of brilliantly
lighted foliage. Often the separate twigs and boughs may stand
out in consequence of dark shadows falling between the leaves,
but the beautiful rounded effect of each particular tree is only
well thrown out by a good side-light. This inferiority of effect
produced by having the sun directly or nearly behind the camera,
on trees in the middle distance, is very striking. Near foliage,
however, bears having the sun behind the camera perfectly well.
But the exquisite beauty of the rounded forms of individual trees
in the middle distance is only well rendered by a side-light.

One reason why this light from behind has been extensively
used is that it is the least exposed to blurring. Whenever dark
masses stand out against a bright sky, the light has a tendency
to get round and intrude upon the shadow ; an effect that arises
from reflection from the back surface of the glass. The partial
opacity of the film scatters the light that passes through it in
every direction, so that portions reach the back at very oblique
angles, and may return to the face at considerable distances
from where they entered. To a large extent this may be avoided
by wet red blotting-paper on the backs of wet plates and glycerine
plates (a precaution which should never be neglected), and by
painting the backs of dry plates.

Near foliage should be represented invariably in half-tone, and
this effect is generally obtained more easily when the sun is not
too bright, especially in the case of the polished leaves already
spoken of. Distant foliage is far more easy to manage, and bears
the brightest sunshine perfectly. It is far better rendered when
the sun falls upon it from the side than when the sun is either
nearly before or nearly behind the spectator. A fine single tree
or grove of trees lighted from the side affords a beautiful play of
light and shade, which disappears 'when the sun is in the line of
view before or behind, or even approaches to that direction.

Natural clouds are a great beauty when they can be included
in a landscape. The difficulties here are twofold. It is not very
common (at least in our climate) that there are clouds such as it

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 219

is desirable to take. In our fine weather we have mostly a clear
or nearly clear sky. And when there are beautiful clouds, the
weather is apt to be too windy for photographic work. But the
greatest difficulty lies in the fact of the great luminosity of clouds.
When the sun is shining, the darkest part of a cloud is generally
more luminous than the whitest object in a landscape. The eye
scarcely realizes this in observing a landscape, but it is easily
recognized on the ground glass. The consequence is that although
the clouds appear in the commencement of development, yet they
are buried in a mass of deposit before the details of the landscape
are got.

There are several methods of obviating this to some extent,
though it must be confessed that they leave much to be desired.

The camera may be provided with a sky-shade, a shutter in
front of the lens (Figs. 92 and 94), which may be slowly raised
during exposure, so as to diminish the light admitted from the sky.

Or the hand, the hat, or the shutter of the plate holder may be
used in the absence of a sky-shade.

In either of these cases a trial should be made of the move-
ments beforehand, and the effect watched upon the ground glass,
that the operator may see in what position of the shading object
the sky begins to be uncovered.

The inclined diaphragm (Fig. 40, p. 66), by reducing the light
from the sky, will aid in obtaining clouds.

To secure clouds, the opportunity also should be favorable.
The landscape should be wide and well lighted, in order that a
brief exposure may suffice for the terrestrial objects.

According to Mr. H. T. Anthony, a developer of double sul-
phate of iron and ammonia 30 grains to the ounce, sulphate of
copper 5 grains, and acetic acid as needed, is yery favorable to
the obtaining of clouds.

An agreeable diversification of the foreground is a capital
point in a landscape. It has been already remarked how much
this is aided by shadows. Almost any characteristic and promi-
nent objects will have a good effect; logs, stones, and, still more,
rocks, bushes — anything that breaks the level and changes the
lines, also attracts and pleases the eye, not in itself, but in the
general character that it imparts. It may generally be affirmed
that scarcely anything can so much detract from the effect of a
landscape as an unbroken foreground, level in form, and uniform

220 PHOTOGRAPHIC MANIPULATIONS.

in light. Such a foreground will mar, if not destroy, the effect of
the finest objects. The artistic photographer will always change
his position to avoid such a foreground; or, if he is tied down to
a particular spot from some imperative cause, he will, if possible,
have some object, such as a log, a large stone, or a trunk of a
tree, thrown where it will support his lines, as explained more
fully beyond. High banks are very picturesque objects, and
often aid to make beautiful foregrounds.

Bringing Out the Foreground. Acceleration of Exposure. — Often
the foreground, especially if consisting, as it so commonly does,
chiefly of foliage, lags behind in development ; and when some
other parts of the picture have reached a full intensity, so that
the development must perforce be stopped, the foreground will
often be still thin and poor. This is a great injury to a picture,
which is helped by nothing more than by a property exposed
and developed foreground.

The writer has succeeded in obviating this difficulty to a con-
siderable extent as follows: He takes a piece of white pasteboard,

shaped as in Fig. 107, and of such a size that
Tig. 107. whilst the top lies flat against the inside top

of the camera, the tapering sides rest upon
the bottom, and act like legs to support the
top in its place. The inside is colored rose-
red with carmine (lump carmine, a grain or
two dissolved in half an ounce of water,
with a drop or two of liquid ammonia, is better than the paint).
The red light diffused and reflected by the surface of this paper
considerably increases the force of the adjoining portions of the
image, without in the least tending to produce fog. The sides
should taper very much, as it is not desirable that any part of
the red paper should be alongside of any part of the sky.

There is in this device a real and solid utility, and the writer
never now goes out to take views without this adjunct. A piece
of pasteboard blackened with ink, and of such a size as to fit
against one of the sides of the camera, and so cover one of the
legs of the red pasteboard in case there is much sky on that side,
is convenient to have.

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 221

§ 3. — Materials.

Camera. — The most convenient form of camera for ordinary
use is that represented in Fig. 94, p. 149, except that, especially
if the camera be large, the writer prefers the wooden brace shown
in Fig. 92. When it is intended to pack the camera, to carry to a
distance, it is convenient to have the bottom jointed and hinged,
though this system weakens the whole construction.

Slides. — If the dry process is worked, the photographer can
use .Changing Boxes, contrived to carry a number of plates, and
transfer them, one by one, to a peculiarly made slide ; or he can
use separate slides, which may be made to carry two plates each,
and are then called Double Backs. This is the plan preferred by
the writer.

Tripods. — A light folding tripod is essential for field work; and
as much of the photographer's comfort will depend upon having
a good tripod, the writer has
made drawings of the parts of
the form which he prefers.

Fig. 108 shows the top table.
It is made of three thin pieces
of wood glued firmly together,
and having the form of a round-
ed triangle. At each corner a
block is fastened underneath,
carrying stout pins, A, B, which
slip into holes in the legs, the
tops of which are shown in the
figure.

At the centre is a circular opening in the top thickness, in the
middle of which circle is set the screw S. There is no screw-
thread in the table, the screw merely passes through it and screws
into the camera. A pin passed through the stem of the screw,
just above where it passes through the table, prevents it from
dropping out; this is a great convenience, often neglected by the
makers, thus subjecting the photographer to the chance of over-
looking the screw in going out, and so losing his day.

The legs, one of which is shown in Fig. 109, fold over in the
middle, to save room. The cross-piece near the upper end moves
on a hinge, and permits of shutting the whole up fiat. In Fig.
110 the writer has drawn the joint on a larger scale. When the

)

222

PHOTOGRAPHIC MANIPULATIONS,

leg is straightened out, a small brass cross-piece, attached by two
screws, confines the lower piece in its position, and a strong thumb-

Fig. 109.

Fig. 110.

screw at the side, when tightly turned, makes the whole perfectly
rigid. It is surprising how light a tripod, thus made, will hold
a heavy camera quite steady.

For additional information on materials, see Chapter XV.

§ 4. — Manipulations in the Field.

If the wet process is the one selected, the photographer will
either use a developing hox, a tent, or a dark room on ivlteels. One
of the simplest tent contrivances is a thick black cloth stretched
over the camera tripod, and kept in place by stones. In the de-
veloping box, the hands and arms only are inserted into sleeves,
whilst the operations are watched through yellow glass.

All the troubles, and there are many, that accompany these
methods of operating, are avoided by the use of dry plates. And
it is certain that the most improved methods of dry plate work
give results fully equal to those of the wet process.

Whichever method be adopted, an observance of the following
rules will save a great deal of vexation and the loss of many
negatives, occasionally perhaps of a whole day's work.

At the commencement of a day's work, see, once for all —

1. That the camera is light-tight, and that there are no cracks
in the front or holes in the bellows body. Cap the lens, cover in

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 223

the head well, and look into the camera with the ground glass let
down, racking back pretty well, to open the folds of the bellows.

2. See that the lens
Is free from dust.
Has no dew on it.

That the parts of the lens and of the mount are properly

put together.
For each exposure make sure.

3. That the camera and tripod are perfectly steady.

4. Invariably use the largest aperture to compose the picture.
Make sure that no near objects out of focus are showing in the
foreground, which may easily happen with shrubs, weeds, and
the like. Also that no overhanging foliage is intruding upon
the upper corners of the plate, to appear, to the dismay of the
photographer, when he develops, as large, formless objects, ruin-
ing probably his picture.

5. Adjust the swing-back. Remember that if the screws which
fasten it are not turned perfectly tight, they will probably move
when the plate holder is pressed up to attach it.

6. If working with dry plates, make perfectly sure that you
are not exposing a plate that has been already exposed before.
If habitually using dark slides or double backs, have each
painted conspicuously with a number on the shutter, and expose
in regular rotation. If using a changing box, adopt a regular
system of changing the plate immediately after, or immediately
before, exposing ; always the same.

7. If the sliding front has been moved up or down or side-
ways, for a previous exposure, make sure that it has been re-
placed. If the camera has been carried a distance, the front
may have jolted down, and if not attended to, some of the cor-
ners may be defective in the image.

8. After arranging and composing the picture with the largest
stop (in order that you may see exactly what the picture will be
like), turn the screw of the tripod under the camera, hard, so that
there shall not be the slightest change of position during the
subsequent manipulations.

9. Now put in the diaphragm which you intend to use, and
focus with it (never with the large one by which the picture was
composed, and for two reasons : 1st. It will not give a good
focus, being too large. 2d. If it did, its focus would not be the
same, the smaller the stop the longer the focus).

224: PHOTOGRAPHIC MANIPULATIONS.

The loose diaphragms that slide into slits in the tube (Water-
house diaphragms) are apt to drop out. To avoid this, bend the
shank a little.

10. Uncap the lens gently, pausing at the moment, to insure
perfect rest.

11. Watch the foliage intently during exposure, and at the
slightest sign of movement, replace the cap until the movement
wholly subsides, and repeat this as often as necessary — a dozen
times if needful.

The same objects will appear so differently in different lights,
that the painstaking photographer will not hesitate to wait or
to return when he finds the illumination to be unsuitable for his
purposes. There is a story told of a distinguished landscapist
that he once waited three weeks to get good weather and a par-
ticular effect of light upon a scene that he had come to photo-
graph. There is some contrast between this and the rapid worker
who points his camera at everything that catches his eye, and
exposes his dozen of dry plates in an hour or two. It should be
laid down as an axiom by every worker, that a good negative is
very valuable, a tolerable negative worth absolutely nothing. It
is at least as troublesome to print a tolerable negative as a good
one, and the prints from the tolerable one are not worth the pains
they have cost in printing. Twenty copies from a good negative
are valuable for exchanging against prints from good negatives
belonging to others; but twenty prints, each from a tolerable and
different negative, are nearly worthless. No multiplication of
indifferent results will give good ones, and the experimenter will
derive more satisfaction from a single thoroughly good negative
than from a score or a hundred of indifferent or tolerable ones.
Good results will come only with care, thought, close observa-
tion, and a resolution to have things right at any cost of time
and trouble. Care-taking soon becomes a matter of course, and
the habit once acquired, is invaluable.

Adapting Flanges. — The inconvenience arising from flanges of
different sizes has been already pointed out (p. 96). The writer
finds this annoyance materially lessened by having adapting
flanges made for lenses, so that several lenses may screw into
one and the same flange. Such adapters can readily be made
by any optician at a trifling cost.

Focussing. — A black cloth which will perfectly exclude the

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 225

light is essential. Black waterproof is suitable, and a piece a
yard and a half square will be a convenient size.

Photographers differ very much in their ideas of how a focus
should be taken. In the first edition of this manual it was
recommended to focus at a point in the foreground half-way
between the centre and a corner, racking back as far as prac-
ticable, and then putting on a small enough stop to obtain the
definition needed.

Now, however, the writer has gradually adopted the following
plan : There will be with any lens a stop which one habitually
uses when the objects are not very different in their distances
from the camera, and another, the next smaller, used when the
differences are greater. Therefore, selecting for the view about
to be taken the stop deemed appropriate, proceed to focus on the
distance, and then rack back the focussing screen just as long as
the distance will bear it, without its definition suffering too much.
This ought to bring the foreground into focus ; if it does not, a
smaller stop must be substituted, or else the position changed so
as to exclude the near objects that cannot be got into focus along
with the distance.

Either of these alternatives is unsatisfactory, because it may
be very desirable to include that particular part of the fore-
ground, and a small stop is always bad.

But if the camera have the valuable aid of the swing-hack, the
question is greatly simplified. The photographer will be enabled
to get an equally good general focus with a larger stop, and con-
sequently with better detail in the shadows, and better spacing
out of the distances. A swing-back should always be double,
that is, have both a horizontal and a vertical motion.

The vertical pivot is to be used when, as so often happens, the
objects at one side of the view are nearer than those on the other.
The side on which the nearer objects fall is drawn a little away
from the lens.

The horizontal pivot is useful in getting the foreground into
focus at the same time with the distance. To this end, focus on
the distance, rack out the focussing screen as long as the distance
will bear it. Then draw the top of the screen awa}^ from the
lens, until the foreground is perfect. Both this and the vertical
action may be combined (see also p. 148).

The usefulness and convenience of the swing-back for bringing
the foreground into focus is exceedingly great, and when once

226 PHOTOGRAPHIC MANIPULATIONS.

used habitually, this contrivance is felt to be indispensable.
There is one case, however, in which particular caution is needed
in its application.

If both the upper corners of the picture be occupied by near
foliage, then any drawing out of the upper side of the swing-
back to regulate the foreground will be apt to throw the corner
foliage out of focus, and deform it. In such cases it will be
needful to move the tripod farther back in order to lessen the
difficulties of the position.

If one upper corner only be covered by foliage, and if the
extreme distance of the view lie towards the other end, we may
then draw out the foreground without danger, because the foliage
in the upper corner can be got into focus again by regulating
the vertical pivot, and thus at the same time the distance at the
farther side will be also harmonized in focus.

Some persons are as anxious for sharpness in the distance as
in the foreground, and will exhibit a print with the boast that
the extreme distance will bear a microscope. As the eye cannot
see natural objects in this fashion, it can scarcely be right to
depict them so. And when we examine the works of the great
masters of landscape painting, we find that, with the power to
draw their distances precisely as they pleased, they did not think
right to make them sharply cut.

We find that, as distance softens down outlines to the eye, so
when outlines are softened down, the eye infers distance.

Not that this principle is to be carried to excess, and made an
excuse for blundering work. It is only that the same sharpness
is not to be exacted in the distance as in the foreground ; espe-
cially as this can only be attained by the use of a very small
stop, which greatly mars the boldness and life of the image.

§ 5.— The Wind.

In all landscapes the chief beauty lies in the foliage, and it is
necessary that this should be absolutely still, to be satisfactorily
represented. Every one who attempts landscape photography
has had severe experience of this sort, and fully understands the
ruinous effect produced upon a picture by blurred masses of

leaves.

It would be difficult to exaggerate the annoyance caused to the

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 227

photographer by this unending source of trouble. It is impos-
sible to foretell what the prospect of wind is, therefore a long
excursion may be taken uselessly, or may be abandoned only to
see, when too late, the wind entirely subside.

The following represents what aid can be given in this direc-
tion : —

Time of Day. — The very early morning is apt to be calm, and,
still more so, the afternoon for an hour or two before sunset.
Both of these are excellent times for photographic work. The
exposures in the late afternoon are necessarily prolonged, but the
quietness of the air generally makes this easy.

Between eight and ten o'clock A. M. the wind is apt to rise,
sometimes earlier, sometimes later. It may subside towards
midday, but quite as often not. Gradually towards three or four
o'clock in autumn, four or five in spring and summer, a sub-
sidence may be hoped for, and then no time should be lost in
improving it. It is one advantage of dry plates that they can
follow each other without losing valuable time in sensitizing and
developing ; the collodio-bromide dry plates hereafter to be de-
scribed are, by reason of their sensitiveness, excellent for after-
noon exposures.

Seasons. — The spring with us is apt to be windy, with, how-
ever, occasional calm days, which become rather more numerous
in June and July. August and September have mostly more
quiet days than any other months. October has beautiful quiet
days occasionally, with fine, soft illumination. By the first of
November the foliage is pretty well gone. Then, in place of the
soft lights and shadows of the woods, we get masses of parallel,
gray trunks, which produce the very worst effects. A single
tree, especially an oak tree, devoid of leaves, is a beautiful object,
its branches give gracefully opposing lines,'- that support each
other ; but there is nothing of this sort in a wood.

When the wind blows steadily it is a mere waste of time and
material to go out to photograph, however tempting the light
may be; except, indeed, we go expecting only to make use of
the late afternoon. On not very windy days we are almost sure
to have an hour or two of calm before sunset.

Often the wind blows in puffs. In this case we closely watch
the foliage and re-cap the lens the instant the first movement
shows itself. With care, quickness, and gentleness, it is wonder-
ful how much may be accomplished in this way. It should be

228 PHOTOGRAPHIC MANIPULATIONS.

remembered, however, that if the puffs of wind between the quiet
times are violent, it does not follow that the leaves, after this
violent agitation, will settle down, each leaf to the exact previous
position.

For the most part, however, it is a waste of time to attempt to
photograph landscapes in windy weather. The evil effects of
very slight winds may be materially diminished by observing
one or two precautions.

When light branches are projected against a bright sky or
clouds, the least motion of the leaves allows the bright light of
the sky to pass in behind them. The result is that the leaves
appear shrunk away and blurred,1 an effect very often seen and
most displeasing. If the sky is very dense, and prints perfectly
white, such branches should always be painted out. A similar
result follows when branches are projected against the reflection
of the sky on water, or against any other bright object.

Again, where boughs with glossy foliage, well illuminated,
stand out against deep shadow, and are moved by wind, they
carry their bright reflection with them, and their image is ex-
tended, in place of being shrunk away as in the previous case.
Each leaf, instead of being small and sharp cut, as we would wish
to have it, is large, blurred, and undefined.

Therefore, if the air be somewhat in motion, the landscapist
will do well to avoid foliage in either of these two positions,
which are those that produce the worst effects. For when foliage
standing before other foliage, and nearly equally illuminated, is
moved, the result, though anything but pleasing, is not so very
injurious as in the other cases.

On those priceless days, when the light is neither too strong
nor too weak, and the foliage perfectly still, the photographer
will do well to turn his attention especially to those landscapes
in which the chief beauty lies in the foreground. Foliage should
be introduced quite near to the camera, provided it can be kept
in good focus together with more distant objects. Projecting
boughs scon against the reflection of sky in water, so objection-
able in the former case, may now be made to produce the most
charming results, especially when accompanied by their reflected
images.

1 When no paper is placed behind the plate (or color on the back of dry-
plates), the same result may be expected by reflection from the back of the
plate, quite independently of any movement of the leaves.

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 229

When it is intended to photograph immovable objects in a
heavy gale, it is very desirable to find, if possible, some suitable
support, such as a wall, a rock, or the stump of a tree, on which
to place the camera, which is then steadied by placing on it a
heavy stone. Perfect steadiness may in this way be obtained.
In the absence of these resources, a cord may be fastened to the
screw under the table of the tripod, and a heavy stone be tied to
the other end, and let to hang down. Or it has been proposed
to tie a loop in the cord, reaching just short of the ground, and
to put the foot into the loop, and thus hold steady the camera.

It remains to say a word respecting the wind, in its relation to
long and short exposures.

It has been said that the wind does not act more injuriously
upon a long exposure than upon a short one, the effect having the
same average in each case, in proportion to the exposure. This
view is, I am persuaded, erroneous. The wind rarely blows
steadily (such weather is to be particularly avoided), but gene-
rally in puffs. And these puffs are apt to come at intervals, such
that, by watching, a short exposure can be caught between them,
when a long one cannot possibly.

Indications of Weather. — As the photographer's success in out-
door work is always dependent upon the weather, all means of
judging beforehand of what weather may be expected, acquire
no small importance. These signs differ materially in different
countries ; thus the writer, after a careful observation of the indi-
cations furnished by the English Admiralty for the guidance of
shipmasters, believes that, here at least, they are quite unreliable.
The following are what, from long experience and personal ob-
servation, have appeared to him useful.

And, first, as to wind. The direction of the wind has much to
do with its probable force. A westerly wind may be expected
to blow moderately ; a northwesterly wind strongly, and often vio-
lently; a north and northeast wind strongly; an east wind (if not
inclining northwards) is in clear summer weather not often strong.
But it is from southeasterly and southerly winds that the best pho-
tographic weather is apt to come, provided they do not bring rain.
Often with them the air is perfectly calm. When the direction
gets round to southwest, we have light breezes, often in puffs, a
state of weather very favorable. Thus we are most apt to have good
photographic opportunities with a southwesterly wind, but the

230 PHOTOGRAPHIC MANIPULATIONS.

best weather we have comes with a southeast or southerly wind,
though such a wind is less sure to bring it.

The clouds give many useful indications. Thus, if in the early
morning we see the clouds moving rapidly, then, although the
air below may be quite still, we are almost sure to have it rise in
an hour or two, and blast the fairest expectations. Much may
be inferred from the forms of clouds. Feathery clouds almost
always bring wind; mottled, irregular clouds like flocks of sheep
may or may not. The most favorable indication for calm air is
when the clouds form in long, smooth, thin forms, imperceptibly
blending into each other and into the sky; this appearance gene-
rally portends a still air and a soft light. Abrupt contrasts in
clouds are more likely to bring wind.

The previous condition- of the weather often affords a means of
judging. The first day after a storm is apt to be windy, each
succeeding day is more likely to be calm, and the calmest weather
is apt to be that which comes immediately before the next storm.

The above indications relate to stillness. As to clearness, the
following will be found useful : —

A mackerel-back sky indicates a change of weather. This name
is given to collections of little clouds, three, four, or more times
as long as they are wide, and arranged in parallel groups. This
indication rarely fails to be followed by bad weather within
twenty-four hours.

A red sunset generally precedes a fine day, a gray sunset a rainy,
or, at least, an overcast day.

Although it is said that with the sunrise these indications hold
but with opposite meanings, yet for such an opinion the writer has
never been able to find any support, but has constantly seen good
days and bad days follow both red and gray sunrises.

After two or three white frosts, rain may be expected. This
fact, and also that when ditches or drains smell more than usually,
rain follows, has long been familiar to all persons living in the
country. On the other hand, all indications drawn from changes
in the moon's quarters, position of the crescent moon, etc., in the
sky, certainly amount to nothing.

Changes in the barometer have not the significance in this hemi-
sphere which they have in the other, and little reliance can be
placed on them.

Finally, it should be observed that although the foregoing in-
dications as to stillness and as to clearness are generally reliable,

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 231

it cannot be affirmed that they are invariably so ; they can be
depended upon as showing the probable course of the weather,
but not as being infallible.

Before terminating these observations on landscape photogra-
phy, another remark needs to be made. In the very highest
class of landscape prints there is sometimes seen a combination
of great brilliancy and perfect softness, that surprises as well as
charms, and leads directly to the question, how is this difficult
combination of excellences obtained ? Not by any secret process,
that we know, for those who succeed best have always given
their formula) freely ; it is, therefore, not the materials used, but
the mode of using them, that is the essential point.

It is certain that —
Softness is promoted by length of exposure and rapidity of de-
velopment.
Brilliancy is heightened by shortness of exposure and slowness
of development.

The difficulty, of course, is that what promotes the one object
interferes with the other, and this is why so few fully attain both.
There is only one way in which it can be done, and this is to seek
for softness by length of exposure, and then to combine this with
brilliancy by a slow development.

In practice : Give a full exposure (using a fair dose of bromide),
such that with an ordinary developer the 'picture would flash up
instantly. So developed, the picture would be full of half-tone,
but flat and tame. Therefore add water and acetic acid to the de-
veloper until, notwithstanding the full exposure, the image comes
out gradually, avoiding, however, all exaggeration, both of ex-
posure and development, and combining the two so that each
shall correct the other's faults.

The best results, however, are always to be obtained by the
use of a specimen of cotton that has had exactly the salting that
suits it. To buy pyroxyline at random, even from the best
makers, and then select a formula for salting at random, even if
it be a formula of the highest authority, and then use a develop-
ment recommended either in a treatise or by a friend, but having
no definite relation to the cotton and salting, is to put the chances
against a full success. In England few even of the oldest and
most skilful landscape photographers make their own collodion ;
they buy ready made some particular sort which experience has

232 PHOTOGRAPHIC MANIPULATIONS.

shown them to suit their particular way of working, often
habitually and systematically mixing the collodion of two
different makers in certain proportions. The collodion maker
manufactures his own cotton, which he keeps as uniform
in character as possible. Very long experience has taught him
the very best salting for it, and he thus delivers a collodion
of very high quality. The photographer thus gets a great advan-
tage; in our system, where the photographer makes his own
collodion, he for the most part gets an inferior article, even with
the best cotton, unless by careful experiment (see p. 132) he finds
out just what treatment some particular cotton requires, and
manages it accordingly. This troublesome investigation he must
either make for himself, or else pursue his work under telling
disadvantages. The great excellence of English landscape work
is partly due to this system of buying collodion instead of cotton,
and partly to the character of the light in that country, generally
soft and broken, with little of the burning brilliancy of ours.

The brightness of the print will also largely depend upon the
albumenized paper. First-class prints will always need first-class
paper : solid, full-bodied paper, well albumenized with sound,
fresh albumen, and paper that has been carefully kept, and not
too long.

'a1

§ C. — Toning of Landscape Prints.

Although remarks on this point belong technically rather to
the head of printing, yet they are so closely connected with the
general subject of Landscape Photography, that I have preferred
to give them a place here.

A landscape print is subject to none of the conventional rules
of color that hold to a large extent with portraits, and even to
some extent with architectural views. Every pleasing tone is
appropriate — light brown, deep brown, warm brown, dark purple,
purple black, steel gray, and pure black. All of these do well.
Blue black is unpleasing, and is presumably never got intention-
ally, but results from accidental over-toning.

All the warm shades up to black do well, as has just been said,
and a wide range of them gives a most agreeable diversification
to a collection of views. It will be found, however, that every
negative lias some particular tone that gives its Ikst effects. This is a
fact that every photographer of refined artistic taste will perceive
and feel: it becomes, therefore, in the highest degree desirable

LANDSCAPE AND ARCHITECTURAL PHOTOGRAPHY. 233

to be able to say approximately of any negative in advance, or
on seeing the first proof taken, what toning will best suit it. The
following remarks may afford some clue to this knowledge.

Some negatives that have been taken with a highly favorable
illumination, and have been developed exactly right,.will exhibit
so exquisite a combination of contrast and harmony of light and
shade, that they will look well with any toning. They have no
defects to soften, and can hardly be spoiled in the printing. For
this higher class of negatives, a rich warm purple black, best
obtained by the acetate of soda or by the benzoate toning bath,
will be the most suitable.

Starting from a supposed perfect negative, we gradually pass
down to less excellent effects. In all, we shall suppose that
both the denser and thinner parts are full of detail (for if either
lacks it the negative will not be worth printing), but that these
parts, though each full of detail, do not work well together. If
the printing be stopped when the thinner parts are right, the
denser have not produced their best effects ; if it be carried on
until the latter are right, the former are too heavy and dark.

Now, this is a fault which may exist in every variety of degree.
If it exists to a large degree, the negative is worthless; if only to
a slight one, the intention here is to point out what course of
action will render such a fault the least conspicuous.

The lighter and the warmer the color, the less this bad effect
will be noticeable, a fact, I believe, which has never been pointed
out before, though possibly some may have acted on it. A print
must be exposed until the detail is out in the high lights, other-
wise it is a complete failure. The effect, therefore, of the dis-
cordance here spoken of, is always to produce heavy black
shadows, without detail, and the lighter and warmer the toning,
the less offensive will be these dark masses, and the more of de-
tail will be left in them. An observation of this rule will go far
towards getting a fair print from a somewhat faulty negative. But
it must be understood in the clearest way, that beyond a certain
point the want of harmony is an irretrievable one.

Conversely, it is evident that if a negative lack contrast, either
from the subject having been too monotonously lighted, or from
an over-exposure, a pure black toning, without too much over-
printing, will do what can be done towards affording a good
result.

234 PHOTOGRAPHIC MANIPULATIONS.

If these precautions be neglected, and if, for instance, a nega-
tive in which the contrast is already too great, be toned up to
full black, the result will be that ks faults, instead of being
softened, will be aggravated. And if the photographer is un-
aware of, or. does not appreciate, the principle here laid down, he
may never obtain more than a passable result from a negative
which, properly handled, might give a really good, though not a
first-rate, print. Generally an acetate toning bath will be found
the best for landscape prints.

CHAPTER VIII.

COMPOSITION.

\ 1. — Landscapes.

Of late years there has been a continually increasing realiza-
tion of the defects and incompleteness of landscape photographs
taken with entire ignorance of the principles of composition, and
it is becoming well understood that mere technical skill cannot
compensate for want of this knowledge, which, even in a very
elementary form, is found to be invaluable. So that, if two
persons, the one having some knowledge of artistic composition,
and the other ignorant of it, undertake to photograph the same
view, the former will always be enabled to make the best choice
of the point at which to plant his tripod.

Cultivated taste has learned that the representation of a land-
scape gives a completely satisfying effect to the mind most easily
by complying with certain general conditions which have been
reduced to fixed rules. Too slavish a compliance with these
leads directly to mannerism and sameness, but some acquaint-
ance with them cannot but be of the highest use to every intelli-
gent photographer.

Line of Direction — Balance. — In examining any picture, we
may discern certain lines of direction. These lines may be of
one prominent object, or may depend upon the directions of the
principal portions of a succession of objects.

It is a rule that these lines of direction should siqyort each other,
as in Fig. Ill, where the longer line is supported by the shorter.

COMPOSITION.

235

The longer line may, for example, be that of a distant range of
mountains, and the shorter that of a conspicuous bough of a tree,
or of any other prominent object in the foreground; or both
lines may depend partly upon distant and partly upon near
objects — it is immaterial. The essential point is only that the
characteristic lines of the picture shall balance each other. But

Fig. ill.

Fig. 112.

if the lines be all in one direction, as in Fig. 112, or even if not
quite parallel, there is a want of balance, and the idea of weak-
ness and of falling is given. Moreover, the effect of the repeti-
tion of direction is generally unpleasing, though it is occasionally
used to convey the idea of receding distance. In any case, how-
ever, it is necessary that these lines should be balanced.

A succession of perpendicular (see Fig. 113) or of horizontal
(Fig. 114) lines is, for the most part, unpleasing. As an example

Fig. 113.

Fig. 114.

of the former, we may take a row of straight-stemmed trees, the
effect of which is infinitely less pleasing than if their directions
are diversified. Parallel horizontal lines are rarely allowable;
sometimes, however, they are employed by artists in " parallel
perspective" — that is, where buildings are represented in full
front view.

As pictures are commonly bounded by four right lines, any
arrangement of the important objects in a picture that brings
them side by side, and at equal distances from the base line, pro-
duces to some extent the parallelism of Fig. 11-1. Similarly, if

236 PHOTOGRAPHIC MANIPULATIONS.

they are directly over one another, they form parallels with the
side, as in Fig. 113. The same principle applies also to the in-
troduction of a tree with a straight, perpendicular shaft, near to
the edge of a picture. It falls into an objectionable parallelism
with the side line. These faults are to be borne in mind and
avoided.

The Diagonal Line. — According to the direction into which the
principal lines of the picture fall, the composition is distinguished

into angular and circular. The diago-
Fig. 115. nal line, the simplest form of angu-

lar composition, is exceedingly well
adapted for representation of perspec-
tive, especially when, to get a better
range of effect, the distance is placed
towards one side of the picture.

It is by no means necessary that the
principal line of direction should pro-
ceed directly from one angle to the other. This angular line
of direction should always be sujiported — that is, the eye carried
along it should not be dropped vaguely, but fall upon some
object, which, though it must be distinct, need not be large.
This object is termed the " ruling point." An inspection of land-
scapes and groups executed by artists will show how far inge-
nuity has often been taxed to hit upon some object of this sort
in which to terminate a line of principal direction. In country
scenes, a dog, or a fowl, or any other small object in keeping
with the general subject, will be introduced into the foreground.
A little examination will show that its exact position has been
determined by a line of principal direction, and that the object
has been placed at its exact intersection with the ground. The
universality of this practice seems to indicate that it is correct ;
the principle is evidently that, after the eye has been carried
from one to another of the striking features of a picture, it
should not finally fall blankly upon nothing, but that there must
be some sufficient object upon which to rest. In most cases the
resting point or ruling point is made dark on a lighter ground,
though in some cases a lighter object than those that surround it
is used.

A beautiful and familiar instance of the balance of opposing
lines of direction is seen in mountains, the opposite sides of which

COMPOSITION. 237

rest against each other thus: A- So a gap between two moun-
tains gives lines that balance each other in the form V-

Circular Composition. — Curved lines of direction are often intro-
duced with very fine effect. Views of lakes, or of curved reaches
of rivers, will be apt to fall into this form, and it is seen in many
other compositions of rural scenery.

The Foreground.

The foreground is the portion generally most under the photo-
grapher's control, and those who desire to obtain the greatest
success will spare no pains in the selection of this part of their
picture.

The foreground should be diversified. A level, unbroken fore-
ground of grass or meadow cannot be expected to give a good
effect. It weakens the effect of the distance, and deprives the
picture of much of the character that it ought to possess.

A portion of the foreground should be occupied by some dark
object, whose effect will be materially enhanced if brought into
immediate contrast with some of the highest lights of the picture.
The best effect is for the most part attained by placing the dark
object in the foreground under the farthest distance. This gives
great tenderness and softness to the distance, causes it to recede
from the foreground, and at the same time supports it by lending
firmness and foundation to it. Too much attention to this point
cannot be given by the landscapist, who will, however, often have
his patience and ingenuity taxed to the uttermost to find anything
like a satisfactory foreground to his pictures.

There is a great beauty in very trifling objects, which many
habitually overlook. Bushes and vines, rocks, stones, logs, often
have elements of attraction that reveal themselves only by ob-
servation and cultivation. A tasteful arrangement of such objects
in the foreground of a photograph lends to it an inexpressible
charm.

The writer cannot, perhaps, find a more striking illustration
than in a clump of brambles. To many, such a thing would
seem to be so essentially ugly that it should be excluded, is pos-
sible, whereas, on the contrary, it is, both in nature and in repre-
sentations of scenery, almost always a very beautiful object. The
stems present often a beautiful combination of right lines and
graceful curves, the leaves have a surface that sends back light

238 PHOTOGRAPHIC MANIPULATIONS.

enough to give brightness to the lights, and, by contrast, depth
to the shadows. Often the more succulent shoots will hang over
in festoons of singular gracefulness. Late in the autumn, banks
of brambles retain their leaves long after the trees are stripped,
and then, if they can be introduced into a picture, they are most
valuable.

When the foreground is so level and unbroken that no diver-
sification can be introduced, a shadow, as of a large tree, falling
across it, at once relieves the tameness, and produces a beautiful
effect.

The Distance.

The distance should never find its place exactly in the middle
of the picture, which by such a disposition becomes divided, as
it were, into two equal halves, to the complete destruction of its
artistic character. In fact, no important object should be placed
exactly at the centre of the picture, which is by artists considered
to be a "weak point." Nor should any important object be
placed exactly upon the middle line which divides a picture from
top to bottom or from side to side. Its effect will be always
better if it is distinctly removed from either of these lines.

A peculiar pleasure is given when the eye is conducted from
the foreground to the distance by lines of direction. These lines
may be one or both banks of a river or stream, a picturesque
road, or other object. The leading should be rather by broken
and diversified lines than by straight ones.

A certain pleasure is communicated when objects in the middle
distance are repeated in the farther distance. Such a repetition
is not to be by the same object, but rather by some other object
in strict keeping. This rule is closely allied to one in painting.
It is laid down in painting, that if a particular color be introduced
in one place only, it has the effect of a spot or blot ; the color
must be carried through the picture, or at least part of it, by
recurring here and there. As in colors, so in objects. If trees
are seen in the foreground or middle distance, the eye is gratified
by seeing them reappear in the distance. If a cottage or other
building be a conspicuous object in the foreground, the eye likes
to see something similar in the distance.

The effect of a high light in the extreme distance is greatly
enhanced by placing a dark object in the foreground, somewhat
under it, but not perpendicularly. This acts partly by throwing

COMPOSITION. 239

the distance farther back, and thus powerfully aiding the impres-
sion of distance, and partly because the light becomes lighter and
the darkness darker through contrast.

If the different planes of distance are not well made out in a
photograph, that is, if they do not appear to occupy the same
relative position in the photograph which belongs to them in
nature, the fault may arise from the use of too small a stop,
which tends to produce a sort of map-like effect, or from the use
of a lens of too short or too long a focus. In the first case the
middle distance is transferred to the extreme distance, and con-
founded with it. In the latter case the middle distance is forced
forward into the foreground. (See chapter on Perspective.)

The Skies.

A blank white sky always disfigures a photograph, and must
be avoided if possible. Several alternatives present themselves,
one or other of which should be adopted whenever possible.

If large slow-moving clouds are present, they may sometimes
be caught, especially if the illumination of the landscape be good,
and so that it comes out rapidly, and without a prolonged devel-
opment, which, in wet plates, always thickens up the skies.
Large stops are always favorable for getting clouds with.

If clouds cannot be taken with the landscape, they may be
taken separately and printed in, for which directions are given
elsewhere.

But it is an excellent plan to cover as much as possible the sky
with foliage or other objects. Large trees in the foreground will
aid in this. In hilly countries the elevations will be a great aid.
In level districts it will often be useful to raise the horizon line.
Fortunately this line is, in landscapes, very much under control.
In architectural subjects, as the camera must always be hori-
zontal, we can only effect this by raising the camera front, or
bringing in the use of the swing-back. But in landscapes with
no buildings a good deal of tilting may be done without evil
effects. The horizon line is thus raised, and the proportion of
sky diminished.

In dry incite work we may often keep the sky thin, and thus
avoid the unpleasant whiteness. This is a very great advantage,
and is especially to be obtained with collodio-bromide plates, a
most important feature of that process.

240 PHOTOGRAPHIC MANIPULATION'S.

Some experienced landscape photographers, who know the
value of even a little shading to the sky, adopt regularly the fol-
lowing plan : When the printing is done, they open one-half the
back, and bend the sky end of the print in a curve backwards,
and so hold it to the light ; it thus becomes somewhat darkened,
and by doing this skilfully, the shading is regular. The amount
of trouble is almost nothing, and the gain decided. The writer
believes, from an inspection of prints by Bedford, Sovvlier, and
other masters of the art, that they constantly avail themselves of
this method.

Position.

The whole picture is generally composed with reference to
some one important object, to which all the rest stand in some
more or less definite relation.

Care must be taken that this object (or indeed any object to
which it is intended to give prominence) shall not occupy the
centre of the picture, which is always the weakest point in the
whole. Such an object may be thrown to the right or the left,
above or below ; it is unimportant, provided it be kept out of
the centre. If the conspicuous object improperly placed there
be small, it will look like a spot or blot ; if long, as, for example,
a tree, it will divide the picture into equal right and left halves.

It is apt to be a blemish if an object be represented as partly
in the picture, and cut off by its edges : it is true that to some
extent this is unavoidable, but it is objectionable, especially
when the subject so cut off is important.

Thus, if in a landscape a river is seen to run into one side, and
out of the other, a peculiarly unsatisfying impression is left upon
the eye, which is removed if the ends of the river are concealed
by trees in the foreground, rising ground, buildings, etc. Trees
themselves arc often unavoidably cut off by the sides and top of
the view. This is supported by the eye; but if a building of at
all a conspicuous character appears in the picture, and is partly
cut off by the edge, the effect is most unpleasing. With the
human figure this is still worse.

It has been held by some that no figure should be introduced
with the eyes directed at objects not themselves included in the
picture, and it cannot be doubted that the unity of effect is broken
by the spectator's attention being thus drawn away from the ob-
jects represented.

COMPOSITION. 241

It is still worse when the figures are represented looking at
the camera itself. This is the commonest of mistakes. At the
moment of taking the picture the camera is of course the central
point of interest to all present, and, unless expressly cautioned
by the photographer, any person who is in sight will inevitably
be found to rest his eyes on that instrument. In a great many
cases the figure will give a better effect if the back or side is
turned to the camera. Let us suppose that we are looking over
the brow of a hill, upon a lake or river below. A figure in the
foreground, resting against a tree, and apparently contemplating
the scene, will have an infinitely better effect than one apparently
watching those operations which it is the special object of the
photographer to avoid recalling. In the one case the figure
draws attention to, in the other from, the subject of the picture.

The figure itself should be thoroughly in keeping with the
scene. Just as a neat trim villa is a particularly uninteresting
subject for a picture, so a carefully dressed person looks com-
pletely out of place in any rural scene that is worth planting the
camera before. A laborer, a pedestrian carelessly dressed, country
children, these are figures in keeping with the subject. If a river
or a lake form part of the picture, a man fishing or wading will
acid to the life of the scene, but his appearance must correspond
with surrounding objects.

Generally speaking, whatever is neat, trim, and elegant, is dis-
pleasing in any view of natural scenery. A handsome carriage
introduced into the picture will look absurd — a farmer's cart
will probably be in place and a great help. It is not so much
the object itself, as its condition. A new market wagon, for in-
stance, with a glazed top, would spoil any picture. An ele-
gantly shaped and prettily painted skiff may look absurd, an
old barge or canal-boat will be appropriate and pleasing. A
gentleman in a dress coat, with a cane, a lady with flowers and a
parasol, introduced into any country scene, will spoil all our satis-
faction in observing it, whilst appropriate figures will be always
useful ; the rule that such figures must not look towards the
camera is never to be forgotten.

Nor should the figures be placed in too close juxtaposition
with the objects of principal interest, from the effectiveness of
which they would tend to detract, whereas in weak points of the
picture they will prove a positive benefit. They should always
assume easy attitudes, and such as will not be ungraceful or ridi-

2-12 PHOTOGRAPHIC MANIPULATIONS.

culous. The writer has seen an otherwise very pretty photo-
graph, in which was a male figure reclining on the ground. As
the face was towards the camera, the body was foreshortened, and
the one conspicuous object about him was the soles of his boots,
which exactly faced the spectator, and which, by reason of the
violent perspective of a short-focus lens, appeared greatly in-
creased in proportionate size. Such errors need only to be under-
stood to be shunned.

The Horizon.

It is always in the power of the photographer to place the
horizon where he will. If there be no subjects presenting per-
pendicular lines, the camera may be tilted at will ; if there be,
the sliding front may be raised or lowered, or inclination of the
lines resulting from tilting may be cured by the use of the swing-
back.

Raising the horizon line will often increase the beauty of the
picture, but, it must be confessed, somewhat at the expense of
truth. If a perfectly correct delineation of any scene be desired,
the camera must be levelled. Raising or depressing the camera,
entirely alters the relative inclinations of natural objects. Thus,
if a road descends a hill, it will equally descend in the picture if
the camera be levelled, but the writer has seen such a road repre-
sented in a negative as perfectly level, the whole descending effect
having been obliterated by inclining the camera downwards.
This raises the horizon line, and with it all the objects beyond
the foreground.

Where the object of the photograph is simply to produce a
beautiful picture, it is perfectly allowable to modify and improve
the scene in any way that we can. But where a truthful repre-
sentation is desired, the greatest care will be needed. There
exists a mistaken idea that photographs, being taken by mechani-
cal means, are necessarily correct representations of natural ob-
jects, and they are consequently offered and received as absolute
proof in courts of law, whereas nothing is easier than to create
false impressions with the aid of photography. No delineation
of natural objects is correct unless made with a lens of not less than
ten nor i.iore than twenty inches in focal length, with a levelled
camera, and with a centrally stopped lens. And before any photo-
graph is received in evidence, the photographer ought to be re-
quired to testify as to these points; at least this is true when the

COMPOSITION". 213

question depends upon relative size or position. Of course, if the
question is simply as to the existence or non-existence of some
particular object, the objections here stated do not exist.

It is an axiom with artists that the horizon lines should never
come across the middle of the picture and divide it into two equal
halves, but always above or below it. From what has been
already said it will be evident that in photographs the horizon
line will be more frequently above than below the middle.

Contrast.

Some of the highest pleasures which the eye is capable of en-
joying depend upon contrast. Contrast is of various kinds. Of
light, where the artist throws his deepest darkness against his
highest light, thus strengthening both. Of size, as, for example,
where the greatness of the majestic oak is made more apparent
by the shrubs or bushes at its base. Of form, as where the grand
elevation of the mountain is further ennobled by the level lake
or plain at its foot. Of character, as when the graceful lines of
pine-trees are contrasted with rugged roughness, as in Alpine
hills, or where slight and tender vines, with delicate tracery, are
seen clinging to strong trees or to the rocky sides of hills, or are
contrasted with the rigid lines of architecture. Of season, as
when winter snows look down from the mountain upon summer
verdure in the valleys beneath. Of mass, as when light clouds,
the lightest of all visible objects, rest upon mountains, which, of
all natural objects, give the most striking effect of weight. In a
word, the beauty of contrast is that which most completely per-
vades all nature. All our ideas are formed by comparison, and
contrast is comparison in its most vigorous form.

The brightest objects in a picture should not be too far from
the centre. If placed close to an edge, the effect is very objec-
tionable. The tendency of a picture should be to converge atten-
tion to the centre, not to scatter it towards the edges.

Repetition.

The repetition of lines of direction, as has been already said,
is for the most part unpleasing, and this holds with both groups
and landscapes.

But the repetition of objects themselves is often very pleasing
The echoing of a near object by a distant one has been already

244: PHOTOGRAPHIC MANIPULATIONS.

spoken of, but perhaps the greatest beauty of repetition is where
we see objects mirrored in calm water. Few persons are so utterly
destitute of the sense of the beautiful as not to appreciate, how-
ever imperfectly, the charm of this exquisite reflection. The
commonest object may in this way be rendered beautiful and
attractive. A log, a branch, a boat, insignificant in themselves,
immediately acquire a charm by being repeated in the water.
Often the inversion that accompanies reflection materially adds
to the charm by the variety which it affords, or by forming, as a
reflection often does when looked on in connection with the
object itself, a charming symmetrical figure.

Atmospheric Effect.

When a scene in nature, embracing objects at various distances
from the spectator, is depicted upon a flat surface, we are enabled
to distinguish between objects near and distant, in two different
ways.

One of these is Linear Perspective, treated of elsewhere. By
virtue of it, distant objects are diminished in size and brought
closer together, thus giving to the eye the information that they
are proportionately remote.

But the effect of linear perspective is greatly enhanced by
another agency, to which the name of aerial perspective, or,
better, atmospheric effect, has been given.

The atmosphere in its usual conditions is not wholly transpa-
rent, but interposes an exceedingly delicate veil, imperceptible
indeed as respects neighboring objects, but becoming more
evidently distinguishable as the distance increases. The eye is
thus greatly aided in judging distances, which it unconsciously
computes by the extent to which the softening effect of the
atmosphere reaches.

If this softening effect of the atmosphere be studied, it will be
found to act as follows : —

1. It diminishes contrasts. Dark shadows lose something of
their darkness, high lights of their brightness. This opposite
effect of the atmosphere on light and on shade needs some ex-
planation. Lights lose part of their brightness by reason of the
slight opacity of the atmosphere through which they pass. But
the darkness of the shadows is lessened by the light which falls,
not on them, but on the atmosphere through ivhich they are vievjed.

composition. 245

"We have a familiar example of this in the sky itself, which is
only the deep shadow of the outer darkness of space viewed
through a not perfectly transparent medium, which medium is
itself lighted up by the sun, and, under a well-known physical
law, diffuses the more refrangible or violet rays, and transmits
the rays belonging to the less refrangible end of the spectrum.
In clear weather the sky is deepest in color, because there is less
opacity in the atmosphere to receive and reflect the sun's light.
On a high mountain the sky is darker still, and at very great
elevations appears almost black.

2. It obliterates details. Smaller objects and parts of objects
easily distinguishable when near by, cease to be so in proportion
to the distance to which the object is removed, and of this the
eye takes due note and recognizes the cause.

3. It softens outlines. The dead limb of a tree near bv, for ex-
ample, cuts boldly and sharply on the sky, but the outline of a
trunk upon a hill in the middle distance is already somewhat
softened, and the outlines of distant mountains are still more so.

Consequently, atmospheric effect tends to give soft grays and
middle tints to distant objects, and to efface all sharp contrasts of
light and darkness. Lines also out each other less sharply. In
nature we find a very wide range of variety as to this influence.
When the air is very free from moisture, as on some of the arid
plains at the base of the Rocky Mountains, atmospheric effect
almost disappears, and distant objects appear unnaturally and de-
ceptively near. It is not too much to say that the capacity of the
eye for judging correctly of distances is actually destroyed. From
this extreme we may pass through every degree to the other,
when the air is so laden with mist that near objects seem farther,
and distant objects disappear altogether.

It is a curious fact, and one of the highest importance for the
photographer to understand, that both the process which he uses
and his lenses themselves may have a great influence on the
amount of atmospheric influence which will appear in his pictures.

The tendency of the ordinary wet process is to give a mode-
rate amount of atmospheric effect. The dry processes differ
extremely in this respect, according to the preservative used.
Thus tannin, cloves, coffee, gallic acid, and similar preservatives
tend to diminish atmospheric effect, whilst gum has the very
valuable property of enhancing it in quite a remarkable way, and

246 PHOTOGRAPHIC MANIPULATIONS.

thus becomes a most valuable adjunot to other preservatives,
though, when well managed, it is capable of acting well alone.

The lens has likewise something to do with this rendering,
though its action has been by some writers a good deal exagge-
rated ; it is the size of the diaphragm used that has more to do
with the atmospheric effect than the lens itself.

A large diaphragm will always tend to increase, a small one to
diminish, aerial perspective. This is caused in two distinct ways,
co-operating to the same result. For a small diaphragm will
always greatly increase the depth of focus, so that when the focus
has been taken, as it always must be, on near objects, a small
diaphragm will cause the distance to be in sharp focus also. This
will increase the detail of the distance, and, as it has been already
shown that one way in which atmospheric effect shows itself is in
tending to obliterate detail, the greater depth of focus necessarily
tends to counteract the effect of the atmosphere. Again, a small
diaphragm always tends to harshness of contrast, and it has been
also shown that aerial perspective especially shows itself by
diminishing contrast. Clearly, therefore, aerial perspective will
be produced in direct proportion to the size of the diaphragm.
This explanation tends to throw additional light upon the fact
stated in a previous chapter, that a large stop materially aids the
effect of distance by placing objects in their proper planes of
distance from the eye.

It is, however, sufficiently apparent, from what has been pre-
viously said, that lenses will differ somewhat amongst themselves,
independently of the diaphragm, as to the rendering of atmos-
pheric effect, inasmuch as some have greater depth of focus than
others.

Those photographers who are accustomed to plant their cameras
in front of any conspicuous object, satisfied if it covers enough of
their plate, and if they can get a clean negative of it, will natu-
rally, in the same spirit, endeavor to get the same sharpness in
the distance (so far as practicable) as in the foreground. Such
will be found working with small diaphragms, and acid baths,
and getting technically perfect negatives, which will yield prints
that no one cares to look at a second time, prints in which the
foreground lies flat upon the middle distance, and both on the
extreme distance, which, instead of striking the eye at once with
a unity of effect, have to be looked at attentively before the rela-

COMPOSITION". 247

tions of the different parts explain themselves — in a word, prints
which are a reproach to photography.

It must at the same time be very clearly understood that the
writer is as far as possible from wishing to say that a photo-
graphic landscape should show a clean cut foreground, and a
hazy, woolly-looking distance. No rules must be carried to
excess, or the truth and beauty that result from them are de-
stroyed by exaggeration. That objects several miles away should
be as distinct and sharply cut as those near at hand, is unnatural,
or at least occurs in certain regions and in peculiar states of the
atmosphere only, with which we have not here to do. It cannot
be right, therefore, and it certainly is not pleasing to an educated
eye, that they should be so represented in a photograph or in any
other form of delineation. As already said, the landscape painter,
with this matter under his absolute control, always softens the
distance.

\ 2. — Portraiture.

What has been said in the foregoing section finds its natural
application also to portraiture. Lines must be balanced and sup-
ported ; light must be brought out by opposing it to shade, in
portraiture as in landscape work.

To give an agreeable and graceful effect to a single standing
male figure, has always been a difficulty which has taxed the
genius of artists to evade. When a man clothed in our modern
habiliments stands erect, the lines of his arms and legs fall into
parallelism with his body, and the objectionable effect of parallel
perpendicular lines has been already pointed out (Fig. 113). There
is perhaps no effectual way by which, in our ordinary portrait,
this difficulty can be disposed of, unless some characteristic occu-
pation or position can be adopted. A soldier, for example, may
rest upon his musket, a fisherman may have his rod so disposed
as to afford a supporting line, and so on; but as the great mass of
those who present themselves to be represented by the camera do
not care to figure in connection with any particular vocation, it
follows that for the most part the best that can be done is to adopt
a sitting posture, not in profile unless the back legs of the chair
can be supported, and try to relieve this by surrounding objects.
Good effects are often obtained by representing the sitter as either
engaged in some occupation, reading, playing on some instru-

248 PHOTOGRAPHIC MANIPULATIONS.

ment, examining some object, or, often better, as having just
turned from having so done.

When several male figures are introduced together, their lines
may be made to support each other; but here, again, a photo-
graphic difficulty is introduced — the necessity of keeping the
heads to a certain extent in the same plane of distance.

The ingenuity of the photographer will often be here taxed
to a severe extent. He may be aided by the following obser-
vations : —

Where two or three heads are present, they should rarely be
placed, as so very often seen, on the same level, but should form
a pyramidal arrangement, or else fall into the diagonal line. Or
the middle head may be the lowest. If a fourth head be intro-
duced, it may either fall into one of the lines of the above forms,
or the lozenge-shaped composition may be adopted. If more
than these are present, they may either have a place in the
principal arrangement, or a secondary group may be formed. It
is always to be remembered that, in obedience to the exactions
of the lens, the farthest figure must be also the most central.

A group of three persons will generally be the most manage-
able. Somewhat less so with two or four. When the number
increases, difficulties are multiplied ; when it diminishes to one,
the difficulties of getting a satisfactory attitude are, as already
said, most serious. A standing portrait of a man gives almost
invariably the effect of a person placed for the express purpose
of having his picture taken, and this is apt to be made worse by
the conscious look generally assumed by the person.

The same remarks apply, though to a somewhat less extent, to
female portraits. The form of the dress considerably relieves
the difficulty, as it represents two opposing inclined lines which
tend to support each other. Nevertheless, single portraits of
standing female figures are apt to bear a stiff appearance, unless
in the hands of very artistic photographers. When sitting,
however, this is wholly changed. The drapery can be very much
varied, and a great support can be got by regulating the folds of
the dress so that these shall run in directions which shall relieve
and support the other lines of the picture — that is, that some of
the lines of drapery shall oppose and support the lines produced
by the direction of the body, the position of the arms, &c. The
position of the arms can often be regulated in sitting figures,
both of men and women, to greatly aid in balancing the lines of

COMPOSITION. 249

the body ; and here a thousand expedients come in to give occu-
pation to the arms and explain their position.

In groups of female figures, or of men and women together,
the same remarks as those made respecting the positions of the
heads for men of course apply.

Two useful observations remain to be made before we close
this very brief section on an important subject.

The lines which connect the heads of a group, form always the
principal lines of the picture. Such lines should never be per-
mitted to simply run out and end in nothing, but when carried by
the eye to the bottom of the picture, should fall on some object,
precisely as already explained in landscape composition. Thus,
if a line of direction, when extended by the eye, reaches a table,
for example, at the point of intersection there should be placed
some small but very distinct object, dark on a light ground, or
light on a dark ground. A book, an open letter, or, still better,
some object characteristic of the taste or occupations of one or
more of the sitters, will be suitable. If a line of direction reach
the floor or a wall, the same principle of course holds good.

Again, a line in some parts of the picture, whose direction
crosses that of the main line of the picture, will give an excellent
effect by supporting it. This line may be anything, a cane or
staff, any object whatever, even the line of an arm. //!*need not
cross the line of direction, only so that its direction does so.

Thus, let A, B, C, be the heads of any group. A B will be the
most important line, opposed and balanced by A G. But, also,

../■

some other line, D E, if introduced, will greatly support the line
A B and balance the picture. And where the line A B, if con-
tinued, would terminate at F, on the ground or elsewhere, there
should be some object for it to rest upon, as explained above.
17

250 PHOTOGRAPHIC MANIPULATIONS.

§ 3. — Influence of Light.1

Our perception of the inequalities of surface, of relative distance,
and in fact of the shape and position of bodies generally, de-
pends almost wholly upon light and shadow.

Take, for example, an outline drawing of a building. The
eye, chiefly by habit and education, understands that a solid
body, and not a flat surface, is intended to be depicted. I say,
the eye understands, for it seems more like a deduction than a
perception.

If now the artist washes in even only a single shade of neutral
gray behind each projection, how these projections suddenly start
out and strike the eye! As if by magic, the whole building has
assumed a visible solidity, and if the work has been correctly
performed and the shades duly graduated, the eye instantly recog-
nizes the length, breadth, and height of the edifice, and is able
to derive whatever pleasure its justness of form is fitted to afford.

Any photographer who frequently passes a public building
with many projections, such as are especially to be found in
Gothic architecture, and who will stop and carefully study the
effects of different lights upon it, will be amply repaid, and will
learn more by a few minutes given twenty or thirty times, or still
oftener, Than by a year's random photographing.

At times the light is so exceedingly uniform and so broken by
clouds, that every portion of a building will be almost equally
lighted. So far from this being an advantage, the structure will
be found on critical examination to look extremely flat and tame,
and if photographed in such a light, its photograph will also be
deficient in relief. This great uniformity of light may occur with
various amounts of illumination, and though more common in
dark weather, will sometimes be seen when the light is tolerably
good.

When the clouds are thinner, a considerable quantity of direct
light (without notable sunshine) may pass through them. In
this case projections cast faint shadows, and the relief is greatly
improved.

With still thinner clouds, faint sunshine passes through. The
inestimable value of a very faint sunshine every experienced pho-
tographer will fully recognize. Photographs of natural scenery,

1 See also ante, Remarks on causes of unsatisfactory results in portraiture.

ON COPYING-. 251

taken in the absence of sunlight, are apt to be tame and monoto-
nous. A faint sunlight gives an exquisite relief and life to the
whole, with beautifully illuminated shadows.

When the sun is fully out, and especially towards the middle
of the day, the contrasts become excessive, and before the details
in the shadows impress themselves, the high lights suffer.

The case of a building has been chosen as an example, but
precisely the same holds good with portraiture. The shape of
features, the character and expression of the face, all these depend
upon light and shade and their due management.

In examining the work of professed portraitists, we constantly
observe the faults here pointed out as being so easily seen and
judged in a building, which last, from its invariable position
and (so to speak) expression, enables us to compare the effects of
different lights so very advantageously. These faults lie, on the
one side, in too uniform a lighting, by which the features are
rendered flat and the expression stupid, or at least less intelligent
than the original ; and, on the other, in too great contrast of
lighting, whereby the character of the features is exaggerated,
and the expression rendered stern and hard.

These two generic faults represent the Scylla and Charybdis
of the portraitist, and, with the varying lights of the day, will
require his most intelligent efforts to avoid.

CHAPTER IX.
ON COPYING.

Copying by photography falls into three classes : —

1. Copying oil paintings and drawings in color.

2. Copying mezzotints and lithographs, and drawings in

Indian ink and sepia, &c.

3. Copying line engravings, wood-cuts, pen and ink drawings,

and pencil drawings.

These three classes will require different treatment, but all the
varieties in one and the same class will require the same, or
nearly the same, management.

Old oil paintings, in which the backgrounds have become very

252 PHOTOGRAPHIC MANIPULATIONS.

dark and the colors have lost their brilliancy, are especially
difficult to copy; in fact, in many cases, it will be impossible to
obtain really satisfactory results.

The best instructions that can be given are, to use a pretty
wide stop, give a long exposure, and use a collodion containing
equal parts of bromides and iodides. (See also Chapter XV.,
Eemarks on keeping plates.)

In the second class above enumerated, we included subjects
which, though in monochrome, present gradation of tint. These
will require to be treated, through all the stages, very much as
views, and with the same care to avoid harshness and excess of
contrast.

On the contrary, the third class will require a widely different
treatment. With these the object will be to get, not to avoid,
strong contrasts. The originals are composed of only white and
black, the half-tints depending upon the presence of more or
less of each of these constituents. A white and black negative
will therefore be wanted.

But it is an entire mistake to suppose, as was for a long time
believed, that this was best accomplished by the use of a collo-
dion containing little or no bromide. The author of this book
long since pointed out that copying was best done with ordinary
landscape collodion. Iodide of silver is more sensitive to a strong
light, bromide to a weak light. Now, as line engravings require
to be copied with a very small stop, the light is always weak,
consequently bromide is needed ; and this view is fully supported
both by direct experiment and by common experience.

To obtain a fine copy of a line engraving, in which the hair-
lines are to be faithfully and sharply reproduced, requires a good
lens, well managed. The stop must be very small, not exceeding
/ 60, or one-sixtieth of the focal length. The lens should be a
large one.

Copying is the most delicate and difficult branch of photo-
graphy. The faint light admitted by the small stop cannot form
a brilliant image; the attraction to the developer is therefore
weaker, and the tendency to the production of stains is greater,
whilst no department of photography requires so absolute an
absence of stains as this. Consequently, photographers generally
confine themselves to the central parts of the plate, or at least
leave a border of an inch or more around the image, as it is the
borders that are most exposed to these troubles.

ON COPYING.

253

The bath must necessarily be in good order, giving clean,
blooming negatives. The developer must have a full, though
not excessive, dose of acetic acid. The development must not
be prolonged, but be rather a brief one, and if a very strong
negative be wanted, recourse must be had to after-intensification.

The best means of effecting this is to place the plate in a solu-
tion of corrosive sublimate until it becomes entirely white, and
then to flow it with a 1-grain solution of cyanide of potassium.
The cyanide instantly blackens the negative, whilst at the same
time it clears away all tendency to veiling, if any existed.

Another excellent method is to chlorize the paper, and then to
apply Schlippe's salt. (For details of both methods see p. 173.)

But, for the most part, an ordinary development, followed if
necessary by a re-development, after fixing, will be sufficient, re-
membering, however, that neither development nor re-develop-
ment should be pushed. The re-developing liquid should be
used no longer than it is quite colorless, instead of serving, as
in other work, as long as it is clear. Heavy deposits of silver,
if allowed, will evidently clog up the finer lines.

The lens to be used must be free from distortion, and have as
flat a field as possible. The old orthoscopic lens, now rarely
made, copied excellently. The view lens is unsuitable. Almost
any centrally stopped lens, except the portrait combination, may
be used with success, the Zentmayer, Steinheil aplanatic, Dall-

Fig. 117.

>AiA|AJAi

meyer rapid rectilinear, Eoss's doublet, the triplet, from any of

these, if a good specimen of its class, good work may be expected.

As the focus is always longer in proportion as the size of the

25-i PHOTOGRAPHIC MANIPULATIONS.

image is large compared with the object, it follows that for copy-
ing, the camera will often need to be lengthened out, and this is
done with an " extending cone." Fig. 117 represents a form
devised by the writer, in which the flap C is hinged on to the
cone, and serves to support and steady it. The cone at B ex-
tends beyond the tube of the lens, so as to form a sort of hood,
excluding extraneous light. Unless means are taken to prevent
extraneous light from falling on the lens, brilliant and clear
copies cannot be obtained.

Generally speaking, it is best to place a line engraving in
full sunshine, Avhich should fall on it in a direct line, and not
obliquely. The more slanting the direction of the sun's rays,
the more conspicuously will the grain of the paper, and also
other irregularities, be rendered in the negative. By using direct
sunshine, it becomes possible to work with the smallest stop fur-
nished with lens, thereby reducing the astigination (p. 61) to a
minimum, and so to obtain the hairlines in the high lights of the
engraving, accurately reproduced.

For copying Daguerreotypes, sunlight reflected by a mirror
gives excellent results. Photographs may be copied in the same
way, or by a good strong out-door diffuse light. They do not
need so very small a stop as line engravings do, and consequently
not so brilliant a light.

Meclianical Appliances. — When an old picture is to be copied,
it will be well cleaned and then hung up in the sunshine. (It
seems probable that an application of glycerine would give a
clearness and brightness that would materially aid in copying.
Afterwards the glycerine could be easily removed with a wet
sponge.) Fix the camera so that each corner of the picture shall
be equally distant from the centre of the front lens, and take
care that all parts of the picture shall be equally illuminated,
also that the direction of the sunlight shall be such that no re-
flections shall reach the lens.

The copying of engravings and smaller pictures may be done
in tin- Bame way. But it is more convenient to make a special
arrangement as follows: — •

A square piece of wood of convenient size is placed upright
upon a long narrow table, giving the piece of wood the same
breadth as the table. At the sides of the board (see Fig. 118)
strips two or three inches wide are fastened, coming some inches

THE STEREOSCOPE.

255

below the table top, and fitting close up to it. These act as guides,
so that when the square piece of wood is pushed backward

s or

Fig. 118.

forwards, it always retains a position at right angles to the long
side of the table. Behind another narrow strip is fastened, to
act as a base and keep the board vertical. Diagonal lines are
drawn from the corners, fixing the centre. The camera is raised
on blocks until the middle of the lens is opposite the intersection
of the diagonals.

If now we place any object to be copied on the centre of the
board, which the diagonals easily enable us to do, we have
simply to move the board backwards and forwards until the size
and the focus are obtained. The general arrangement secures
what is always essential in copying, viz., that the object to he copied
shall he exactly parallel with the focussing screen. In the arrange-
ment here described, the camera is always kept with its sides
exactly parallel to the table, then the board being at right angles
with the side of the table, the necessary parallelism is insured.

Plans may be well copied by simply laying them on sensitized
paper and exposing. This gives a paper negative, which is to be
laid on other sensitized paper and exposed — if the resulting posi-
tive is not strong enough, it is brought up by development.
Plans of several feet square, made for the Treasury Department
at Washington, are thus beautifully multiplied by Mr. Walker,
the photographer of the department.

256

PHOTOGRAPHIC MANIPULATIONS.

CHAPTEE X.

Fig. 119.

THE STEREOSCOPE.

This ingenious invention of Prof. Wheatstone depends upon
the fact that the two eyes see the same objects differently in con-
sequence of their difference of position. If we view a collection
of objects, as, for instance, trees in a grove, and then moving
our position by a few yards, we view them again, their relative
positions will seem changed. A smaller change produces this
in a lesser degree, and even the space between the eyes cor-
responds to a change of aspect, which, small as it is, aids greatly
in fixing relative positions. This will be better exemplified as
follows : —

Let the polygonal figure (Fig. 119) be viewed by the eyes E
and E'. Its distance from them and its size may easily be
imagined such that the eye E will see the five
sides, 1, 2, 3, 4, 5 ; whilst E' will see the five sides,
2, 3, 4, 5, 6. The eye has, by long experience,
learned unconsciously to combine these two por-
tions of the polygon, and to understand thereby
that it is a solid body, and not a mere projection
on a fiat plane.

If we suppose, instead of the polygon at Fig.
119, that we look at a pillar, of a portion of which
that polygon is a section, the mind realizes that
it is a solid body by its consciousness that the one
eye sees partly round it on the one side, and the
other upon the other side.

If then, whilst viewing any scene, we close
first the one eye and then the other, it is evident
that we shall see slightly different scenes with the respective eyes,
the combination of which two scenes gives us a distincter sense
of distances and positions, than what would result from observa-
tion by either eye separately.

Now, if we place two lenses in positions of distance corre-
sponding with that of the two eyes, each will be capable of pro-

MICROSCOPIC PHOTOGRAPHY.

257

ducing an image corresponding with those seen by the separate
eyes. And if these pictures be placed side by side before the
eyes, and each be looked at by one eye separately, these two
images may be combined by the brain, precisely as the two views
seen by the eyes in observing a landscape. Such pictures are
made in the stereoscopic camera, in which, however, the lenses are
placed somewhat farther apart than the distance which separates
the human eyes, it having been found by experiment that the
effect so obtained is more striking than if the actual distance
between the eyes were maintained with the lenses, which also it
would not be easy to carry out in practice.

All the operations with the stereoscopic camera are precisely
the same as with the ordinary, except the mounting of the prints
when finished. These should be cut with care to a convenient
size, keeping the centres of the cut prints to correspond as nearly
as possible with the point directly opposite the centre of the lens.

In pasting, they must be reversed, that is, the print which is
on the right hand side as printed, must be mounted left. It has,
however, been shown that this may be avoided by cutting the
sensitized paper to twice the length of the negative, and folding
its ends till they meet at the centre.

The figure represents the paper loosely folded. B and G are
pressed down till the edges E E' meet. The sensitive side of the
paper is outermost. Apply the side
B G to the negative; a print is taken.
The sheet is then turned round and
the other side printed. Cutting
through at A, and opening out, B
and the piece behind it give one
print, and G and that behind it,
another, each with the sides cor-
rectly placed for mounting, and not needing to be reversed.

A pair of stereoscopic views may be obtained with a single
lens. The two views are taken separately, and the camera moved
a little laterally for the second view.

The stereoscope, which for some time enjoyed an almost un-
bounded popularity, has latterly been much less prized. Larger
views, from half size to 10 x 12, are capable of so much more
artistic effect, that they are taking the place, and deservedly, of
the stereoscopic slides, and will, no doubt, increasingly in future.

Fig. 120.

258 PHOTOGRAPHIC MANIPULATIONS.

CHAPTER XL

MICROPHOTOGRAPHY AND MICROSCOPIC PHOTOGRAPHY.

The first of these processes has for its object the production of
extremely small images of objects intended to be viewed by the
microscope. The second is the impression upon a collodion film
of the image seen in the microscope.

§ 1. — Microphotography.

If a negative be placed in a suitable apparatus, and its image,
extremely reduced in size, be thrown by a very short focus lens
upon a sensitized albumen plate, that image may readily be de-
veloped by appropriate means, and a sharp fine positive image
be got, which, when viewed by a sufficient magnifying power,
may exhibit satisfactory detail if all the manipulations have been
well performed. The process evidently involves no real difficulty,
except that the image is so exceedingly small that its develop-
ment requires to be followed by the microscope.

The form in which this description of work first attracted public
attention was in the reproduction of objects which, by magnify-
ing, were made to exhibit striking details, lettering, for example.
A monumental tablet, for instance, reduced until much smaller
than a pin's head, when placed under the compound microscope,
showed many lines of lettering, all perfectly distinct.

Subsequently, however, M. Dagron gave a new impetus to the
matter by substituting for the microscope a modified Stanhope
lens, having one end a plane surface, to which the microscopic
print was attached permanently by Canada balsam. These lenses
were manufactured out of glass rods at an infinitesimal price, and
enormous quantities have been sold in Paris. In this country
they have attracted but little attention.

In the late war between Germany and France, immense use
was made of microscopic photographs, by sending them on collo-
dium plates with the aid of carrier pigeons, into Paris.

MICROSCOPIC PHOTOGRAPHY. 259

§ 2. — Microscopic Photography.

In microscopic photography the images are enlarged greatly,
above the natural size. The operation differs from ordinary en-
larging, both in its object and method.

In ordinary enlarging, the object is usually to reproduce from
a small negative a large paper picture, though we also may
obtain enlarged negatives on glass. But in microscopic photo-
graphy the object is to get negatives, large or small, of micro-
scopic objects, often enormously enlarged.

Dr. "Woodward, of the U. S. Army, has far exceeded all other
experimenters in this direction, whose results have come under
the writer's notice. Amongst other interesting specimens re-
ceived from him are images of test plates made with different
kinds of light. The effects obtained with sunlight are altogether
inferior to those yielded by the artificial lights, and of these the
magnesium light and the electric light obtained with carbon
points gave better results than the calcium light ; even the latter,
however, proved itself far superior to sunlight, the inferiority of
which last could hardly have been anticipated in the absence of
decisive tests.

A powerful beam of light, from any of these sources, is thrown
through a compound microscope, and the image is received upon
a sensitized collodion film. An ordinary nitrate bath was used
by Dr. Woodward, with the author's collo-developer (see p. 164)
and an after-intensification with Schlippe's salt, or with mercury.

By these methods Dr. Woodward has been "enabled to pro-
duce pictures of the utmost sharpness, and perfectly satisfactory
in every other respect, with powers up to two thousand and five
hundred diameters, and these pictures bear a further enlargement
of from six to eight diameters in a copying camera. We have
thus obtained excellent pictures up to ten thousand diameters."

Ordinary collodions were found to work very well. For great
enlargements, where the light was weak, a collodion containing
two grains of bromide of magnesium and five of iodide of magne-
sium was found useful, the deliquescent action of the nitrate of
magnesium formed preventing the drying of the film.

With the very highest powers, such as Powell & Lealand's
one-fiftieth objective, the correction of the objective to suit the
violet light was found to be so small as to be practically unim-
portant. But with one-eighth, for example, it was found to be

260 PHOTOGRAPHIC MANIPULATIONS.

essential. As a general thing, images taken with the one-eighth
and enlarged, gave results as good as those obtained directly with
the one-fiftieth.

Drs. Woodward and Curtis have obtained many valuable mi-
croscopic photographs by this process, which is exceedingly well
adapted to increase our knowledge of the structures of animal
and vegetable tissues. The writer has received from them beau-
tiful enlargements of minute bloodvessels and blood-corpuscles,
etc. One of their most successful amplifications has been that
of the Pleurosigma angulatum, of which they have obtained good
photographic prints on paper, magnified up to nineteen thousand
diameters.

CHAPTER XII.

DEVELOPMENT ON PAPER.

§ 1. — Positive Development on Chloride of Silver.

Development on paper requires to be differently managed
according as we wish to obtain positives or negatives. These
operations will be considered under different heads, commencing
with positives.

Positives may be developed on paper with the aid of either
iodide, bromide, or chloride of silver, or with a mixture of these
substances. From his own trials, the writer long since decided
on chloride as being the best, and the process published by him
several years ago has been largely adopted with or without con-
siderable variations.

If paper be impregnated with chloride, bromide, or iodide of
silver, be exposed for a short time under a negative, and then be
thrown into a saturated solution of gallic acid, a picture will
soon be developed, which will go on increasing in strength, and,
when satisfactory, may be taken out, washed, and fixed. Such
was the original idea of development, which we owe to the late
Eev. J. B. Reade, though it was shortly after taken up and per-
fected by Mr. Fox Talbot, to whom, by many, it has been as-
cribed. Both these experimenters operated with iodide of silver,
and turned their attention rather to negative development than
positive. Some years later, Blanquart Evrard took the process
up, used a mixture of bromide and iodide of silver, fumed with
hydrochloric acid, and toned his pictures with hyposulphite and

DEVELOPMENT ON PAPER. 261

gold. His results were magnificent, and for a while it was as-
serted that none of his pictures had ever been known to fade.
With increasing lapse of time, however, this has ceased to be
true, and his pictures have in some cases faded.

The process which the writer brought forward was based upon
the use of lead in connection with gallic acid. It had been known
before that the addition of acetate of lead to gallic acid greatly
increased its powers of action, but as a precipitate was formed,
rendering the liquid muddy, this objection interfered with the
use of the lead salt, and the fact remained without application.

Having ascertained that gallate of lead, the precipitate formed
when acetate of lead was added to gallic acid, was soluble in
acetic acid, the writer applied this observation to development
both positive and negative, and with excellent results, especially
in the former case. The economy of gallic acid was enormous,
the rapidity of development was heightened, and, what was of
far more consequence, the clearness of the development was
greatly enhanced, so that of all kinds of development, this was
the safest and least liable to accident. The course was so regu-
lar and uniform that many prints could be developed at once, and
the bath kept in working order for a longer time and with a
greater number of prints. This was probably because the large
quantity of acetic acid used restrained the precipitation of the
silver, whilst the action of the lead expedited the development.

The following are the details of this process.

For a twenty-four ounce developing bath, dissolve four grains
of gallic acid in a few ounces of water, and add about half an
ounce of a solution of acetate of lead, thirty grains to the ounce,
of which a stock may be conveniently kept on hand. A thick
white precipitate falls. Next add acetic acid till this precipitate
redissolves — a little excess of acetic acid does no harm, but is
rather beneficial. Filter this and dilute to twenty ounces. To
four ounces of water add a few drops of solution of nitrate of
silver from the positive printing bath, and mix with the rest.

These various operations should be performed a short time
only before the bath is wanted, as naturally it will not keep.

The development may be effected either on plain or on.albu-
menized paper. It is commonly believed, universally it might
be said, that development on albumenized paper is impossible,
but this is a mistake. The treatment of the paper must be dif-
ferent, but either sort will develop in the foregoing bath.

To develop on plain paper, float it for one minute upon a five-

262 PHOTOGRAPHIC MANIPULATIONS.

grain solution of sal-ammoniac. Sensitize on a nitrate bath acidu-
lated with tartaric acid, as follows : —

Nitrate of silver 1 ounce.

Tartaric acid 26 grains.

Water 13 ounces.

Good results can be obtained with half this strength, but for
general use it is not advisable to economize the silver so much.
It is almost superfluous to say that this sensitizing, and the
placing in and taking out of frames, will be performed in a room
by yellow light, and not as in the preparation of ordinary posi-
tive paper. The same care in excluding white light as in the
wet collodion process must be exercised.

The paper, when dry, is placed under a negative and exposed
to light, direct sunlight is best, for from fifteen to sixty seconds,
according to the light, the season, and the negative. The writer
advises to continue the exposure until the image reaches a pale
chocolate color. Some stop at the pale violet. Good results are
got either way, but the former seems preferable. Of course the
frame must not be opened for examination.

It is a mistake to assert, as some have done, that no details are
got in the development that were not visible faintly in the print
when taken from the frame. On the contrary, much that is not
any way visible, comes out distinctly in the development.

In fact, the writer has proved this capacity of chloride to yield
details in development, which were originally invisible, in rather
a striking manner. A piece of paper sensitized with a chloride
only, was taken and placed behind a negative, and a single mag-
nesian spiral was burned at a little distance. On removing the
paper nothing was visible, but the careful application of a de-
veloper brought out the image with all the details, in a surprising
manner. The details were as full as if iodide of silver had been
used, but the picture was very flat.

When, then, the print is judged to have been sufficiently ex-
posed, it is removed from the printing frame, and plunged evenly
and quickly into the developing bath. With the bath above
described, the development requires about five minutes to com-
plete it. The prints should generally be stronger than they are
intended to be when finished, for they lose in the fixing.

As soon as the print is judged to be sufficiently developed, it
is thrown into water to stop the action, and is then toned with
gold precisely in the same way as with any other positive on
paper. If not toned, it will have an unpleasant coppery color,

DEVELOPMENT ON PAPER. 263

which seems almost unavoidable in developed prints. The writer
has, however, obtained a pleasant purple tone by using serum of
milk (whey, see foot of p. 264) in the salting of the paper.

It will be seen that the above bath, though containing only
one-sixth of a grain of gallic acid to the ounce, acts much like
an ordinary developing bath, made twenty times stronger. This
shows how remarkable is the agency of lead in increasing the
activity of gallic development.

For albumenized paper a larger dose of tartaric acid is ad-
visable. Take —

Nitrate of silver 1 ounce.

Tartaric acid 3G grains.

Water 12 ounces.

Float on this ordinary albumenized paper for two to three
minutes, and then proceed otherwise as before.

Paper prepared in this way, although albumenized, bears de-
velopment very well, and gives good results. . Not so good, how-
ever, either on albumenized or plain, as with sun-printing, though
sometimes not far behind. Still, it must be said that when the
sun's light is left to do its perfect work, that work is better and
more completely done than when we break it off just commenced,
and force our solutions to complete it. It would seem that it
could not be otherwise. There is less depth in the shadows and
less brilliancy. The developed print is apt to be softer than the
direct sun print, and shows less contrast ; it is also more sunk in,
and shows the grain of the paper more. And, although the de-
velopment can be effected on albumenized paper, it is more diffi-
cult and less certain than on plain.

This last described paper has good keeping properties. If
placed in a tight tin case, thoroughly protected from light, it
shows but little tendency to spontaneous decomposition, and I
have succeeded in developing a perfectly clean picture, after an
interval of at least ten days after sensitizing.

§ 2. — Negative Development on Paper.1

Calotype Process. — Float paper on a 20-grain plain solution of
nitrate of silver, and then, after drying, upon a 25-grain solution

1 An interesting negative process on paper, by Mr. H. J. Newton, will be
found in the Philadelphia Photographer, vol. iv. page 187. The writer regrets
that space will not allow him to extract it in full.

264 PHOTOGRAPHIC MANIPULATIONS.

of iodide of potassium ; on the first solution for one minute, on
the second, ten minutes. Dip in water to wash off the excess of
iodide and dry. In this condition the paper keeps well, if pro-
tected from light.

Make now 6 ounces. of cold saturated solution of gallic acid,
dissolve 300 grains nitrate of silver in 6 ounces of water, mix the
two and add an ounce of strong acetic acid. No more of this
sensitizer should be made than is needed, as it will not keep more
than a few hours. Therefore, in sensitizing a few sheets it is
better to make much less and brush over the paper instead of
floating. Whether dipped or floated, the solution is left on but
a minute ; the sheet is dipped into water, the excess of moisture
blotted off with bibulous paper, and the sheet is ready for use.
A very brief exposure is sufficient to form an image which will
go on strengthening in the dark, or may be hastened by washing-
over with the sensitizing mixture, just above described, and
holding to the fire.

This process gave excellent results, and was long a great
favorite, until the collodion process superseded it. The negative
so obtained may be paraffined as follows.

Paraffining. — Take a fine translucent paraffine candle — not the
parafnne that resembles spermaceti, but the very translucent,
sort — and scrape it down to shreds with a knife or piece of broken
glass. Strew some of these on a piece of filtering paper, lay the
negative upon them, put more shreds on the negative, then another
piece of filtering paper, and iron with a right warm, but not hot,
flat-iron. If on looking at the negative it is not found to be
moist all over, put more shreds on the dry part, and repeat.

Wax Paper Process. — Legray showed that paper might be first
waxed, and that, even after this, it would take up sufficient iodide
of potassium if immersed in the solution, to admit of sensitizing
on solution of nitrate of silver and exposing in the camera. Serum
of milk, or whey, was found useful in this process, and the writer
has used it with good effect in developing positives. After wax-
ing good photographic paper with fine bleached wax, soak it for
an hour in —

Serum of milk 25 ounces.

Milk sugar i ounce.

Bromide of potassium 48 grains.

Iodide of " 180 "

To obtain whey, heat the milk to boiling, add a very few drops
of acetic acid till it turns, then the white of an egg to clear, and

DEVELOPMENT ON PAPER. 265

filter through paper. Milk sugar can be had of the druggist.
Dry aud put away between folds of paper. Sensitize, when
wanted, on a thirty-five grain solution of nitrate of silver to
which glacial acetic acid has been added in the proportion of one
ounce of acid to fourteen of bath. Immerse in two waters suc-
cessively, dry between folds of blotting-paper. Expose in the
camera either between two pieces of plate glass, or else paste the
edges of the paper over the edges of a piece of glass. Develop
with a saturated solution of gallic acid, to which nitrate of silver
has been added in the proportion of one grain to two ounces of
gallic acid solution and a little acetic acid. Probably the lead
developer, already described, would be every way better. (See
section 1 of this chapter.)

§ 3. — Paper Enlargements.

Life-sized portraits may evidently be obtained in the same way
as ordinary, portraits, provided we proportionately increase the
size of the lens. But unfortunately the defects of lenses increase
with their size, and this is especially true with respect to depth
of focus. The larger the lens, therefore, the more difficult it will
be to get different parts of the subject simultaneously in focus,
and consequently, Avhile it is by no means impossible to take life-
sized portraits direct, it is much more common to effect this object
by enlarging, with the aid of a solar camera, from a small nega-
tive, generally made expressly for this purpose (see p. 177).

Enlargements, printed by the solar camera, may be finished in
the camera, that is, the whole work may be done by sun-printing,
precisely like printing in a frame. But the method of develop-
ment is also practicable, and this may be done in the manner
already described, by chloride development, or, at the option of
the operator, the negative process on bromo-iodized paper may
be used, of course without taking means to render the paper
transparent. But as the negative process is specially intended
for those cases where the illumination is very weak, as in the
camera obscura, and as the light of the solar camera is always
abundant for chloride development, that process will give the
most satisfaction, provided, as before said, that the operator de-
sires to develop, and not to finish in the usual way. Also when
the picture has been supposed to be finished, and has been found
to be too weak, development may be resorted to to bring it up.
IS

266

PHOTOGRAPHIC MANIPULATIONS.

§ 4. — The Solar Camera.

The apparatus for enlarging from a small negative may be
arranged in several different methods ; these instruments are
known as solar cameras.

Woodward's Camera. — In this instrument the solar rays are
received upon a mirror of silvered (not quicksilvered) glass,
whose office it is to reflect them horizontally. They then pass
through a plain convex flint glass condenser of eight inches in
diameter.

Fig. 131.

R R R, parallel rays from the sun falling upon the mirror M,
which reflects them horizontally through the opening in the wall
W W of an apartment. Inside is the condenser C C, which con-
verges them to a focus F, where a photographic objective is
placed. A negative N being interposed between the condenser
and the objective, its magnified image is formed on the screen.
In Woodward's apparatus the lens at F is an ordinary portrait
objective.

The mirror M is mounted with racks and pinions, and requires
to be moved every few seconds to keep the rays horizontal.

Van Monckhoven 's Camera. — The objection made to Woodward's
apparatus has been that the condenser was not large (eight inches
diameter), and consequently the working was slow. The size
could not be increased without introducing much spherical aber-
ration and injuring the sharpness of the image.

To avoid this evil, Van Monckhoven introduced a negative lens
behind the condenser, a thin meniscus, and also replaced the ob-
jective by one of a construction devised by himself.

Light is thrown upon the apparatus in the same way as with
Woodward's. Or a heliostat may be very advantageously applied
to any solar camera. In this instrument the mirror is regulated

DEVELOPMENT ON PAPER. 267

by clock-work, so that it moves with the sun and takes always
such an angle that the rays reflected by it fall horizontally upon
the condenser.

Very good work has been executed with Van Monckhoven's
camera.

Other Solar Cameras. — The same optical principle which was
adopted by Woodward, has been made the basis of a number of
different arrangements, by Shive, Eoettger, Fontayne, Gales, Car-
butt, and others. In Shive's, Roettger's, Fontayne's, and Carbutt's
the direct rays of the sun are used without a reflector. The dif-
ference in these instruments depends upon the mechanical con-
trivances applied to carry out the optical arrangement. In all a
plano-convex lens is placed with its convex side to the light.
Between its posterior surface and its focal point the negative is
introduced. At its focal point the photographic objective is
placed, and the image is thrown upon a screen in the back of the
camera. Roettger claims for his, to which he gives the name of
"parallactic," a greater facility for following the sun's path.
The most recent modification is Carbutt's, which is itself a modi-
fication of Stuart's; in it the whole tripod moves. The base of
the tripod is a triangle, moving upon a hinge at one corner.
The corner falls directly under the condensing lens; this gives
a facility for making a great angular movement in a very little
space. The apparatus is mounted permanently in a room at the
top of the house. A section is removed from the south end of
the roof, to admit the direct sunshine.

It will be seen that the only modification of the optical prin-
ciples of Woodward's camera which has been made is that of V.
Monckhoven, who introduced the negative meniscus into it, to
correct the spherical aberration, and thereby enable him to use
a larger condenser. The size of the condenser is of material im-
portance, for on it depends the intensity of the image. Wood-
ward's condenser was eight inches in diameter, while V. Monck-
hoven was enabled to raise his to twenty. The time required
for printing an enlargement of a given size with the two would
be approximately inversely as the squares of the diameters,
namely, as 400 to 64, or as 6 to 1, or thereabouts.

268 PHOTOGRAPHIC MANIPULATIONS.

§ 5. — Printing by the Solar Camera.

Little special need be said on this head. Albumenized paper
is attached to the screen, and the image gradually appears, re-
quiring a time which may extend from half an hour to many
hours to reach full strength.

This slow printing, requiring, as it does, incessant attention to
keep the apparatus duly placed as respects the sun, unless the
operator possesses a heliostat, is very objectionable and annoying,
and therefore leads to the extensive use of development in order
to shorten the time. This part of the subject has been already
explained.

Efforts have been made to shorten the time required for sun-
printing. That of M. Yan Monckhoven, founded upon the use
of nitroglucose, has been well spoken of, but does not seem to have
passed into general use. The nitroglucose process may be used
either for direct printing or for enlargement.

Nitroglucose is prepared by adding one part of pulverized
sugar to one of sulphuric acid previously mixed with one of
monohydrated nitric acid. After an action of about five minutes,
the mass is to be removed from the acid and washed with cold
water. This crude nitroglucose is to be purified by dissolving
in alcohol and precipitating by adding water, in which it is in-
soluble.

This nitroglucose, according to Dr. V. Monckhoven, does not
precipitate nitrate of silver, but acquires that property if its alco-
holic solution is kept for eight or ten days at a temperatue of
110° F. Its application is as follows : the paper is passed through
an alcoholic solution ten grains to the ounce, is hung up to dry,
and is then immersed for two hours in an ordinary salting solu-
tion. Next, sensitized on a twenty-five grain plain solution of
nitrate of silver, and hung up to dry. So prepared, it keeps for
many months.

In use, the paper is exposed in the solar camera for about a
minute, and is then developed with gallic acid live grains, water
ten ounces, glacial acetic acid fifty minims. The author of the
process claims for it that a gallic development causes albumenized
prints to turn yellow in the whites, whereas with the nitroglucose
process the whites remain perfect. Now, when the development
on albumenized paper is carefully conducted on the principles
laid down in this manual, the whites do not turn yellow. More-

SILVER PRINTING. 269

over, V. Monckhoven observes that the operation for making nitro-
glucose is so delicate that the method would be useless were it not
for a modification discovered by him, and as yet unpublished.

The writer has himself prepared nitroglucose, and found no
difficulty whatever in it. He has found it advantageous to sub-
stitute fuming sulphuric acid for one-half of the ordinary acid.
The mixed nitric and sulphuric acids must be allowed to cool
thoroughly in a covered vessel after mixing, powdered white
sugar is then stirred in, enough to make a thin paste. Soon a
kind of grayish dough makes its appearance, which is at once
removed with a spatula and thrown into water. This is con-
tinued till the dough ceases to form, when a little more sugar
may be added, though its yield will be much less in proportion
than that of the first.

The nitroglucose must at once be kneaded up with water to
get out the excess of acid with which it is saturated, and which
by remaining in it might cause its decomposition. For completer
purification, the nitroglucose is dissolved in alcohol and precipi-
tated by water. The alcoholic solution should be poured into
water (not the reverse), with constant stirring. The nitroglucose
separates a thin dough, which is to be washed by agitating with
several waters, and then should be kept under water.

CHAPTER XIII.
SILVER PRINTING.

Elementary directions will be found in the Introduction.
Here will be given some special remarks on the various branches
into which the subject divides itself, including the description of
a new and hitherto unpublished method of sensitizing paper for
positive prirrting, recently devised by the author, and which has
for its object the preparation of paper which can be kept for a
long time after silvering, without deterioration, and ready for use
at any moment. (See sec. 6.)

§ 1. — Selection of Paper.

The paper preferred in this country almost universally is the
Saxe paper, of which the genuine is manufactured by Steinbach,

270 PHOTOGRAPHIC MANIPULATIONS.

and of which there are many imitations. Some of Marion's paper
is also sold here, often as "Saxe paper," even as the writer has
seen done, with Marion's name water-marked on the edge. "Eive"
paper is little known here, nor Canson. "Whatman's paper, much
liked in England, especially for negative work, scarcely finds its
way to this country.

The qualities required in paper are — to be made of good stock
— that is, fine clean rags ; to have had the chlorine used for
bleaching thoroughly removed, as also the antichlor (generally
hyposulphite of sodium). Chlorine left in the paper tends to in-
jure the fibre, but is otherwise of little importance, but even the
slightest traces of hyposulphite make ineffaceable stains and dis-
colorations. A print thrown by mistake into hyposulphite wash-
ings, turns black all over, the hyposulphite being decomposed,
and sulphide of silver formed ; of course a similar reaction takes
place when hyposulphite is left in the paper — faint traces make
brownish spots, visible in the sensitized paper before printing.

Again, the paper must be free from all kinds of metallic grains,
which, without care, are liable to drop into the pulp. Metallic
dust, abraded from the machinery, forms imperceptible specks,
which, however, reduce the silver from the nitrate bath, and
make spots in the print.

In this country, prints are almost universally made upon white
paper, but rose, purple, and other tinted papers are being intro-
duced, and serve to give an agreeable variety.

§ 2. — Albumenizing Paper.

Few operators take the trouble to albumenize their own paper.
But as original experimenters require to understand every por-
tion of the process of photography, and as it may happen that
photographers may desire to print where albumenized paper
cannot be got, the writer gives the formula which he has used
with good results.

Take the whites of perfectly fresh eggs and add thereto liquid
ammonia in the proportion of five drops for each egg. Measure
the quantity, and take six grains of sal ammoniac for each ounce
of albumen. This may be dissolved in an ounce of water for
each five eggs, or if very high albumenizing is desired, it may
be dissolved in the smallest possible quantity of water.

Add the sal ammoniac solution, and let the whole be beaten up

SILVER PRINTING. 271

to a froth, so that no liquid portion be left. Set away for twelve
hours or more (a cool clamp place is best), and pour off the liquid
portions which have settled out of the froth. These are per-
fectly clear and free from foreign matter.

The albumen thus prepared is placed in a flat pan and the
papers rested on it for three or four minutes, and then lifted off
and hung up to dry. The faster the drying the higher the gloss,
and therefore these papers, when prepared commercially, are
often dried in rooms kept at a suffocating heat.

In small experiments, the albumen may with a little dexterity
be applied with a broad (two-inch or more) camel's-hair brush.
With care, streaks may be avoided.

Some have recommended the use of glacial acetic acid (three
drops to each egg) instead of the ammonia. Lyte remarks that
this tends to yellowness in the whites of the prints, and the
author's experience has been the same.

In salting, considerable latitude is allowable. Eight or ten
grains of sal ammoniac is about an average quantity, which is
sometimes reduced to six, sometimes increased to twelve. An
absurd secrecy is practised by many makers of albumenized
paper as to their salting, and this introduces some uncertainty as
to the proper treatment : strong salting requires a stronger bath,
and with paper of which the salting is not known, some trials
may be requisite to determine the appropriate bath.

The weaker the salting the less is the exhaustion of the posi-
tive printing bath, but it is not quite sure that the pictures so
produced are quite as permanent.

In the preservation of albumenized paper, two things are to be
borne carefully in mind. First, that if the paper be kept in a
moist atmosphere, it will not give brilliant prints. This is be-
cause the salt used becomes to some extent dissolved in the
hygroscopic moisture absorbed by the paper, and is drawn by
capillary attraction into the body of the paper ; thus the silvered
surface is less perfect. This is more the case with common salt,
chloride of sodium, and less with chloride of barium, than with
chloride of ammonium. Common salt is the most deliquescent,
chloride of barium the least soluble of the three.

On the other hand, excessive dryness is to be avoided, the coat
of albumen becomes too horny and not sufficiently permeable.
Many adopt the plan of keeping the stock of albumenized paper
in a thoroughly dry place, but take out what will be wanted for

272 PHOTOGRAPHIC! MANIPULATIONS.

one day's printing, and leave it twenty-four hours in a damp
cellar, in order that it may take the nitrate bath more evenly.

Generally speaking, the fresher the paper the better, and the
less chance of defects. To be sure of obtaining the quality of
paper desired, it is best to purchase directly from the maker or
his authorized agent.

Decomposed albumen is always hurtful. If it be kept so long
before applying to the paper as to acquire a bad smell, it must
be rejected. And if the paper be kept in a very moist place, the
albumen may putrefy on the surface of the paper.

\ 3.— Salting Plain Paper.

In salting ordinary paper, the most various proportions of salt
have been recommended. Two, three, or four grains to the ounce
are about a recommendable proportion, and give good results.
A little gelatine may be advantageously introduced; the latter
should not exceed two grains to the ounce, and may be less. It
will need the aid of heat to get it into solution. If not over
one grain be used, the liquid will scarcely gelatinize in cooling.

The following may be taken : —

Chloride of ammonium . * 50 grains.

Gelatine 16 "

Water 10 ounces.

By some, chloride of barium is preferred. The greater equiva-
lent weight of this substance requires that it should be used in
larger proportion. As follows : —

Chloride of barium 200 grains.

Gelatine 45 "

Water 30 ounces.

A difference of opinion exists as to the proper mode of prepa-
ration. High authorities recommend that the paper be drawn
through the solution. But as it is the invariable object to keep
the materials on the surface, it is perhaps better to float the paper
for a few moments in the bath. In any case, it is desirable that
it should be rapidly dried, before the solution soaks too much in.

Arrowroot paper may be purchased ready salted. The effect
of the arrowroot is to keep the picture more on the surface, and
so avoid a sunk-in, mealy effect. If warm tones are wanted, use
the benzoate or acetate toning ; if black, the lime. These papers

SILVER PRINTING. 273

need vigorous printing, and should not (according to Liesegang)
be toned in a fresh toning bath, but only after some albumen
prints have been toned in it.

Good results may be obtained by floating albumen paper with
the albumen side up. This gives the print a good deal the effect
of being made on plain paper very highly finished. There is
not the transparency of shadow which makes the peculiar beauty
of the albumen print, but there is also less gloss and glitter.

§ 4. — Sensitizing.

Since the first edition of this book was published, fuming with
ammonia in one shape or other has come into general use, and
with this change the practice of making the " ammonio-nitrate
bath" has comparatively passed out of use.

When paper is to be fumed, it is not very important whether
the sensitizing bath is acid or alkaline, because the fuming
always renders the paper alkaline, either beforehand, as when
the fuming box is used, or during the exposure, or when fumed
pads are employed. The usual strength of the bath is now 50
to 60 grains of nitrate of silver to the ounce. A satisfactory
bath will be : —

Positive Bath.

Nitrate of silver

3 ounces

. 24 "

The usual practice is to make this bath faintly acid with nitric
acid, though some excellent operators make it slightly alkaline
with ammonia.

On this bath the albumenized paper is to be floated about a
minute — a little less in hot weather, a little more in cold.

After the sheet has floated for a proper time, it is to be pinned
or otherwise fastened up to dry. Buff shades to the room, if
wide enough to cover the window jambs, will be a sufficient pro-
tection; if too much white light be admitted, the high lights of
the prints cannot be expected to be satisfactory. In some
establishments a table is provided with a back or screen towards
the left, seven or eight feet square. This protection, and keeping
the sensitized paper and prints in drawers, is found sufficient,
provided that the table is near a wall, so that but little diffuse
light can pass round the screen.

274 PHOTOGRAPHIC MANIPULATIONS.

Consumption of Nitrate of Silver. — Different photographers have
calculated the amount of nitrate of silver consumed in sensitizing
an albumenized sheet of 18x22, and have varied between wide
limits, some fixing it as low as 60 grains, others as high as 110
or over. Seventy-five to eighty grains is probably about the
true quantity that is abstracted from the silver bath, part of
which is subsequently recovered from the washings.

Alum in the Printing Bath. — Mr. H. T. Anthony recommends
the addition of alum to the bath; about 2 grains to the ounce of
bath seems to be the right proportion, and to tend to keep the
bath clean and free from discoloration. By this means, he states,
he gets as good results from a 35-grain bath, as on the old plan
with a 50-grain. He advises, after the printing is done, to soak
the prints in water acidulated with acetic acid, before toning
them.

Blotting Sensitized Paper. — Some very successful workers Hot
all their paper, to obtain equal action and avoid drops of bath
solution collecting on the surface in drying. Thick blotting pads
are provided, rather larger than the sheets. On one the sensi-
tized sheet is laid face down and pressed, then another pad and
another sheet, and so on. The pads may be used many times
over before they become too much charged with solution — finally
they are burned to recover the silver. The abstraction of the
silver solution does not reduce the vigor of the prints, which are
obtained very uniform in character and free from stains.

If the paper is allowed to dry between the pads, it will be apt
to turn yellow. It is, therefore, best, as quickly as the liquid is
completely absorbed, to remove the sheets, pin them up, and let
them dry.

Management of Bath. — The positive bath by use soon turns
yellow and loses strength. The first trouble is to be remedied
by shaking up with half an ounce to an ounce of kaolin, accord-
ing to the size of the bath. The strength must be kept steadily
up to the mark originally fixed, and this is either done by watch-
ing carefully the character of the prints, and adding silver liber-
ally as soon as they show any signs of deterioration, or by means
of the argentometer, a sort of hydrometer expressly made for the
photographer, and which, by sinking more and more deeply into
the bath, indicates the exhaustion of the nitrate of silver. With
the age of the bath, however, its indications become less reliable,

SILVER PRINTING. 275

in consequence of the accumulation of other nitrates in the

bath.

These, however, appear to some small extent to take the place
of nitrate of silver. At least, Meicke's experiments showed that
the quantity of silver abstracted from an old bath was less than
from a new one, sometimes by as much as 15 or 20 grains to the
sheet, and it seems not unreasonable to suppose that the alkaline
nitrates gradually accumulating in the bath had something to do
with this. A sharp controversy was carried on in England for
some space of time over the question of the utility of alkaline
nitrates in the bath. Generally, nitrate of soda was tried. The
bulk of the rather conflicting evidence seems to have been in
favor of the advantage of the addition, a result undoubtedly
confirmed by Meicke's experiments above mentioned.

§ 5.— Washed Sensitive Paper.

One of the serious annoyances connected with photographic
printing lies in the rapid deterioration of the paper, which quickly
turns yellow, thus destroying the brilliancy of the white. It is
rarely safe to keep the paper from one day to another, especially
in hot weather. Two bad results follow: that if the weather
changes from fair to dark, a portion of the paper prepared for
the day's use is apt to be spoiled; whilst, on the other hand, it
the day changes from dark to bright, there is no paper ready to
profit by it.

The preparation of a paper with good keeping qualities has
consequently been felt to be an object of the greatest importance.
Such paper has been prepared commercially in France; its mode
of manufacture, however, has been kept absolutely secret. So
far the only published method of obtaining a paper that can be
kept is the Washed Paper Process, here to be explained. This
process, however, involves a considerable amount of additional
manipulation in the washing of the paper after sensitizing it.
The writer has lately taken up and finished some investigations
commenced some years ago, and has succeeded in finding a method
free from this objection, and requiring no more labor to prepare
than the ordinary silvered paper, yet sufficiently permanent to
be kept for a considerable length of time without deterioration.
This method will be described in the next section following.

276 PHOTOGRAPHIC MANIPULATIONS.

In the Washed Paper Process, the paper, as soon as it is
removed from the printing bath, is thrown into water, to remove
the excess of nitrate of silver. As to the amount of washing that
the paper will bear, different operators have reached very differ-
ent conclusions, and the practice has not been so generally
adopted as to have led to the accurate fixing of these conditions.
Some succeed best by simply drawing the paper through one
water; in this condition it approximates more nearly to ordinary
silvered paper. Others draw it through two, three, or even four
waters, so that the last water shall show no clouding by reason
of chlorides present in it, thus indicating that the whole of the
nitrate is washed out. When thus treated, the salting must not
be too low, and the silver bath must be kept ivell up to the mark,
strengthening, from time to time, with fresh nitrate, according to
the number of sheets sensitized. The amount of silver abstracted
will depend upon the salting, but for average paper it will be
fair to estimate from five to six drachms for each four sheets of
paper of 18 x 22. After what number of sheets the strengthening
will be required will, of course, depend much upon the quantity
of bath used, but it is best always to be on the safe side ; a rule
used by some experienced operators is to strengthen after each
five sheets. After each strengthening, try the bath with test-
paper, to make sure that it is alkaline, but not too much so. If
too alkaline, the albumen will be dissolved off the surface of the
paper. If the strengthening of the bath be neglected, the prints
will want vigor.

Paper thoroughly washed has been kept, according to M.
Baden, from March till October, without deteriorating. When
it is intended to keep the paper for a long time, much more
care with regard to light must be exercised through the opera-
tions of sensitizing, washing, and drying, and in keeping it in a
dark and dry place. The prints themselves cannot be kept with
the same safety as the paper, because of the faming before
printing, but they may lie over for some days or even longer.

An advantage in using several waters is that the first pan can
be used many times, until its contents become very rich in silver,
and fit to evaporate down and recover the silver fit for use.
Then the second pan receives the first, and so on, fresh water
taking the place of that which was previously the last.

The washing of the paper after sensitizing does not take the

SILVER PRINTING. 277

place of the subsequent washing, but the prints, after they come
from the printing frame, must be again washed before toning.

Care is also necessary with the fuming, which may easily be
carried too far. Pad fuming (see p. 279) is said to answer best.
If the prints are fumed in a box, and are left in too long, they
will tone to a cold blue. It is said, however, that this over-
fumed paper, by keeping for a day or two, will lose some of its
excess of ammonia, and give better tones. Five minutes is about
the right time to leave this paper in the fuming box.

The high salting of the paper above spoken of, appears to be
essential. This introduces a difficulty, inasmuch as the photo-
grapher rarely prepares or knows how much salting is contained
in the paper that he habitually uses.

It will be easily understood, from the foregoing, that there is
more or less uncertainty connected with this method. Some
have obtained very satisfactory results with it, whilst others
have been disappointed and have rejected it. This uncertainty,
and the considerable additional manipulation required, appear to
render the method much less advantageous than the following.

§ 6. — New Method of Sensitizing Paper.

Some years ago the writer, whilst investigating the subject of
Paper Development, ascertained that by the addition of tartaric
acid to the sensitizing bath the paper could be kept for ten days.
As paper for development is still more liable to deterioration
than that prepared for positive printing, it appeared to him likely
that this property of tartaric (probably also of citric) acid might
be made the foundation of a new printing process of great utility.
Other occupation, however, interfered with the prosecution of
the matter till recently, when the experiment was tried, and with
complete success. At the time when this sheet goes to press, the
writer has kept this new paper about seven iveeks, at the expiration
of which time it was still in excellent condition, giving brilliant
prints with whites just as perfect as when freshly made, and
toning with the utmost ease.

Formula.

Crystallized nitrate of silver 2 ounces.

Tartaric acid 40 grains.

"Water 16 ounces.

278 PHOTOGRAPHIC MANIPULATIONS.

The nitrate and the tartaric acid are not to be thrown into the
water together, but dissolved in separate portions, mixed, let to
stand some hours, and then filtered. This bath is then used and
treated precisely like an ordinary printing bath, except that it is
best to keep it out of the light. The albumenized paper is floated
for the usual time and hung up to dry. More care should be
taken in excluding the light than in the case of ordinary silvered
paper intended to be used at once, and when the paper is dry it
is to be put aside in a close-fitting box and kept in a dark, dry
place until wanted for use.

Sometimes the author adds —

Gelatine 4 grains,

Glycerine 3 drops,

to each ounce of the bath. The gelatine should "Be set to swell
in a part of the water, and then be dissolved by warming, add
the glycerine and tartaric acid to this, and pour it into the rest
of the water in which the silver-nitrate has been dissolved.
Although the bath now contains four grains of gelatine to the
ounce, the tartaric acid prevents any gelatinizing, even if one
employs, as the writer has sometimes done, a much larger pro-
portion of gelatine. It also filters easily. When gelatine is used,
the prints as taken from the frame have a bright brown color ;
they tone to any shade desired as easily as the others. The
use of gelatine would seem to tend to keep the print more on the
surface, but whether there is any real benefit in it is scarcely
certain. Perfectly satisfactory prints are obtained without it.
The object of the glycerine is to remove the stiffness which the
gelatine tends to give the paper.

The fuming is done shortly before using, and requires no par-
ticular care, and the print is washed and toned in any of the ordi-
nary methods. The writer uses the acetate toning bath. "What is
rather curious is that while the albumen side of the paper remains
white, the back often acquires by keeping a brownish coloration,
which, however, disappears entirely in the toning or fixing, and no
one, in examining either the face or the back of the print, could
distinguish it from one made on paper just dry after the printing
bath. It seems possible that the quantity of silver in the bath
might be reduced, but in these examinations it was thought
better to adhere to the proportion of silver actually employed by
the most successful workers with the ordinary bath.

SILVER PRINTING. 279

It will be seen from the foregoing description that paper with
excellent keeping properties is as easy to prepare as paper that
spoils immediately. It is only adding a few grains of tartaric
acid and proceeding otherwise precisely as usual. The advan-
tages are very great and the trouble nothing. The method will,
the author trusts, be found a valuable alleviation to the troubles
of printing.

§ 7. — Fuming.

A convenient and close-fitting wooden or tin box is provided
with a door, and either pieces of cork are attached to the sides
near the top inside, or else cords are stretched across. To these
the dry sensitized paper is attached for fuming. This operation
lasts for ten minutes, and is best performed only a few minutes
before printing. If the fuming be too much prolonged, the print
may be expected to be flat and mealy, and to be severely reduced
in the fixing bath. On the other hand, an irregular spotty effect
indicates insufficient fuming.

In a saucer at the bottom of the box is poured some strong
liquid ammonia. The quantity is not very important; for a
small box and a dozen or twenty quarter sheets of paper, an
ounce and a half to two ounces will be sufficient. For a large
box and twenty or thirty whole sheets, two dishes with two or
three ounces in each will be sufficient, if the. ammonia be good.
(The liquid ammonia of commerce is very variable in strength.)
Carbonate of ammonium has been recommended by Dr. Liesegang
as an advantageous substitute for the liquid ; the mode of ope-
rating is precisely the same, except that a larger quantity is
employed, and may be used many times.

It is best that the fumed paper should be exposed to the air for
ten or fifteen minutes, to allow the adhering arnmoniacal fumes to
pass off, before laying upon the negative.

The effect of fuming is to give rich, brilliant prints with ease
and certainty. This method, now in very general use, was first
proposed by Mr. H. T. Anthony.

Pad Fuming. — Another plan, which has lately been a good
deal used, is to fume pads instead of the sensitized paper.
These pads are left for some hours, or over night, in the fuming
box, and are placed behind the silvered paper whilst it is in the
printing frame. In this way the ammonia acts upon the silvered

280 PHOTOGRAPHIC MANIPULATIONS.

surface during the operation of printing. The influence of this
fuming can be heightened by putting pieces of oiled silk directly
behind the fumed pads, in order to prevent all escape of ammonia.
Another plan has been recommended, that of simply rubbing the
pad with a lump of carbonate of ammonia, taking care, of course,
to leave no grains or dust on the pad.

Fuming with a pad is less likely to injure valuable negatives
than fuming the paper itself.

§ 8. — Printing.

Before placing the paper in the frame, it is necessary to be
certain that it is perfectly dry, otherwise the negative may be
injured; a careful examination should be made of every part of
the sheet before it is cut to pieces, bearing in mind that a single
moist spot may cost a valuable negative. The paper, especially
if albumeuized paper be in use, must be set in the frame neither
roughly nor carelessly. For it is to be always borne in mind
that a negative is a delicate thing. Even the best varnish is
no protection against rough handling, and a slight scratch may
easily occur in some place where touching out may be either
impossible or nearly so. The paper should never be drawn over
the plate, especially when pressed close to it. It must be laid
flat down in its proper position, and the pads laid easily and
squarely down upon it and secured by the back.

Printing may be done either in the direct rays of the sun or in
diffuse light; the choice between the two will. depend upon the
nature of the negative, and the preparation of the paper must be
regulated accordingly.

The characteristic of printing in the sun is softness, of printing
in the shade, strength and contrast. Nevertheless, prints made
in sunshine are mostly the stronger, simply because strong, hard
negatives require sun-printing. And so, soft prints will often be
found to have been executed in the shade, because taken from
verv thin negatives which could not be made to yield a good
print in any other way. For want of understanding this, very
contradictory and erroneous statements have often been published
on the subject of sun and shade printing.

A photographer will, for example, start out with the intention
of printing in the shade, and will make all his negatives very
thin with that intention. If these negatives were printed in the

SILVER PRINTING. 281

sun, the prints would be utterly worthless. By the time that the
shadows were deep enough to stand toning and fixing, the lights
would be discolored and the prints spoiled. To examine his
prints and observe his mode of printing might lead to the conclu-
sion that shade-printing gave soft prints, whereas the fact would
be that the thin negative gave soft prints in spite of the mode of
printing.

Another will prefer bold, vigorous negatives, and will develop
and redevelop till he gets them. These, if printed in the shade
until details were got in the high lights, would lose all transpa-
rency of shadow, which would be converted into black patches.
The exposures would be tedious and the prints bad. But exposed
to a bright sun, the intense rays pierce through the dense parts
of the negative, and give us the details in the lights before the
shadows are overdone.

Under the head of Salting, it has already been remarked that
both the salting and the nitrate bath must be regulated so as to
act as a counterpoise to the printing. With a thin negative the
bath must be a rich one, or the picture will tend to flatness. A
bold negative will print well upon a less highly sensitized paper.
In this lies the explanation of the much discussion over strong
and weak printing baths, some succeeding with what fails with
others, all depending upon the nature of the negative. Again,
when, by accident, a very hard negative is taken, which gives a
harsh black and white picture, its prints may be improved by
using an extremely weak sensitizing bath (prolonging the floating
of the sheet upon it proportionally). Extremely hard negatives,
so hard as to be unserviceable in any other way, are made to
yield good prints by washing the paper after sensitizing it, so as
to remove all free nitrate, then drying and exposing.

Very thin negatives, that only give fiat prints under the ordi-
nary treatment, may often be made to yield excellent prints (pro-
vided they are not actually deficient in detail in the shadows, so
that they are wanting in density only, not in graduation ; the
distinction is important) by printing under one or more folds of
tissue-paper.

It will easily be understood that where negatives are printed
in large quantities for sale, they are likely to give better results,
because the treatment for any particular negative, in respect to
salting, sensitizing, and exposing, can be well made out.

The proper degree of salting will always depend upon the
19

282 PHOTOGRAPHIC MANIPULATIONS.

strength of the sensitizing bath, and correspond with it. A rich
nitrate bath should follow high salting, and the reverse. "Where
it is wanted to get a soft print from a very hard negative, the
salting may be reduced to one or two grains per ounce of water
or albumen, to be followed by a weak printing bath of twenty to
thirty grains nitrate of silver.

Another remark of importance is this, that the image produced
by a strong light stands the subsequent operations better than
that produced by weaker light. A print made in direct sunshine
is less reduced in toning and fixing than one made in the shade.
Consequently, a shade-print requires more over-printing in the
frame than a sun-print. The sun-print is undoubtedly the stronger
picture of the two, and the writer holds that, other things being
equal, its chance of permanence is greater than that of the shade-
print.

The lime required for printing will of course vary extremely;
in extreme cases, from a minute or two to many hours. The
prints are to be examined by carrying the frame to a dark corner,
loosening one end of the back, opening it and observing the con-
dition of the print. Particular care is necessary to avoid injuring
the negative with the nail in lifting back the print. The usual
test of sufficient printing is when the shadows begin to bronze.
At this time the highest lights should be either still quite clear
or only just commencing to darken, so little that it will be re-
moved in the subsequent operations and the white left pure. If
in sun-printing the whites begin to darkeu before the shadows
are sufficiently printed, it is a sign that the negative is thin and
will require shade-printing. If in shade-printing the shadows
are fully printed before the details in the high lights are got, it
is an indication that sun-printing is needed; and if this defect
appears in sun-printing, it is a hint that the negative in use will
require paper less highly silvered.

Printing on Carbonate of Silver has been introduced in France,
and has acquired considerable popularity. The paper is first sen-
sitized with an alkaline carbonate, and then silvered on a plain
silver solution (not ammonio-nitrate). Such paper keeps long
after sensitizing, but requires thorough fuming before use, and
to have oiled paper or oiled silk behind the back of the paper
whilst printing, to retain the ammonia. It is asserted that the
prints can be kept a month, if desired, before toning and fixing.

SILVER PRINTING. 283

Printing under Ground Glass. — The effect produced upon the
printing of a negative by interposing a plate of ground glass
between the light and the negative is undoubtedly very curious.
A great softening is produced ; negatives which, printed in the
ordinary way, give harsh and blocky prints, will sometimes, by
this treatment, yield excellent results. The writer has seen soft,
beautiful, and delicate prints got from negatives that must have
been rejected, had they not been rendered useful by the applica-
tion of this ingenious contrivance.

It is, of course, chiefly in portraiture that this device is useful.
The writer, without ever having used it himself in landscape
printing, has seen fine prints made by its help from hard nega-
tives.

Printing under ground glass has somewhat the same effect as
printing under tissue-paper in softening the image. To what has
already been said under the head of " Berlin Portraits" (p. 194),
it may be here added that some vary the effect by coating the
ground side of the glass. This communicates a part of the grain
of the glass to the print, producing somewhat the effect of an
engraving.

Mezzotint Effects. — The method of obtaining these is explained
at p. 194. It remains to mention here that the printing should
be done in direct sunshine, and that it is found that the best re-
sults are got when the sun shines perpendicularly on the negative.
M. de Constant suggests driving a nail perpendicularly into the
face of the printing frame ; when this nail casts no shadow, it is a
proof that the frame is perpendicular to the sun's rays.

Portraits softened in these ways lose the harshness so con-
spicuous in some photographic work. They show less definition
and boldness, but more harmony and softness. The improve-
ment obtained in this way can never equal that resulting from
retouching the negative ; but, where this is not practised, it may
often be useful.

§ 9.— The Pressure Frame.

The construction of the frame is of too great an importance not
to receive a word of comment here. Two very serious troubles
arise from bad pressure frames, breakage of negatives, and blurred
prints. Pressure frames generally distribute the pressure very
badly.

284 PHOTOGRAPHIC MANIPULATIONS.

Take an ordinary piece of glass, the size of the frame, lay it in,
put in the pads you commonly employ ; take hold of the frame
in both hands, the fingers on the back, the two thumbs resting
on the glass near the centre. Press forcibly with the thumbs,
until the glass moves back a little, and observe the amount of
resistance. Next bring the thumbs up to one end, and press
there ; you will probably be surprised to find how much less the
resistance is there, and, consequently, how unequal the pressure.

This inequality is a principal cause of the breakage of nega-
tives in the frames, and is also a disadvantage to the print; for
wherever the contact is not good, the sharpness of the print will
be impaired, and this more so with shade-printing than printing
in direct sunlight. The writer has already expressed his prefer-
ence for the bar-frame, Fig. 12, p. 45.

Many operators are extremely careless as to what padding they
use between the back of the frame and the print, considering that
anything is good enough — mill-boards, old newspapers, etc. This
is quite wrong; such inelastic substances cannot give good con-
tact, and always endanger the negatives. Moreover, as the mate-
rial for this purpose lasts indefinitely, it is worth while to provide
it right, once for all.

The one thing that is better than anything else is piano-cloth.
This is a soft, thick, green felt-cloth ; when really good, it is about
a quarter of an inch thick. It is expensive, but as a yard will
make pads for twenty whole plate frames, the cost is not worthy
of consideration when the safety given to the negatives is con-
sidered. A single thickness is sufficient, and a fine, elastic,
equable pressure is obtained, which is invaluable. If by long
use the felt has become flattened down, all that is necessary is to
slightly wet it and let it dry.

The next best substance to this is probably a good thick flannel
— woollen or cotton; the former is the more elastic. Whatever
substance is used, should of course be of some non-actinic color.

The Registering Pressure Frame, for combination printing, has
already been described. See Figs. 102 and 103, p. 183.

To accomplish the printing of as many frames as possible at
once, a platform is set up outside of the windows and on the level
of their sills. On this are placed slanting blocks, so that, when
the frames rest upon them in rows, each frame will be inclined
so as to face the sunlight as much as possible. At different
times of day the frames are differently placed ; when the sun is

SILVER PRINTING. 285

low, they are kept more nearly perpendicular, and as the sun
rises, they are placed more level. Much time is saved by having
the frames kept well facing the sun.

A southeast exposure is the most desirable, though it is con-
venient to have at least one window with a westerly exposure
for shade-printing. Some negatives will do best when not only
printed in the shade, but also by having tissue-paper interposed.
It is therefore convenient to have some frames kept permanently
with tissue-paper stretched across the borders.

§ 10.— Vignetting.

When the print softens into a white border, it is called a vignette,
and this mode of printing offers a beautiful variety. The nega-
tive is usually taken in precisely the same way as for ordinary
printing, and the difference is made in the printing, though the
effect can be very well produced once for all in the negative, if
desired, as will be presently explained.

It should always be borne in mind that a vignette requires a
light background. A sketchy effect (see section on Backgrounds)
is very pleasing in vignettes.

Vignetting with a Frame. — This is the most usual way. The
negative is placed in a frame on the face of which are springs
which confine blocks of wood; in these blocks oval holes are
cut, widening on the under side which is next the negative. On
the upper side, farthest from the negative, tissue-paper is pasted
to soften the light.

Vignetting frames are also made expressly. These commonly
have pieces of tin set in front, provided with wire rings, over
which the tissue-paper is to be pasted. For large negatives a
convenient vignetting frame may be made by tacking a piece of
stiff pasteboard upon the front of the frame. In this a hole is
cut of the size desired, and this hole is covered with tissue-paper.

Vignetting glasses are sold in which a deep orange enamel is
applied to the border, leaving an oval space in the middle, of
clear glass ; of course the color is shaded off at the edges of the
oval. This glass is to be placed in the frame between the nega-
tive and the light.

Any one accustomed to photographic manipulations may pre-
pare such glasses for himself, by photography. Cut a small piece

286

PHOTOGRAPHIC MANIPULATIONS.

of oval hard wood, smaller than the part of the negative that is
to be printed. Prepare a collodio-chloride or albumen plate for
positive printing, lay the little block on it, and expose to diffuse
light, turning the plate now and then. It is evident that the part
of the plate that is covered by the block will be completely
protected, and the portions round it will be shaded off. Or, by
reversing the operation, and using a hole in a shield instead of a
block, a reverse vignetting plate may be got, that is, a shaded
centre in a transparent border. This may be used as a negative
from which any number of vignetting plates may be prepared,
either by contact printing or by development. The writer can-
not recommend this as being a very easy method, but it is per-
fectly practicable, as he knows from having devised it and used
it several years since. More lately, it has been proposed and
advocated by others in print.

Vignetting with Cotton. — A piece of stiff mill-board is tacked to
the front of the frame, in which an opening is cut considerably
larger than the size of the portion of the negative which it is
intended to print. White cotton-wool is pressed under the mill-
board, and allowed to project beyond it until only that part of
the negative is exposed which it is intended to print.

Vignetting with Paper. — In this case and in that immediately
foregoing, the part of the negative that is to be printed is exposed
uncovered. A piece of thin tissue-paper is cut with an opening

the size of the part of the nega-
tive that is to be fully printed ;
then another piece with the
opening a little larger, and so
on for a considerable number.
These are pasted together and
form a graduated shield, acting
somewhat like the vignetting
glass already described. By
fastening this paper shield on
the glass side of the negative
and printing in the shade, the
lines of the successive layers of
paper can be concealed.

The sketch in the margin is
taken from Mr. Blanchard, as
showing a set of elegant and ap-

Fic. 122.

SILVER PRINTING. 287

propriate curves suitable for card size (the size of the cut is
necessarily smaller than that of a card portrait, but the curves
are preserved of full size). Models of each of the diminishing
openings are to be cut into card-board or thin tin; these once
provided, any number of tissue vignettes may be made from
them by using them to guide the point of the penknife in cutting
the tissue-paper. The same photographer recommends, for other
and more irregular shapes of vignettes, to attach to the back of
the negative a piece of tracing paper, to run round lightly with
the pencil the portion that is to print full tint, and again outside
that, the portion to be quite white. This last is rendered opaque
with any red or black color, and the space between the two lines
where the softening is to be is graduated by rubbing in color
with a common artists' stump.

Vignetting with a Lens. — This ingenious method is practised by
some professional photographers to the exclusion of all others,
and has the advantage of great rapidity. A burning-glass of some
size (four to six inches in diameter) is set in a wide frame, or a
piece of thin board. The negative is placed with silvered paper
behind it in an ordinary frame, and the concentrated sunlight
through the lens is allowed to fall upon the face. The lens is
kept moving with a little circular motion, confining the light to
the parts intended to be printed. In from ten seconds to half a
minute the printing is finished. As the heat as well as the light
is concentrated by the lens, it is necessary to have a thin piece of
plate glass in the frame between the negative and sunlight, to
prevent injury to the negative.

All these methods give excellent results. The last is evidently
applicable chiefly to small heads, but the writer has seen beau-
tiful vignetted cards made by it.

We next come to vignetting on the negative.

Vignetting by Development. — When the dark slide comes from
the camera, the back is opened and an opaque shaded object of
the shape and size of the vignette desired is laid on the back of
the plate, which then, and without removing from the slide, is
exposed for a few seconds to weak diffuse light. When the
image is developed, of course all parts of the plate not protected
by the opaque screen just described are developed black, in con-
sequence of the second exposure. As the image is invisible at
the time the opaque screen is applied, this last must of course

288 PHOTOGRAPHIC MANIPULATIONS.

have been arranged in such a way by the image, as seen in the
camera, as to make sure of the screen being correctly applied.

Vignetting hy a Screen. — Another method has been proposed.
A large white screen is to be prepared with an oval opening.
This screen is to be placed between the camera and the sitter, who
is thus seen through the oval opening. The screen being white,
reproduces itself by opacity on the negative, and being so much
nearer to the lens than the sitter as to be completely out of focus,
it of course has an indistinct shaded border. There seems an
objection to this plan, that it tends to throw so much white light
into the lens. It has also been proposed, instead of a large stand-
ing screen, as just explained, to have a small one, only a few
inches from the lens, and attached to the camera itself, capable
also of being regulated in distance and position.

These last methods are rather exceptional ; the use of the
tissue-paper fastened over openings in wooden blocks or on
metal rings, as above described, is almost universal.

\ 11. — Toning.

After the prints are removed from the frame, they may either
be thrown directly into water or may first be trimmed ; the latter
method is found preferable by those who operate on a large scale.

The prints are washed by placing them one by one in a pan
of water, where they all lie for a short time. This water is to be
repeatedly changed, and of course is to be saved, at least the two
or three first washings. It is rich in silver, which is to be thrown
down as chloride by common salt. A neglect to wash the prints
sufficiently is liable to produce two evils, a yellowing of the
whites in the toning bath and a difficulty in toning; these
troubles may come separately or together. This is the case
especially with the toning baths now commonly in use. Those
toning baths into the composition of which sulphocyanide of
ammonium or hyposulphite of sodium enters, do not present
this difficulty, and although it is best to wash the prints before
toning in them, it is not absolutely necessary, nor need it be so
carefully done.

The principle of toning is the substitution of gold for silver in
the print. If a washed print be simply thrown into a dilute solu-
tion of chloride of gold, it will tone, but the acidity of the solu-
tion will lead to a great reduction in the strength of the picture.

SILVER PRINTING. 289

It is, therefore, needful in some way to neutralize the acidity,
which may be done with carbonate of sodium, carbonate of cal-
cium, or certain salts that have an alkaline reaction, such as
phosphate of sodium, acetate of sodium, or borate of sodium,
each of which substances forms the foundation of various toning
formula. The explanation of their action is this : part of the
alkali present becomes converted into chloride, which enters
into combination with the chloride of gold, forming, for ex-
ample, in the case of soda, chloraurate of sodium. The acid pre-
viously in combination with the alkali is set free, but being in
all the above cases a weak acid (carbonic, phosphoric, acetic,
boracic), is without injurious influence on the bath. In fact, other
combinations of alkali with weak acids may be substituted. The
writer has obtained excellent results with benzoate of potassium,
which he some time since proposed for making the toning bath
with, and which has been very favorably reported on by others.
Tune/state of sodium has also been used with good effect. Certain
acids have a reducing effect upon salts of gold; oxalates and
formiates cannot be used for this reason. Citrate of sodium has
been used and was highly recommended some years back, but is
now little employed.

VARIOUS TONING FORMULAE.

Alkaline Carbonate Toning Bath. — To make this very popular
bath, the gold solution is simply rendered alkaline with bicar-
bonate of sodium ; the following proportions may be used : —

Water 32 ounces.

Chloride of gold 1 to 3 grains.

Bicarbonate of sodium 5 grains.

Mix twenty-four hours before using.

The gold gradually tends to precipitate from this bath, whereby
it becomes inactive. Some operators, after using, add just enough
hydrochloric acid to make it turn litmus-paper red, and then,
before using again, add enough bicarbonate of sodium to cause it
to turn red litmus-paper blue. In this way it keeps indefinitely.

Calcio- chloride Toiling Bath. — A solution of chloride of gold is
made, one grain to each ounce of water, and a couple of grains
of precipitated chalk to each ounce are added and shaken ; next
day it is ready for use, diluting each ounce with ten to twenty of
water.

290 PHOTOGRAPHIC MANIPULATIONS.

This bath tones much like the preceding ; gives brown, purple,
black, or black tones, and, by overtoning, blue. Succeeds best
with paper sensitized on neutral baths.

Acetate of Sodium Toning Baths.

Chloride of gold . 10 grains.

Water 80 ounces.

Acetate of sodium 1 ounce.

This bath differs considerably from the foregoing. It will not
give black tones, no matter how prolonged its action, but gives
splendid warm purple shades that cannot be excelled and cannot
be equalled by the common carbonate of sodium bath. If wanted
for use in the shortest time, it should be mixed with warm water
and let to stand.

Benzoate Toning Bath.
Bicarbonate of sodium 5 grains.

Benzoic acid 10 "

Chloride of gold 1 grain.

Water 10 ounces.

Gives warm tones similar to the preceding. This bath, origi-
nally proposed by myself, works satisfactorily and keeps very
well. It acts, perhaps, a little more uniformly than the preceding.
Instead of the benzoic acid and bicarb, sodium, an alkaline ben-
zoate may be employed.

Although any of these, or of the following, can be used for
almost any purpose, yet certain baths will always have uses for
which they are specially adapted. Landscapes should be toned
only with the acetate or the benzoate bath. Small heads, as, for
example, card portraits, are best toned with the carbonate bath.
Eeproductions of engravings, needing a pure black, may be toned
with the carbonate, but still better with the chloride of lime bath,
to be presently described.

The following special formulas have been adopted and published
by experienced and successful photographers : —

Mr. Notmarfs Formula.

Water 210 ounces.

Acetate of sodium 1 ounce.

Bicarbonate of sodium £ "

Nitrate of uranium 10 grains.

Chloride of gold 12 "

SILVER PRINTING.

291

Keep twenty-four hours before using. "When about to use,
add eight grains more gold, and continue to add according to the
quantity of prints toned.1

Dr. Shepard's Formula.

Chloride of gold .
Water ....
Neutralize with powdered chalk.
Chloride of lime .

4 grains.
1 ounce.

4 grains.

Let stand a few hours; pour the whole, including sediment,
into twenty ounces water; shake well ; let stand over night, and
pour off the clear part.

After use, return to bottle, shake up, add gold in proportion
to prints toned, and a grain of chloride of lime for every grain
of chloride of gold, or thereabouts, keeping the bath smelling
faintly but distinctly of chlorine.2

This bath gives a variety of good shades, up to full black. In
fact, a pure black seems to be obtained more easily with a chlo-
ride of lime bath like this, than with the other formulas. The
bath keeps in order for many months, always ready for use.

Dr. Liesegang* s Fo

Water .

Fused acetate of sodium
Phosphate of sodium
Chloride of lime

Water

Chloride of gold aud potassium

mulct.

50 ounces.
1 ounce.
45 grains.
15 "

50 ounces.
15 grains.

These two solutions are to be kept separate and mixed in equal
bulks as wanted, immediately before use.

It seems useless to farther multiply formulas, but it may be
remarked here that, as the function of the substance added to the
gold solution is to neutralize it, and prevent the corrosive action
of the chloride of gold in its primitive state, it follows that alka-
lies combined with almost any iveah acid are likely to give good
toning baths, of which an almost endless variety may be com-
posed, differing considerably in the tones which they impart.
In addition to the baths given here, alkaline tungstates and borates
are occasionally used and liked by operators. Those who desire
to experiment can take the second formula and substitute for the
acetate of sodium such other salts as they may like to test.

Philada. Phot., III. 252.

2 Ibid., II. 109.

292 PHOTOGRAPHIC MANIPULATIONS.

Slow toning gives the richest and finest effects. The work
may be expedited by heating or by using stronger baths, but the
results are not so fine. "When a bath refuses to tone, a little
more chloride of gold may be added to start the action.

§ 12. — Toning and Fixing Baths.

It remains to speak of certain baths which effect at once the
toning and fixing. These are made either with hyposulphite of
sodium or sulphocyanide of ammonium.

Hyposulphite Fixing and Toning Bath. — If two ounces of hypo-
sulphite of sodium be dissolved in eight ouDces of hot water, a
grain of chloride of gold previously neutralized with carbonate of
sodium (ammonia or phosphate of sodium will not answer) be added
after the hyposulphite has dissolved and been stirred up, we obtain
a mixture which, after half an hour's standing, is in condition to
fix a print, at the same time toning it to a rich purple black.

Great fault has been found with this mode of toning, and it
is certainly less safe than the foregoing. If used a few hours
after mixing, and if a very moderate number of prints be fixed in
it, they are as permanent as those treated separately. But, after
standing, or if more than a very moderate number of prints be
fixed in it, these are sulphur-toned, and speedily fade and turn
yellow.

Good tones are more easily got by separate toning than by this
bath, which often gives coppery tones when it is difficult to find
a reason why.

Sulphocyanide Toiling and Fixing Bath. — The writer believes
that he was the first to show that a toning and fixing bath could
be made with a sulphocyanide and chloride of gold. His experi-
ments were made in 1865, and are referred to in the British
Journal for 1866, p. -160 and p. 508. A solution of sulphocyanide
of ammonium mixed with chloride of gold is quite free from the
objection of fading. But the prints must be left some time in a
second and fresh bath of sulphocyanide, otherwise a silver com-
pound remains in the paper, and eventually darkens.

To prepare this bath, chloride of gold is to be precipitated with
a very few drops of ammonia, and redissolved with sulphocyanide
of ammonium. This rose-colored solution, if used fresh, stains
the lights rose-color. But if kept twenty-four hours, it becomes
colorless, and then no longer stains the lights. Dr. Liesegang

SILVER PRINTING. 293

finds the addition of a little sal ammoniac very advantageous for
preserving the whites clear.

When toning baths lose their toning properties, there frequently
remains gold in them which has passed to an inactive state.
This can be thrown down by making the bath acid with a little
hydrochloric acid, and then adding a few drops of solution of
sulphate of iron. The gold falls immediately as a brown powder,
which may be collected on a filter and preserved.

§ 13. — Fixing the Prints.

After the toning is finished, the print is passed through clean
(but not necessarily distilled) water, and is thrown into the fixing
bath.

Hyposulphite of sodium 1 pound.

Water 4 to 5 quarts.

Using it a little stronger in winter than in summer. A print
ought to be completely freed in ten to twenty minutes. Too long
a time in the fixing bath will diminish its beauty.

Until lately, the substance exclusively used for fixing positives
on paper has been hyposulphite of sodium. Within a year or
two sulphocyanide of ammonium has been proposed as a substi-
tute, on the ground that the prints were thereby secured from the
injurious action of partly used hyposulphite, which causes fading.

When either chloride or nitrate of silver is added to a solu-
tion of hyposulphite of sodium, decomposition takes place, with
formation of tetrathionate of sodium,1 an unstable substance
which readily undergoes farther decomposition. Tetrathionate
of sodium will itself tone a print very beautifully, entirely with-
out the aid of gold; its toning action seems to depend upon the
formation of sulphide of silver, an intensely black substance, so
that this process may be likened to some extent to the blackening
of a collodion picture with alkaline sulphide, with this difference,
that the action of alkaline sulphide is far more powerful and
extends to chloride and iodide of silver, which it blackens readily
and intensely. Tetrathionate of sodium, or rather the hyposul-
phite bath containing this substance, will not do this, nor will it

1 Tetrathionic acid (S405) differs from hyposulphurous acid (S202) in having
one-fifth less oxygen.

294 PHOTOGRAPHIC MANIPULATIONS.

attack the albuminateof silver which remains to some extent all
through the substance of the picture. A sulphur toning bath
spares, therefore, the whites of the albumen print, which a solu-
tion of alkaline sulphide would turn brown.

The tendency to fade seems to be distinct from this production
of sulphide, although it mostly accompanies it. The mere pro-
duction of sulphide of silver could not cause fading, for sulphide
of silver is a very permanent substance. This we see abundantly
proved in the case of negatives which have been treated first with
solution of iodine and then with a bath of sulphide of potassium,
and which have no disposition to fade, even by long keeping.
The addition of three or four grains of bicarbonate of sodium to
the ounce of fixing bath, is useful as checking somewhat the
tendency to produce unstable prints.

Generally speaking, the print tends to gain in permanence by
a prolongation of the action ; some which the writer left for over
an hour in a joint toning and fixing bath exhibited remarkable
resistance to the destructive agencies of various tests which he
applied to them. But the loss of brightness by long immersion
indisposes photographers to permit it.

No more important advice can be given to the photographer
than Do not spare the hyposulphite. Even a fresh bath should not
be used for too many prints, and a bath which has stood over
night after using, should be unhesitatingly rejected, because the
decomposition goes steadily on, and such a bath is in much worse
condition the next day than it was at the end of the day of use.

It is always difficult to induce photographers to act upon cor-
rect principle as respects the toning bath, not merely on account
of the expense of the gold solution (it requires a better toned
print to withstand the action of the fixing bath when the latter
is fresh and in right condition for the permanency of the print),
but because it is easier to work with a decomposed fixing bath ;
so much so, that ten years ago it was even recommended to start
decomposition in the bath by substances purposely added. But
the photographer who really desires to do justice to his work
will not allow himself to be swayed by such considerations, and
may be assured that with a little care he will obtain admirable
tones that will resist the fresh hyposulphite and give prints that
will not disgrace him by turning yellow and fading out.

SILVER PRINTING.

295

§ 14.— Washing.

The subject of washing is one that demands the greatest care
on the part of the photographer, and there is an almost positive
certainty that unless it be done systematically and thoroughly,
the prints, however carefully managed in other respects, will'
rapidly fade. To work thoroughly, the water must be used
abundantly, and must be continually changed.

If prints be thrown into a tank, and a stream of running water
be made to flow into it for several hours, a few prints may be
satisfactorily washed. But if the number be large, they will
interfere with each other, and the washing will be more or less
imperfect.

The simplest contrivance for obviating this difficulty is to have
a plug in the bottom of the tank which can be removed from
time to time and the tank emptied. Both the time of washing
and the quantity of water necessary are in this way very much
diminished, but care is necessary that the prints be not drawn
into the orifice.

To obviate the necessity of attending to the washing and re-
moving and replacing the plug, a siphon may be adapted to the
tank, which will come into ope-
ration as soon as the water
reaches a given height (see Fig.
123). The sjphon pipe passes
under and through the bottom.
The opening in the bottom which
communicates with this pipe is
to be covered with a strainer.
Or, what is much better still, is
a plan adopted by the writer :
a ledge is made all round the
sides at a height about an inch
above the bottom, and on this
rests a sheet of metal pierced
with a great many holes about
a quarter of an inch in diameter. The prints, as the water drains
away, rest on this plate and get a very thorough draining away
of the wash-water. There is an additional advantage in this
arrangement, that it is impossible for prints to lie over and block

296 PHOTOGRAPHIC MANIPULATIONS.

up the exit pipe. The sheet should be made of sheet tin, var-
nished, and not of zinc.

Considerable care must be taken in the arrangement of the
siphon to make it do its work regularly. To empty the tank, the
water must of course run out faster than it is supplied ; the dia-
meter of the siphon must therefore be larger than that of the
supply pipe, especially as the water comes from the street mains
under a stronger pressure than it runs off, and therefore it is sup-
plied faster than the mere proportion between the pipes. This
larger size of the siphon introduces this difficulty, that the water
tends simply to drain off through it, instead of starting the action
of the siphon and so emptying the tank. This difficulty the
writer finds may be lessened by lengthening the lower limb of
the siphon, and contracting it a little at the opening of the lower
end.

The stream of water should, in all cases, be thrown obliquely
against the side of the tank ; this gives a rotary motion to the
whole body of water and keeps the prints constantly moving, a
most important consideration, and which should never be neg-
lected. The flow of water through the siphon will be regulated
as to rapidity by the difference between the length of its legs.
The greater length given to the long leg the more rapid the flow
of the water, and the less danger of draining off without starting
the siphon.

Other and more complicated plans for supplyi-ng the water
have been proposed, such as carrying a pipe round the inside
top edge, and piercing it with holes, so as to sprinkle the surface
of the water with small jets. But unless these are so contrived
as to send slanting streams, and so keep up a rotary motion, a
great advantage is lost.

An ingenious arrangement consists in dividing the tank into
two parts by a compartment, underneath which, and under the
bottom of the box, is placed a fulcrum on which the tank balances
backward and forward with a see-saw motion. The compartment
that is uppermost receives the stream of water till it reaches a
certain height; it then rocks over, and the other side receives
the water. Meantime the first side is emptying out, and, when
empty, rises again and again fills. In a narrow compartment or
drawer under the tank, and attached to it, a quantity of bullets
are placed loose. These roll from end to end, and by their
weight prevent the end that is lowest from rising too soon.

SILVER PRINTING. 297

In whatever way the photographer elects to wash his prints,
he must satisfy himself that the work is done effectually. The
mortification which must be experienced by those who have dis-
tributed handsome-looking prints, at finding them turn yellow
and fade, cannot be otherwise than very great, and nothing has
acted upon photography so unfavorably as the universally recog-
nized uncertainty as to the durability of its most attractive pro-
ductions.

There are several ways of testing whether hyposulphite is com-
pletely washed out. Two simple but not very accurate methods
are the following : —

1. Touch the white of the print with a little weak solution of
nitrate of silver. If a brownish mark is made, it is certain that
the print is very imperfectly washed.

2. Touch the white of the print with a little very dilute solution
of iodine in alcohol. A blue mark indicates that the print is
pretty nearly free from hyposulphite. Before using this test, it
should be ascertained that the particular paper used is sized with
starch, or at least has some starch in the sizing, which strikes a
blue tint with iodine when no hyposulphite is present. To fix
this point, touch a piece of the paper that has not been sensitized
with a little very weak solution of iodine in alcohol, on the back.
If no blue stain is produced there is no starch in the sizing, and
this test cannot be used.

3. By far the best test is the following : Take a clean beaker,
or even a two-ounce vial, provide a small piece of white blotting-
paper, on which make some irregular marks with a glass rod
dipped in weak solution of acetate of lead.

Fill the beaker or vial nearly full of water, add a few drops
of sulphuric acid, and mix. Then put in a part of the print to
be tested, several square inches at least, and drop in ten or twenty
grains of granulated zinc, and immediately cover the mouth with
the blotting-paper marked with acetate of lead, which must be
still moist. Leave the whole for ten or twenty minutes. If the
markings turn brown, it is a proof of insufficient washing. Prints
that will stand this test may be considered as thoroughly washed,
which cannot be said of (1) and (2), which are less exact.

It is necessary to be sure of the purity of the sulphuric acid and

zinc employed, and the best way to accomplish this is to try the

experiment d blanc, that is, go through it without the print to be

tested. If then the markings become brown, it is a proof that

298

PHOTOGRAPHIC MANIPULATIONS

the materials are impure. This preliminary trial entails very
little trouble, as one may immediately afterwards proceed to test
the print, adding it to the other materials, and, if necessary, a
few drops more acid to keep up a very gentle escape of gas.

Where sulphocyanide of ammonium is used as a fixing agent, it
is probable that a materially less amount of washing is sufficient.
But care must be taken that the fixing has been effectual. This
may be ascertained by covering one-half of a print and exposing
the other half to a bright sunlight for three or four hours, or,
better, a day. If any difference in the purity of the whites is
perceptible in the two halves, the fixing has been insufficient.

§ 15. — Finishing the Print.

The fixed and washed print will next require to be trimmed
and mounted.

When very large quantities of prints are trimmed, machines
are made that cut them out of the required shape at a single
blow. This method is peculiarly suited to portraits, especially
card portraits. Landscape prints require more attention, and the
trimming can often be so regulated as to improve the general
effect.

An extremely convenient arrangement is to procure a thick
plate of glass with its sides exactly at right angles to each other,
and to rule on it with a diamond a number of
lines parallel to the sides. Then resting the
plate on the print, some one of these lines is
kept parallel with a vertical or horizontal line
of a building, or with the line of the horizon
itself. Then a sharp blade is run round the
edges.

It is convenient to have one end of the plate
dome-shaped. The edges should bevel a little,
receding as they rise from the print; the ruling
should be on the under side.1
Some operators use brass frames. These are very objection-
able, as fine fragments are chopped off and ground into the paper,

1 These plates are made and for sale in London, but, apparently, not here.
Mr. B. Shoemaker, of this city, has made one for the author, of 8x10, a larger
size than is kept in Loudon. Probably when they are better known here, they
will be kept by dealers.

y. 124.

SILVER PRINTING. 299

eventually making stains. Steel edges to glass plates are excel-
lent, but brass edges to glass plates are to be condemned.

The trimmed print is next to be attached to the mount with
some adhesive substance. Glue is undoubtedly the best, but not
the least troublesome, and is therefore less used than paste and
gum.

Whatever is used should be applied freely, and a few minutes
given to swell, otherwise the print cannot be applied smoothly
and evenly to the mount. Whatever adhesive material is used,
should be freshly made. Sour paste is very objectionable.

Many amateurs like to paste their prints into scrap-books
instead of mounting on cards, attaching them to the leaf by the
four corners only. A good deal of annoyance is often caused by
the cockling up either of the print, the leaf, or both. The writer
finds that this trouble can be perfectly avoided as follows : —

Place some powdered gum-arabic in a wide-mouthed vial with
a long thick cork. Moisten the bottom of the cork with the
tongue, place it in the bottle, reverse it, and some powder will
adhere ; moisten again slightly, and gently rub the under corners
of the print with the cork, transferring thus a very thick muci-
lage, which dries almost instantly, and without cockling. No
one who uses this method will ever use any other. It has, beside
its freedom from cockling, the advantage of being always ready,
and yet always affording a perfectly fresh material, free from
danger of sourness, and certain not to black the corners of the
print.

Too little attention is paid to the quality of the pasteboard
used for mounting. If this contain hyposulphite of sodium, used
as " antichlor" by many papermakers, the eventual destruction
of the print is almost certain, as in damp weather enough moisture
penetrates to transfer the hyposulphite to the print. It has been
affirmed that three-fourths of all the mounts in the market give
indications of hyposulphite when tested carefully.

It is therefore no small protection to the print to have a litho-
graphic " tint" printed on the board for mounting, and extend-
ing a short distance beyond the print all round. In this way
the transfer of soluble ingredients from the mount to the print
is rendered well-nigh impossible. As various adhesive prepara-
tions adhere much less well to thick " photographic tints" than
to ordinary paper, it is generally necessary to use good glue,
otherwise the prints readily peel off.

300 PHOTOGRAPHIC MANIPULATIONS.

In damp weather the drying of the adhesive application between
the two hard surfaces proceeds slowly, and care must be taken
not to pile up the prints too soon, or the evaporation may be checked,
and the paste or other material may mould, and immediately
stain the prints. Hundreds are sometimes lost in this way before
the danger is perceived.

Boiling. — Prints, after mounting, are always rolled, usually in
powerful presses between steel surfaces. This forces together
the fibres of the paper, gives a hard, fine surface, darkens the
print a little, and improves its appearance materially. It is best
done just before the print is dry after mounting. The steel sur-
faces must be kept bright, which is often troublesome. Nickel
plating greatly diminishes the trouble of preserving a high sur-
face.

Encaustic paste is prepared by dissolving white wax in essential
oil of lavender, or any other volatile solvent, to a pasty consist-
ency. This mixture, well rubbed into a print with a tuft of
flannel, adds considerably to the transparency of the shadows,
and, in many cases, decidedly improves the picture. It has also
a favorable influence upon the durability of the print. Salomon,
whose prints are remarkably fine, gives the following formula: —

Pure virgin wax 5 ounces.

Gum eleini 44 grains.

Benzole 2 ounces.

Essence of lavender 3 "

Oil of spike 66 drops.

Grune boils equal parts of white wax and castile soap in an
earthen vessel with a little water, enough to make a soft paste.

§ 16. — Permanence of Silver Prints.

Great discredit has been thrown upon photography by the
fading of silver prints, an effect which the author believes to
have resulted from negligence in washing. A well washed and
toned print is, according to his experience, very durable. Of
gold-toned prints made by the writer of this manual not a single
one has faded or altered in any respect.

The writer believes that in very many cases of fading, espe-
cially of views made for sale, there has been no gold toning at
all, but simply a sulphur toning. With albumenized paper this
toning is sure in the long run to decolorize very much, though

FAILURES IN PHOTOGRAPHIC OPERATIONS. 301

some specimens on plain paper, executed by him many years ago,
are still as good and as pure black as the day they were finished.
The different modes of gold toning seem all to yield results
equal in respect of permanence. Developed prints, although
gold-toned with equal care, are less permanent, according to
careful and extended experiments made by the writer, than sun-
prints. Of these last, the strongest seem to be those that have
been over-printed enough to bear a very full time (twenty minutes
or thereabouts) in a strong fresh hyposulphite bath.

CHAPTER XIV.
FAILURES IN PHOTOGRAPHIC OPERATIONS.

The beginner in photography will be very apt to find that,
after proceeding reasonably well for a time, his success suddenly
terminates for some reason quite undiscoverable to him. He
appears to be proceeding exactly as before, yet he cannot get the
same results. A very simple and useful course will be to change
each of his materials in succession, collodion, bath, and developer,
and so endeavor to detect the proximate source of the trouble.
This plan does not always, however, succeed, for the new mate-
rial substituted may have precisely the same fault as the old ; it
may not be in any respect bad or impure, but may be simply
unsuitable to the other materials with which it is employed.

Not only the beginner, but even the experienced photographer,
will occasionally find that things go wrong ; no one can claim
entire immunity from photographic troubles. For these reasons
the writer has endeavored to make this chapter a very complete
one, believing that it will be very frequently referred to, and
with advantage. He has collected the information here given
partly from personal experience, but also very largely from other
sources in various languages. For convenience of reference, it
has been carefully classified under different heads : —

802 PHOTOGRAPHIC MANIPULATIONS.

I. Failures Common to Negatives, Ambrotypes, and Fer-
rotypes.

Sec. 1. Fogging and Veiling. Seepage 302.
" 2. Thinness of Film. Page 310.

" 3. Irregularity of Film, Crapy and Structural Lines, Gran-
ularity, Warty Lumps, etc. Page 310.
" 4. Transparent Mottling at Corners. Page 312.
" 5. Defects in the Image. Page 313.
" 6. Splitting and Slipping of the Film. Page 316.
" 7. Want of Sharpness. Page 317.
" 8. Streaks. Page, 318.

" 9. Transparent Spots and Pinholes. Page 321.
" 10. Opaque Spots, Comets, etc. Page 324.
"11. Lines. Page 326.

" 12. Stains and Surface Markings. Page 327.
" 13. Feathery Markings : Imperfect Fixing. Page 330.
" 14. Faults in Varnishing. Page 330.
" 15. Miscellaneous. Page 333.

II. Failures belonging especially to Negatives. Page
334.

III. Failures belonging especially to Ambrotypes and
Ferrotypes. Page 335.

IV. Failures belonging especially to Paper Develop-
ment. Page 336.

V. Silver Printing.

1. Failures Common to Glass and Paper Work. Page 336.

2. Failures Peculiar to Silver Printing on Paper. Page 338.

3. Failures Peculiar to Collodio- Chloride Printing. Page 342.

I. Failures Common to Negatives, Ambrotypes, and

Ferrotypes.

§ 1.— Fogging.

Fogging is a trouble that affects different operators very vari-
ously : some are very frequently, others almost never affected
by it. The learner may expect to be frequently troubled; the
experienced operator will have learned how to avoid it, except,

FAILURES IN PHOTOGRAPHIC OPERATIONS. 303

perhaps, when he works under unusual conditions, or with chemi-
cals different from those which he habitually employs.

Before proceeding to the particular sources of fogging, some
observations of a general nature may advantageously be made.

General Remarks. — When a case of fogging presents itself, a
careful study of the appearance of the plate will often afford a
clue to the source of the trouble.

A fogged plate may present a uniform sheet of blank fog all
over, without a trace of a picture. Or an image may come out
with more or less strength, but, after showing itself, may pre-
sently become covered with a dense deposit of silver. Or, finally,
the fogging may be very slight, leaving all details of the image
perfectly visible, but ruining it by veiling the deep shadows
sufficiently to prevent them printing to a full rich black.

The above various cases are alike in this, that the action of the
fogging is uniform all over the plate. We, therefore, presume
that the trouble lies either in the chemicals, the light, or the
atmosphere of the dark room, and, if we cannot get rid of the
evil by the addition of a little iodine to the collodion, we must
commence a series of systematic trials (see p. 306), to detect the
source of the trouble. We do not, however, in the above case,
suspect the camera. For, if the camera leaks light, the effect of
that light is invariably partial and irregular. The unequal con-
traction and expansion of the wood round the flange, into which
the lenses are screwed, will often produce a crack; this will give
a mass of fog somewhat denser in the middle, and shading off
towards the ends of the plate. A hole in the bellows body will
produce an irregular mass of fog on some part of the plate on
which the light falls. If the dark slide does not fit tight, the
fogging will mostly be at one end of the plate. A crack in the
shutter will produce a bar of fog lengthwise of the plate, and
shading off on both its sides. Cracks in the woodwork will send
in fan-like masses of light, and so on. These appearances will
aid at once in the detection of the cause of the troubles (see also,
beyond, "White Light," p. 306).

Another very valuable distinction is drawn as follows: —

A superficial fogging, one that rests on the film and not in it,
and can be rubbed off with the finger, is always attributable to
the chemicals, never to exposure to white light, which last always
produces an action in the interior of the film.

Therefore, if the fogging be internal and not superficial, it is

301 PHOTOGRAPHIC MANIPULATIONS.

most probably owing to intrusion of light; this cannot be affirmed
with entire positiveness, but is the most likely cause, for faults in
the bath, collodion, etc., most generally give rise to superficial
fogging. That is, fog from chemicals is generally superficial ;
superficial fog is always from chemicals.

1. Chemicals in Fault. — Generally speaking, when fog shows
itself, and when the presence of white light is not suspected, the
first thing done is to treat the bath.

But, in all such cases, the first step should be invariably to try
another collodion, or to add a little tincture of iodine to that in
use. Iodine tends to make the bath slightly acid. Therefore, the
addition of acid to the bath, or iodine to the collodion, is, in each
case, a step in a somewhat similar direction. And it would at
first seem more correct to add the acid to the bath, as that brings
the bath at once to the requisite point of acidity, and stops there,
whereas, by adding iodine to the collodion, every plate tends to
render the bath more acid.

But, in practice, it is found that the results of the two treat-
ments are very different. Sometimes a very little iodine will
effect a cure when acid seems to have no effect. For example,
the writer has seen a bath made of fused nitrate of silver abso-
lutely refuse to give a clean picture, even when acidified beyond
what is proper, and yet work excellently by adding a very little
iodine to the collodion — a collodion which was not new, but had
worked perfectly a month before, in cooler weather, with a nearly
neutral bath.

When a neutral nitrate has been used, acidulation should not
be carried beyond one drop of nitric acid or twenty-five drops of
No. 8 acetic acid to every fifteen or twenty ounces of bath, and
this much is only allowable when the nitrate of silver was free
from acid. When the acidifying has reached this point, if the
picture is not clean, the remedy is most certainly needed in the
collodion. And it must never be forgotten that these treatments
with acid or with iodine are but necessary evils, and that the
more nearly neutral the bath and collodion the more rapid will
be the work. There appears to be no doubt that excess of nitric
acid in the bath may cause fogging.

The bath, however, may have been alkaline, and may therefore
need neutralizing and acidifying. This will be ascertained by
introducing a piece of red litmus-paper. Alkalinity may arise
from having introduced an alkali intentionally, especially if am-

FAILURES IN PHOTOGRAPHIC OPERATIONS. 305

nionia have been added, previous to sunning. Bicarbonate of
sodium renders a bath rather neutral than alkaline, and is the
only substance that should ever be employed for removing an
excess of acidity. Or alkali may have been carelessly introduced,
when glasses cleaned with caustic soda or other alkali have been
insufficiently washed before collodionizing.

The use of fused nitrate of silver, that has been kept too long
jn a state of fusion, or heated to too high a temperature, may tend
to produce fog. Eemedy : add very dilute nitric acid very cau-
tiously, or try an older collodion.

An old bath, highly charged with impurities, may lead to
fogging. As a palliative, add bicarbonate of sodium till a per-
manent precipitate falls, and then expose for several days to the
sun. Filter, and acidify if necessary.

Sometimes an old bath will lead to fogging, not by reason of
impurities, but simply by having become too weak by mere
exhaustion of the silver. This will be more apt to happen with
baths whose evaporation is checked by being kept covered.
Remedy : add crystals or fused nitrate of silver.

Or the collodion may be in fault. A very new collodion, espe-
cially one containing little or no alkaline salt, but chiefly cad-
mium salt, particularly if used with a nearly neutral bath, will
sometimes refuse to give clean, bright pictures. (See also p. 136.)

In this case, especially if the collodion be very pale, it is well
to add to it a little tincture of iodine, and so apply the remedy to
it rather than to the bath. Or the admixture of a little old (but
not too old) and more highly colored collodion will be found
useful.

The developer may be in fault. If, when thrown upon the
plate, it becomes almost immediately muddy, more acetic acid is
wanted. Or, a developer that has hitherto worked well, may
cease to do so in consequence of a change of weather and tem-
perature.

It has been affirmed that excess of acetic acid may produce
fogging.

If copper be used in the developer (sulphate of copper, blue
vitriol), and the plate have been left in the bath for a time insuf-
ficient to convert all the soluble iodides into iodide of silver,
brown fog may be produced by the formation of iodide of copper
in the film.

Old specimens of pyrogallic acid used in developing or rede-
veloping, have been known to produce blue fogging.

306 PHOTOGRAPHIC MANIPULATIONS.

2. The vessels may be in fault. India-rubber or vulcanite bath,
or even dippers, may lead to fogging, and are more likely to
when new than old. In work in the house, they should never
be used. Even for work in the field, the writer advises a glass
bath with a case and screw cover. L^ut if weight is very im-
portant, and a rubber bath is to be used, it should, if new, be put
aside for twenty-four hours with a strong solution of caustic alkali.
The "concentrated lye," sold in sheet-iron boxes, is very good
for this purpose, and may be dissolved in eight or ten times its
weight of water. In the case of an old bath, it should be scrubbed
out with a sponge tied to a stick between each using.

3. The water may be in fault. It is said that cases of fogging
have been traced to this source, but the writer has never expe-
rienced it. The sorts of water said to cause it are — water con-
taining iron; water containing much lime; rain-water collected
off of dirty roofs, or water from wells into which any decaying
matter penetrates, or any foul drainage.

4. White light will, of course, cause fogging. As already said,
a careful examination of the appearance of the plate will gene-
rally indicate whether light has been admitted into the dark room,
or has made its way into the camera, because, in the first case,
its action extends uniformly over the whole plate, in the other it
does not, but mostly appears in bars, fans, brushes, or long slant-
ing rays, the positions of which will always aid in tracing out
the cause, remembering that the more indistinct the boundary
of the fog the farther is probably the opening or leak from the
plate.

A few systematic trials will always force out the source of the
fault.

Develop a plate without exposure and without removing it
from the dark room. If no tendency to fog appears, the fault
was clearly in the camera or the dark slide. Then sensitize a
plate and carry it into the glass room in its dark slide. Leave it
a few minutes and develop it again without having exposed it or
withdrawn the shutter. If it then fogs, the leak is in the dark
slide; if not, then it must be in the camera.

Let us, on the other hand, suppose that the plate fogged, when
developed, without having been removed at all from the dark
room. Then the fault is, either that white light gets into the
dark room, or the chemicals are in fault.

FAILURES IN PHOTOGRAPHIC OPERATIONS. 307

A simple way of deciding this is to try a plate at night. Use
only a candle or lamp, well protected with yellow or green glass.
Sensitize a plate, lay it on a dark object, put a worthless negative
over it, and carry it into another room, in which is a gaslight,
turned on. Hold the plate a foot from the burner for fifteen
seconds, taking care that the back is perfectly protected. Then
carry and develop, by the light of a lamp or candle, behind yel-
low glass. If a clean picture comes out, it is a proof that white
light gets into the dark room in daytime. If it fogs still, when
tried thus, the chemicals are wrong, and must be changed, one
after another, until the wrong one is detected.

This simple but systematic and exhaustive search will invari-
ably lead the operator straight to the source of his trouble.

If the foregoing examination shows the fault to be with the
camera, it must be carefully overhauled. Carelessly made cameras
are quite worthless, and a great many such are exposed for sale.
The writer dislikes walnut, although this wood is so great a
favorite, because it cracks so much, and prefers mahogany, and
next to it, cherry. Look, therefore, carefully for cracks. Exa-
mine if the shutter works close in the dark slide. Notice if a
hole has been worn into the bellows body. But the commonest
place to crack is the camera front, which often splits at the screws
that fasten the flange in. When a crack once appears, do not
trust to filling it up, but get a new front. A crack slowly widens,
and so leaves a space between the edges and the filling. A crack
may, however, be neatly mended by a good workman. The front
is cut half-way through at the crack, for half an inch each side,
and a piece set in. Then if the crack widens, it can do no harm,
and another crack is not likely ever to form, as the tension that
caused it has been relieved.

When a camera is used in the open air, it must invariably be
covered with a thick cloth. Strong light, especially direct sun-
light, will make its way through almost any camera, unless so
protected.

5. Sunlight falling directly upon the lens may cause fogging,
though this result does not necessarily follow.

6. 'Atmospheric Causes. — The sources of fogging may depend
upon impurities in the air. These may be of several sorts.

A. Chemical. — Fumes of various sorts may cause fogging.
Ammonia is especially to be avoided. See that the ammonia

808 PHOTOGRAPHIC MANIPULATIONS.

bottle has a well-fitting glass stopper — not a cork. Sulphuretted
hydrogen, arising from exposure of solutions of sulphide of potas-
sium, or of Schlippe's salt, is even worse.

B. Certain organic substances have a tendency to cause fogging.
The vapor of turpentine and of fresh paint. The smell of kero-
sene lamps in the dark room does not seem to be hurtful, as might
be supposed.

0. Foulness in the air is liable to cause fogging. Emanations
from drains, cesspools, and the like, or any putrefying or decay-
ing organic matter. Emanations from stables are always ammo-
niacal, and tend to fogging. It should be borne in mind that
immunity from these sources at one time, is no proof that they
may not be acting at another. Dampness acts very remarkably
as a vehicle for odors, and emanations may rise in wet weather so
as to cause fogging, when they would not at other times. Inde-
pendently of this, the state of the barometer controls currents and
movements of air remarkably. When the barometer is rising, a
room will be supplied with air from channels quite different from
those that act when the barometer is falling. Drafts of chimneys
are always worse with a rising barometer. Whether carbonic
oxide, the gas which flues are intended to carry away from fires,
will cause fogging, the writer cannot state, but no one is justified
in permitting this most dangerous gas to escape into apartments
by defective flues. Its danger is not greatest when it asphyxiates,
for then the evil is noticed in time, and remedies are applied.
But if inhaled continually in small quantities, it causes diseases
of the brain and spine. Leakage of illuminating gas may cause
fogging.

7. Errors of Manipulation. — Under this head the following are
to be classed : —

a. Plate left too long in the bath. This, especially in warm weather,
is a fruitful cause of foggy plates. When the plate is perfectly
free from oiliness, it is ready for removal. The sensitiveness in-
creases by leaving in for a full time; the brightness and cleanness
are greatest when the plate is taken out as soon as the oily lines
are gone. In the latter case, undecomposed bromide remains in
the film, diminishes sensibility, but checks veiling and fogging.

b. Too long a development, rendered necessary by too short an
exposure.

c. Neglect to add acid to the developer or the redeveloper.

d. Insufficient washing oil" of the developer, so that enough
remains to act.

FAILURE'S IN PHOTOGRAPHIC OPERATIONS. 309

e. Considerable over-exposure with a large stop will produce fog-
ging, or rather an appearance closely resembling the effect of fog.

f. Re-dipping the plate into the negative bath before development
is very apt to cause stains and fog, especially with a bath not in
first-rate order.

g. Too strong a developer, or using in summer a developer suit-
able for winter.

h. Keeping on the developer after spangles of silver show in it.

i. Developer turns muddy at once. Developing vessel not duly
cleaned. Use the bichromate solution. Bad condition of the
nitrate bath. Keeping and using pyrogallic acid dissolved in
water instead of alcohol.

In the case of glass positives, fogging, when superficial, may
be wiped off carefully with soft cotton-wool.

7. Temperature of the Dark Room. — Either extreme of tempera-
ture may cause fogging. In very hot weather, use less iron and
more acetic acid. Some operators find it advantageous to place
the bath in a vessel of cold water, to keep down the temperature.

In very cold weather, if the dark room be not artificially heated,
the chemicals will not act well. Great perplexity is sometimes
caused to inexperienced operators in this way, who will perhaps
suddenly find that they pass from success to failure without any
assignable reason, and only learn by the most painful experience
the real source of their trouble. A temperature of about 65° is
always the best, though considerable variation may occur before
evil results.

Veiled (that is, very slightly fogged) negatives often print as
well as brighter looking ones. If the veiling reaches the extent
of slight fogging, a clearing process may be resorted to in either
of several ways. A very weak solution of sesquichloride of iron
may be washed over the plate. Or it may be washed a little
with weak Lugol's solution, and then thrown into the fixing
bath. Or the plate may be chlorized (see article on After-inten-
sification) to a very moderate extent, and then passed through
the fixing bath. Whichever plan is adopted, experience should
be' first gained on worthless negatives.

8. Dew Collecting on the Lens. — In hot damp weather dew may,
at any time, collect upon the lens almost in a moment. This is
especially apt to happen in passing from a cool, shaded spot to a
warm, damp one. Watchfulness for this cause of trouble will be
particularly needed in warm, damp, steamy weather.

310

PHOTOGRAPHIC MANIPULATIONS.

9. In portraiture, an excess of diffused irregularly reflected
light may veil the plate.

§ 2. — Thinness of the Film.

A thin gray film, so appearing when removed from the sensi-
tizing bath, may be caused by too strong a bath, which at first
acts rapidly upon the film, but gradually diminishes its density.
This is the case with ordinary collodion. With a collodion con-
taining bromide only, intended for the dry process, thinness of
the film results from too weak a bath.

A thin bluish film, with wet plates, indicates insufficient salting
of the collodion, or insufficient time in the bath. With collodio-
bromide plates, it indicates that the collodion has not stood long
enough after sensitizing.

Very old collodion will sometimes give very thin, transparent
films, as will also a foul nitrate bath.

Fig. 125.

lip

\ 3.— Irregularity of the Film, Crapy and Structural Line, Warty

Lumps, Granularity, &c.

Crapy Lines. — 1. Too watery alcohol or ether. (Fig. 125,
lower corner.)

It does not necessarily follow that the materials are in fault as
purchased, for the water may have been in-
advertently introduced by the photographer
himself. After cleaning a bottle, in which
collodion is to be made, proceed as follows :
Drain it well, pour in an ounce or two of al-
cohol, shake well so that the alcohol wets
every part, pour it out, and repeat the opera-
tion. The quantity of water that may be in-
troduced by a wet bottle is more than would
be supposed.

2. Neglect to rock the plate from side to
side, after collodionizing, especially when using a rather thick
collodion. If this is the case, thin with equal parts alcohol and
ether. Before deciding, however, that the collodion requires
thinning, the operator, if not experienced, should endeavor to
satisfy himself that the fault is not in his manipulation: thinning
should not be unnecessarily resorted to.

FAILURES IN PHOTOGRAPHIC OPERATIONS.

311

The larger the plate the thinner must be the collodion. A
small plate can be managed with a collodion which will inevita-
bly give crapy lines when used for a large one.

Excessive cold may produce crapy lines.

Ridges. — 1. Too much pyroxyline in collodion. 2. Too much
alcohol and too little ether. (Both these defects are cured by
adding a little ether.) 3. Excess of ether may, however, produce
a similar effect. 4. Bad cotton, tending to gelatinize; or the col-
lodion may have become too thick by the agency of bromide of
cadmium. The action of this substance upon collodion is very
remarkable, and varies extremely at different times.

Mottling may arise from irregularity in the porosity of the film,
so that the developer penetrates irregularly. It usually results
from using too thick a collodion; sometimes from not plunging the
plate into the bath soon enough after coating. Mixing with
ether and immersing as soon as set will usually remove this
trouble, which is most apt to show itself in the flat tints, espe-
cially in semi-opaque skies. Or it may arise from a bad quality
of cotton. Cottons vary extremely in this respect; some have
much tendency to mottling, others none at all. Or the alcohol
may be too watery.

Collodion that has thickened through the agency of bromide of
cadmium, may be made to work by mixing with ver}- fluid collo-
dion. Much circumspection is, however, needed. The mixture
should stand for several days, with occasional shaking, and then
be carefully filtered.

Blistering is not a common fault, but arises from using a too
old and rotten collodion.

Warty Lumps. — As the collodion film dries after coating, any
solid particles present collect around them a
portion of the collodion, making little raised
prominences. Most commonly, these are
caused by fine filaments, either of wool, from
the dust caused by wear of clothes and car-
pets, or of undissolved fibres of pyroxyline.
These little warty places, examined with a
microscope, present the appearance seen at
Fig. 126. When motes are visible as the film
flows over the plates, they can often he floated
off by pouring on an abundant quantity, and
managing to make the collodion, as it flows off, carry away the

Fig. 126.

A warty lump magui-
fied, showing a filament
nucleus.

312 PHOTOGRAPHIC MANIPULATIONS.

mote. Careful filtering of the collodion, and thorough brushing
off of the plate immediately before coating, are the best preventives.
In field work it is often best to take several small bottles of col-
lodion rather than one larger one.

Want of homogeneity in the collodion must result in irregu-
larity of density and streakiness. If different collodions be
mixed without sufficient shaking; collodion that drains off from
the plate is always denser, and sinks to the bottom if drained off
into other collodion. By standing a long time, the mixed collo-
dion may become homogeneous by diffusion, but it is unsafe to
trust to this.

Again, suppose the drainings from the plates have been re-
ceived, as they always should be, into a separate bottle, and that
a quantity of such be filtered in a collodion filter, of which the
bottom part is already partly filled with collodion, each drop
will sink to the bottom, and the two collodions will remain quite
separate. If poured out, and handled carelessly, there will be
formed an irregular mixture which cannot diffuse itself with
perfect regularity over glass plates.

Therefore, collodions either should be kept thoroughly separate,
or, if mixed, should be mixed thoroughly by shaking, and then
be either filtered in separate lots, or allowed to settle separately.
Those curious to observe the action of collodions in mixing, can
tinge one portion with a little rosaniline, by which means it can
be distinguished in its movements.

Granularity. — After a certain time of action, the iron developer
will always become muddy; and if allowed to remain on the plate
in this condition, it may fog ; or, if it does not, it will probably
form a gray, granular deposit, destructive to the fineness of the
negative. A negative, to give a rich, velvety print, should be
made up of an extremely fine silver deposit. Too much bromide
in the collodion will also cause granularity in the image.

§ 4. — Transparent Mottling at one Corner of the Plate.

This is owing to the heat of the fingers. It will be found that
these marks always come at the corner by which the plate was
held whilst being collodionized. (See Fig. 125, upper corner.)
Often, if the plate be held up to the light before putting into the
dark slide, these irregularities will be perfectly visible.

What is remarkable is that, in the great majority of instances,

FAILURES IN PHOTOGRAPHIC OPERATIONS. 313

the plate can be held without this result following. It appears
to come only with certain temperatures and conditions of the
atmosphere, and principally in cool weather. The remedy is to
fold up a piece of paper, and keep it between the finger-ends and
the bottom of the plate. In fact, this sort of marking is so great
an annoyance where it comes, and so irregular in its coming, that
it is a good plan always to use the paper ; it is little trouble, and
the cure is perfect.

In making dry plates, this precaution should never be neglected.

This sort of mottling can always be distinguished from that
which arises from bad cotton or bad alcohol (see last section) by the
marks corresponding with the shape and position of the fingers.

§ 5. — Defects in the Image.

Image strong but coarse. Too much pyroxyline.

Image fine but weak. Too little pyroxyline.

Too much Contrast. — 1. Under exposure followed by over-de-
velopment is by far the most common cause. 2. Too little py-
roxyline in the collodion. 3. Bromide either wanting entirely
or too little of it. 4. The introduction of a great deal too much
bromide will produce the same effect. That is, a little too much
bromide will make the image too flat, whilst a still greater excess
will render it harsh. 5. Acidity of collodion. (See also §13, Insen-
sitiveness.) 6. Use of old, red collodion. 7. It has been said
that alkalinity of collodion may also produce this defect. 8.
Insufficient salting of collodion. 9. Old and foul nitrate bath.
Although by good management a negative bath can be kept in
working order for a very long time, still the best rendering of
strong contrasts will always be made by a nearly new and pure
bath. Shaded foliage in well-lighted scenes and instantaneous
effects will be better rendered by plates made under these con-
ditions. If the bath wants sunning, it may be expected to give
harsh pictures. 10. Too intense a pyroxyline. 11. Working in
too cold temperatures.

Too Little Contrast. — 1. Over-exposure. 2. Too much bromide.
3. Alkaline collodion.

Too Much Vigor. — Powerful, slow-printing negatives, requiring
sunshine and long exposure to print, come with a thick, highly
salted collodion and rich nitrate bath. Such will need to be
printed with a weak positive bath and sunlight.
21

314 PHOTOGRAPHIC MANIPULATIONS.

Too Little Vigor. — Good negatives, except that they are thin,
yet very delicate and full of detail, are got with fluid collodion,
lightly salted and sensitized in weak baths. Such will need a
rich positive bath and printing in the shade.

This fault may arise from under or over exposure, the effects
of which are, however, different. In the under-exposed image,
the least defective parts will be the high lights of the object,
which will in general be good, and the worse lighted parts will
be defective. Where the picture is over-exposed, the reverse
will be the case. Generally speaking, in an under-exposed pic-
ture, especially after redevelopment, the contrasts will be too
great. An over-exposed picture will be gray and feeble, and
deficient in contrast.

It may easily happen that a negative may be condemned as
thin and flat, when in reality it may need nothing else than
printing on paper sensitized with a materially richer positive
bath.

AVeakness may also arise from exhaustion of the negative bath,
in which case it must receive more nitrate of silver. Now that
more bromide is used in the collodion, a thirty-grain bath is no
longer sufficient, but forty to forty-five grains give a better result.
The employment of these strong nitrate baths has become much
more general than at the time when the first edition of this
manual was published. A strong negative bath tends to keep
the iodide and bromide of silver (and consequently the image)
within the film. A weak bath tends to give a superficial image.

Thin While or Gray Image difficult to Intensify.— Tins is gene-
rally the result of having too much nitric acid in the bath. Add
a very little bicarbonate of sodium. If, at the same time, the
bath gives pinholes, dilute it, render it alkaline with bicarbonate
of sodium, sun it, filter, and then faintly acidulate.

The following causes are assigned by Hardwich as leading to
weak and slaty-blue images: Negative bath newly made with
impure crystals of nitrate of silver. Too much free iodine in the
collodion. Camera image very weak, as in copying old manu-
scripts, etc., full size. Use of a negative collodion made from
weak pyroxyline. Sulphuric acid left in the collodion from im-
perfect washing. Coating large plates too leisurely in hot
weather: the film dries, and there is no penetration of the de-
veloper. Over-exposure.

FAILURES IN PHOTOGRAPHIC OPERATIONS. 815

Half Tone. — The greatest beauty of result will always depend
upon the presence of plenty of varied half-tone, relieved and
supported by a certain quantity of deep shadows and high lights.
A negative that consists chiefly of dark shadows and bright lights,
with but little half-tone, will always be greatly inferior in effect.
Nothing can compensate for the absence of these broad soft half-
shades, which are abundantly present in all good work. No
royal road to this result can be indicated: it comes by a full,
but not excessive, exposure; collodion well, but not excessively,
bromized ; careful arrangement of light ; and judicious develop-
ment. Those who find great difficulty in subduing contrast may
find it a valuable hint to increase their exposures, and dilute their
developer proportionately, as otherwise the prolonged exposure
might lead to flatness.

Two Images at Once. — Imperfect cleaning. Eemedy : Use the
bichromate mixture.

Blurring or Halation. — Several different sorts of blurring pre-
sent themselves.

1. Internal reflection, i. e., from the back surface of the glass.
This vexatious evil occurs in proportion to the transparency of
the film, except that, in the wet process, there is apparently left a
portion of iodide and bromide unconverted, at the bottom of the
film, which tends to check it. Therefore this difficulty exists
less in wet than in dry plates. Nevertheless, wet plates are far
from being free from it. In taking views of interiors, the win-
dows are apt to be blurred. Generally speaking, blurring shows
itself most where a brilliant light comes next to a deep shadow.
Especially where a dark portion is surrounded by high lights,
as in the case where dark objects are projected against the sky,
or, still more, against bright clouds. In this way, roofs of houses,
instead of being bordered by a well-defined line, will shade oft",
as it were, into the sky. Small objects projected against the sky,
as, for example, a lightning-rod, may be obliterated almost en-
tirely. With wet plates the remedy is to apply a piece of wet
red blotting-paper; with dry plates, to paint the back with a
mixture of annatto, glycerine, and water, as directed under the
head of dry plate Avork.

2. Where a high light meets a dark shadow, if the portion of
the light next the shadow is too light, the result is that the dark
object is surrounded by a light band. This is only seen in wet

316 PHOTOGRAPHIC MANIPULATIONS.

plate work. In the shadow, the development consumes but little
of the nitrate of silver, so that the adjoining part of the high
light is developed in the presence of a solution richer in silver
than the rest of it.

3. The image seems to slide off into the portion next below.
This only happens with wet plates, and in cases of difficult de-
velopment, owing to a cold temperature, a weak image, etc.

4. Objects moved by the wind are also blurred. If a bough
be projected against the. sky, and moves during exposure, the
white light from the sky may almost obliterate the image of the
bough. Any blurring by the wind produces a most disagree-
able effect upon the picture.

Part of the Image weaker than the Best, with a distinct Boundary.

This is occasioned by not carrying the developer over the

whole plate with a single sweep.

Irregular Refractions. — When a piece of smooth ground inter-
venes between the camera and the objects, a strong sun falling
upon the ground may give rise to irregular movements of rarefied
air, which are capable of destroying the sharpness of that part of
the image that is just over the line of the ground.

§ 6.— Splitting and Slipping of the Film.

1. Splitting in Sensitizing Bath. — 1. Immersing too soon in the
bath, before the film is properly set. 2. Ill-cleaned, greasy, or
damp glass. 3. Omitting to roughen the edges. 4. Too much
alcohol in the collodion. 5. Too much salting. 6. Alcohol too
watery. 7. Immersing the plate too roughly. 8. Pyroxyline
made in too strong acids.

2. Splitting in Washing. — Bad quality of pyroxyline ; also, the
faults above enumerated may exert their influence in the washing
as well as in the sensitizing.

3. Splitting in Drying. — This may also be the fault of the
pyroxyline, but it is apt to result from the treatment which the
film has received. Much redevelopment with pyrogallic acid
and silver is very apt to cause the film to split. Treatment with
mercury for forcing (which see) also makes the film very tender.
Kemedy : coat the rest of the plates (when warned by one split-
ting) that are in danger, with a solution of gum in water, about
thirty grains to the ounce, or with one of gelatine, about half as

FAILURES IN PHOTOGRAPHIC OPERATIONS. 317

strong. This will not take the place of varnishing, which must
be done as usual, unless but few copies are wanted, and little
value is attached to the plate.

Splitting in drying may also arise from an insufficient quantity
of pyroxyline in the collodion, or from too large a proportion of
ether. Too alkaline a collodion gives a weak film.

In the case of dry plates, a tendency to split at the edges will
occur with some sorts of cotton that otherwise are all that can
be desired. In such cases edge with solution of rubber in ben-
zole, not only before coating as usual, but a second time before
developing.

Slipping off of the Film. — Omitting to roughen the edges. Bad
or imperfect cleaning. Old and acid negative bath. Immersing
too quickly. Pyroxyline of bad quality, or too old.

§ 7. — Want of Sharpness.

1. The necessity for having the sensitive film occupy the pre-
cise position of the ground glass, has been before dwelt on.
Without the nicest attention to the perfect adjustment of the
camera in this respect, perfect sharpness is impossible. Careless
focussing may also have been done. And some lenses have no
focus at all, but may be racked in and out for half an inch,
without great variation, being really sharp nowhere. Such are,
of course, worthless, and with a bad lens nothing can be accom-
plished. It will sometimes happen that, after a lens has been
taken to pieces to clean, the parts will be put together wrongly,
either through simple inadvertence or from want of knowledge.
When bad results are got, they seem inexplicable, and perhaps
the optician is blamed for sending out a bad lens. The figures
in the earlier portion of this book will show the proper arrange-
ment of the parts of the various combinations.

2. Camera Moving During the Exposure. — This may arise from
carelessness or from the wind. A simple mode of avoiding the
latter consists in fastening a string to the under part of the tripod
head which hangs down and ends with a loop reaching nearly to
the ground. The foot placed in this loop and pressed forcibly
down, holds the camera securely in its position, supposing always
that the legs rest on a hard surface. On a yielding surface, the
legs might sink during the exposure, enough, at least, to destroy
the sharpness.

3. Want of coincidence between the chemical and visual foci.

318 PHOTOGRAPHIC MANIPULATIONS.

§ 8.— Streaks.

There are several causes that are fruitful in streaks which may
utterly ruin the negative.

1, Immersing the Plate too Rapidly. — The mixed alcohol and
ether, with which the film is saturated, gives it a repellent action
to the bath solution, and if the plate be rapidly lowered into it,
parallel streaks may follow. As some collodions are more repel-
lant than others, a degree of rapidity may produce this result
with one that does not with another.

2. Removing too soon from the Negative Bath. — When this has
been done, oily-looking branching lines may be seen at once, if
the reflection of a light be caught on the surface (for this reason
the light ought to be arranged with special reference to observing
the surface of the plate as it is removed from the bath). These
streaks will appear in the development.

8. Repellent Action of the Film on the Developer. — The developer
for an old bath must always contain a certain amount of alcohol
to keep up its relation with the bath solution. When the nega-
tive bath is charged with alcohol and ether, the developer may
cease to mix quickly and evenly with the bath solution on the
plate, and may collect on it in ridges; under these ridges the
plate develops faster, and consequently they are represented by
dark streaks in the image. (See B, Fig. 127.) One point is es-
pecially worthy of attention. Often the developer on the film is
in a condition that it just barely holds together in an even film
so long as the plate is level, ready to break into ridges the
moment the plate is tilted up to look through, for the purpose of
judging whether it is sufficiently developed. The moment this
breaking up takes place, the development becomes unequal, and
streaks are formed. Numbers of otherwise successful plates are
spoiled in the development in this way, and the danger must
constantly be borne in mind. Generally it may be said that
(unless the operator is quite sure that his materials have no ten-
dency to this defect) it is a safer way to let the iron development
go as far as is judged safe, then first wash it off, and then hold
up to the light and examine. Unless the picture flashes up very
suddenly and quickly, it is safe to let the iron development do
all it can, before washing. Then wash off; if the negative is
found, on looking through it, to be of the right density, all is
right. If not, redevelop with pyrogallic acid, citric acid, and

FAILURES IN PHOTOGRAPHIC OPERATIONS. 319

nitrate of silver, taking care not to pour on the solution till
every atom of the pyrogallic acid is dissolved, or else to keep
the pyrogallic acid in solution.

When, in examining a negative, it is found that along the edge
which was farthest from the operator during development there
are streaks, especially branching streaks, the operator may be
pretty sure that the fault arises from the cause here described.
And if he doubts it, let him watch the plate from the first appli-
cation of the developer to its complete washing off, making sure
that the film was unbroken, and even for every second of time.
On that negative the streaks will be absent, always supposing it
was not removed too soon from the negative bath. (See 2.)

Where a great tendency exists in the negative bath to form
these streaks, it is well to agitate the plate, during immersion,
from side to side, as well as up and down. Tn fact, this last is a
very good practice for habitual adoption. A repellent action in
the film may arise from the use of too strong alcohol and of too
much ether in the collodion. Such films dry rapidly, do not
take the nitrate bath well, and repel the developer.

Blanchard has remarked that, the keeping qualities of plates
may be greatly increased by using a good proportion of bromide,
two to two and a half grains to the ounce, and removing from the
bath as soon as the oily lines disappear — further, hastening that
time by keeping the plate constantly in motion from its first
entrance into the bath. In this way some of the bromide may
remain undecomposed by the silver bath, and, decomposition
continuing after the removal from the bath, the concentration of
the nitrate of silver and its consequent evils are prevented. He
affirms that in this way he has been able to keep a plate for three
hours. Such plates must be developed without sulphate of copper
in the developer, or brown fogging may result.

4. Omitting to wipe the back, or to drain sufficiently.

5. If the table is allowed to be sloppy, it will follow that the
bottoms of the developing vessels will become wet. AVhen they
are turned over in throwing the developer on the plate, there
will be a tendency in any liquid adhering to the bottom to run
along the side and mix with the liquid poured out from the vessel
upon the plate. Such a result can hardly fail to produce ugly stains.

6. Inequalities of Temperature. — It has been affirmed that when
a material difference in the temperature of the bath and developer
exists, this may be the cause of streaks.

320 PHOTOGRAPHIC MANIPULATIONS.

7. SlreaJcs Descending more or less Perpendicularly from the Upper
Part of the Plate. — During exposure the bath solution drains
down to the edge of the plate, and tends to flow thence upon the
edge of the dark frame. When collected there in a drop, it easily
rises again by capillary attraction as the film becomes drier by
standing, and mounts up the film again, so giving rise to a streak.
Eemedies: 1. "Wipe out the dark slide. 2. Attach a piece of
blotting board to the edge of the plate. 8. Drain better after
removing from the bath and before placing in the dark slide.

Another source is changing the position of the plate after it
has drained after removal from the sensitive bath. If the plate
after draining be turned so that what was the bottom becomes a
side, the change in the direction of the currents will produce
streaks that infallibly ruin the negative.

Neglect to keep the dark slide always in one position till the
plate is out of it will evidently produce the same result.

In a word, the plate, after it has once begun to drain, must re-
main with the same side down till, by the completion of the
development, danger is ended.

8. Streaks in (he Direction of. the Dip may be caused by the
projection of the dipper that holds the plate; this may cause
irregular currents over the plate as the dipper descends. Where
this tendency exists, it may be checked by lowering the plate
very gently and slowly into the bath. The ether in the collodion
mixes only very slowly with the bath solution, and by rising in
currents along the surface of the plate may cause streaks.
Eemedy : move the plate from side to side as well as up and
down. In fact, this lateral motion is well to practise as a habit,
together with the regular up and down movement. Scum on the
surface of the bath may also cause this defect ; a piece of blot-
ting-paper drawn lightly over the surface will remove the scum.

9. Streaks along the Border, or working in from the Borders. — 1. If
the film becomes loose at any part of the edge, hyposulphite may
remain under it and escape complete removal by a short washing.
If then the plate be reinforced with pyro and silver, brown streaks
may result. 2. Redeveloper getting under the film.

10. Parallel Sets of Smeary Streaks or Lines. — Cleaning marks.
Every sort of cleaning and rubbing upon the plate leaves invisi-
ble traces, which may subsequently come out. Whether or not
they will do so depends upon various influences: If the develop-
ment is much pushed; if the bath or other chemicals are in a

FAILURES IN PHOTOGRAPHIC OPERATIONS. 321

condition tending slightly to fogginess, the tendency to abnormal
deposit will be apt to show itself by first depositing on the clean-
ing marks. Much also will depend upon the cleaning, as, if the
plate was well cleaned first in the bath; if the chemicals used in
cleaning were removed or not ; if the paper or rags used in rub-
bing were clean and fresh, or old and soiled ; if rubbing were too
hard.

Or the operations immediately preceding coating may have
been in fault, as if the broad soft brush used for removing dust
were soiled or damp ; or if there were any deposit of dampness
from the atmosphere on the plate when brushed, which dampness
would by the brushing be drawn into streaks, and, moreover,
soil the brush and spoil also the next following plate. Eemedy,
or, rather, prevention : keep the plates between sheets of clean
blotting-paper in a tin box, and the brush with them, removing
each plate as wanted only. Avoid removing the plates from a
cold to a warmer room shortly before using.

§ 9. — Transparent Spots and Pinholes.

Pinholes. — Even to experienced photographers pinholes are a
source of no small trouble. They consist of s"mall transparent
dots in the negative, and are generally occasioned by the pre-
sence of opaque matter adhering to the plate and interposing
between the light and the plate. During the subsequent opera-
tions these are removed, and the portion of iodide beneath having
been sheltered from the light, dissolves out in the hyposulphite.
These pinholes have been traced to the following sources : —

1. Dust in the bath— remedy, filtration.

2. Crystals of iodo-nitrate of silver floating in the bath.
Iodide of silver is capable of dissolving in nitrate of silver,

and certain conditions of the bath appear greatly to favor this
solution. A new bath may be pretty thoroughly saturated with
iodide of silver and yet give no pinholes, whereas an old bath
can at times scarcely be kept free from them, and, even if removed
by appropriate treatment, they quickly return. The treatment
is as follows : —

a. Add a few drops of solution of sal ammoniac, and filter.
This is a palliative; the pinholes mostly soon return.

b. Take one-half the bath, and pour it slowly into a quantity of
water about its own bulk (do not reverse this), that is, if you have

322 PHOTOGRAPHIC MANIPULATIONS.

a thirty-ounce bath, pour fifteen ounces of it into fifteen ounces
of water, and filter. Add the rest of the bath, without filtration,
and then add forty grains of nitrate of silver for each ounce of
water added, unless the bath was at the time impoverished, in
Avhich case, of course, the addition must be larger. Sun it, and
filter.

In some states of the bath this treatment will give effectual
relief for a considerable time. But an old bath seems to acquire
an increasing tendency to dissolve out the iodide of silver from
the plate and precipitate it in these irritating crystals. When it
is found that this tendency to recur is obstinate, it is better to —

c. Evaporate the bath to dryness in a porcelain basin ; and if,
after going down to thorough dryness, the heat be raised gradually
till the saline mass fuses, it will be so much the better. But
even evaporation to dryness, without fusing, will be a valuable
help. For the presence of alcohol in the bath, introduced by the
collodion on the plates, seems greatly to facilitate the solution of
the iodide and the formation of iodo-nitrate; the dry mass when
dissolved in water gives a milky liquid, by reason of the iodide
now become insoluble, and which is got rid of by filtration. If
the heat have been raised to the fusing point, the riddance of the
iodide seems to be still more complete; the fused nitrate may be
used as new, remembering, however, that it contains alkaline
nitrate, and is not all silver-nitrate, more, therefore (if weighed),
will be needed than of unmixed nitrate of silver. Probably the
bath will not require acidulating, and acid should not be added
till it is found that a trial plate is fogged without.

3. Another source has lately been brought forward as causing
pinholes, viz., the presence of sulphuric acid, or sulphates, in
the water. Trouble from this source is, however, rare.

4. Some hold that acidulating with acetic acid gradually leads
to pinholes by reason of formation of acetate of silver.

5. If the salting in the collodion is not thoroughly dissolved,
it may remain as a fine powder in suspension, and every grain of
it may be expected to cause an insensitive spot, which maybe much
larger than the grain itself, as its influence will extend around.
The bromides are less soluble in alcohol and ether than ,thc
iodides, especially the bromide of potassium ; and this substance,
even if hot introduced as such into the collodion, will always be
formed if iodide of potassium is used in connection with any

FAILURES IN PHOTOGRAPHIC OPERATIONS. 323

bromide. The stronger and better the alcohol and ether the
more liable they will be to this trouble.

Therefore, if it be considered essential to introduce a potassium
salt, it will be necessary to select a cotton which will work well
with alcohol not too high. In this respect cottons differ very
widely, some requiring the strongest solvents, and some working
with quite watery ones. Cotton having this last quality will be
appropriate for ambrotypes and ferrotypes, as it is for such that
potassium is commonly introduced into the collodion.

As a remedy, introduce a few drops of water, shake thoroughly,
set in not too cool a place, and at the end of twenty-four hours
filter through a close filter.

Or dilute the collodion with a little plain collodion, thus in-
creasing its solvent powers. According to V. Blanchard, this is
very effective, when, after working for some time well, one is
suddenly troubled with pinholes. The explanation of the remedy
is evident.

Continual moving of the plate whilst in the nitrate bath, with-
out ceasing till it is withdrawn, is also recommended by the same
photographer.

Large Clear or Hazy Spots. — 1. When the developer is not swept
along the upper edge as here recommended, but poured over the
plate in the same manner as the collodion (as is practised by some
operators), a transparent spot, half an inch or more in diameter,
is very apt to be formed unless the operator rapidly moves the
hand which pours on the developer. This spot is caused by the
washing away of the bath solution, so that when development
sets in, that part of the film is deficient in free nitrate of silver,
and is proportionally weaker in effect. 2. Collodion poured too
suddenly back into the vial, making an irregular film. 3. Bad
cotton, which does not thoroughly dissolve in the fluid, and which
has not been properly filtered. 4. Bad collodion, too thick, or
with alcohol and ether badly proportioned (i. e., alcohol should be
i to |, ether J to §). 5. A new bath, not saturated with iodide
of silver, will corrode the first plates. 6. An over-strong bath
may produce the like effect. 7. Keeping too long before develop-
ing may produce roundish hazy spots, especially when the bath
is acidulated with nitric acid. Apparently, this happens most
easily in hot weather, when the. evaporation is most rapid. The
bath solution becomes concentrated and dissolves out portions of
the film. It does not act equally, because as it evaporates it has

324

PHOTOGRAPHIC MANIPULATIONS.

a tendency to collect in drops on the surface. 8. Fragments of
collodion (generally from the back of the plate) in the bath.

As mentioned elsewhere, small transparent spots in a negative
should always be touched out with opaque color. This causes
them to print white spots in the print, which are easily retouched
.and brought up to the surrounding shade. But a transparent
spot prints dead black, and this is much more difficult to manage
and the blemish is never so well concealed.

Rings. — If the collodion bottle be held too high above the plate in
collodionizing, rings may appear in the development.

Fig. 127.

A, A', Comets.

B, Development staius.

§ 10. — Comets and other Opaque Spots.

The name comet (A, A', Fig. 127) very aptly designates those
larger or smaller spots with tails, opaque in the negative and

showing more or less white if printed, so
that unless but a few prints are wanted,
and the photographer is willing to touch

M~^^ out the comet's mark, the negative may

^y# generally be considered as worthless.

The heads of these comets mostty are
towards the direction from which the de-
veloper came, and the tails pointing to
the side on which it ran off. They may
be caused by anything that forms reduc-
tion at some chance point. A fragment of undissolved pyrogallic
acid, unaltered solutions of sulphate of iron, organic dust on the
plate, or in the sensitizing bath, or floating on its surface, any of
these causes may produce comets. Their appearance may be
taken as a plain indication that one or more of the solutions
worked with wants filtering.

Or, suppose that hyposulphite is spilt about the room. The
grating of the feet on the floor or carpet grinds off dust which is
charged with hyposulphite. If the glass be rubbed immediately
before coating, it b'ecomes electrical, and every floating mote near
it is drawn to it. These are imbedded in the collodion, and on
plunging the plate in the bath, they become centres of reduction.
Sometimes these are even observable as dark spots on removing
the plate from the bath. But if the proportion of hyposulphite

FAILURES IN PHOTOGRAPHIC OPERATIONS. 32o

is infinitesimal, yet they may escape attention on withdrawing
the plate, and cause comets.

If this dust is about the room, it can scarcely but get into the
dark slide, and then in moving, especially if roughly moved, it
may be transferred to the plate, and lead to comets.

Metallic hinges to the dark slide will sometimes grind off par-
ticles of metal which may be transferred to the plate. Each be-
comes a centre of reduction, and must lead to the formation of
a spot of some sort, probably a comet.

Imperfectly filtered collodion may give rise to opaque spots.
Also, neglect to wipe thoroughly the lip of the vessel from which
the collodion is poured.

•■Where any cause of comets is present, a strong developer tends
naturally to aggravate the evil. A rather acid developer is the
easiest worked with, but does not give as fine results, viz., as
much transparency of shadow. At the same time, it diminishes
the tendency somewhat to stains, and helps detail in high lights,
such as white dresses in portraiture, or a strongly illuminated
distance in landscapes ; also fine lines in copying line engravings
(not mezzotints, photographs, lithographs, or India-ink drawings),
for all of which a well balanced, i. e., moderately acidified, deve-
loper is needed. Finally, the developer, if not kept in continual
motion over the plate, may allow particles of metallic silver to
fall, which presently become nuclei of development.

Opaque s2)ots may be caused by a lumpiness of the film, arising
from some insoluble substance in the collodion. Often minute
fragments of dried collodion are carried over from the neck of
the pourer, by neglect to wipe after every pouring. The least
dust in the collodion will cause these spots ; after it is examined
with a lens they will be found to be caused by a minute fibre of
wool : it is surprising how much thickening a single fibre may
cause in this way. These fibres may get into open vessels of
collodion, or may have settled into vials or pourers before they
were filled with collodion. Or (as this is the commonest case)
they have settled on the plate itself, either from neglect to brush
it off, or from doing so too long before coating, so that dust set-
tles on it between times. Dust is a foe to many photographic
operators, and most of all to albumenized plates, and every care
should be taken to exclude it.

326

PHOTOGRAPHIC MANIPULATIONS.

11. — Lines.

Fig.

128.

l(L

1. A pause, "however momentary, in the immersion of the plate,
produces a line, generally as thin as a hair, at the place where

the pause took place. With a vertical bath,
such a line is necessarily a straight, or nearly
straight, one (see A, Fig. 128). With a hori-
zontal bath the most curious curves and sinu-
ous lines are seen (B B, same figure). If the
horizontal bath has not been deep enough to
cover the plate with a single wave, but pauses
for a fraction of a second, the mark of that
pause will inevitably appear in the develop-
ment, and the negative is of course ruined-
Remedy : with a vertical bath, immerse the plate with perfect
regularity. With a horizontal bath, have plenty of solution,
raise the bath at one end, place the plate in at that end, raised so
high that the solution leaves it, and then, at the same time, lower
that end and let the other end of the plate fall gently in.

2. Wavy Lines at Edges. — Developer too small in quantity, or
too slowly applied, especially where the plate has been kept
some time after leaving the bath.

3. Fine Parallel Vertical Lines in Direction of Dip. — The writer
has seen this result from sulphate of iron in the silver bath,
thousands of such lines being thus produced.

4. Sinuous Lines over the Plate. — If the film be of a very repel-
lent nature, the bath solution may, instead of remaining as an even
film, gradually collect in oily lines, or the plate may by inatten-
tion have been removed from the bath with these lines actually
upon it. This repellent character (see p. 318) may come from

various sources: 1. Bad quality of
cotton. 2. Alcohol and ether too high ;
add a very little water. 3. A horny
and contractile collodion.

5. Parallel Lines, darker than the Ad-
joining Parts. — When a plate which has
not been very well cleaned is subjected
to a long and severe development,
traces of the lines of the cleaning will
be forced out in the development. (See Fig. 129.) Sometimes
these are simply parallel lines as at A, sometimes they show

Fig. 129.

FAILURES IN PHOTOGRAPHIC OPERATIONS.

327

angles as at B. These angles are where the direction of the
hand was changed in the cleaning. Kemedy: Clean better and
rub longer.

Fisr. 130.

§ 12. — Stains and Surface Markings.

Marbled Stains. — " Oyster-shell" stains of reduced silver (also
called " matt silver stains"), with a gray metallic surface and in
curious curved and arabesque patterns, occasionally make their
appearance. They are exceedingly peculiar and unlike any other
stains, and have occasioned much speculation and discussion.
They come from too long an interval between collodionizing and
plunging into nitrate bath, too strong a de-
veloper, or too long a development, espe-
cially with sulphate of iron.

The longer a plate is required to wait be-
tween sensitizing and development the worse
will be these stains. Plates which when de-
veloped within five or ten minutes after
withdrawal from the nitrate bath are per-
fectly clean, will sometimes, if kept for
half an hour, show abundance of these
stains. Some operators find them come on
large plates when they do not on small.

Or they may be caused by neglect to wipe the back of the
plate, or to let it drain a sufficient time before putting it into the
dark slide. In these ways bath solution may run down to the
bottom of the back, and work round to the collodion film. They
may also arise from scum on the surface of the bath, which is
taken up by the plate, and is subsequently developed by the
action of the developer. According to some reliable photo-
graphers, iodide of ammonium in the collodion tends strongly to
the formation of this species of stains. They usually, however,
indicate too long an interval between collodionizing and de-
velopment. Kemedy : Let the operations follow each other more
rapidly. If this cannot be, use more bromide, agitate the plate
the whole time that it is in the bath, and remove it from the
bath the moment the oily lines disappear.

In very hot weather these stains will show themselves upon
plates otherwise every way perfect, even with a bath quite suffi-
ciently acidulated, and with a collodion containing iodine. The

"Marbled" or "oyster-
shell" surface stains.

32S PHOTOGRAPHIC MANIPULATIONS.

longer the interval between the operations the larger and more
numerous they are. They appear to depend upon the drying of
the collodion film on the surface, and upon a partial return by
capillary action of silver solution which has drained down to
the corner. Silver solution which has once touched the holder
becomes sufficiently changed to throw down its metal much more
rapidly under the developer.

The writer has devised and used the following remedy with
great advantage. A piece of thick blotting pad is cut to the
length of the lower edge of the plate, and made about an inch
and a half wide. A very narrow portion, say an eighth of an
inch or less in width, is bent over to a right angle for the whole-
length, and after the plate is put into the holder it is raised up a
little, and this bent edge is pushed in between the plate and the
corners. Thus the edge (not the face) of the glass and of the
collodion film touch this blotting-paper over the whole length,
and whatever solution drains down is absorbed by the blotting
pad, and is drawn round by it to the back. This remedy was
found very valuable.

Or it is advisable, when such a tendency appears : 1. To care-
fully wipe out the dark slide with a wet cloth, in order super-
ficially to wet the surface. 2. To place a piece of thick blotting-
paper on the back, as just explained. 3. To diminish the inter-
vals before the development as much as possible. 4. If neces-
sary, to roll the dark slide in a damp cloth. The first remedy is,
however, by far the best. (See also p. 344.)

It has been stated that these oyster-shell markings may arise
from something in the acetic acid used in the developer, and that
they have instantly disappeared by changing the specimen of
acid used. Others, again, have attributed them to the greater
thickness of the film at the corner where poured off, so that this
portion, drying more slowly, is exposed to become loose in the
nitrate bath, and to retain some bath solution beneath it.

Stains of this sort are very superficial, and, by dexterous
manipulation, may often be entirely removed. The surface of the
collodion is to be thoroughly wetted, best with alcohol, and a piece
of very soft paper is well moistened, and a point of it carefully and
repeatedly drawn over the stain. Unless the pressure is exceed-
ingly gentle, the film gives way, but when care is taken, the stains
disappear wonderfully. The writer has seen a third of the surface
of a negative covered with these stains, and yet has succeeded in

FAILURES IN PHOTOGRAPHIC OPERATIONS. 329

getting rid of them with care and patience. A kind of very thin
brown paper, made of jute, is that which has been found to
answer best. It becomes exceedingly tender when wet. The
operation is best performed after fixing.

Brown Stains. — If it is desired to reinforce after fixing with
hyposulphite, careful washing is necessary before the pyro and
silver are applied ; if traces of hypo remain in or under the
film, a brown stain of sulphide of silver makes its appearance
the instant the redeveloping solution is put on the plate.

These stains are also said to arise from using pyrogallic acid
with too little acetic acid, when the water is hard (limestone
water), and sometimes from white light admitted to the dark
room. Eedeveloper getting under the film will stain brown.

If the collodion be alkaline it will be highly sensitive, and
tend to give flat images, and at the same time to stain with the
slightest cause. The least impurity on the glass, the least mis-
management of development, may be expected to spoil the plate.

Neglect to keep the plate-holder clean will give rise to very
troublesome markings. The all but universal use of glass corners
in the slides has largely diminished the injuries from dirty plate-
holders, nevertheless it is still advisable to be on the safe side.
Paraffining the slide, or, what is easier, rubbing it well with lard,
prevents the soaking in of droppings and drainings, and renders
the slides more easy to keep clean.

It seems scarcely necessary to say that any solution left upon
the glass corners for want of wiping is transferred to the next
plate, and may show itself in the production of different sorts of
stains according to the condition of the chemicals.

Irregular Markings are said, in some cases, to arise from the
use of too strong alcohol and ether in the collodion. Mr. Terry
mentions a case as occurring in a gallery in which not a perfect
negative had been made in a week, and where the trouble was at
once removed by adding a few drops of water to the collodion.
It had been made by the photographer himself; absolute alcohol
was used instead of 95 per cent.1

1 Really absolute alcohol is rarely to be met with in commerce. The differ-
ence between 95 per cent, alcohol and absolute is over 25 drops of water to the
fluidounce, rather more than 5 drops to each hundred. It will thus appear
how important it is to understand the exact strength of the materials used.

330 PHOTOGRAPHIC MANIPULATIONS.

g 13. — Faults in Fixing.

Feathery Markings over the Plate. — Yellowish feathery markings
are owing to insufficient fixing. These may appear at any part

of the plate, most frequently, however, at
Fig. 131. the corner at which the collodion was

poured off. At times a yellow shade is left
over the whole plate ; this indicates a still
more imperfect fixing.

When this fault is not noticed until the
plate has been washed and dried, particular
care is necessary ; for plates thrown into
hyposulphite a second time are almost cer-
tain to loosen in the film, or to split in some
part of the operation, either in the fixing, or
washing, or the drying ; therefore, the best
precaution is to take a grain solution of
India-rubber in benzole, to pour out an ounce or two of it into a
pan, and tilt the pan upward at one side, so that the solution may
lie in the angle opposite. We thus have a pool the length of the
pan, and about one-fourth of an inch deep in the middle. The
four edges of the plate are to be plunged in this successively,
giving each a full minute to allow the varnish to soak in, and
also to allow the previous side to drain and dry before it becomes
the top. The plate thus cemented fast at the edges, will stand
the necessary treatment without difficulty. After refixing and
washing, coat with gum-water or dilute albumen, dry and
varnish.

Image Weakens too much in Fixing.— The fixing bath may be
too strong and need weakening. The result may also come from
too weak a negative bath, used too long without strengthening up.
The iodide of silver is then formed too much on the surface of,
instead of within, the film. Or the development may have not
been continued sufficiently long. It should be borne in mind
that the portions of the image formed by redevelopment are less
easily attacked by the fixing bath than those formed in the first
development.

§ 14.— Faults in Varnishing.

Drying Bead. — This may result from one or more of three dis-
tinct causes.

FAILURES IN PHOTOGRAPHIC OPERATIONS. 331

1. Want of dryness of the film. As water curdles varnish by
precipitating the resin, so any dampness in the film will produce
a similar effect. Surface drying is insufficient. The film must
be dry clear through to the glass. By standing for a day, the
film dries sufficiently in dry weather, but a damp atmosphere,
even in sunny weather, will dampen films to that extent (even if
they were previously dry) that the varnishing may be affected.
As a general thing, it is best to varnish in dry weather only ; but
if it is to be done in damp weather, artificial heat must be used.
Merely warming the plate will not dry it ; it must be kept warm
for some little time.

2. Insufficient penetration. Varnishes penetrate rather more
slowly than many persons imagine, and if poured off before pene-
tration has taken place, the varnish continues to soak in, and
thus the upper portion has not enough left to give it a glossy
surface. After the plate has been completely covered, the writer
advises to count ten or twelve seconds before beginning to pour off.

3. Insufficient heat. Some varnishes require more heat than
others, and if enough is not applied they dry dead. Most var-
nishes require heat both before and after applying.

Remedy for Deadness. — Flow with alcohol (see below).

Ridges. — If the pool of varnish be allowed to stop too long in
any position, it dries at the edge and makes a ridge, and the
tendency will always be greater in proportion as the plate is
hotter. If, while varnishing, the photographer sees that he has
made a ridge, he can, if it is not a bad one, get rid of it by
pouring an abundant supply of varnish on, and letting it remain
longer on the plate than usual.

Different varnishes work differently, and sometimes the mere
change from one that the photographer is accustomed to, to an-
other equally good, but different, will cause him to make ridges.

When, after drying a negative by heat, the varnish is found to
have made a ridge across the film likely to show in the printing,
or has dried sufficiently dead to unfavorably affect the print^ it
is not necessary to remove the whole of the varnish. The writer
simply flows the negative over with 95 per cent, alcohol, letting
it stand on the film for two or three seconds, and pours off';, then
warms the plate and applies another coat of varnish. For this
last varnishing it is best to use a thinner varnish, lest the coat
become too thick. Therefore dilute the varnish (if a spirit var-

332 PHOTOGRAPHIC MANIPULATIONS.

nish, and the writer advises to use none other) with an equal bulk
of alcohol. The same remedy applies for drying dead.

Scaling Off after a Lapse of Time. — This arises from leaving the
varnish on too short a time before pouring off. Those places
where it has not soaked through to the glass will always be liable
to scale off. Or if the plate has been badly washed and hypo-
sulphite crystallizes under the film. Exposure of the negative to
damp atmosphere. Great changes of atmosphere, as if the room
is allowed to frequently become very cold and then is strongly
heated. Bad varnish, containing no essential oil (oil of lavender,
etc.). Coating with gum-water before varnishing, in order to
prevent splitting in drying.

Anv varnish which tends in the least degree to show this
defect should be rejected without hesitation. Under the head of
varnishes, will be given further on several formulas for varnishes
which will resist the action of moisture so completely that nega-
tives varnished with them may lie under water for many weeks
without injury of any sort.

Dissolving of the Image in Varnishing. — The cotton too soluble
in alcohol alone without ether. Alcohol in the varnish too
strong. Eemedy : add a little water ; shake well, and if not quite
bright, filter through paper ; or use a benzole varnish. This
trouble comes chiefly with pyroxyline made at a low temperature
with weak acids ; and as, of late years, the tendency has been to
strengthen the acids, and counterbalance this by raising the tem-
perature, the tendency to dissolve in varnishing occurs less fre-
quently than formerly.

Honeycomb Cracks. — The varnish after a time rises in ridges,
and finally parts. Cause : insufficient removal of hyposulphite in
washing. If attended to in time, this may be remedied. Alcohol
is put into a pan, and the plate put over it, face down, until the
varnish softens and returns to its position ; or the plate is simply
flowed over with hot alcohol. The ridges sink down sufficiently
not to affect the printing.

Parallel Lines running diagonally down the Plate. — Certain var-
nishes, and especially thick ones, require to be rocked whilst
draining and drying, for want of which this trouble may arise.

JScratehi7ig in Handling. — Too thin a varnish will not afford an
adequate protection to the film, which may thus be unable to
stand ordinary wear. A habit of thinning the varnish with
alcohol may easily be carried to excess, and lead to this trouble.

FAILURES IN" PHOTOGRAPHIC OPERATIONS. 333

Generally speaking, the solid gum should be in the proportion of
one ounce to seven fluidounces of alcohol, with some essential oil
to prevent cracking.

A more common source of this trouble lies in the use of var-
nishes made with too soft gums. Lac is liable to this objection.
The sandarac varnish, for which a formula will be given in the
chapter on varnishes, gives an extremely strong, hard coat.

Specks and Irregularities on the Surface. — Although the var-
nish have been perfectly clean and bright, and although the
negative may have been carefully brushed off immediately before
applying the varnish, it will often happen that there will be
specks and irregularities. Examined with a lens, these will
mostly show a filament of wool (from abrasion of clothes or
carpets) in the centre as the cause. The air is mostly much fuller
of dust than we imagine, and these filaments will settle on the
plate even in the few seconds between brushing and coating.

\ 15. — Miscellaneous.

1. No Image at all. — In copying by a bad light, if too small a
diaphragm be used, and a much too short exposure be given, with
insensitive chemicals, the developer may fail to bring anything
out. A very exceptional case. In some states of the negative
both cadmium collodions will fail to give any image at all, when
the mere substitution of a collodion made chiefly with salts of
ammonium will lead to good results immediately (p. 136).

2. Insensitiveness arises either from too acid a condition of the
negative bath or from the use of too old acid, or dark collodion.
If from the latter cause, it will be at once removed by substi-
tuting a collodion in good condition. And if the old collodion
be not too defective, it may be used up by mixing with some
that has been very newly prepared of thoroughly neutral mate-
rials, preferably with cadmium salts only, and which by the
admixture of an older collodion will at once pass into good con-
dition.

It is usually collodions made with alkalies that become insen-
sitive. Cadmium collodions will keep in cool places for several
years.

As to the proportions in which to mix new and old collodions,
one part of old may be added to three, four, or five of new, ac-

334 PHOTOGRAPHIC MANIPULATIONS.

cording to circumstances. If the old collodion be quite dark, it
will hardly be safe to add in larger proportion than five. Over-
acidity of the bath is generally the result of tampering with it —
as a general rule, after your bath is once rightly made, ascribe
all troubles to anything else, and apply no remedies to it, until
it is certain that it is in fault. If too much acid has been
added, by mistake, in making it, bicarbonate of sodium may be
added very cautiously until a precipitate falls, then filter and
acidulate again.

An old bath, choked with organic matter, may cause insensi-
tiveness.

3. The Film, after Fixing with Cyanide, shoivs a Bluish Color. —
Insufficient washing off after development, so that iron salt re-
mains on the plate.

4. Want of Adherence. — Too much cotton in collodion. Im-
mersing too quickly. Greasiness of plate. Too much alcohol
in proportion to ether.

5. Iodide comes off in the Bath, in Flakes. — Too little cotton in
collodion.

6. Developer Pepelled — fails to moisten, or to act upon the film
or parts of it. Collodion too gelatinous by reason of cadmium
salts. Too much ether for the alcohol. Alcohol and ether too
strong. Bad cotton. "Waiting too long before immersion. Plate
kept too long after removing from negative bath, so that it be-
comes surface-dry in spots.

7. Bluish Deposit in Shadows. — Insufficient acid in negative
bath. (This appearance is not unfrequent in the glycerine and
honey process.)

8. Ghost or Flare. — Indistinct thicker spot on the plate opposite
centre of lens. Faulty lens needing to be rejected.

9. Transparent Insensitive Band around the Plate. — Too long
delay between coating and immersing the plate.

10. Plates have a Dusty, Powdery Look. — Excessive deposit of
iodide of silver. Filter after diluting, precisely as for pinholes.
Note, this is not to be confounded with Granularity, which see,
but the film is in this case more veiled.

II. Failures belonging especially to Negatives.

1. Too Little Density. — 1. Too weak a bath. 2. Too strong a
bath. 3. Over-exposure. 4. Too short a development. A be-

FAILURES IN PHOTOGRAPHIC OPERATIONS. 335

ginner is often so afraid of fogging, that he cuts short the develop-
ment when the negative has only reached the ambrotype stage.
5. Insufficient illumination.

2. Excessive Density. — 1. Over-development, especially with
under-exposure. 2. Too much salting.

3. Solarization, results from over-exposure. For a film ex-
posed to light for a gradually increasing time gains in strength
up to a maximum point, then remains stationary for an exceed-
ingly short time (in case of iodide of silver), and then loses again
in the over-exposed parts, showing little tendency to take a de-
posit under the developer. A great disposition to solarization
in a collodion indicates an insufficiency of bromides ; the ten-
dency of bromides is greatly to prolong the stationary point just
spoken of.

III. Failures belonging especially to Ambrotypes and

Ferrotypes.

1. Want of Detail in Shadows. — Under-exposure. Too little
bromide in collodion. Too old and red a collodion. Insufficient
development. Too acid a negative bath. Too thin a collodion.

2. Want of Detail in High Lights, which are at the same time
vigorous and dense. Too much development, so that the plate
tends to become a negative.

3. Grayishness or Want of Contrast. — Over-exposure: in this
case the shadows are good in respect of detail, but want depth.
Use of hyposulphite of sodium as a fixer instead of cyanide.

4. Veiling of the Shadows. — Over-exposure. Too new a collo-
dion. Add a little tincture of iodine, or mix with some old red
collodion.

5. Excessive Contrast. — Too old a collodion ; too acid or foul a
bath. Too little bromide in collodion. Under-exposure.

6. Dark rounded Spots visible after backing. Pouring on the
developer like collodion instead of sweeping it from along one
edge.

7. Want of Transparency in the Film when Dry. — Bad cotton.

8. Too Slow a Development, may arise from too much acidifica-
tion of the bath.

9. Green or Blue Color in the Film, according to Hardwich, may
arise from too scanty a deposit of silver, depending upon either

336 PHOTOGRAPHIC MANIPULATIONS.

insufficient development or over-exposure, or from too thin a
collodion film. A bad cotton or a disordered bath may likewise
affect unfavorably the color of the image.

IV. Failuees in Paper Development.

Much that has been already said applies itself necessarily to
working with paper, especially the remarks on fogging, and
effects of under and over-exposure.

Harshness. — -Too much iodide.

Stains are often ascribable to handling with not perfectly clean
fingers. Indeed, so absorbent is paper, that almost any touch
will become visible to the developed print, even with very clean
fingers. The addition of bromide has a great tendency to check
the staining ; and in the case of positive printing by development,
where extreme brevity of exposure is not important, it will be
found best to develop on chloride of silver.

The use of very weak gallic acid in connection with a lead salt
and acetic acid, as proposed by the writer, and explained else-
where, exposes less to danger of stains than other modes of
development.

Sunk-in Appearance. — All development tends to this effect ;
developed pictures are always less brilliant than sun-prints — the
picture does not so much lie upon the surface. Nor is it easy to
state the causes upon which a more or less sunk-in effect depends,
though the quality of the paper appears to have very much to
do with it. It is far more difficult to find a good paper for de-
veloping upon, than for ordinary silver printing. When the
photographer finds paper that will yield a bright print by deve-
lopment, such paper should be carefully placed aside for this use,
and an exact note should be made of the details of the method
which was found to give good results with it.

V. Silver Printing.

§ 1. — Failures common to Glass and Paper Prints.

1. Weak Gray Prints. — Use of negatives destitute of light and
shade, generally from over-exposure or bad manipulation. Also
may arise from bad paper or too weak or exhausted positive bath.

2. Harsh Black and White, or Snowy Prints. — Over-developed
negatives. Strong negatives, which would give good prints with

FAILURES IN PHOTOGRAPHIC OPERATIONS. 337

sunlight, may produce this fault in printing by diffuse light,
especially if the light is weak, or the nitrate bath very rich.

3. Whites turn Yellow. — Throwing the prints into the toning
bath without thoroughly removing the nitrate of silver by wash-
ing, tends to yellowness of the whites. Also exposure of the
sensitive surface to light. Old hyposulphite causes the same
fault. Paper kept too long after sensitizing. Eemedy : Use the
author's method of printing described at page 277.

Some hold that the turning yellow depends upon the bath
solution having penetrated through the albumen to the paper
beneath, and that consequently the shortest practicable time that
the paper is left on the bath the better, especially in hot weather.

It is found that paper, after sensitizing, may be washed off with
pure water, and that in that condition it keeps many days. Be-
fore use, the sensitiveness is to be restored by strong priming.
Even without this it will print with very strong dense negatives.
Hyposulphite dust about the room. Eemedy: Tone in a separate
room.

4. Prints weakening in the Toning Bath. — Use of bath too soon
after making. Insufficient printing. Use of an acid toning bath.
Eemedy: Add bicarbonate of sodium, or better, acetate of sodium.

5. Prints refuse to Tone. — Toning bath badly made or acid
(see article on Toning Baths). Too acid or too weak a printing
bath. An acid printing bath often gives prints that will not tone
well. Eemedy: Drop in ammonia till the bath is alkaline to test
paper. Or fume adulterated chloride of gold, or exhausted bath.
Insufficient washing before immersion in the toning bath. Too
cold a temperature ; the bath generally works better at blood-
heat. Print kept too long after printing. Impurity introduced
into the toning bath, especially a trace of hyposulphite. Toning
bath too freshly mixed or too strong. Fuming for too long a
time with too much ammonia.

6. Prints lose too much Intensity in Fixing. — Insufficient print-
ing, but oftener too thin a negative ; or may arise from too weak
a positive bath. Or they may have been fumed too long.

7. Toned and Fixed Print too Red — Insufficient toning. Con-
tinue the toning till the redness is gone when the print is held
up to the light and looked through, but avoid over-toning.

8. Fixed and Toned Print too Blue. — Over-toning. Poor tones,
or a want of richness of tone, may arise from conducting the
toning operation too rapidly.

338 PHOTOGRAPHIC MANIPULATIONS.

9. White Spots. — Air-bubbles.

10. Albumen dissolves in the Sensitizing Bath. — The bath is either
too weak, or alkaline; the remedy is obvious.

11. Over- Printing. — A very weak solution of cyanide of potas-
sium is the best means of reducing over-printed positives. It
must be applied carefully, both as respects the print and the
operator, and the fingers should not be immersed in it. Strength
proper will be about a half grain to ounce of water, or even less.

§ 2. — Failures Peculiar to Silver Printing on Paper.

Allmmenized Paper repels the Positive Bath. — Paper too dry.
Leave for twenty-four hours in damp place before sensitizing, or
blot off the paper immediately on taking it from the printing
bath, between folds of clean, white blotting-paper.

Stains in the Print as it comes from the Frame. — 1. Soiled fingers
handling the paper. Too much care can never be taken in hand-
ling photographic paper. The sources of stains by soiled or
moist fingers undoubtedly often precede the purchase; in this the
professional photographer has a great advantage over the ama-
teur, that his paper is purchased in quantities, and so undergoes
far less fingering. Two corners of the sheet, whether whole or
cut up, should at once be folded down at the commencement of
operations, and no other part of the paper be touched from first
to last.

Care will not only be required as to the handling, but as to
everything that the paper comes into contact with.

2. A very common source of stains is the presence of very fine
metallic particles in the paper, produced by the grating of the
mill-machinery. These particles, however infinitesimal, become
causes of reduction, and inevitably make stains.

3. Imperfect removal of hyposulphite used in bleaching.

4. Foreign substances of almost any sort, constituting invisible
imperfections in the paper. These may act in several ways. They
may diminish the penetrability of the paper locally. Such por-
tions will take up less silver and print lighter than the rest.
Often these foreign matters can be detected by holding the paper
up to the light and observing its regularity.

5. Irregular distribution of resin or other sizing material
through the paper. Resin easily combines with silver, making a

FAILUEES IN PHOTOGRAPHIC OPERATIONS. 339

sensitive compound. If the resin is not equally distributed, the
quantity of silver compound will vary accordingly.

6. Eeflected light from bright objects near the printing frame.

7. Printing by sunlight through a window-frame, with irregu-
larities in the glass.

8. Paper not well floated on the bath, or left on it an insuffi-
cient time for the equal absorption of nitrate, causing irregular
marbled stains.

9. Impurities floating on the surface of the printing bath, taken
up by the paper.

Irregular or patchy effects in printing may be caused by fuming
for too short a time.

Spots appearing in the Toning. — Neglect to keep the prints
moving. Where one print rests upon another, the action of the
toning bath is slower, and a spot results. This is a very common
source of trouble, unless the necessity of care is borne steadily in
view ; or if the print floats on the bath, instead of being kept
under the surface.

Spots in the Fixing. — Adhesion of prints to each other in the
bath, by neglect to continually move them.

Want of Brilliancy. — Floating the paper too long on printing
bath. Half a minute to three-quarters is sufficient, and gives a
far better print than a longer time.

Prints have a Sunk-in or Mealy Appearance. — Insufficient albu-
menizing. Bad paper. Old and foul, or acid, printing bath.
Too much salting. Old albumenized paper that has not been
kept thoroughly dry, especially if chloride of sodium has been
used for salting. Dampness causes the chloride, which should
be wholly in the layer of albumen, to penetrate into the body ot
the paper. Printing bath too newly made, or paper floated too
long. Too much fuming with ammonia, or too strong fuming,
tends to produce a flat, mealy print.

Print refuses to Bronze in the Shadows while Printing. — This de-
pends upon the salting bath having been too strong for the print-
ing bath. Eemedy : Add more nitrate of silver to the positive
bath, or change the paper. Paper kept too long after sensitizing.

If the image does not bronze in the shadows by the aid of the
printing, a brilliant print cannot be expected. An opposite cause
may be expected to produce the opposite effect, viz., too deep
bronzing and too harsh a print.

Print takes a different tone at the two ends, as, one end black

340 PHOTOGRAPHIC MANIPULATIONS.

and the other blue, or one black and the other brown. Cause,
irregular albumenizing of the paper, so that the coat of albumen
is thicker at one part than another; where the albumen is thinnest
the toning proceeds most rapidly. For this reason it is especially
important, for large prints, to select the paper carefully.

Black Dot with a White Tail. — If the pin to which the sheet
hung to dry was put through a wet place, a local reduction fol-
lows with this result. Pins left for some hours in an old cyanide
fixing bath become silvered, and are exempt from this trouble ;
silver may be dissolved in cyanide for the purpose.

Albumen dissolves off in the Silvering Bath. — Bath is either too
alkaline or too weak in silver.

Failures appearing only in the Toned and Fixed Print. — Troubled
appearances in the substance of the paper. 1. If the chloride of
silver has not been thoroughly, or rather has been very imper-
fectly removed, the print has a mottled look on holding up to the
light, and as this remaining chloride of course darkens by con-
tinued exposure to light, the mottled appearance becomes with
time more perceptible. This imperfect removal may arise from
not leaving long enough in the hyposulphite bath, or from the
exhaustion of the bath, or, possibly, by exposure to light before
fixing. The first are the most probable causes. Eemedy : Use
hyposulphite of sodium liberally ; one pound to twelve sheets is
none too much. Make no more than wanted, and begin each
day afresh, under no circumstances using a bath a second day,
even if but a single print was fixed in it the previous day.

2. Cases have been observed in which the prints were in per-
fect order when toned and fixed, and yet exhibited stains after
the final washing. This has been found to arise from the use of
zinc vessels, or a zinc bottom to the washing trough. The more
thoroughly the vessel is cleaned, the worse the spots. Remedy :
Varnish thoroughly the whole surface of the zinc, or have a
wood bottom with a layer of white quartz pebbles (which may
be obtained from those who make a business of gravel-roofing).
These are easily kept clean.

Over-contrast. — If necessary to print from a negative too harsh,
the excess of contrast can be reduced by exposing the paper to
light for a few seconds, or a minute, before placing it in the
printing frame. The print is thus somewhat improved, but will
never be first-rate.

Hard negatives will require light silvering. It often happens

FAILUEES IN PHOTOGRAPHIC OPERATIONS. 341

that a negative is full of detail, and unobjectionable in every re-
spect except that of being so dense that the shadows of the print
are overdone before the detail in the lights come out. Such
negatives will need paper very lightly silvered. Often the paper
after going through the regular sensitizing may be floated for a
minute on water. The writer has seen most beautiful results got
in this way from negatives that would not give any good effect
with ordinary silvered paper.

Blurred Spots. — A bad frame may not have brought the paper
home to the glass everywhere. Many printing frames are very
defective in this, that they throw all the strain into the middle of
the plate, thereby endangering the safety of the negative, and get-
ting bad definition at the edges, which is apt to be attributed to a
falling off in the power of the lens. Try the frames always with
a piece of plain glass, fastening down the springs and pressing up
the glass with the thumbs on various parts in succession, to find
how the pressure produced by the springs is distributed. The
old pattern, with bars at the back, is the best by far.

Blistering of the Albumen. — 1. Peculiarity of the albumen film
which will not bear the sudden change from the fixing bath to
pure water without endosmose. Remedy : Let the prints lie for
a short time in a weak intermediate bath of hyposulphite, between
the regular fixing bath and the washing. 2. Acid washing after
toning in an alkaline gold bath containing alkaline carbonates.
3. Over-dryness of the albumenized paper. For this and other
reasons it is a good plan to leave the paper for a day before using
it in a damp place; not too damp, however, nor for too long a
time, as this would lead to the working inwards of the salting,
occasioning a loss of brilliancy to the print.

It has been said that the addition of a small quantity of ether
(\ ounce to 20 -ounce bath) to the fixing bath will prevent blister-
ing.

Fading of the Prints. — Insufficient washing. Old hyposulphite
fixing baths. A solution of hyposulphite of sodium in water
keeps perfectly. But if used, it should be rejected and not em-
ployed on any subsequent day to that on which it was first used.
Acid in the fixing bath. Use of a fixing and toning bath.

Black Sjjecks showing first after Mounting. — Appearances of this
sort may almost invariably be traced to the agency of fine metal-
lic particles. These, by the aid of atmospheric moisture, gradu-
ally act upon the print and produce the specks. They come —

3-i2 PHOTOGRAPHIC MANIPULATIONS.

1. By trimming the print upon a brass plate. The point of the
knife detaches fine particles of metal, these are by the pressure
forced into the print and soon make stains upon it. Glass or hard
wood should be used to cut on.

2. By using a brass form to trim by. Particles are abraded
and enter the print in the same way as before. Steel or glass
forms should be used exclusively.

3. By using Bristol board for mounting, on which borders or
designs have been printed in gold or bronze. The designs are
printed in varnish and the metallic powders are rubbed on;
grains adhere elsewhere than on the design, and are not entirely
removed in the subsequent brushing, but eventually destroy the
print.

Crystallizations in the printing bath or on the paper may occur
in consequence of the nitric acid used in preparing the ammonio-
nitrate bath containing sulphuric acid : sulphate of silver is but
very slightly soluble in water. A bath so contaminated may be
brought into order by adding nitrate of baryta in solution so long
as a precipitate forms. The same substance may be used to test
the purity of the nitric acid used, and also to purify it, if found
contaminated. When nitrate of baryta is added to a liquid con-
taining sulphuric acid, sulphate of baryta, a very insoluble salt, is
thrown down as a heavy white powder, easily separated either
by decantation or nitration.

Cracks or Ruptures in the Albumen Coat are sometimes produced
by drying the print too rapidly. Dry slowly at ordinary tem-
peratures.

§ 3.— Collodio-Chloride.

Fading is said to be owing to the use of albumen as an under-
stratum.

Bad Tones. — Citric acid in collodion. Substitute tartaric.

Slow Toning. — Repellent collodion. Moisten the plate before
immersing in the toning solution with equal parts of alcohol and
water.

Flat, weak Pictures. — Insufficient quantity of pyroxyline in
collodion. Omitting to fume when fuming is needed.

Sunh-in Prints. — The cotton may not be suitable.

Splitting of Film. — Neglect to edge the plate.

Spots. — According to Mr. Simpson, the discoverer of the pro-

FAILURES IX PHOTOGRAPHIC OPERATIONS. 343

cess, spots are caused by — 1. Too much free nitrate of silver in
the collodio-chloride. 2. Keeping the plates too long after coat-
ing. Dry before a fire and expose at once.

Crystallizations in the Film. — Excess of nitrate of silver in the
collodion. Add more salting.

Insensitiveness. — Insufficient quantity of nitrate of silver, more
will be needed.

Detaching of the Film (from paper in the collodio-chloride paper
process), want of sufficient sizing in the paper. Few or no papers
have the necessary quantity, and a coat of gelatine is usually
necessary.

Rolling up of the Prints. — This is an annoying peculiarity of
the process, and difficult to avoid. It is said that plunging for an
instant into very hot water will destroy the tendency.

Blue Tones. — The toning is much more rapid than with albu-
menized paper, and unless care is taken, the print may be over-
toned before the operator is aware.

Final Observation. — In closing this chapter on Failures, which
the writer has endeavored to make as complete as possible, he
feels compelled to remark that whilst the sources of non-success
are almost innumerable, none do anything like so frequent and
fatal damage as want of care and of perfect cleanliness. The
commonest sources of trouble are —

1. Use of insufficiently cleaned vessels.

2. Immersing of fingers into solutions, which fingers have been
in other solutions without intermediate washing.

3. Tables slopped with solutions, which thus adhere to the bot-
toms of bottles, measuring glasses, beakers, &c, so that when
these are poured from, a fatal drop runs along the outside from
the bottom and mixes with the other materials. A drop of hypo-
sulphite solution will spoil almost any other chemical solution
with which the photographer works. All these sources of trouble
have this in common, that they introduce foreign matter into the
photographer's materials unknown to him, and this is the most
frequent of all causes of failure.

344 PHOTOGRAPHIC MANIPULATIONS.

CHAPTER XV.

OUT-DOOR PHOTOGRAPHY WITH WET AND PRESERVED

PLATES.

§ 1.— Wet Plates.

In Chapter VII. most of the information necessary for view-
taking has been given, nevertheless some special details remain
to be noted.

When negatives are to be taken at a distance from the dark
room, we are obliged either to work with a tent, to use " pre-
served plates," or to resort to " dry plates," which last method
will be considered in subsequent chapters.

Although plates are apt to deteriorate pretty rapidly by keep-
ing after sensitizing, yet, with care and attention, remarkable
delays may be supported, especially in cold weather. Heat
hastens the destruction of the plate. Since the first edition of
this Manual went to press, the writer has paid particular atten-
tion to this subject, and has succeeded in keeping wet plates in a
very satisfactory way. His method will be found below.

The following are the troubles which will be apt to show them-
selves : —

1. Fog.

2. Marbled stains. (See also p. 327.)

3. Transparent or hazy spots of various sizes up to one-quarter
of an inch diameter, generally nearly round.

Fogging is not a very common trouble, and seems to depend on
newness of collodion, for which a riper must be substituted.

Marbled stains are very apt to come, especially in hot weather.
After a careful study of these sources of trouble, the writer ad-
vises as follows : —

1. Use a rather ripe collodion containing a liberal proportion
of bromides (from 2 h to 3 grains of bromide to 4 of iodide), and
immerse the plate into the sensitizing bath as soon after coating
as possible. In hot weather just as soon as the drops cease to
fall.

2. Adopt the excellent system of having two negative baths,

OUT-DOOR PHOTOGRAPHY WITH WET PLATES. 345

one to make the film, 35 or 40 grains to the ounce, and the other
20 to 25 grains to the ounce, exclusively reserved to pass the
plates into after the film is completely made to the first. Thus
the plate is always covered with a comparatively fresh, pure
bath solution. This is an excellent plan for general adoption ;
but when the plates are to be kept long, it is indispensable.

3. Withdraw the plate as soon as the oily marks are gone.

4. Apply thick wet blotting-paper on the back. This must
not be too wet, or it will make stains by running down the back
of the plate and getting round the bottom and irregularly diluting
the liquid on the film.

5. But the most important precaution of all lies in avoiding
accumulation of bath solution. For this purpose, the writer,
after draining the plate thoroughly on successive pieces of folded
blotting-paper, and wiping the back thoroughly, sets it in the
frame, of which the corners have been carefully and thoroughly
wiped out immediately before. A piece of the thickest blotting
pad has been provided, about an inch wide and as long as the
plate. On the long side of this a narrow edge, about an eighth
of an inch wide, is folded over at right angles. This strip is laid
along the bottom of the plate, but the chief peculiarity of the
arrangement is that the plate is lifted up to the narrow edge passed
under it. This edge is not to pass between the face of the plate
and the glass corners, but tender the bottom edge of the plate. It
thus comes just into contact with the bottom edge of the collodion
film, which it keeps steadily drained during the whole delay.
This has a really wonderful influence in preventing marbled stains,
for which it is a perfect cure.

By operating in this way, the writer has been able to keep
plates with facility and certainty for an hour, and even much
longer. On one occasion a plate was carried twelve miles, and
developed at the end of nearly two hours (1 hour 55 minutes),
and gave an excellent negative. No preservative was applied,
and the success depended upon the foregoing precautions, of
which a second bath of weaker and purer solution, and the blot-
ting pad under the edge, were the most effective. Plates kept for
two and a half hours gave hazy spots, but were free from all other
faults. This mode of operating the writer strongly recommends.

The hazy spots are very annoying and troublesome when the
delay is very long ; difficult by their size to touch out, and ruin-
ing the picture if left in. They appear to arise from a concentra-
23

34:6 PHOTOGRAPHIC MANIPULATIONS.

tion of the bath solution reacting upon the iodide of silver in the
film. The presence of acid, especially of nitric acid, has seemed
to the writer to increase this tendency. For plates that are to be
kept, acetic acid is better than nitric. The addition of a few
grains of acetate of potash or soda, with a little acetic acid, will
change a bath from a nitric to an acetic bath. The proportion is
roughly about a grain to five or six ounces of bath. Dissolve in
half an ounce of water and pour slowly into the bath, stirring.
The cloud of acetate of silver at first formed will speedily dis-
appear.

Tripods. — See Chap. VII., sec. 3.

Tents and Boxes. — When the distance of the object makes it
clearly impossible to carry a wet plate, we must either use a dry
one, or else take the means with us for preparing wet plates on
the spot.

In using a tent, the operator works inside. With a developing
box, he passes his arms through sleeves provided with India-rubber
rings, and watches his operations through yellow glass let into
the front of the box. Of the two methods the former is the more
satisfactory. With the box there is more clanger of spilling hypo-
sulphite, and so exposing the delicate operations of photography
to the effects of hyposulphite dust.

Of tents, probably Carbutt's is as convenient as any. A still
more convenient mode of operating is with a van, either altered
or built for the purpose. Mr. G. W. Wilson, the well-known
Scotch photographer, recommends a very light tripod covered
with two thicknesses of black calico and an inner one of yellow.
The calico is a foot longer than the tripod, on which extra foot-
stones are placed to steady the tent and exclude light. There is
probably nothing better than this simple and convenient plan.
The tripod may be very light, and of course folds up into a small
space, so that the whole weight, including that of the cover, is
trifling. An umbrella has been found an excellent support for a
tent ; it is secured to a stake driven in the ground, and an opaque
cloth thrown over it ; a piece of yellow muslin set in, lets in light
enough to work by, and water is introduced from a vessel outside
bv a flexible tube. An exceedingly convenient arrangement has
been made by altering an old barouche, the front part being
arranged with an operating table and racks for bottles, the photo-
grapher sitting on the back seat to sensitize and develop.

AVherethe object is rather lightness than folding up into short

OUT-DOOR PHOTOGRAPHY WITH WET PLATES. 347

lengths, three pieces, or four if preferred, of cane-angle may be
fastened together at one end and a cloth thrown over them.

Any of these plans seem preferable to the more elaborate sort,
which are heavier to carry, and require the loss of valuable time
to put them together and get the whole concern into working
order. It is to be remarked, both with this plan and that of the
tripod, that the wider the stride given to the legs the steadier the
whole arrangement.

Shortening the Out-door Work. — Various plans have been found
useful to cut short the development and postpone the fixing (also
a redevelopment, if needed) until it can be conveniently finished
in the dark room at home.

The first plan used was to flow the plate with glycerine to
which a little water had been added, but this has given way to
the syrup treatment. A filtered mixture of clear syrup molasses
and water is provided, and as soon as the development is over,
the plate is carefully flowed with it, and in this condition may be
kept for a day or two. Mr. Gulliver makes a decoction of saffron
in water, to be used in the same way, and lines the top and bot-
tom of the plate box with wet felt. Some, in using syrup, add
alcohol, as follows :—

Syrup molasses 10 ounces.

Water 10 "

Alcohol 6 drachms.

The plate is then slid into a groove in a light tight box of
wood or tin. It must be well washed before redeveloping.

$ 2. — Instantaneous Photography.

When objects in motion are to be photographed, it becomes
necessary that the exposure should be so reduced that the move-
ment shall be inappreciable. To these exposures the name of
"instantaneous" has been applied, although they are in many
cases reduced to a small fraction of a second. "Various contriv-
ances have been devised for effecting them. The most usual and
one of the best is to have a slide attached to the camera front,
capable of moving up and down in a groove. In its centre is a
circular opening of an inch or two in diameter. When the slide
is up or down it covers the lens, but in descending it uncovers it
for the space of time that the circular opening takes to pass the
front of the lens.

348 PHOTOGRAPHIC MANIPULATIONS.

For exposures which, though brief, are to be longer than those
attained as above described, the cap may be removed and instantly
replaced. This is best done by raising the lower part whilst the
upper part is held nearly still, almost like turning upon a hinge.
In this way the foreground gets a much longer exposure than
the distance and sky. Another method is to let the focussing
cloth hang over the uncapped lens ; the palm of the hand is placed
over the lens, and the corner of the cloth held between the thumb
and the lower part of the forefinger. The hand being then turned
upwards over its own back edge as an axis, uncovers the lens
for a moment and is instantly returned, in both cases carrying
the cloth with it. As in the former case, this exposes the fore-
ground longer than the sky.

The conditions under which instantaneous pictures are to be
taken differ extremely. Widely extended views throw back a
great volume of light and much facilitate the operation. Ships
at sea, with breaking waves, offer no ver}r serious difficulty, if
the size of the plate is not too large. River scenes, with sail
boats and steamboats, are similar in character. Instantaneous
views of these subjects will be best taken with the Steinheil
aplanatic or the Dallmeyer rapid rectilinear, remembering always
that the shorter the focal length the more powerful the image,
and that success is thereby very greatly facilitated.

On the other hand, objects in motion near by, sending back
comparatively little light, no matter how brightly they are illu-
minated, will be most easily managed with a portrait lens. But
as this lens has comparative^ little depth of focus, care must be
taken to get the objects pretty nearly into the same plane; and
as the corners will be very apt to be out of focus, it may be
necessary to vignette the negative in printing.

The Chemicals. — The bath should be forty grains to the ounce,
new or nearly new, and nearly neutral. The collodion should be
just old enough to work, and, what is of special importance, must
be made of cotton of a very sensitive character. Cotton capable
of giving intense images that need no redevelopment, does not
possess the exalted sensibility necessary for instantaneous work ;
we need a cotton of a very impressible character, and this is
usually accompanied by a tendency to form images needing re-
development. AVithout a suitable cotton, it will be hopeless to
attempt the work. The developer must contain no restraining
acid, and be simply an eighty -grain solution of sulphate of iron.

OUT-DOOR PHOTOGRAPHY WITH WET PLATES. 34:9

The development must be very brief, or such a developer will
produce fog.

The subject must not present difficulties too great. The illu-
mination must be good eve^where, and there must be no strong
contrasts. Objects in motion will be much more easily taken
when their line of movement is either towards or from the ope-
rator. An object passing rapidly, directly in front of the camera,
will be exceedingly difficult to catch successfully ; it is, however,
accomplished.

Instantaneous views are most easily obtained in the spring, at
which season the light is more active than at any other. There-
fore those who especially interest themselves in this branch of
work find it desirable to accomplish it in May and June.

It is a not uncommon mistake for those who desire to have a
"quick acting collodion," to seek for it in some special formula.
This is all a delusion. A highly sensitive collodion is one made
with a highly sensitive cotton. As for the formula of salting, a few
trials of different proportions of bromide must determine what is
best suited to it. But what suits one specimen may not suit
another. One way is to make with the cotton a collodion con-
taining but little bromide (as, for example, by Reutlinger's
formula, p. 142). If on trial it seems sensitive, make up another
portion by a formula rich in bromide, and compare these, and
one or two mixtures of each, in different proportions.

Mr. Chapman recommends after the iron development has done
all that it can, to wash it off and to apply an alkaline develop-
ment with pyrogallic acid (see Chap. XVI.); when this ceases to
act, to finish with acid pyro and silver in the ordinary way.

The writer has found that a very material acceleration can be
obtained by lining the inside of the camera with pasteboard
which has been colored red with carmine dissolved in water with
the aid of a drop or two of ammonia. This pasteboard is not
to line the whole of the inside (see Fig. 107, p. 220), but only
those parts where the light is least strong — opposite ground and
trees, but not sky.

The red rays of light have a continuing, but no exciting power.
They, therefore, exalt the action of the image upon the plate,
and, when rapidity is an object, this method will be found de-
cidedly advantageous.

Animals. — Very beautiful photographs are obtained of horses,
dogs, cattle, &c. In order not to risk motion of the subject, it is

350 PHOTOGRAPHIC MANIPULATIONS.

best to make very brief exposures, simply uncapping and in-
stantly replacing the lens. A quarter-size portrait lens is the
most suitable. If larger pictures are desired, it is best to take
the small size just mentioned and to enlarge afterwards. This is
the method adopted by Mr. Schreiber, of this city, who makes
this subject a specialty, and who has shown the author of this
manual some very fine enlargements, taken from quarter-plate
negatives. He prefers to take even small animals, such as dogs,
in the open air, with appropriate surroundings, rather than under
the skylight.

\ 3. — Preserved Plates — The Glycerine Process.

The preserved plate stands intermediate between the wet and
the dry. Of various preservative processes, the glycerine and
honey, first brought prominently forward by Mr. W. H. Harrison,
is the best. A plate coated and sensitized as usual is plunged
without previous washing into a bath prepared as follows : —

Price's glycerine . . . . ._ . ' . 2 ounces.

Pure honey 2 "

Ordinary bath solution 2 "

Water 2 "

Glacial acetic acid 8 drops.

These are well shaken up and set in the sun for a few hours,
or still better, a day, then half an ounce of kaolin is added, well
shaken up, and the whole, after standing for a day, is filtered into
a bottle. A large funnel with a filter in it is left permanently in
the neck of the bottle. When wanted for use, a sufficient quan-
tity is to be poured into a pan. After using it, it is poured back
into the funnel ; it is a saving of trouble to have the funnel large
enough to carry the whole at once; the mixture is then always
through and ready for next day. The glycerine keeps the filter
moist and ready to filter well and rapidly.

The sensitive bath is a common acetic bath, a bath acidulated
with nitric acid does not work well. The usual formula for the
glycerine preservative does not include the acetic acid as above,
but the writer has found a marked advantage from adding it.

As above directed, the preservative bath contains about eight
grains of nitrate of silver to the ounce. By use it becomes con-
tinually richer in silver, and thereby deteriorated — from eight to
ten grains is its proper dose. Therefore we must add glycerine

DRY PLATE PHOTOGRAPHY. 351

and honey, and if necessary a little water from time to time to
maintain a correct proportion. After such addition it must inva-
riably be sunned and shaken up with kaolin again.

The development of these plates takes place in the ordinary way
with an iron developer or with a pyrogallic one. In the former
case, an exposure about three times as long as for wet collodion
is proper. With a pyrogallic development a longer exposure is
needed; this mode is preferred by Mr. Harrison, as allowing of
more latitude in exposure. The writer's trials have worked best
with iron development; for this purpose he does not like the
plain iron developer so much as the sugar developer. (See p. 164.)
The development is generally best done in a pan. The edges
sometimes become a little dry, especially if the plate has been
kept six to twelve hours ; and then these do not take the de-
veloper evenly, and the edges may be defective even when all
the rest of the plate is good, unless developed in a pan. A red
transparent sky indicates over-exposure.

This method will, when well managed, give results about as
good as ordinary wet work, but scarcely up to the best wet work.
It has no great capacity for mastering contrasts, because over-
exposure causes a deep red solarization, obliterating every trace
of detail. It is, therefore, necessary to be extremely careful to
avoid over-exposure. It is probable that this process would
work well with a collodion containing bromides exclusively.
Filtration before each using is necessary. No under-stratum is
required.

It seems exceedingly probable that the introduction of glyce-
rine into the negative bath would enable us to obtain plates that
would keep for a long time, especially if the method of two baths
be adopted, the glycerine used in the second one.

CHAPTER XVI.
DRY PLATE PHOTOGRAPHY.

Before describing specific processes, the writer proposes to
give such manipulations as belong to all dry work, and which
need not be repeated in connection with individual processes.

Formerly it was held that only second-class work could be

352

PnOTOGRAPHIC MANIPULATIONS.

done with dry plates. But it is now established that soft and
delicate negatives, full of half-tone, can be made on dry plates,
and that in place of the tedious and exaggerated exposures needed
by the older method, dry plates can be made as rapidly as wet.

§ 1. — Preparation of the Glass.

It will be desirable to clean the glass by the bichromate pro-
cess already described. Before receiving the coat of collodion,
they should have an edging of India-rubber dissolved in benzine.
Procure some fresh clean India-rubber, wet the blade of a
knife and pare off the outside and reject it. Cut the rest into
very thin strips, put about a quarter of an ounce of it into half a
pint of good benzine; common benzine will not answer at all,
but a pure specimen is needed. Shake up well, and in a few
days solution will take place. This solution may be diluted by
adding twice its bulk of benzine; it is then ready for use. (It is
said that moistening the strips of India-rubber with chloroform
will aid the solution.) The writer has always succeeded in
making the preparation without this aid.

Tie a camel's-hair pencil to a glass rod of medium size a little
way from the end. Take a wide-mouthed four-ounce vial, and
into the cork make a hole that will just receive the
glass rod. Into the vial put the diluted rubber solu-
tion to the depth of half an inch. Push the glass
rod down so that when the cork is in, the rod will
touch the bottom. (See Fig. 132 ; the rod should
project about ten inches above the cork.)

When ready to begin, take a plate, hold the glass
rod against its edge so that the brush will press on
the face of the plate. Draw the rod round, and thus
make a neat border an eighth of an inch wide round
the plate. Edge half a dozen plates in this way, and
set them in a rack to dry (they dry immediately)
before beginning to coat.

Many sorts of dry plates blister — that is, the solu- .
tions penetrate the film and get between it and the
glass, raising the film into blisters. It is best, there-
fore, to leave the corners open, so that this may have
a fair chance to run out, or rather; it is better to carry the coat-
ing along the longer sides, but leave a break at the ends of the

Fig. 132.

DRY PLATE PHOTOGRAPHY. 353

shorter side. This allows the liquids to drain easily out of the
breaks in the edging. (See Fig. 133.)

With plates larger than 6| x 8|, however, or when the films
show themselves tender, it is an excellent precaution to varnish
the edges just before developing, as well as
before coating. This double application gives Flg- 133,

great steadiness to the film, without interfering
with the escape of any liquid which may have
worked through. The writer has often saved
plates in this way which would undoubtedly
have split without the second edging.

Some edge the plates after exposure, but the
protection afforded is inferior by very much,
and the trouble fully as great. Some use
albumen as an under-stratum for the whole plate; the method of
doing this has been described at page 155. Others use an under-
stratum of thin solution of India-rubber over the whole plate,
which plan the writer does not think well of.

The writer recommends always, when possible, to prepare dry
plates at night, because at that time the windows can be kept
raised enough to thoroughly ventilate the room, and so diminish
the injurious effects of the fumes of collodion.

§ 2.— Drying.

Thorough drying is necessary for dry plates, and may be effected
by spontaneous drying, by heat, or with sulphuric acid.

Heat. — A 4-sided vessel is made of sheet-copper, in shape a
truncated pyramid. A ledge at bottom keeps the plate in its
place. The vessel is half filled with
water, and heat applied from below. If
the water is boiling, or nearly so, the
plates will be safely dry in twenty-five
to thirty minutes. They should always
stand five or ten minutes to drain before
the heat is applied. Irregular surface
markings, which at one time caused the
writer considerable annoyance, he suc-
ceeded in tracing to this cause, and they at once disappeared
wholly by taking the precaution of letting the plates stand and

354

PHOTOGRAPHIC MANIPULATIONS.

drain. The hotter the drying temperature the longer the plates
should wait.

Drying by Sulphuric Acid. — The writer believes that much of
the difficulty experienced in making good dry plates depends
upon the method of drying. The slow, even drying obtained by
placing the plates in a tight box with a pan of sulphuric acid, as
recommended by him many years ago, gives a remarkably even
and perfect plate, and he uses it exclusively.

Drying Box. — After planning and having made several sorts
of drying boxes, all of which proved unsatisfactory, the writer
has contrived that shown in the adjoining figure, and which, after
full trial, has seemed to him to leave nothing to desire.

The box (Fig. 135) has the front hung on strap-hinges so that
it turns entirely over and rests on the top, as shown in the figure.

Fig. 135.

Fig. 136.

When brought down, it closes upon a rebated edge, and is secured
by the turn buttons T T. About five inches from the bottom
are placed at each end the cleats A A, and at the same level, the
bridges B B. On these four pieces the rack (Fig. 136) slides in,
and when the front is brought down and secured, the rack is per-
fectly protected from light. A small door, D, permits the pan,
containing about a pound of sulphuric acid, to be slid in. This
door opens outwards, not inwards, as represented in the cut, by
an error of the engraver.

The rack (Fig. 136) is constructed as shown in the section (Fig.
137). B B are two long strips of light wood, into these are mor-

DRY PLATE PHOTOGRAPHY.

355

r>-

tised cuttings of thick plate-glass FiS- 137.

about half an inch wide, over a quar-
ter thick, and about seven inches
long. These are laid with the flat
side against B and are mortised in,
but not fully, so that when the out-
side pieces, A A, are screwed against
B B, they hold the glass firmly in
its place, and leave spaces, E E.

Between each two glass uprights, these spaces, E E, extend all
the way to the top. On the pieces A A, strips of glass, C C, are
cemented.

If the reader will carry the construction of this section over to
the full view (Fig. 186), he will see that every sensitive plate, when
set in, is supported in six places, and yet touches nowhere any-
thing but glass. It leans back on the two uprights behind it, at
the lower front edge it touches the two uprights in front of it,
and near its corners it touches the outside edges of the glass
strips, C C. It is consequently held very securely, and also the
drainings are conducted away at four different points from each
plate. As the back of the plate rests against two points only
(the tops of D D, Fig. 137), the backing can be applied as soon
as the plate is out of the sensitizing bath, and the back and front
thus dry together, saving much handling.

In Fig. 136 the rack contains, for simplicity, ten pairs of up-
rights, accommodating nine plates. In the box used by the
writer there are twenty-five pairs, accommodating two dozen
plates of any size, from half-plate up to 8 x 10. In fact, this
form of rack has the advantage that it will support any size of
plate, and if the box were of suitable dimensions, would contain
plates from half-size up to 10 X 12, or larger.

If the box is not kept in the dark room, it should have a thick
black cloth cover. The writer usually leaves his plates in the
box thirty-six hours before using them, in order to insure per-
fect drying in every part.

A simpler but less compact mode of making a drying box is
simply to take an empty box, set a pan of acid in the bottom and
a range of empty tumblers round the sides. In each tumbler set
the lower corner of a plate, and let the upper rest against the side
of the box. Cover up securely from light and from change of
atmosphere.

356 PHOTOGRAPHIC MANIPULATIONS.

Drying spontaneously is effected in a dark cupboard, or even on
shelves in a dark room. Drain the plates for a minute or two,
not more, on blotting-paper, and then set them in the cupboard,
each with the lower end resting in an empty tumbler, its upper
corner against the wall. Some allow the plates to dry on blotting-
paper ; this has the disadvantage of keeping the lower end very
long in drying, and so risking unequal action in development.

§ 3. — Backing the Plates.

Dry plates are almost always more transparent than wet ones,
so that the tendency to internal reflection is greater than with
wet plates. The result is blurring, otherwise called " halation,"
and its effect is that the high lights work into the adjoining
shadows. Thus the foliage adjoining the sky is more opaque
than it should be. Eoofs of buildings shade off towards the sky.
Boughs of trees, when bare of leaves and projected against the
sky, are especially apt to become blurred, as the light works in
on both sides. These effects are ruinous to the work, so that it
becomes advisable always to coat the backs.

After much careful study, the writer has finally come back to
annatto as combining, on the whole, more advantages than any
other substance with which he is acquainted. It is, however,
essential to use glycerine with it, or the whole coating will
gradually become everywhere penetrated by fine cracks. Quite a
small proportion of good glycerine will wholly remove this diffi-
culty. The writer uses iivo fluidrachms of thick syrupy glycerine
to the quarter pound of annatto in lumps. A convenient way of
managing the mixture so as always to have it ready is the
following: —

Provide a half-pint porcelain bowl with cover and handle (to
be obtained from a dealer in chemical utensils). Put into it a
quarter pound of annatto with a little more water than necessary
to cover it, and set aside for several days. The annatto will
soften, and can now be easily worked into a smooth paste. Add
two fluidrachms of glycerine and work it well in. This mixture,
if kept closely covered, will keep good for weeks, and if too
thick can be thinned by stirring in water. As the quantity
diminishes, add more weighed annatto in lumps, taking care to
add also the proportionate quantity of glycerine. The additions

DRY PLATE PHOTOGRAPHY. 357

of glycerine are always to be proportionate to the quantity of
annatto added, and not to the water. This last will, of course,
be added when needed ; the mixture should, however, form a
pretty thick paste, and is to be put on liberally.

The writer has examined many other mixtures. Gum may be
colored deeply by aniline brown or other suitable pigment. To
prevent cracking, sugar must be freely added, so that the quan-
tity of sugar will be nearly up to that of gum, say in the pro-
portion of three to four by weight. But the annatto is preferable,
and in practice does not cost more, as it goes much further.

A round bristle brush as thick as the thumb will be found
convenient for applying the paste. Bring it up to within a
quarter of an inch of the edge all around. It should be thick
enough not to run : annatto has much less tendency to run than
mixtures of gum, and this is no small advantage.

When plates are dried by sulphuric acid or spontaneously, the
backing may be put on as soon as they are out of the preserva-
tion bath. In drying by heat this cannot be so well done, at
least the heat has a tendency to liquefy the backing and make it
run down.

The character of the coat when dry should be carefully tested.
Not only should it show no tendency whatever to crack, but it
should resist perfectly when tried with the thumb-nail. Even,
however, if the coating appear perfect when examined from the
back, it may have separated in places from the glass sufficiently
to be no longer in optical contact, and from that moment it is per-
fectly useless. That it is then useless not only follows from
theoretical considerations, but is abundantly proved by expe-
rience, as the writer has seen in his own work. If a dry plate,
after thorough drying, be examined in the dark room, catching
the reflection upon the film side, it should have a perfectly even
coloration and a certain dark look all over. If it appears here
and there lighter in spots, then in these spots the backing is no
longer in optical contact, however perfect it may seem, and the
film at these spots is unprotected and liable to blur if any cause
of blurring be present.

Before developing, sponge off the back thoroughly with cold
water.

353 PHOTOGKAPHIC MANIPULATIONS.

§ 4. — Acid or Silver Development.

This is conducted in precisely the same way as the pyrogallic
development of an ordinary wet plate, except that the silver is
added very cautiously, so as to avoid too rapid a deposit upon
the high lights. The acid development of dry plates has, how-
ever, almost wholly given way to the

\ 5. — Alkaline Development.

This method shortens the exposure to one-half or one-third,
giving at the same time softer and more harmonious effects.

The first idea of using alkali for the development of dry plates
originated with Mr. Borda, of Philadelphia. The next steps in
it were made by Mr. H. T. Anthony, of New York. These
gentlemen were undoubtedly the discoverers of the principle of
alkaline development. Subsequently it was taken up in Eng-
land, and gradually brought into its present shape by Mr. Glover,
Mr. Leahy, and especially Major Russell, who made the discovery
that the development might be controlled and restrained by add-
ing a few drops of solution of bromide of potassium to the alka-
line developing bath. This last discovery has given us the means
of managing the whole operation at pleasure, and producing every
variety of negative, from the most veiled to the most transparent.

Management. — Prepare the following solutions : Pour some
alcohol into an ounce vial of pyrogallic acid, and filter the solu-
tion into an eight-ounce vial, washing the filter with alcohol
until the vial is full. This gives a solution of nearly 60 grains
to the ounce.

Take 6 ounces of good clean flinty carbonate of ammonia, and
pour over it enough warm water (not hot, hot water decomposes
it) to cover it. After standing an hour or two, filter into a quart
(32-ounce) bottle, add more water to the undissolved residue, and
so on until the whole is dissolved in the 32 ounces. This gives
a solution of about 80 grains to the ounce, which must be kept
well corked.

Dissolve bromide of potassium in water in the proportion of
60 grains to the ounce.

In commencing to develop a lot of plates, put into a small vial
half an ounce of the 60-grain bromide solution, and three-

DRY PLATE PHOTOGRAPHY. 359

quarters of an ounce of 80-grain carbonate of ammonium, and
mix well by shaking.

Next, for a whole size (6| x 8|) plate, take a 7 X 9 porcelain
pan, and put into it 4 ounces of water. Add J drachm of the
solution of pyrogallic acid, and immerse the plate so as to wet
it equally and avoid lines of unequal development when the
alkali is added.

Now remove the plate and add to the bath 15 to 20 minims of
the mixture of bromide and carbonate, mix, and return the plate.
The image should rapidly come out, and when its details are well
out, add, without waiting longer, half a drachm of the carbonate
of ammonium solution. Density rapidly comes, and when the
plate has reached printing strength, fix it as an ordinary wet
negative. Except that with plates made with a collodion con-
taining bromides only, the fixing bath must be very weak, one
part of hyposulphite to fifty of water.

Heat in Development. — The water used in making the develop-
ing bath should never be cold, but rather of the temperature of
70 to 80°. A higher temperature than this is very useful in
case of under-exposure. If in the development of a plate it is
evident that it has been considerably under-exposed, and there
are other plates that have had a like exposure, it will be well to
develop them in a bath at about .blood-heat, or even a little
warmer. This will be found to aid materially in getting out the
image, and will often save plates that would otherwise be lost.
A little more bromide in the developer will be advisable when
it is used hot.

Acid Development to Pinish the Alkaline. — In the writer's expe-
rience, it is always best, if possible, to finish the plate wholly by
the alkaline development. The results are softer and more har-
monious, and the shadows more luminous. Some, however, pre-
fer only to bring out a thin image, and then finish with pyro-
gallic acid and silver. The writer does this only when, from a
material under-exposure, it is impossible to get printing density
without it. It should, however, be very clearly understood that
in such cases it is better to resort to an acid development than to
push the alkaline under circumstances that lead to fogging.

If the alkaline development stops entirely (if it even goes on
very slowly, it is .best to let it take its time), it can generally be
started again by adding a little more carbonate of ammonium.
But, after carrying this addition to a certain point, it is best to

360 PHOTOGRAPHIC MANIPULATIONS.

stop. The writer does not find any good effect, but rather mis-
chief, result from raising the proportion of carbonate over one
and a quarter, or at most one and a half, grain to the ounce.

If, then, the addition of carbonate has reached this point, and
the development has quite ceased, it will be well to redevelop
with acid. The first thing needed is to wash the plate under the
tap, to get the alkaline liquid out of it, which, in contact with
silver solution, would cause instantaneous fog. Meantime, suffi-
cient water is placed in a clean basin, and acetic acid (No. 8) is
added in proportion of about one-twelfth of the water and mixed
by agitating. Into this the plate is put, that the acid may remove
the last traces of alkali before the silver is applied (if the plate is
put into the acid solution without previous washing, bubbles of
carbonic acid gas may form under the film and detach it, as the
writer has seen happen). Pyrogallic acid and the usual solution
of silver (nitrate of silver 10 grains, citric acid 15 grains to the
ounce) are added in very moderate quantities to the bath.

§ 6. — Failures in Dry Plate Operations common to Dry Plates

generally.

Dry plates are much more exposed to accidents than wet, partly
because the latter remain in the sensitive stage so short a time
and are used at once. There is also in dry-plate work a greater
need of strict cleanliness. Any operator, for example, who ever,
under any circumstances, places hyposulphite in any vessel used
in any of the operations other than fixing, actually invites failure.
The least trace of hyposulphite in the developing pan will cause
the development to fail. A pan that has been once used for fix-
ing must never be used in any of the other operations, neither as
a water pan for soaking the plates before the preservative nor for
any other use whatever. Each pan must have its special use, and
be reserved for it.

Again, dry plates must never be exposed to the air, especially
not the air of a work-room, which may have in it gases of various
sorts. The plates, both before and after fixing, must remain in
tight boxes, perfectly excluding air and dampness, for all damp-
ness is destructive to dry plates. And as to gases, the vapor of
acetic acid, which is often in the air of the dark room, tends to
destroy the latent image. Sulphur vapors of any sort tend to fog.

Another source of trouble lies in wet tables. The bottles or

DRY PLATE PHOTOGRAPHY. 361

other vessels resting on the wet take up some, and when turned
over to pour from, a drop or two from the bottom may run along
the outside and fall unnoticed along with the contents.

Keeping. — Although many sorts of dry plates show good keep*-
ing qualities, yet their sensibility in most cases slowly diminishes,
so that plates a month old should have full one-half more to
double the exposure of fresh ones. Also, the image, after ex-
posure, tends to fade in the delicate details ; it is, therefore, com-
monly said that the golden rule of dry-plate work is to develop
as soon as possible after exposure. The same evening is the best
time of all, but generally two or three days' delay will not be
very important. For longer delays a longer exposure should be
given. But it is to be carefully borne in mind that, quite apart
from fading, the longer a plate is kept after exposure the more
it is exposed to adverse influences of all sorts.

Errors as to Length of Exposure. — This is a serious source of
difficulty with dry plates. With wet, the first plate tried gives
a clear idea of the character of the day's light, and the rest are
measured thereby. But with dry plates, all on any one excur-
sion must be exposed on a venture, and there is no criterion from
the first to the rest. Fortunately, there is a good deal more lati-
tude with dry plates than wet, and in exposing, it is best to err
on the side of too much rather than too little. Certain points
are of consequence to remember.

1. After midday the light soon falls off, and about three hours
before sunset, at some irregular time, the diminution begins to
be very considerable.

2. In the beginning of September the light is already materially
weaker, and a great allowance must be made for its failing.
October, compared with May or June, will need about a triple
exposure.

3. Cloudy days, excellent for soft effects, are often deceptive as
to strength of light. With very thin clouds, the light is some-
times extremely powerful. With a grayish color in the clouds,
the light is much weaker.

4. Sheltered places, partly under trees, receive a great deal
less light than open ones ; the difference is so much greater than
appears, that such views are extremely apt to be under-exposed.

The Ratio of Exposure, compared with wet plates, varies with
different sorts of dry plates, but it must never be forgotten that
the proportion of exposure increases always as the light is fainter.
24

362 PHOTOGRAPHIC MANIPULATIONS.

Thus, a dry plate which in a good light needs a threefold expo-
sure, will in a poor light need four or five times the exposure of
a wet plate in the same light, and in very dull, rainy weather
will scarcely receive any impression at all.

Non-actinism of the Film varies greatly with different processes,
so that in changing one's process, one is apt to be deceived.
Two plates by different processes, looking equally dense, will
probably differ very much in the printing.

Irregularity of Surf ace before Developing. — This peculiarity the
writer has been able to trace to the use of too strong preservative
solutions. Some films will hold in them much more solid matter
than others, and what they will not retain in them of the solids
dissolved in the preservative bath solution must come up to
their surface in drying. Merely thinning a collodion with alco-
hol or ether may cause it to give a thinner film, so that the
preservative in use can no longer be held wholly in the film.
Use more pyroxyline or weaker preservative, and wash such
plates before developing them.

Image, after advancing aivhile, goes back. — Too much carbonate
of ammonium, which never should exceed one and a quarter grain
to the ounce of developing bath.

Fogging. — Same cause. Also, too much pyrogallic acid. Ex-
posure of plates to deleterious gases. Pushing too far the deve-
lopment of under-exposed plates. Using pans that have had
hyposulphite in them.

Want of Detail in Shadoivs. — Under-exposure. Too much bro-
mide used in the development. Insufficient development.

Surface Stains. — Drying by heat without allowing to drain five
or ten minutes before applying the heat.

These stains, like the irregularity explained above, may depend
upon the preservative. If the preservative solution be pretty
strong, and collodion not a full-bodied one, the film, as it contracts
in drying, may not be able to hold all the dry preservative, and
thus this will be forced up to the surface in places as it dries,
and dry in superficial stains. The coffee process is subject to
this difficulty. Eemedy : Change the collodion or dilute the pre-
servative.

Want of Intensity. — Bad pyroxyline. Under-exposure. Over-
exposure may produce same result. In the latter case the whole
picture flashes up — in the former the high lights come easily, and
the rest very slowly.

DRY PLATE PHOTOGRAPHY. 363

Stains. — Insufficient cleaning. Handling with dirty hands, or
touching the plate at all.

Dampness. — Exposure, even temporary, to dampness, gives rise
to more or less decomposition of the sensitive film, resulting in
insensitiveness and other troubles. The writer invariably, in all
weathers, wraps his slides in waterproof black cloth, using a
piece sufficiently large to cover them with several folds. Another
piece, about four and one-half feet square, is again wrapped over
this; the latter serves as a focussing cloth also. Slides, even
when so wrapped, should never be laid on the ground or on damp
stones. In a word, every precaution must be taken to insure
dryness before and after exposure.

Transparent Dots and Filamentous Marks. — Dust in the pre-
servative solutions, or falling on the plates in the slides or in the
camera.

Blistering. — This annoying trouble depends upon the pyrox v •
line. Often the sorts otherwise the best, blister badly. Leaving
open places in the edging, that the water may wash out, is the
best remedy. (See Fig. 133, p. 353.)

Mistakes in Exposing. — Nothing is more vexatious than to ex-
pose by mistake a second time a plate that has been already used.
Ever}- dark slide should have a number plainly painted on it,
and the slides should be exposed in the order of their numbers.
Those who find a tendency to mistakes of this kind may render
them impossible by pasting a strip of paper, one end to the slide
and the other to the shutter. The exposure cannot be made
without breaking or cutting the strip previous to withdrawing
the slide, and thus the condition of the strip indicates at once
whether the slide has been exposed or not.

Accidental Uncovering. — If the slides are carried far, and much
jarred or bolted, the shutters will sometimes slip aside and un-
cover one end of the plate.

With single dark slides the writer always has a small flat hook
attached to the slide and fastening to the shutter handle. With
double slides this cannot so well be done, and the best way is to
tie twine round them.

Noxious Fumes. — Any reducing vapor or gas must destroy
plates. Sulphuretted hydrogen, or any foul emanation from
drains or water-closets, chemical vapors of many sorts, probably
also carbonic oxide, the so-called " gas" that comes from badly
drawing stoves. Sulphurous acid would also destroy plates.

364: PHOTOGKAPHIC MANIPULATIONS.

Eesinous wood used for drying-boxes or for plate-boxes, or
freshly-varnished wood surfaces would be very suspicious.

It will be observed that all of these sources of trouble point
amongst other things to the necessity of the complete exclusion
of external influences. And this can, perhaps, in no way be
better effected when plates are to be carried to any distance, and
preserved for any time, than by inclosing the cases in thick
brown or dark green or red paper, saturated with India-rubber
varnish. Where this cannot be procured commercially, it might
easily be made by the photographer himself. The joints of the
paper must, of course, be pasted down with the varnish also.

CHAPTEE XVII.
DRY PROCESSES.

In the foregoing chapter the writer has endeavored to group
together those details that are common to all dry processes.
Therefore, before undertaking any of the following methods, it
is presumed that the photographer has made himself acquainted
with its contents.

In learning any one dry process a step will have been made
towards all, so much have they in common. At the same time
they are nevertheless very distinct. The best advice that can be
given is to hold persistently to some one process until it is com-
pletely mastered. Then, if desired, others can be experimented
with, with the view of settling down upon some one. It is an
important matter to be able to judge by the inspection of a dry
plate whether it has the right density and modulation to print
well. This can scarcely be done if the photographer changes
about, because some dry plates are very non-actinic, whilst others,
ecpually dense to the eye, are comparatively very transparent to
the chemical rays. Hence much changing will lead to continued
mistakes in development.

As, in the writer's opinion, the collodio-bromide process gives
the most sensitive plates and the softest negatives, and as these
plates are the most easily and rapidly prepared, it will be placed
first.

DRY PROCESSES. 865

§ 1. — Collodio-Bromide Dry Process.

The first idea of adding nitrate of silver to a bromised collo-
dion, and of thus dispensing with the negative bath, originated
with Messrs. Sayce and Bolton, and was by them pat into a prac-
tical and workable shape. After several years of constant use
and experiment, however, the writer has been enabled to greatly
increase both the rapidity and the certainty of the process by
radical changes made in every part of the mode of proceeding, viz.,
by introducing aqua regia into the collodion, by adding the
nitrate of silver in a state of solution, and also by changing the
preservative. The tedious washings are done away with, and a
better and more sensitive plate is made with greatly diminished
trouble and manipulation.

The Pyroxyline. — For collodion to be used in this process, a
very intense cotton is desirable. The best course is to obtain
specimens from two or three sources, of cotton believed to be
intense, and to try them, securing a good supply of that which
answers best.

Formula for Collodion.

Ether 2 ounces.

Alcohol 1 ounce.

Bromide of cadmium 15 grains.

Bromide of ammonium 3 "

Pyroxyline 21 "

The two bromides should be placed together in a test-tube or
flask, and dissolved in part of the alcohol, with heat if necessary.
Previously dissolve the pyroxyline in the ether and rest of alco-
hol. Set the bottle in a light warm room, where the sun will
fall on it for several hours a day. It will be fit for use in three
weeks, and be good for three or four months, after which the
film is more apt to be weak, that is, to split in washing.

Aqua Regia. — Put into a stoppered bottle an ounce of ordinary
hydrochloric acid and half an ounce of ordinary nitric acid.
Stand in a warm place ; as soon as the mixture takes an orange
color, remove it and keep it well stoppered.

Gum Solution. — Several different preservatives may be used,
but in all the best, gum makes an essential part. It should be
dissolved and kept in quantity. Upon one-quarter pound (avoir-
dupois) of good clean gum-arabic pour six or eight ounces of hot

366 PHOTOGRAPHIC MANIPULATIONS.

water, stir well, and, after a portion of gum has dissolved, pour
the liquid on a filter, add more hot water, and continue till the
gum is got in solution in thirty ounces water. Take an equal
quantity of clear white sugar (one-quarter pound), and dissolve
this in portions in the gum-water before filtering. After filter-
ing, add about two-thirds of a drachm of carbolic acid, and the
mixture will keep for a year in perfect condition.

As gum-water is very slow and troublesome in filtration, it
will be well to use a percolator. (See Part V., Chapter II.)

Sensitizing the Collodion. — Measure out into a graduate as much
collodion as is expected to be wanted, and add to each ounce, in
hot weather, two drops of aqua regia. The easiest and safest way
to drop it is to plunge a glass rod in the acid bottle, and let drops
fall from the end into the collodion.

"Weigh out ten grains (10 grains) of finely powdered nitrate of
silver (fused is best, but crystallized will do) for each ounce of
collodion taken, and place it in a small flask. Measure some 95
per cent, alcohol in a graduate, allowing a quarter of an ounce to
each ounce of collodion taken. Pour about half of this into the
flask upon the nitrate of silver, warm it over a Bunsen's burner
or other gas flame, agitating gently all the while. As soon as
the alcohol boils, remove it and continue to agitate. In a few
moments return the flask or tube to the lamp till boiling recom-
mences. In this way most of the nitrate will dissolve ; this is
poured into the collodion, and the operation is repeated with
some more of the alcohol, leaving a little for a third application.
All of the silver will thus be easily got into solution.

The addition of the nitrate solution to the collodion should be
made in the dark room ; all the previous operations may be con-
ducted by ordinary light. In adding the nitrate solution, a little
should be poured in at each time, shaking a little between each.
The hot solution should not go down the sides of the bottle, but
straight into the collodion. On the sides it might chill and crys-
tallize a little.

Most of the nitrate dissolves in the first portion of the alcohol;
as soon as this is all in the collodion, shake up well for a couple
of minutes. After adding each following portion, half a minute's
shaking will be ample.

A long narrow vial is preferable for this operation, and should
not be more than about half full, otherwise the shaking will act

DRY PROCESSES. 367

less effectually, and must be continued longer. It is a good plan
to keep the bottle rolled up in yellow paper, to exclude all light.

After the last addition has been made, and the contents shaken,
the bottle is to be put aside. Too much shaking is more likely
to do harm than good.

The mixture should stand for a time that depends somewhat
upon the temperature of the room and the season, and may vary
from ten hours to sixteen. It is then ready for use as soon as
filtered.

No more should be made than is intended to be used up, and
the residues should be rejected. If kept over about sixteen
hours, there is no certainty of the working of the plates, whereas,
when made as here directed, they are more uniformly successful,
and free from fog and stains, than are wet plates.

Filtering. — Before using, the sensitive mixture will need to be
filtered through a bit of clean sponge forced into the neck of a
funnel. This should neither be put in too tight nor too loose, the
collodion should run through in a very thin stream, or a rapid
succession of drops. The mixture filters quite as easily as plain
collodion, the bromide of silver in suspension being apparently
entirely without effect upon the filtration. In addition to the
sponge, the writer likes to use a linen filter. A yard of the
finest and closest linen is boiled for a few minutes in a gallon of
water, with an ounce of common crystallized carbonate of sodium.
It is then thoroughly washed out with clean water, and left to
soak, then well wrung out with clean water. This furnishes a
large number of excellent collodion filters, and one has more
certainty of getting films free from specks when this is used in
addition to the sponge.

Coating the Plate. — More care is necessary than in ordinary
coating, as the collodion has more tendency to set unevenly.
Pour on in the same way as usual, but without sending back to
the far corner, put on plenty, cover the plate rapidly. Raise the
far end of the plate as little as possible, just enough to enable the
surplus to drain off. Keep it so, and rock steadily. In ordinary
coating, at the end of the draining we raise the plate almost ver-
tically : this is exactly what is not to be done here, the plate is
kept almost horizontal until the collodion has set.

Operating in this way, if we do not get an even plate the mix-
ture is too thick and will require to be diluted. This may be
done either with plain collodion or with ether. Generally the

368 PHOTOGRAPHIC MANIPULATIONS.

former is the best ; but it must be plain collodion made with the
same cotton : this is essential. In hot summer weather the sen-
sitive mixture is much more difficult to manage, and will some-
times need the addition of ether before it will work smoothly.

It is impossible to judge of the character of the plate by hold-
ing it between the eyes and the light. But if held a little to one
side of the light, every slightest inequality will become con-
spicuous. A perfect plate will look perfectly smooth, but plates
that show only a slight irregular cloudiness will give perfect
negatives. If the cloudiness reaches a certain point, it will be
liable to show in the flat tints, sky, water, &c. When the cloudi-
ness reaches to a still greater extent, it is liable to produce mottliyig,
which shows especially in the skies.

Before proceeding to coat the plates, they will need to be edged.
(See p. 352.) As the coating should not instantly follow
the edging, it is best to edge half a dozen or a dozen, and stand
them in a rack. Each plate, before coating, should be carefully
brushed with a broad flat brush, and a piece of folded paper
should be interposed between the fingers of the left hand and the
under side of the plate, or else a pneumatic holder should be
used.

As soon as the plate is set, it is thrown into a pan of water and
lies there until it no longer shows greasy marks when taken out,
but exhibits a perfectly uniform surface. It is best to have three
or four pans of water, and coat a plate for each in succession,
agitating the pans gently from time to time. As soon as they
cease to show greasy marks and are smooth, they are ready to
transfer into the pans of " preservative." In these they remain
from five to eight or ten minutes, at the convenience of the
operator. The time is not very material, provided it is not less
than five minutes nor much over ten.

If the plates are not to be dried by heat, they may be backed
at once. The plate is taken out of the preservative bath, reared
on end, and the back wiped with blotting-paper, because if the
wet is left on, it thins the backing too much. The colored paste
(see p. 356) should be as thick as possible to manage; it is
put on thickly and carried up to within an eighth, or, at least, a
quarter of an inch of the edge.

If they are to be dried by heat, the backing, if applied first,
will be apt to liquefy and run.

DRY PROCESSES. 3(39

When plates are to be dried by heat, they should drain five or
ten minutes before the heat is applied, or surface markings may
be expected.

Preservatives.

Almost any preservative that can be used with common dry
plates made with a bath, can be used also with collodio-bromide
plates.

The writer of this manual has devoted a great amount of time
to investigating the qualities of a great range of substances as
preservatives. He finally adopted two as being superior to any
of those previously proposed or used. These are, first, pyrogallic
acid ; and second, a special preservative made from cochineal.

Pyrogallic Preservative.

The writer uses for all purposes in which pyrogallic acid is
employed, a solution made by pouring alcohol into an ounce
bottle of pyrogallic acid till it reaches the neck. A bottle hold-
ing just 8 ounces (or marked with a diamond on the side at the
point to which 8 ounces fill it) is adopted for regular use, and
the above strong solution placed in it. More alcohol is poured
into the original pyrogallic acid bottle to rinse it, and this is
poured upon the filter and so on, till the filtrate amounts to 8
ounces. This is the simplest mode of operating and avoids all
waste of material, as both the bottle and filter are well washed
out. Shake well to mix the different portions.

To make the pyrogallic preservative, take

Of above solution 1 drachm.

Of gum and sugar solution, already described (p. 365) 10 drachms.
Of water 6 ounces.

In making a batch of plates, it is convenient to prepare three
such baths to save time, as the plates are rapidly worked through.
Each plate, as soon as set, is slid into a pan of water ; as soon as
the oily appearance is gone, it goes into the preservative bath,
and then in five minutes is ready for drying. Both the water
pans and the preservative pans should be occasionally agitated a
little by lifting one end and letting the liquid pass in waves over
the plate.

The writer has never been in the habit of making more than

370 PHOTOGRAPHIC MANIPULATIONS.

six or eight plates in one bath. Using three baths, and making
a batch not exceeding two dozen plates, there will have been
eight to each bath.

If the plates are to be dried without heat, it is always most
convenient to back them as already described, as soon as they
are out of the preservative bath.

Cochineal Preservative.

Grind one and a half ounce of good clean cochineal in a mor-
tar with one fluidounce of fuming sulphuric acid. As the paste
gets gradually thicker, add more acid, until in all two fluidounces
have been added. "When well mixed, transfer into a wide-mouth
bottle, wipe the neck clean inside, set in a vessel of hot water,
and leave till cold. Let it stand for a week, then pour out into
about a quart of water. Add slaked lime until a piece of litmus
paper dipped into the solution turns blue. Then filter and pour
water upon the filter until the filtrate amounts to eighty ounces.
Add a quarter of an ounce of carbolic acid, and the mixture will
keep indefinitely. As but little of it is needed, one making such
as the above will be sufficient for a season's work.

To apply it as a preservative, take of the above

Solution ..." 6 drachms.

Gum and sugar solution (p. 365) . . . .10
Water 6 ounces.

This, placed in a pan just large enough to hold a plate of 6|
by 8|, will make a convenient bath for that size of plate ; or the
quantity may be increased or diminished for larger or smaller
sizes.

As to the choice between these two excellent preservatives, it
is not easy to decide. The cochineal gives very dark, blackish
plates; the pyrogallic acid, light brown, not unlike wet plates.
The cochineal gives the softest, the pyrogallic acid the brightest
negatives. The writer has had much more experience with the
cochineal, having used it exclusively for view-taking through an
entire season, and with great satisfaction. He has kept plates as
long as three and a half months in good order.

The pyrogallic preservative he has only discovered much
more lately, and cannot as yet report upon its keeping qualities.
Judging by analogy, they ought to be excellent.

Either of these processes, by increasing the dose of bromide in

DRY PROCESSES. 371

the development, will give more and more contrast and absence
of deposit in the shadows, so that it is easy in this way to give
the negatives an arnbrotype appearance. For a soft printing
negative this is not desirable, but this property might be useful
in making transparencies for the lantern, for which the pyrogallic
process seems particularly applicable — more so than the other.

Oilier Preservatives for the Author's Collodio- Bromide Process.

As already said, almost any preservative that will work with a
common dry plate is suitable for collodio-bromide plates. Next
in order of excellence to the foregoing the writer places the Tea
preservative, first proposed by Mr. Newton. This preservative is
undoubtedly superior to tannin, to coffee, or to gallic acid.

In the writer's hands, tea has worked better without gum and
sugar than with them. It is sufficient to take a tablespoonful of
good black tea, let it infuse in boiling water in a covered cup in
a warm place for an hour or two, filter and dilute until the liquid
amounts to eight ounces. As before, the plate, as soon as the
water has rendered it smooth and uniform, is put into this bath
for five or ten minutes, and then backed and dried. The results
are good, but distinctly inferior to the foregoing.

Coffee Preservative. — Make a decoction of an ounce of coffee in
eight of water, and filter. This preservative does best with gum
and sugar. To the above quantity, an ounce and a half of the
gum and sugar solution may be used.

Tannin. — In the use of tannin a great mistake has been gene-
rally made by using too much of it. The writer prefers —

Good tannin 16 grains.

Gum and sugar solution 10 drachms.

Water 7 ounces.

This is about one-eighth as much tannin as generally directed,
and gives much softer and more harmonious pictures. If a de-
ficiency in brightness and density is found, increase the tannin.

Exposures.

For the author's preservatives, two first described, give with a
good light the same exposures as for wet plates ; with an inferior
light, the exposure must be longer than for the wet. For the
tea plates, give once and a half as long as for the wet. For the
coffee and tannin plates, give twice as long as for the wet.

372 PHOTOGRAPHIC MANIPULATIONS.

It will be observed that through all these various treatments
the writer's collodio-bromide process -gives much greater sensi-
tiveness than is attained with the ordinary dry processes used
with the same preservative.

For Drying, see p. 354.

For Development, see p. 358.

§ 2. — Dry Plates made with a Negative Bath.

This is the older way of managing dry plate work, and for
those who habitually use the wet process, and occasionally need
a dry plate, it is the more convenient. It is also preferred by
many habitual dry-plate workers.

For this method of dry-plate work the regular negative bath
suffices, though it is an advantage to have it a little more acid.
Ordinary collodions may be used if they are pretty old ; generally
they are improved by adding a little simply bromised collodion
to them, or a grain or two of bromide of cadmium to the ounce.

But they will work still better with a very intense cotton,
giving a porous and not a skinny film. If made specially, the
collodion may be salted as follows : —

Iodide of ammonium 2 grains.

Iodide of cadmium 2 "

Bromide of cadmium 3 "

Add a little tincture of iodine and keep in a warm light room
for several week. If the pyroxyline has a good deal of intensity,
it may be used sooner, but age and ripeness have much to do
with success in dry plates.

The plate should be edged with rubber solution, as described
at p. 352, remembering that the collodion must not be poured
on till the edging is dry. When set, the plate is to be slid into
a pan of water until the greasiness disappears, and is next to be
washed thoroughly under the tap until all free nitrate of silver
is removed. It is then plunged into the bath of preservative,
whichever it may be intended to use, and is finally backed and
dried, or dried first and backed afterwards.

The preservatives have been already described pretty fully
under the head of the collodio-bromide process, and the manipu-
lation is much the same in both cases, except that, in the present
case, the work is much more laborious. The collodio-bromide

DRY PROCESSES. 373

plate was put into the pan of water immediately after coating,
whereas the present sort must first be sensitized in the nitrate
bath. Again, the collodio-bromide plate goes direct form the
water-pan into the preservative, whereas the ordinary dry plate
requires a thorough washing under the water faucet to be inter-
posed between these two operations.

Thus it requires twice the time and trouble to prepare an infe-
rior and less sensitive plate.

Pyrogallic Preservative. See p. 369.

Tea Preservative. "j

Tannin Preservative. > See p. 371.

Coffee Preservative. J

Clove Process.

The writer has found that a preservative of cloves gives most
excellent plates. Clove nuts, not the ground cloves, are taken
and broken up. Over a quarter pound, pour a quart of hot water,
and, after some hours, filter. To seven ounces of water add one
ounce of this decoction and one hundred grains of gum. Treat-
ment in all respects the same as with tannin.

A decoction of Malt is with some a favorite process.

Eesin Process.

Despratz first showed that if common rosin, or some other
sorts of resin, be added to the collodion, the plates need no pre-
servative, but may be simply washed and dried, after going
through the negative bath. At first the process was much ob-
jected to on the ground that it rapidly deteriorated the negative
bath. But it appears that this may be easily restored to working
order by adding a thirty-grain solution of permanganate of potas-
sium until the bath retains a faint reddish coloration ; then filter
and acidulate. The collodion should be of an intense character
and porous structure, and to it is added two grains to the ounce
of common rosin, or one grain rosin and one grain Canada balsam.
After passing through an ordinary nitrate bath, wash it tho-
roughly. It is advisable to use distilled water for the first and
last washings. The plates are more sensitive when newly pre-
pared than after keeping.

Development same as tannin; or a weak iron development.

37-i

PHOTOGRAPHIC MANIPULATIONS.

Morphia Process.

By Bartholomew. Said to be more sensitive than many other
processes. Proceed exactly as in the tannin process, but make
the preservative bath a solution of acetate of morphia, one grain
to the ounce. The writer has found it advantageous to add to
the bath acetic acid No. 8 (Beaufoy's), two or three minims to
the ounce. Plates keep only from five to twelve days.

Gum Gallic Process.
Gordon recommends for collodion: —

Alcohol and ether, each ^ ounce.

Iodide of cadmium 3 grains.

Bromide of cadmium 3 "

Iodide ammonium 1 grain.

Pyroxyline, not over 6 grains.

Negative bath forty grains. Leave in ten to fifteen minutes ;
plunge into two successive baths of distilled water; leave two
hours in a third. Or use four successive pans.

Preservative Bath.

Water (warm) 8 ounces.

Gum-arabic 1G0 grains.

Sugar candy 40 "

Gallic acid 24 "

It is advised to apply a substratum of albumen, and, before
developing, to edge with India-rubber. Probably edging at first
with India-rubber would be sufficient.

Development may be either alkaline (managed as in the tannin
process), or an iron developer containing two grains of gelatine
to the ounce of developer may be employed. The gelatine should
be first dissolved in the acetic acid. A redevelopment Avith acid
pyro and silver is needed. Fix in hyposulphite. Exposure three
times as long as for the wet. Should the alkaline developer veil,
use more bromide in it, adopting the proportions given for col-
lodio-bromide plates.

NEGATIVE VARNISHES. 375

CHAPTER XVIII.

NEGATIVE VARNISHES.

It is of the very highest importance to the photographer to
obtain a varnish as nearly perfect as possible. Upon it he must
depend for the preservation of all his work, and it would be
difficult to adequately describe the losses that some have suffered
in consequence of trusting their negatives to varnishes of a de-
fective character.

This consideration, and the very contradictory nature of the
opinions held by good judges, have led the writer of this manual
(although fortunate enough in his own case never to have used a
bad varnish) to undertake a very thorough and careful study 01
the subject within a short time past. The results which were
reached proved not only very important, but were to a consider-
able extent contrary to opinions which have obtained general
acceptance, and which had been up to that time entertained by
the author himself.

Five different varnishes formed the subject of this study, each
one of a sort that has been highly recommended. One was a
bleached lac varnish, two were of unbleached lac, one of sandarac ;
these four were spirit varnishes. To these was added a benzole
varnish, and as the writer has never been in the habit of making
benzole varnish for his own use, a commercial benzole varnish
was selected, of a high character and largely used. The four
spirit varnishes were made by the following formulas : —

No. 1. — Bleached Lac Varnish.

Bleached lac, best quality 9 ounces.

Sandarac 3 "

Essence lavender . . . . . . . 5 "

Alcohol 69 "

Filter.

No. 2. — Unbleached Lac Varnish.

Orange lac, best 220 grains.

Sandarac 80 "

Essence lavender \ ounce.

Alcohol 4 ouuces.

All the ingredients mixed at once.

376 PHOTOGRAPHIC MANIPULATIONS.

No. 3. — Unbleached Lac Varnish.

Best orange lac 200 grains.

Alcohol 4 ounces.

Dissolve, filter, and add

Sandarac 80 grains.

Essence lavender 1^ fluidracbm.

Filter again.

No. 4. — Sandarac Varnish.1

Sandarac 10 ounces.

Canada balsam 1 fluidounce.

Essence lavender 2 ounces.

Alcohol 64 "

No. 5 was the commercial benzole varnish before mentioned,
and of which the writer has not the formula.

These varnishes were applied on waste negatives with heat
before and after, and exhibited the following characteristics : —

Smoothness. — Nos. 1, 3, 5, perfectly smooth ; 4 was somewhat
thready and more difficult to work ; 2 a little irregular, but less
so than 4.

Clearness. — Excepting that 5 showed a very slight tendency to
dry dead, all were perfectly clear.

Hardness. — This important quality was tested by rubbing
steadily with a moderately soft lead-pencil, in one place, until
the film was cut through, and noticing how much resistance each
exhibited. It was found necessary to make this test with great
care, as one and the same film varied much in different parts,
resisting best always where the image was densest (because there
was more varnish absorbed and retained there). It was, there-
fore, necessary to choose a portion of each of equal density, and
to repeat the trial many times to avoid error. Besult: No. 4 the
hardest and No. 5 the softest by a good deal, the rest inter-
mediate. No. 3 was harder than 1 and 2, evidently because of
the more sandarac and less lavender. It was estimated that No. 4
resisted four times as much friction as No. 5; that No. 2 was
half-way between. No. 3 was intermediate between 2 and 4, and
No. 1 was next in softness to No. 5.

Resistance to Heat. — The amount of resistance to heat exhibited
by a varnish is of very great importance. In our hot summer
weather negatives in the direct rays of the sun may become

1 For this formula the writer is indebted to Mr. Fennemore.

NEGATIVE VARNISHES. 377

greatly heated. It is a fact well established in physics, that glass
allows the heat rays direct from the sun a much freer passage
than the dark rays returning from an object beneath the glass.
Therefore there is a tendency for the heat to accumulate in the
film, paper, and packing, and thus to subject- the varnish to a
most severe trial. If it softens in the least, adhesion of the paper
takes place, and the negative may easily be destroyed.

In order to subject the varnishes in question to a decisive test,
they were placed on a metal vessel filled with hot water, and
heat was applied below till the water boiled. Prom time to time
slips of paper were pressed forcibly upon the varnished surface,
and then were gently raised to observe if the slightest adhesion
took place.

One curious result observed was that when the heat was mode-
rately raised, Nos. 1 and 2 showed signs of slight adhesiveness,
which, when the heat was raised higher, instead of increasing, en-
tirely disappeared. This evidently indicated that, in applying heat
immediately after varnishing, the heat had not been applied long
enough to drive off all the essential oil. So that when, in this
experiment, a considerable heat was applied, the remaining essen-
tial oil softened the resins, but presently evaporated, leaving the
film more solid. This shows how much depends upon a thorough
application of heat after varnishing.

It was found that, as all these varnishes were good, a higher
degree of heat than that which could be obtained by boiling the
water in the vessel was necessary to decide as to the superioritv.
Therefore fresh pieces were taken, cut from the same negatives,
and these, without a gradual heating, as in the former case, were
suddenly placed upon a piece of iron so hot that a drop of water
let fall on it instantly boiled away. This high heat brought out
the differences in a very decisive way. Kos. 4 and 5 were still
almost wholly free from any tendency to stickiness. Nos. 1, 2,
and 3 did decidedly less well.

Resistance to Moisture. — When varnished films (Jrack and break
away in progress of time, this evil generally results from damp-
ness penetrating the film. Under its influence the collodion film
would naturally swell, the varnish not, and this unequal action
tends to detach the film from the glass and crack the varnish.
As this action generally requires years to become apparent, it
was thought that the most expeditious, as well as severe, test of
25

378 PHOTOGRAPHIC MANIPULATIONS.

resistance to moisture would be made by plunging the negatives
under water.

Accordingly pieces of the same size in each case were cut out
of negatives varnished with the different varnishes, applying the
same quantity, as nearly as possible, of each, and drying by equal
heat. These were placed side by side in a large deep porcelain
pan and kept covered with water.

At the end of. four days No. 5 gave way ; the rest were all in
good order.

They were examined from time to time, and all appeared per-
fectly sound, until, at the end of six full iveeks, it was noticed
that Nos. 1 and 3 showed a very slight puckering at one corner,
as if there might be a commencement of detaching. Nos. 2 and
4 appeared to be in as good condition after six weeks' immer-
sion as they were before they were placed in the pan.

The writer cannot but consider this result very remarkable.
It indicates that, with several of the varnishes of which the for-
mulas are here given, the action of moisture amounts virtually
to nothing.

To sum up : If we examine which of all the varnishes ex-
hibited the greatest number of good points, we shall find it to be
the much condemned sandarac varnish (No. 4). It was the hardest
in resistance to mechanical injury, one of the two best resisting to
heat, and one of the two best resisting to moisture. Its only fault
was a tendency to threadiness when applied, requiring a little
more dexterity to make a good even coating.

The benzole varnish did not stand high at all, its only good
points being its resistance to heat, in which it was equalled by the
sandarac, and in hardness, in which it was excelled by the same.
In resistance to moisture it was very far behind all the rest.

The two orange-lac varnishes (Formulas 2 and 3) exhibited
good qualities. Number two resisted moisture for six weeks as
well as the sandarac. Both were easily applied, and gave
smooth, even films without trouble. But they were deficient
in hardness, and their resistance to heat, though fair, was infe-
rior to Nos. 4 and 5.

In view of these objections to the lac varnishes, and of the
verv poor resistance of the benzole varnish to moisture, the pre-
ference must evidently be given very decidedly to No. 4, the
sandarac, a most excellent varnish.

TREATMENT OF RESIDUES. 379

Varnish is generally best left to clear itself by standing. It
quiclcly clogs a filter, especially if it contains lac.

Varnishes will dissolve some collodions, it is said, though the
writer never saw this happen. In such cases it is recommended
to add about one or two per cent, of water. The addition of
water, even to a small extent, will often diminish the solvent
powers of the alcohol for some of the constituent parts of the
varnish, and cause a cloud to form, rendering filtration necessary,
and perhaps changing the character of the varnish. It should,
therefore, never be done unnecessarily.

In view of the results of the above careful examinations, there
would be no advantage in giving additional formulas for other
and comparatively untried varnishes, when qualities so excel-
lent have been proved to exist in some of the foregoing.

The highly polished surface of a heat-dried negative does not
easily take color or shading. In addition to the methods already
given for overcoming this difficulty, it may be mentioned here
that finely powdered resin, rubbed on the part of the film to be
operated upon, has been found to be an excellent treatment.

CHAPTER XIX.
TREATMENT OF RESIDUES.

Every photographer should endeavor to avoid wasting the
valuable metals that he employs, but the extent to Avhich this
care should be carried will depend largely upon the scale on
which he carries his operations. It would be, for example, a
waste of time for the amateur to attempt to extract the silver
from his hyposulphite solutions, but the professional photo-
grapher should never reject them without first removing the
silver, unless indeed he operates upon a very small scale. But
the amateur will always wish to recover the silver from baths,
positive and negative, that have become useless.

Residues may be worked in two ways, either the dry or the
wet. Both are chemical manipulations of the very simplest
order, can be explained in a few paragraphs, and can be readily
mastered by any man of ordinary intelligence. The writer would

380 PHOTOGRAPHIC MANIPULATIONS.

recommend the professional photographer to use the dry way,
and the amateur, the wet.

§ 1.— The Dry "Way.

Old Baths. — These will be thrown down with common salt.
Take good coarse but clean salt, make a strong solution of it in
any convenient vessel of glass or wood. Pour in the baths with
constant stirring. Make sure that the salt has been added in
excess, or large quantities of silver may be wasted unknowingly.
To make this certain, let the whole have a most thorough agita-
tion, then let stand some hours to settle, "take off some of the
supernatant liquid, and add to it a little clear solution of salt.
If no precipitate falls and no cloudiness is produced, the operator
may feel assured that all the silver is thrown down as white
chloride of silver, changing to violet whenever exposed to the air.

This chloride must next be washed. The liquid over it is
carefully and completely drained off, clean water added in abun-
dance, the whole thoroughly well stirred up and allowed to settle,
then poured off, and this is repeated several times ; the oftener
the better. The vessel should be capacious, so that the chloride
of silver, after settling for some hours, should not form a layer
extending one-tenth the height of the water in the vessel. (It
should be carefully borne in mind that if any hyposulphite baths
are poured into this, that, so far from anything being precipitated
from them, the hyposulphite will dissolve large quantities of
chloride of silver, if this has been already thrown down, or pre-
vent its precipitation, if added earlier.)

The chloride of silver, after being washed and dried, is put into
a crucible, after being mixed thoroughly with half its weight of
dry carbonate of soda and one-quarter its weight of clean sand.
The crucible should not be plunged suddenly into a hot fire, or
it will almost surely crack. But a few live coals should be put
into the furnace, then a thin layer of fresh coal, then the crucible
on that, and more fresh coal heaped round it. Bring the fire
gradually up to a bright red heat, and when the silver is melted,
stir it up with an iron rod. The most suitable crucibles are of
Paris clay, to be had of the dealers in chemical apparatus. Com-
mon sand or " Hessian" crucibles are porous : if these are used,
they should have the pores filled up beforehand by fusing a little
borax in them, to prevent the silver from sinking in.

TREATMENT OF RESIDUES. 381

Cuttings and Spoiled Prints. — These should be carefully burned
in any convenient vessel, the ashes gathered up, and these may
be added to the foregoing. Some have advised to heat the ashes
with nitric acid, but this does not exhaust all the silver, and the
nitrate of silver obtained is too impure for use without re-
ducing it.

Hyposulphite Baths. — The silver is best extracted from the old
fixing baths, positive and negative, by precipitation with liver
of sulphur (sulphide of potassium). The silver is thus thrown
down as sulphide of silver. This sulphide of silver is a heavy
black powder, from which the sulphur is recovered by melting
with an equal weight of saltpetre. But in doing this, two pre-
cautions must never be omitted.

First, the sulphide must be heated red-hot by itself (that is,
before the admixture of the saltpetre) in an iron pot. The object
of this is to burn off the sulphur powder thrown down along
with the sulphide of silver, and which, if it remained with the
sulphide of silver when melted with the saltpetre, might cause
dangerous explosions.

And secondly, it is necessary to be certain that the whole of
the sulphide of silver is decomposed. This may be materially
aided by stirring the mixture after it has been some time fused,
with an iron rod, and continuing this for some time.

The writer, believing that all photographic operations should
be carried on with nitrate of silver of the best quality, not only
advises not to mix the silver got from the sulphide with that re-
duced from the chloride, but either to dispose of it to a refiner
for further purification, or else to purify it by dissolving it in
nitric acid, and adding this solution to the spent baths, to be with
them precipitated as chloride. Many will doubtless hold this to
be excess of caution, but a bath, and especially all negative baths,
ought to be beyond suspicion.

Gold- Residues. — The least troublesome way of managing them
is undoubtedly that recommended by Davanne, to acidulate the
spent toning baths ; add thereto solution of persulphate of iron,
and to add the precipitate obtained by the addition of the iron
solution to the chloride of silver, and place them in the crucible
together. Then the lump of silver contains the gold alloyed
with it, and, when the silver is dissolved in nitric acid, the gold
remains behind.

The residue containing the gold, after nitric acid has dissolved

3S2 1'IIOTOGRAPHIC MANIPULATIONS.

all that it can dissolve, is a dark-colored powder, which may be
treated with hot nitro-hydrochloric acid (nitric acid one part,
hydrochloric acid two parts), in which it easily dissolves.

§ 2.— The Wet Way.

This method is here recommended chiefly for amateurs who
wish to work over their positive and negative baths. A gallon
precipitating jar is to be about one-third filled with a solution of
clean salt, and the baths are turned into it and thoroughly stirred
up. After the chloride has settled, and leaves the liquid clear, a
portion of it is placed in a clean glass, and tested with more solu-
tion of salt, to make sure that the precipitation is complete.
After being well washed by repeatedly stirring up with water,
and pouring off again, the water is finally poured off closely, a
little sulphuric acid is added, and then a lump of good zinc.
For each pound of silver an ounce of sulphuric acid and a half-
pound of zinc will be ample. The chloride rapidly shows signs
of blackening, and this slowly proceeds until the whole of the
metallic silver is revived in the form of a grayish-black powder.

At the end of about two days, during which the contents of
the vessel should be occasionally shaken, the operation will be
complete. The lump of zinc is removed, a little more sulphuric
acid is added, stirred up, and the whole left for some hours.
The revived silver is then washed precisely in the same way as
the chloride, with eight or ten waters (first breaking it well up
with the fingers), and is then ready to dissolve in nitric acid. To
effect this solution, place a quantity of nitric acid of good quality
in a vessel of which it does not fill over one-fifth or one-sixth.
Throw in the silver powder, waiting between each addition till
the effervescence subsides, and avoiding most carefully to inhale
any of the red fumes evolved ; to which end the operation should
be performed under a well-drawing chimney. When all the
silver is dissolved, the solution, which is always very acid, is to
be filtered, evaporated down, and either crystallized or fused ;
the writer decidedly prefers the latter.

In fusing nitrate of silver, care must be taken to use a suffi-
ciently large porcelain basin ; for if, when the solution is very
much concentrated, it reaches nearly to the edge of the basin, it is
liable to perform what is known to chemists as "travelling" —
that is, it will creep over the sides, and a crust once established,

VARIOUS PHOTOGRAPHIC PROCESSES. 383

more and more will get over by capillary attraction, make a crust
on the outside, and run down, half crystallizing and half fused,
upon the table. The writer once left a capsule with nitrate pre-
paring for fusion, for a short time, and, on returning, found over
half a pound outside. Capsules of Berlin or Meissen porcelain
only can be trusted for fusing nitrate of silver.

This method of operating gives satisfactory results if carefully
carried out. The zinc used should be pure. The Bethlehem
zinc, sold in the Atlantic cities of America, is excellent for this
purpose. Granulated zinc is not near so good for use as zinc in
lumps, for, though it may work a little faster, there is always
danger of small portions being overlooked and remaining in the
silver, failing to be dissolved by the acid. The Bethlehem zinc
comes in ten-pound ingots. Instead of granulating it, set it on a
good fire till it is nearly ready to melt at the corners; remove
it, and it will be found that, when thus hot, it will break up
under a hammer with the utmost facility.

With many photographers it will be an object to have as little
to do with chemical manipulations as possible. Such cannot do
better than to sell their residues to some fair-dealing reducer.
The residues should be kept in good condition, and the three sorts
kept separate, viz., chloride, from throwing down old baths with
salt ; sulphide obtained from fixing baths by precipitating with
liver of sulphur; and lastly, ashes from clippings, failures, etc.

CHAPTER XX.

PHOTOGRAPHY ON GLASS AND ENAMEL, AND COLLODIO-

CHLORIDE PRINTING.

§ I. — Printing on Glass by Development.

Positives may be obtained on glass in a variety of ways, both
by development and sun -printing, and each different method has
its advocates, and is capable of giving good results. These posi-
tives, when made on ordinary transparent glass, are known as
Transparencies, when printed on white opaque glass they are
known as opal pictures or opalotypes. The difference depends

384

PHOTOGRAPHIC MANIPULATIONS.

solely upon the material used as a support, arid either may be
obtained by development or by the direct action of sunlight.

When made by development, two different methods may be em-
ployed. An image may be obtained in the camera, and be sub-
sequently developed, or the negative may be laid on the sensitive
plate and exposed to a weak light, and followed by development.

Printing in the Camera. — When it is intended to print in the
camera, by far the best method is to have a camera expressly
constructed for this purpose, with two bellows and two racks
and pinions. -Suppose the bottom of an ordinary camera to be
extended in front, another camera to be attached, and beyond, a
frame to receive the negative. In this way a total exclusion of
diffuse light is effected ; no ray can reach the lens except through
the negative. The frame containing the negative at the front can
be racked in and out, as also can the dark slide and focussing
screen at the back ; the lens occupies a stationary position be-
tween the two.

In Fig. 138 the portion A receives the dark slide in the usual
manner. B is similar to the front of an ordinary camera ; it car-
ries the flange, and into it the lens is screwed. At N is a special

Fig. 138.

arrangement to receive the negative which is to be printed. The
front, N, is raised and pointed at a bright cloud, or a mirror may
be placed in front of it, inclined so as to send light from the sky
directly upon the negative, and the focussing is done by racking
the back, A, in or out. The space from A to B is shorter than
from B to N, because the centre of the tube of the lens (which
projects beyond B towards N) should correspond with the middle
of the base-board. To copy a whole size plate of equal size with
the original, the space from A to N must be fully four times the
focal length of the lens employed. A ten-inch Steinheil aplanatio
will be useful for the purpose. In this case the space from the

VARIOUS PHOTOGRAPHIC PROCESSES.

385

negative frame to the focussing glass should be from three feet
six to four feet. B is stationary. A and N rack backwards and
forwards. If the photographer has two cameras of suitable size,
they may be combined so as to give very much the effect of the
double camera, shown in the figure. The second camera has its
lens removed, its front is turned towards the front of the other
camera, and the end of the tube of the one is thrust through the
flange of the other. The ground glass is also removed, the nega-
tive to be copied is secured in the focussing frame in its place.

Or the arrangement represented at Fig. 139 may be used.
Four strips of wood extending from the camera support a light

Fig. 139.

frame, in which the negative is to be secured, and during the
operation the space between the camera and the lens is covered
over with a piece of black muslin or a focussing cloth. A mirror
placed in an inclined position throws light through the negative.
The object of arranging the legs as shown in the figure, is to
admit of pushing the portion supporting the mirror outside of a
window, in order to receive light direct from the sky above. The
same object may be attained by nailing a board of the proper
width and length upon an ordinary table, and making it project
at one end in the same manner.

The larger the size of the transparency, in proportion to the
original negative, the greater must be the distance between the
ground glass of the camera, and the frame holding the negative.
It has been already said, that when the copy is to be of the same
size as the original, the distance will be approximately four

386 PHOTOGRAPHIC MANIPULATIONS.

times the focal length of the lens when focussed on a distant
object.

The transparency will need to have the same brilliant clear-
ness as the negative, which will be got in the same way — a full
exposure, a rapid development with plenty of restraining acid,
and fixing immediately.

It is scarcely necessary to say that the negative for this pur-
pose must have precisely the same properties as those intended
for enlargement (see p. 177.) It must not be dense ; print must
be easily legible through the densest parts. The deep shadows
must be represented by clear glass, free from all trace of veiling.

Contact Printing followed by Development. — Transparencies may
also be obtained by the wet process without the use of the camera.
A wet plate is prepared in the ordinary way, and after thorough
draining, strips of thin letter paper are laid on its face near the
edges where it is not important to get the image, and the nega-
tive is laid face down on these, which preserve it from actual
contact. It is then held for half a minute or thereabouts, accord-
ing to the density of the negative, under an argand burner, and
development is effected in the usual way. A dense negative will
not answer.

The treatment of the positive after development will depend
upon the object in view. If the object be to produce a picture to
. be viewed in the stereoscope or hung against a window, the plate
after fixing will be blackened with corrosive sublimate, or, better,
will be treated with iodine and then with sulphide of potassium.
(See p. 171.)

If the intention is to produce an enamel by Griine's process
(which see), the plates will be toned with bichloride of platinum.

The same results as the above are got by using a dry plate,
exposing under the negative in a frame for a few seconds to diffuse
daylight, or for about a minute under an argand gas-burner, or to
magnesium light ; the latter being the most certain, as when the
quantity of magnesium required for one operation has been once
determined, it is easy to repeat without danger of error.

Transparencies for the Magic Lantern, or " Stereopticon" may be
made in several ways. Contact printing on wet collodion, as
just described, may be used, or they may be printed on the
camera, as above, or dry plates may be used ; the latter method
was habitually employed by a photographer who for a long time
supplied most of our dealers with lantern slides. Equally good

VARIOUS PHOTOGRAPHIC PROCESSES. 387

results are got by wet collodion. Tn any case the lights must be
perfectly transparent. A long exposure, rapid and very acid
development, quick fixing, and then a treatment with corrosive
sublimate, followed by cyanide of potassium or sulphide of po-
tassium, will be suitable. (See p. 172 for details.)

The Albumen Process. — The albumen process, which was used
for making negatives before the discovery of the collodion method,
and which was superseded by it, gives finer transparencies on
glass than any other method in use. A good deal, however,
depends upon the personal skill of the operator. It was, for ex-
ample, long believed that Ferrier's magnificent specimens were
produced by some secret process of his own, but eventually it
appeared that he used the regular method, as follows : —

The whites of twenty fresh eggs are taken, clear of yelk.
Iodide of potassium one hundred grains, and five grains of iodine,
are dissolved in a little water and added to the albumen, and the
whole is beaten up to a froth, and set in a cool place to subside.
As in this process it is of the greatest importance that no dust
shall settle on the plates, it is necessary that the operating-room
should be cleaned the day before by wiping off the floor, walls,
and woodwork, with a wet cloth. Shortly before commencing,
the floor is to be sprinkled with water.

A stout iron plate is fixed in a horizontal position over a gas-
burner, or any other efficient lamp. The albumen having been
poured off perfectly clear, is then extended over
the plate (absolutely clean), an operation which
is aided by first breathing gently on it so as to
let the moisture condense. Four silk cords
have each a little hook at the end, the other
ends are tied together and held in the hand ; the
hooks are slipped under the plate, which is then
supported by the cords. In this way it is sus-
pended over the hot plate and a rotating motion
is given to the threads, which keeps the albumen !
distributed over the plate ; presently it is dry. J

These plates are stored away, and when wanted for use are
sensitized in an acid silver bath prepared as follows: —

Nitrate of silver 1 ounce.

Acetic acid (glacial) 2 ounces.

Iodide of potassium ....... 2 grains.

Distilled water 14 ounces.

388 PHOTOGRAPHIC MANIPULATIONS.

From a quarter of a minute to a minute is needed for sensi-
tizing, after which the plate is rinsed under a tap, and laid in
fresh water ; then dried in any suitable way (p. 353).

The exposure is made in a suitable frame under a negative, for
a few seconds, to diffuse light. The development is effected by
plunging into a bath of gallic acid, one grain to the ounce.
Silver is gradually added until the plate acquires the desired
density. Ferrier is said to have toned his transparencies by first
plunging them in a weak sublimate solution, and then, after
washing, into a one-grain solution of chloride of gold.

§ 2. — Sun-Printing on Glass by the Collodio-Chloride Process.

Instead of developing a weak image on glass, we may carry it
to its full strength by direct printing. There are two methods
usually employed for this purpose, the collodio-chloride process
of Mr. Simpson, and the albumen process; the first is the easier
and most generally employed, the second (to be described in next
section) is more difficult, but gives richer effects.

"When a collodion containing chlorides only, instead of iodides
and bromides, has nitrate of silver added directlv to it, the
chloride of silver which is formed, in place of falling at once to
the bottom, remains for a long time suspended in the collodion,
giving it a milky appearance. The nitrate of silver is kept a
little in excess, and when this liquid is coated upon glass or
paper, a surface is obtained which may be printed upon very
much in the same way as albumenized paper. (Respecting
collodio-chloride on paper, see § 4.)

Mr. Gr. "W. Simpson, who first proposed this method, directed
to make an ordinary plain collodion with equal parts alcohol and
ether and six grains of pyroxyline to the ounce, and salt it with

Chloride of strontium 2 grains.

Citric acid 1 grain.

to each ounce, and to sensitize by adding nitrate of silver in
the proportion of 1\ grains to each ounce, in fine powder, shaking
up well.

Chloride of strontium has the advantage of easy solubility in
mixed alcohol and ether (the chlorides as a rule are less soluble
in this mixture than the iodides and bromides), but experience
has shown that it does not give as good a tone as some other
chlorides.

VARIOUS PHOTOGRAPHIC PROCESSES. 339

The writer finds as the result of his experiments with thi3
process, that it is better to use considerably more pyroxyline in
the collodion than six grains, especially when the surfaces are
not very large. With glass plates of quarter and half size f\
nine grains to the ounce may be used, and the effects are much
richer than with less quantities. lie has also found that the
addition of carbolic acid greatly improves the richness and depth
of effect, but unfortunately this treatment can only be used with
collodio-chloride on paper; it does not answer on glass, as the
carbolic acid separates out in drying on glass.

The writer also finds it a material improvement to dissolve
the nitrate of silver in a part of the alcohol. "When put in in
powder, part doe3 not dissolve. Some have tried dissolving the
nitrate in water, but this renders the collodion much less manage-
able and more apt to give irregular films and mottled and spotty
effects.

Lr. Liesegang has lately published the following formula: —

Alcohol and ether, equal parts 1 on:

Pyroxyline ......... '.) grains.

Chloride of lithium 1 grain.

Citric or tartaric acid 2 grains.

Zsitrate of .silver 8 "

"Where chloride of lithium is not to be had, chloride of cadmium
may be substituted, using twice the quantity. For pyroxyline,
Dr. Liesegang recommends one-half of his pyroxyline and one-
half ordinary soluble cotton. He shakes up the nitrate of silver
in crystals, and at the end of a day removes the undissolved part,
powders it in a mortar, and returns it.

The author recommends to dissolve whichever chloride is used
in half the alcohol, adding to it the ether, and dissolving in the
mixture the pyroxyline. The powdered nitrate of silver is to
be put into a large test-tube or small flask, and the alcohol ad
in separate portions and boiled. In this way the nitrate is
speedily got into solution, and this solution is poured into the
collodion and shaken up. Operating in this new way, all the diffi-
culties encountered of having the chloride of silver to fall in
clots are done away with, and a clear, smooth emulsion is ob-
tained, which keeps in excellent order for weeks.

The author has obtained prood results with fused chloride of
calcium in the collodion, instead of chloride of lithium or cad-
mium. Of the calcium salt, one and a half grain to the ounce

390 PHOTOGRAPHIC MANIPULATIONS.

of collodion will be proper, and eight grains of nitrate of silver.
With chloride of calcium, tartaric acid must not be used, or a
gradual precipitation takes place which ruins the collodion.

To keep the film from slipping from the glass, edge it with
India-rubber dissolved in benzine, as described for dry plates
(see p. 352), or with albumen, but in neither case should the ap-
plication extend beyond the edges, a full substratum is injurious.
Print till the shadows are bronzed, but not too deeply, remem-
bering, however, that an under-printed plate is wholly worthless,
whilst an over-printed one can be reduced by using a stronger
fixing solution and leaving longer in it. Tone in any gold toning
bath, using it very weak.

To fix, leave for five minutes in a weak fixing bath, one and a
half ounce of hyposulphite to the pint of water.

M. de Constant first proposed fuming the plates, and certainly
they print more quickly and deeply when so treated. The ques-
tion whether fuming is necessary will depend very much on the
character of the cotton. When a deep tone cannot easily be got,
fuming will be found to help. Remove the stopper of an am-
monia bottle and pass the plate a few times over the mouth.

Special frames are made for printing on glass which permit of
examining the print. The sensitized glass plate is held between
two iron straps which are secured by screws. The vignetting
boards furnished with the frames rarely fit as closely as they
should do. Any motion is of course fatal to the sharpness of the
print, therefore the boards should be well wedged up.

Miniature Effects on Ivory are best got by transferring collodion
films to the ivory, the surface of which is to be prepared before-
hand by polishing it with a little fine cuttle or pumice powder,
and then immersing for a minute in a warm solution of gelatine
(about 20 grains to the ounce). The image is printed on glass
fir.<t coated with gelatine, and then with collodio-chloride (or on
enamel or collodio-chloride transfer paper). After toning and
fixing in the usual way, wash in a few changes of cold water,
then immerse in warm, when the film will float off. (Acidulating
the water with a drop or two of sulphuric acid to the ounce will
facilitate separation.) Eemove the film to a vessel of cold water,
and float on to the prepared ivory surface. (B. J. Edwards.)

VARIOUS PHOTOGRAPHIC PROCESSES. 391

§ 3. — Albumen Positives on Glass.

Clear white of egg by beating it to a froth, adding first to
twelve ounces of albumen a quarter of an ounce of clean, pure
sal-ammoniac dissolved in an ounce and a half of water. Coat
the plates, dry, and sensitize.

The silver bath is made by dissolving two ounces of nitrate of
silver in sixteen of water, acidulating with acetic acid.

When albumen positives on opal glass are thoroughly well
made, they exhibit greater force and more transparency of shadow
than collodio-chloride work. They are, however, extremely
slow in printing, and the success of different operators has been
very various.

Positives on glass appear to require longer and more thorough
washing than negative glass work, to preserve them from fading.

§ 4. — Collodio-Chloride Printing on Paper.

The sensitive collodio-chloride mixture (p. 389) may be coated
on paper instead of glass, and be printed and toned in the same
way. But as the film is very apt to detach itself from the paper,
this last must be prepared with a coating of gelatine. The writer
has never met with any paper of which the sizing was qualified
to take the place of this coating, which may be prepared as
follows : —

Nelson or Coxe's sparkling gelatine . . . 400 grains.
Syrupy glycerine . . . . • . . ^ fluidounce.
Water 16 fluidouncea.

The gelatine used alone renders the paper excessively stiff;
this led the writer to experiment with glycerine added, the effect
of which is to greatly reduce the stiffness. Even with this addi-
tion, however, the paper curls up somewhat, and therefore, after
it is quite dry, it should be laid in press for some time, and
comes out exceedingly flat.

The annexed cut represents a piece of the coated paper laid on
a convenient piece of thin flat board, provided with a handle at
one corner. The two farther corners of the paper to be collo-
dionized are secured with pins, the thumb keeps down one other
corner, whilst the fourth is left open, from which to pour off the
excess.

392 PHOTOGRAPHIC MANIPULATIONS.

Fiff. 141.

It is, however, very convenient to lay the paper on such a
board, and, instead of pinning it, to fold up the edges about an
eighth of an inch high, in order to keep the collodion from work-
ing over, and especially from getting upon the back of the paper,
which result quickly follows if the collodion is carried all round
the sides without turning them up.

The writer has found that a considerable increase of richness
and tone is got by the addition of phcnic (carbolic) acid. To a
measured quantity of the sensitized collodion add about ten per
cent, of this acid, and it will be found that a much richer tint is
produced than when the carbolic acid is omitted. This method
works well upon paper, but not upon glass. The printing is
done in the ordinary way, and the succeeding operations are the
same as when glass is the support. (See sec. 2.)

§ 5. — Photographic Enamelling.

Of all forms of picture-making, the enamel may be considered
the most permanent. Even the carbon process is liable to the
objection that the paper on which the print is made is a very
perishable substance, and positives on glass by the collodion
process are liable at best to many injurious influences from which
an enamel, burnt in upon glass or porcelain, is evidently free.

For reproducing photographs in enamel, several ingenious pro-
cesses have been proposed. Two at least have been worked
commercially upon a large scale : that of Lafon de Camarsac, in
Paris, and that of Griine, in Berlin. Lafon has maintained his a
close secret, whilst Griine, with commendable liberality, has given
his to the public. It is his that will be here first given.

There exists no difficulty whatever in transferring a collodion
film to any other support. For this purpose it is best to diminish

VARIOUS PHOTOGRAPHIC PROCESSES. 393

the adhesion of the collodion, by rubbing the glass beforehand
with a little wax dissolved in ether; or, as proposed by Mr.
Woodbury, add to the collodion two or three drops to the ounce
of a saturated solution of beeswax in ether, which, renders the
film easily transferred without affecting the photographic proper-
ties of the collodion.

The operator prepares a glass collodion positive, which must,
of course, be a positive by transparency, and not an ambrotype.
This may be done in several ways (for which see the previous
sections of this chapter).

The next step will be to tone with weak solution of bichloride
of platinum instead of chloride of gold; wash and dry. Run a
penknife round the edges, plunge the negative in water, and
float off the film. It will be advisable to add a little acetic acid
to the water ; acids tend to loosen films from their supports,
alkalies to increase the attachment. Receive the film on the
porcelain surface, and, after allowing it to dry, dissolve out the
collodion film with mixed alcohol and ether. The image in pla-
tinum will remain upon the porcelain. It then only remains to
apply a suitable flux, and burn in the picture in a muffle. Grime
has not given the composition of the flux that he uses, but it is
probable that Leth's flux will be found satisfactory. It is made
as follows : —

Bed lead 6 ounces.

Fine quartz sand, or pounded quartz . . 2 "

Borax 1 ounce.

Melt in a crucible, and, after cooling, reduce the glass formed
to a fine powder. Strew this over the plate, place in a muffle,
and raise the heat just high enough to fuse the coat of flux into
a transparent glass over the picture.

This process can also be used for producing designs in gold
upon glass or porcelain. To effect this, the positive is toned
with gold, thoroughly, and the rest of the treatment remains the
same, except that a reducing flux must be used. No half-tone
can be obtained in this way, because the gold, no matter how
thin, exhibits its full metallic color. It easily acquires a brilliant
surface by polishing. Beautiful designs in gold of the most com-
plicated figures, have been burnt into porcelain by Grune by this
process.

Those desiring further details may consult the Photo graphisches
26

394 PHOTOGRAPHIC MANIPULATIONS.

Archiv, Band VI., 346; PJwtog. News, IX., 457; or Martin's
Handbuch der Email-phoiographie, Weimar, 1867.

§ 6. — Photolithography.

To be able to tranfer a photograph to stone or metal, and to
print a large number of copies therefrom, is evidently a most
valuable application of the science; and this is now accomplished
in a very admirable manner.

It is evident that the production of half-tone is more difficult
than the simple obtaining of black and white, and that different
means must be employed. The processes therefore will be classi-
fied under these two different heads: —

A. — PROCESS GIVING ONLY WHITE AND BLACK.

Liesegang's Process. — Liesegang floats ordinary albumenized
paper (the salting is not objectionable) upon a solution of chro-
mate of ammonium. Then exposes under a strong, clear negative,
till a strong image is got. Next lays it against a zinc plate, and
passes through a press. Next lays it, face up, on cold water, till
the image becomes visible. Takes a clean sponge, previously
cleaned well with chlorhydric acid to get rid of grit, and removes
the excess of ink. Then transfers in the usual way of litho-
graphic transfers.

Liesegang attaches importance to the nature of the ink used
for inking in the zinc as above mentioned. He takes —

Venice turpentine 85 ounces.

Wax 1 ounce.

Palm oil 1 "

These are to be heated in an iron pot until they take fire. Then
stir in —

Lithographic transfer varnish 33 ounces.

Linseed oil varnish, No. 2 lGi "

B. — PROCESS GIVING HALF-TONES.

Albertype. — The older processes are likely to be quite super-
seded by the albertype, of which the following is the specifica-
tion for the French patent. Coat in the dark room a heavy glass
plate with —

VARIOUS PHOTOGRAPHIC PROCESSES. 395

Filtered water . . . . ' . . . .300 parts.

Albumen ' . 150 "

Gelatine 15 "

Bichromate of potash 8 "

Dry in the dark, and then expose to light through the glass, care-
fully protecting the other face in order that the hardening may
proceed from the bottom (next the glass) to the surface, and be
perfectly solid. Half an hour to two hours' exposure. Coat
again with —

Gelatine 30 parts.

Bichromate 10 "

Water . 180 "

Expose under a negative, wash for about fifteen minutes, and
dry. Then slightly wet it and work it on a lithographic press in
the ordinary way with ordinary printing ink.

§ 7. — Photogalvanography.

It has been known for a period of years that when a mixture
of gelatine and bichromate was extended on glass and exposed
under a negative, all those parts protected from the light could
be made to swell up by soaking the film in water. Consequently
the image is produced in relief.

The writer of this manual worked out the details of a process
himself, and was the first to publish any practicable method,
which will be found in full detail in the British Journal of Pho-
tography for February 10th, 1865. Briefly, the process consists
in coating glass with a film of —

Gelatine 200 grains.

Water 4 ounces.

Cold saturated solution bichromate of potash . 5 drachms.

When dry, expose under an average negative to direct sun-
light for two to three minutes. Then leave in water for aobut
two hours, changing frequently, then let dry.

The surface may receive a conductor in several ways. Brush
over with an ethereal solution of chloride of gold, let dry, place
in sunshine, and apply a solution of protosulphate of iron. This
is the writer's method of gilding the film, which takes a brilliant
gold surface, and is then ready to be plunged into the electrotype
bath. v

But, on the whole, the writer preferred to treat the dry gelatine

396 PHOTOGRAPHIC MANIPULATIONS.

film (after the bichromate, of course, had been thoroughly re-
moved) with alcoholic solution of nitrate of silver, and then to
fog it with pyrogallic acid.

By means of the electrotype bath, a copper reproduction of the
relief is obtained from which to print.

Woodbury's Relievo Process.— The above method is evidently
applicable only to the reproduction of engravings and wood-cuts ;
negatives of natural objects, made up of half-tones, cannot be used
for it. Woodbury ingeniously avoids this difficulty by a very
valuable process, which has been patented.

It is easy enough, by the process just above described, to obtain
a reproduction in copper of a gelatine relief of objects containing
half-tones. This reproduction will not, of course, have lines like
a copperplate, but will consist of undulating depressions and
elevations. The difficulty lay in making this to print. Mr. Wood-
bury's idea was to mix a little black pigment with gelatine, to
spread this over the plate, and then with a flat surface to remove
the excess. A piece of paper being then pressed against the
plate, receives the remaining gelatine. In the portions but little
sunk, there will have been but little pigment, and these will
print light, and just in proportion to the depth of the sunk por-
tion will be the blackness of the print.

Work of remarkable beauty has been executed by this process,
which is applicable to printing on paper, glass, wood, or any
other surface.

§ 8. — Various Processes.

Willis's Aniline Process. — This process has likewise been pa-
tented. The work produced by it is of rather a common order;
its recommendation is its extreme facility and cheapness.

Taper is impregnated with solution of bichromate of potash, to
which a little phosphoric acid has been added. After exposure
under a transparent positive, it is exposed to vapors of aniline,
which develop a grayish image. The print is then merely fixed
by simple washing. As a positive affords a positive, plates, draw-
ings, &c, can be copied without the intervention of a negative or
the use of a camera. The process is carried on commercially by
the patentee in England.

Prints in Color. — Float close-grained, fine photographic paper,
plain or albumenized, on a warm solution of gelatine, six hundred

VARIOUS PHOTOGRAPHIC PROCESSES. 397

and fifty grains ; water, twelve ounces ; bichromate potash, three
drachms; glycerine, half fluidounce ; letting the gelatine swell
first in part of the water. Dissolve the bichromate in the rest.
When the gelatine has well swelled, dissolve it by heating, and
add (in the dark room) the bichromate solution. Dry the paper
in the dark. Expose briefly to direct sunshine under a 'positive.
A light picture results on a brown ground. Throw into water
for thirty-six hours : the whole disappears, and the back must be
marked to distinguish it. Now blot off the exposed surface gently
with bibulous paper, leaving it very moist, and rub on powdered
color with a wet hift of cotton. The color adheres to the parts
protected from the oven, and thus a positive results.1

Very pretty effects are obtained by laying on the paper ferns,
grasses, &c, and developing with a green powder, " chrome green"
(chrome yellow and Prussian blue, sold ready mixed under this
name) answers very well. In this way, positives of a green color
are obtained at a single operation. They are perfectly permanent.
If the color does not adhere on the image, the exposure has been
too long; if it adheres on the image, and elsewhere also, too
short. When the color has been applied, hold the print a few
moments under a stream of water to clean the whites.

Printing Processes with Salts of Iron. — Most of the salts of the
peroxide of iron are reduced by light to the corresponding salts
of the protoxide, with a loss of one-third of their oxygen. By
applying reagents which act differently on the two oxides of iron,
this reduction is made apparent, and a colored picture is pro-
duced. Thus, if red prussiate of potash be applied, all the part
acted upon by the sun becomes blue; with gallic acid the unex-
posed part becomes black, and so on.

Chloride of Iron. — Take

Percliloride of iron 50 grains.

Tartaric acid 15 "

Water 1 ounce.

Expose under the object itself or under a transparent positive.
Plunge for an instant in distilled water, and then in a saturated
solution of gallic acid, a decoction of nutgalls, or a mixture of
gallic and pyrogallic acids, according to the time allowed. The

1 This method of operating, described by the writer in the Philadelphia Pho-
tographer for May, 1865, has since been published as new in Berlin, and, with
trilling alterations, patented in England.

398 PHOTOGRAPHIC MANIPULATIONS.

impression is here in ordinary ink, gallo-tannate of peroxide of
iron.

Oxalate of Iron and Ammonia. — Exactly saturate one ounce of
oxalic acid with ammonia, add another ounce, and digest the
mixture with freshly-precipitated and still moist peroxide of
iron. The filtrate, after the liquid is fully saturated with per-
oxide, gives, by evaporation in the dark, large and splendid
green crystals of the double salt.

Paper is sensitized by floating in a minute or two upon a tolera-
bly strong solution of these crystals, seventy to one hundred
grains to the ounce, and dried, in which state it will keep for a
long time. Exposed under a negative, an almost invisible image
is obtained after a brief exposure, which, by ferridcyanide of
potassium, becomes a blue picture. This process is due to
Herschel. It has the disadvantage that it does not give clean
whites.

The writer imagined a remedy for this, which has been very
successful ; it consists in adding a little oxalic acid to the solution
of ferridcyanide, the whites thus remain brilliantly clear. It is
necessary, however, to be careful about putting the fingers into
the bath. The free ferriprussic acid liberated by the oxalic acid
continually decomposes, with production of prussic acid, in a
very dilute form, it is true, but still active enough to render care
advisable.

CHAPTER XXI.
CARBON PRINTING.

\ 1. — Introductory Remarks.

Carbon printing, in the form now in use, has been the result
of the action of many minds, and the honor of its discovery can-
not be ascribed to the ingenuity of any one person. It may be
traced back as follows : —

The first step was the remark that paper imbued with solution
of bichromate of potash, darkened when exposed to light. This
was made in 1839 by Mr. Mungo Ponton.

The next was the discovery that gelatine, gum, and some other

CARBON PRINTING. 399

bodies, were rendered wholly insoluble when exposed to light in
presence of bichromate of potash. This observation was first
made by M. Becquerel ; subsequently Mr. Fox Talbot patented
a method of photo-engraving based on it.

The next idea evolved was, that the gelatine, made insoluble
by light, might be made to imprison particles of coloring matter.
Thus, where light acted, these would remain ; where it did not
act, they would wash out by reason of the solubility of the por-
tion of the film in which they were contained. Tbis was an
important step, and was made by M. Poitevin in 1855.

This was, in fact, a carbon process ; but in this, and in all the
efforts made for some time subsequently, the half-tone was ex-
tremely defective.

M. Laborde seems to have been the first to perceive that the
action of the sun was at first superficial, and only by degrees
penetrating through the layer of gelatine. Thus those portions
under the transparent parts of the negative became deep black,
because the sun rendered the layer of gelatine insoluble through
and through, and so attached it fully to the paper. But in the
half-tones this penetration did not take place ; the action was
comparatively superficial ; the lower part of the film remained
soluble, so that the impressed portion above it was undermined
in developing, and broken away. The only indications of half-
tone obtained seem to have been due to inequalities in the paper.
M. Laborde, though he perceived the evil, did not find a remedy
for it except to suggest exposing from the back.

The honor of devising the method of transferring is due to
Mr. Swan. He showed that the true plan of developing lay in
attaching the exposed surface to paper or other support, remov-
ing the original paper support, and so developing on the under side.
Thus all the half-tone was excellently preserved, and the picture
was re-transferred to another and final sheet of paper.

Details. — Since the first edition of this manual was published,
the carbon process has been somewhat simplified, and is passing
more and more into use in England, where it is better understood
than anywhere else.

"Tissue" for carbon printing is sold ready prepared, and is to
be sensitized by plunging into a solution of bichromate of potash,
one ounce in thirty of water. If more sensitive paper is wanted,
the proportion may be increased. As tissue so prepared is liable

400 PHOTOGRAPHIC MANIPULATIONS.

to spontaneously harden, and at best keeps but for a day or two,
the writer pointed out some years ago the advantage of adding
liquid ammonia to the bichromate solution, whereby the sensi-
tive properties are preserved for several weeks. Lately this
method seems to have come into commercial use.

After the sensitized tissue has been dried, which operation
must be performed rapidly, but not at too high a heat, lest the
gelatine melt and run, it is exposed under a negative ; the exposed
surface is next moistened and pressed against another sheet of
paper. "With some sorts of highly sized papers, the exposed and
moistened surface of the gelatine will adhere without difficulty.
Other paper will require a coating of gelatine, or albumenized
paper may be employed of which the albumen has been coagu-
lated. The adhesion is made complete by pressure with a wet
sponge, or a roller or " squeegee," and then the two papers, with
the layer of gelatine between, are thrown into water scarcely
lukewarm ; presently the original support can be removed, and
the print, by lying in the water for a short time, becomes deve-
loped. It is finally cleaned off by gentle agitation in cold water.

Under and Over-exposure. — It is of course very desirable that the
right exposure should be hit, but a certain latitude of error can
be .compensated for in the development. If the print clear itself
with difficulty, hotter water may be cautiously applied, not, how-
ever, until its necessity has become apparent.

On the contrary, under-exposure will show itself by a tendency
to clear rapidly as soon as the temperature of the water has been
a little raised and when it is barely tepid. This will indicate the
necessity of keeping down the temperature and finishing the print
in water as cool as will clean the lights.

The print thus obtained is of course reversed. In some cases
this is a matter of indifference, but more frequently it is neces-
sary that the print should correspond with the object itself, as
does an ordinary silver print. This correspondence is obtained
in either of two ways: —

By taking Reversed Negatives. — A reversed negative bears the
same relation to an ordinary one as an image in the looking-glass
does to the object itself. Accordingly, one method of reversing
negatives is to have a small mirror placed just in front of the
lens, making an angle of forty-five degrees, so that the reflection
in the mirror, not the object itself, is taken on the film. The

CARBON PRINTING. 401

mirror must have only one reflecting surface ; must be silvered
on the face instead of the back.

Another method is to put the film side of the negative away
from the lens. Two precautions are here necessary : the glass
must be plate, and perfectly free from scratches and faults ; the
ordinary brass spring at the back of the plate must be removed,
and long springs of silver be placed at the ends, so that tips of
the springs will rest upon the corners of the plate.

In practice, the first system has been the most successful.

By Double Transfer. — With non-reversed (ordinary) negatives,
if the final print is required to be non-reversed, a re-transfer
must be made on paper prepared with gelatine.

Evidently it will be prudent to keep down the temperature in
the early stages of the operation, and to raise it only as far as
becomes manifestly necessary.

Re-transferring. — This is done with gelatine solution.

Water 40 ounces.

Glycerine 1 ounce.

Gelatine 4 ounces.

Heat this long enough to expel all air-bubbles, but do not keep
unnecessarily long in fusion, as by such treatment gelatine loses
to some extent its power of setting.

Cover the surface of the print very carefully and evenly with
solution, either by floating or brushing, then hang up to dry.
Dampen carefully the mount, whether this be paper or cardboard,
avoiding to dampen too much, lay the print on face down, and
pass at once through the rolling press.

The print is now left for a day to dry thoroughly before under-
taking the last operation, that of removing the paper which has
acted as a support during development. This is done by vigor-
ously rubbing with tufts of cotton dipped in benzine. Then
raise a corner, selecting one of the deep shadows where the film
is thick, with a blunt knife, bend it well back and peel it gently
off. In mounting on paper, Mr. Swan is in the habit of subse-
quently laying the print for an hour in a five per cent, solution
of alum, a step which the writer believes he was the first to
suggest.

402 PHOTOGRAPHIC MANIPULATIONS.

§ 3.— Other Methods.

Carbon Direct Printing. — In the case of objects devoid of half-
tone, and consisting altogether of white and black, the transferring
is unnecessary. If gelatine or gum be mixed up with solution
of bichromate of potash, and a pigment be incorporated with it,
this mixture may be spread evenly on sized paper, and, if exposed
under a negative, a positive copy is obtained.

The writer has shown elsewhere that gum is preferable to gela-
tine for this purpose, inasmuch as it may be spread evenly over
the paper with a brush ; gelatine mixtures cannot, as they con-
geal in the operation. He also showed that the perfectly pure
whites could be obtained by adding albumen to the mixture, and
not without it.

Printing through the Pajjer, etc. — Laborde first suggested this
idea, but, in spite of many efforts, it has never been practically
successful, the grain of the paper interfering, unless, indeed, Mr.
Pouncy's prints have been, as stated, so obtained.

Pouncy^s Process. — Excellent prints have been obtained by Mr.
Pouncy, an early and unwearied laborer in the field of carbon
printing. In this process the sensitive pigment is composed of
asphaltum, printer's ink, and a fatty matter, with or without bi-
chromate of potash. The matters are incorporated with the aid
of heat, and strained. All the information given by Mr. Pouncy
is that there must be more ink than asphaltum, that it should be
as thick as cream, and give an opaque coating when applied to
glass. Only some sorts of asphaltum give good results.

The sensitive pigment is to be applied to paper with a broad
camel's-hair brush, leaving the brush in the pigment when not in
use. The paper dries in a few minutes, and keeps for months.

The paper to be used should be a very transparent tracing
paper, or bank-post rendered transparent with poppy oil. Ex-
pose with the paper side next to the negative, and develop by
immersion in turpentine.

These prints are advantageously transferred to white paper.
After the print has become thoroughly hard by exposure to light
and air, after development, varnish the surface with a broad
camel's-hair brush, and lay the picture face down on the surface
to which it is to be transferred, and press in a copying press ;
when dry, moisten the transparent paper, and it will come off',
leaving the print behind.

CARBON PRINTING. 403

The exposures in this process are long; from three to five
times those of chloride paper. The prints are very beautiful,
and probably have the highest claim to permanence of any pho-
tographic work on paper, without exception.

Carbon Printing on Glass. — The writer has devised an extremely
simple mode of operating. " Tissue," as sold, is placed in a solu-
tion of bichromate of potash, one ounce to twelve of water, a
clean piece of plate glass is slipped under it, the tissue pressed
close, and thus contact is secured without bubbles. After drying,
the glass face is cleaned, the negative placed against it (the glass
side), and the printing is done by reflected sunlight, or by placing
in the bottom of a box three or four feet long, so as to exclude
diffused light. Develop in tepid water. No transferring is
needed. This method, when well managed, gives a clean, sharp
image, and involves but very little trouble.

PART IT.

THEORETICAL CONSIDERATIONS.

CHAPTER I.
GENERAL OBSERVATIONS.

"WriEN we attempt to study the functions of light, we find our-
selves face to face with questions which continually extend and
expand as we consider them, until we are lost in the immensity
of the subject.

For all life, such as we know it on this planet, has been ordained
by its Creator to exist only under the influence of light. By that
agency, carbon is separated from the carbonic acid of the atmo-
sphere, and is combined into all those organic forms of nutriment
upon which we rely to support life, either directly as food, or
indirectly to nourish those animals which are eventually to con-
stitute our food. Thus, everything that lives upon the face of
our planet owes its existence to light.

Light is so powerful in its influence upon organic bodies that
there exists scarcely one which is not directly affected by it. If
an organic body be formed by the affinities of its component parts
acting in the absence of light, then when that body so formed is
submitted to the action of light, the affinities of its elements are
in a vast number of cases so altered that decomposition results, at
least if moisture be present. As familiar examples may be men-
tioned that almost all colors are bleached by exposure to sun-
light, almost all organic substances are essentially altered in their
nature by long action of sunlight. Perhaps no more striking
instances can be adduced than those of the whole vegetable
world. Plants of every description undergo incessant changes
under the action of light; these changes take one course so long
as the plant lives; with its death a new order of changes sets in.

GENERAL OBSERVATIONS. 405

During its life it not only forms cellular and woody tissues and
chlorophyl, &c, characteristic of vegetable life generally, but
also vast numbers of complex organic bodies, such as the vege-
table alkaloids, the gums, the resins, the sugars, the vegetable
oils, the essential oils, &c. &c. After the death of the plant, an
inverse action is set up, and these substances tend to resolve
themselves, under the influence of light, heat, and moisture,
more or less completely into carbonic acid and water.

Inorganic bodies as a class are less sensitive to light, but there
are, nevertheless, very many even of these in which a change of
affinities is brought about by its agency.

Most commonly the action of light is a reducing one, that is,
there is a tendency to part with oxygen (similarly with other
chlorous bodies, as iodine, bromine, and chlorine). This is analo-
gical with the action of light in producing vegetation by which
the carbonic acid of the atmosphere is made to part with oxygen,
and enter into new forms of combination. So that the regular
and normal action of light may be said to be the reducing one.

Occasionally, however, the action is contrary, and a combina-
tion with the oxygen of the atmosphere is promoted. Phosphorus
is an example of this exceptional action, its union with oxygen
is accelerated by light. Another prominent exception may be
cited in the action of light upon a mixture of hydrogen and
chlorine, bodies which, when mixed together, show no tendency
to unite in the dark, but do so with explosion when light is
allowed to fall upon the glass vessel in which these gases are
mixed in proper proportions.

An examination into the action of light in those processes
which the photographer employs, shows that so far as it is chemi-
cal, it is invariably reducing. Thus, when a bichromate is ex-
posed to light in the presence of organic matter, the agency of
the light enables the organic matter to oxidize itself at the ex-
pense of a part of the oxygen of the chromic acid. When a
per-salt of iron is exposed to light, it tends to lose one-third of its
oxygen, and to pass to the condition of a proto-salt. The same
thing takes place in the salts of uranium, which principle forms
the basis of the so-called Wolhhjlyjje process. Some other metals
are acted upon similarly : the salts of mercury tend to lose half
their oxygen, chloride of gold may lose the whole of its chlorine,
and the gold may be revived in metallic form.

406 PHOTOGRAPHIC MANIPULATIONS.

CHAPTEK II.
ACTION OF LIGHT ON COMPOUNDS OF SILVER.

§ 1. — Chloride of Silver.

Light exerts a distinct chemical action upon chloride of silver,
of a reducing nature, that is, the chloride passes into sub-chloride
with elimination of free chlorine, or of hypochlorous acid. If
pure precipitated chloride of silver, well washed and freed from
all organic matter, be exposed to light in a sealed glass tube, it
gradually assumes a violet color, and loses chlorine. In the dark
it regains its whiteness by recovering the chlorine lost. If free
nitrate of silver be present, that is, if the chloride of silver be
moistened by solution of nitrate of silver, the coloration proceeds
much more rapidly.

If organic matter be present, the decomposition is more rapid
still, and in many cases the sub-chloride of silver appears to unite
with the organic matter, giving rise to the production of com-
pounds much more deeply colored than the simple sub-chloride.
Of these is the dark chocolate-colored substance, passing almost
to black, which constitutes the body of an albumenized paper
print before toning.

§ 2. — Iodide of Silver.

The study of the action of light upon iodide of silver presents
very great difficulties, and has given rise to considerable differ-
ence of opinion.

In studying this subject, it becomes necessary, as the writer of
this manual has more particularly pointed out elsewhere, to con-
sider the question in two different forms, and distinguish between
the action of light upon iodide of silver in the presence, and also
in the absence of organic or other bodies capable of exerting
special influences on it.

To be able fully to eliminate the effect of these latter, the
writer devised the method of precipitating metallic silver upon

ACTION OF LIGHT ON COMPOUNDS OF SILVER. 407

films of glass, and then iodizing these films with iodine dissolved
in solution of iodide of potassium. It had been held, indeed, that
iodide of silver formed in presence of excess of iodide of potas-
sium was insensitive to light ; this view, however, the writer dis-
proved by decisive experiments, and it is now abandoned.

As the film of iodide of silver upon glass was very liable to
slip about, an expedient was found to fix it, but substituting ground
glass, and this method of experimenting is now the only one
known that is capable of affording reliable results.

By these experiments, which cannot be detailed here, the
writer was enabled to show —

1. That pure iodide of silver isolated undergoes no chemical
decomposition even by very prolonged action of light. Thus a
film exposed for many hours to brilliant sunshine was placed
aside for a day or two in the dark. It was exposed for a second
or two under a negative, and the image of that negative was then
developed upon it without difficulty.

2. But if an organic substance be present, then chemical de-
composition does take place. Thus, if a film of iodide of silver
upon ground glass be washed over with a solution of tannin, and
then be exposed for a sufficient time under a negative, a visible
image of the negative is obtained.

Development on Iodide of Silver. — Very erroneous notions of the
nature of development on iodide of silver have often been enter-
tained, and the writer himself was at one time under the convic-
tion that iodide of silver might undergo such a physical impression
as to predispose it to decomposition when brought into contact
with certain substances. Careful and extended experiment has
led him to return to his older opinion, that the physical impres-
sion of light upon iodide of silver is such as merely to predis-
pose it to receive a falling precipitate. This conception should
be fully mastered by the student, and may be explained as fol-
lows : —

If we take a saline solution which is just ready to let fall a
precipitate, and stir it well in a glass vessel, allowing the end of
the glass rod to touch the sides of the vessel in stirring, we shall
find that (in many cases) the precipitate will form first and in
preference on all those parts of the glass which have been touched
by the rod. Thus it may be said that the previously invisible
path of the rod over the glass has been developed by the precipi-
tate. The surface of the glass was only physically, not chemi-

408 PHOTOGRAPHIC MANIPULATIONS.

call}r, altered by the passage of the rod over it ; and yet it
attracted, more powerfully than the rest, the descending precipi-
tate. Just so the part of the iodide film which has been touched
by light, exerts a more powerful attraction upon the descending
precipitate of metallic silver from the developer than those por-
tions which have not been touched.

It appeared to the writer that although the similarity of these
phenomena was sufficiently obvious, yet the two might be brought
closer together if he could show that an iodide film could receive
a species of latent image by mere pressure, independently of light,
capable of being developed by an ordinary developer. Experi-
ment realized this without difficulty. Sensitive collodion films
were pressed with various surfaces having raised or sunk devices.
Then a developer poured over them brought out these devices
with great distinctness, the silver being attracted ahvays in 'prefer-
ence to those parts which had received the pressure. The writer does
not, however, mean to affirm that the action of light is necessarily
mechanical, as in the foregoing illustration and experiment.

It is very remarkable that although invisible images may be
developed on both chloride and bromide of silver, yet the phe-
nomena are of quite a different nature. Development on pure
iodide of silver results simply from a power in the film to attract
to itself a descending precipitate, and is independent of any de-
composition of the iodide in the film, either under the action of
light, as may take place in the case of chloride of silver and
bromide of silver, or under that of a developer, as may happen in
the case of bromide of silver.

That the development in the case of iodide of silver is perfectly
independent of any decomposition of the iodide film, is shown by
experiments published by the writer, together with Dr. Shepard,
of Providence, in which, after an image had been developed on an
iodide film, it was dissolved away with solution of acid pernitrate
of mercury, and was then, after washing, re-produced by a second
application of a developer. This exhibits in a striking light what
the writer holds to be the peculiar and characteristic action of
iodide of silver, viz., that it is so modified by the action of light
as to be capable of forming an image out of the silver in the
developer, without itself having undergone decomposition either
during exposure or under development. In this way only does
it seem possible to explain the fact that a developed image may

ACTION OF LIGHT ON COMPOUNDS OF SILVER. 409

be dissolved away, and the power nevertheless be left in the film
to reproduce the image by a second development.

It has been already explained that in the presence of certain
organic and other bodies, iodide of silver undergoes chemical
decomposition, and the same seems to be true when nitrate of
silver is present. When, therefore, instead of experimenting
upon a film of iodide of silver, isolated on glass, we take a com-
mon sensitized plate in which both nitrate of silver and an
organic body (collodion) are present, the conditions are essen-
tially changed, and chemical decomposition undoubtedly takes
place. Consequently, in the ordinary wet collodion process,
there appear to be two invisible images simultaneously present
in the film — one a lateut physical image due to the action of
light upon the iodide, the other a chemical image, invisible
simply by reason of its tenuity. Both of these may serve as
bases of development.

For want of distinguishing clearly between these conditions,
and of remembering that what takes place in the case of iodide
of silver isolated from all other bodies is very different from
what takes place when free nitrate of silver or certain organic
bodies are present — for want of bearing this steadily in mind,
much that has been written on the subject of this latent image
has little or no real value.

The above are the views which the writer has entertained and
endeavored to prove. In the opinion of some photo-chemists,
however, the action of light upon iodide of silver is always
chemical, and no impression is formed except by actual decom-
position. But this opinion seems to be at variance with observed
facts, and the reactions of iodide of silver cannot be satisfactorily
explained by it.

It will be interesting to note that in the case of iodide of silver
the chemical latent image always offers a stronger basis of develop-
ment than the physical Now it has been already explained that,
according to the view entertained by the writer, the chemical
image is never produced upon isolated iodide of silver, but only
when some suitable body is present to give rise to its production,
consequently it follows that the presence of that body capable of
giving rise to the production of a chemical image, may greatly
exalt the sensibility of the iodide. It is for this reason that the
presence of the bath solution (containing free nitrate of silver)
in wet plates, and certain bodies, such as tannin, gum, gallic acid
27

410 PHOTOGRAPHIC MANIPULATIONS.

etc., in dry plates, greatly diminishes the exposure needed. These
latter substances have been called ])reservalives, though it is evi-
dent that they are sensitizers precisely as nitrate of silver is a
sensitizer.

As the production of a " chemical image," i. e., one depending
upon the actual decomposition of the iodide, must always arise
from a separation of iodine to a greater or less extent from the
silver present, so it seemed natural to suppose that the greater sen-
sitiveness, or, in other words, greater proneness to decomposition
resulting from the presence of so-called preservatives, had its
origin in an affinity of the preservative for iodine, which affinity,
insufficient in itself to produce decomposition, would neverthe-
less aid the action of the light. This explanation was first made
by Poitevin, and has received general acceptance. Vogel has
affirmed that all preservatives have this characteristic, that they
show their affinity for iodine by decolorizing the blue solution
of iodide of starch.

But few experiments appear to have been made to test this
view. The writer, at a time when he was experimenting with
many new preservatives, tested many of those which had shown
themselves useful, with the iodide of starch, found that they all
decolorized it. What tends, however, somewhat to weaken this
argument, is that the most powerful sensitizers were not always
those that most rapidly decolorized the blue test. Thus tincture
of stramonium showed itself to be a most powerful sensitizer,
but exhibited so little action upon the blue solution, that twenty-
four hours were necessary to render the action visible.

§3.— Bromide of Silver.

The action of light upon bromide of silver has been less studied
than that of iodide, because the difficulties which it presents have
been less evident than those in the case of the iodide. For it was
easily shown in the case of bromide of silver that a chemical
decomposition docs take place by continued action of light.1
Hence it was supposed that no physical action of light took place,
inasmuch as none was apparently needed to explain the pheno-
mena observed.

1 This fact the -writer has carefully verified upon films of bromide of silver
isolated upon surfaces of ground glass.

ACTION OF LIGHT ON COMPOUNDS OF SILVER. 411

But the writer has pointed out elsewhere that the mere fact of
the possibility of development by pyro gallic acid in the absence of any
free soluble silver compound, is in itself an unanswerable argument
for the existence of such a physical image.

Upon a dry collodio-bromide plate perfectly washed and hav-
ing present no trace of the nitrate of silver, the application of
pyrogallic acid will develop a visible image. Whence does this
come ? The image is evidently a sub-bromide of silver, perhaps
combined with organic matter, but that the bromide of silver in
the film afforded the sub-bromide by decomposition is sufficiently
clear.

Now although this image may be developed where there was
no image visible upon the plate after its exposure, let us even
suppose for argument that there was a faint visible image. If
the development were conducted with nitrate of silver present,
this faint visible image might certainly act as a foundation upon
which the strong image was built up. But nothing of the sort
can take place where the alkaline development is conducted in
the absence of all silver compounds except those in the plate.

It, therefore, appears clear that a latent physical image may
exist on bromide as well as on iodide of silver.

But the difference between these compounds in respect of the
action of light upon them is very striking.

On iodide of silver the latent physical image is produced where
the iodide is isolated.

But on bromide only where a "sensitizer" is present.

On bromide isolated, the action of the light can only produce
a chemical image ; on iodide isolated, it can produce a physical
image only.

The action of the light upon bromide of silver, isolated, must
be enormously long to produce an impression capable of being
developed ; the sensitizer abridges this period vastly more than
in the case of iodide.

But on bromide isolated, the long-continued action of light
may produce a strong, visible image (in an experiment by the
writer this was attained by four hours' exposure to strong sun
under a negative), which cannot take place in the case of iodide.

Development on Bromide of Silver. — In the case of iodide of
silver, we have seen that development is essentially the attraction
to the film of a descending precipitate, the film itself remaining
(chemically) unaltered. But in the case of bromide of silver

412

PHOTOGRAPHIC MANIPULATIONS

(acted on by light in the presence of tannin, or other sensitizer)
the alkaline development consists essentially in a reduction of the
bromide in the film, and the production thereby of a more or less
complex, deeply-colored substance, forming the image.

The remarkable distinctions between these two developments,
as respects their essential characters, correspond to equally great
differences in the practical operations based upon them. So that
in the wet processes, in which iodide of silver is the altogether
essential body, we see those forms succeed best in which a de-
scending precipitate is applied to the invisible image.

But in the dry bromide processes we find only one thing essen-
tial : that to the exposed plate there shall be presented a substance
like pyrogallic acid, which has a natural tendency to provoke
reduction. This substance at once starts a decomposition in those
parts that have been exposed to light. "We may enhance its
decomposing action by alkalies, and so exalt that decomposing
agency until it is alone sufficient to produce such an image as we
want ; or, we take the image so produced, and by adding silver
and acetic acid, we may build upon it a denser image for our pur-
pose. So far as this building up is concerned, we proceed upon
the same principles as in the wet process, but this second step
does not in the least affect the character of the first, and that first
step differs absolutely and essentially from anything that belongs
to the wet development.

It is then (and this is what, if the writer is not mistaken, has
not before been correctly presented) by a careful consideration of
the essential characters of these two developments, that we arrive
at the essential differences between the invisible image as formed
on iodide, and on bromide of silver. Each in its absolute essence
and freed from such accidental phenomena as may accompany it
(and may lead to the production of a chemical image), is physical
and not chemical in its nature. But in the iodide the physical
impression is one tending to cause the attraction of a descending
precipitate, in the bromide it is one predisposing to decomposition
when a reducing agent of a proper character is presented.

*WlffilWw|Sl®i?

W^^gS^^

ACTION OF POETIONS OF THE SPECTRUM. 413

CHAPTER III.
ACTION OF VARIOUS PORTIONS OF THE SPECTRUM.

When, instead of exposing sensitive bodies to ordinary light,
we let fall upon them a solar spectrum, we find that its different
portions exercise widely different influences.

We find, also, that the nature of the prism used singularly
affects the influences exerted by the different portions into which
it separates white light. Thus, for example, with a flint glass
prism, the most powerful actinic force is exerted by the invisible
rays just beyond the violet. But if a prism filled with sulphide
of carbon be used, a spectrum is formed, devoid, or nearly so, of
invisible ultra violet rays, capable of acting upon sensitive paper.
A series of very interesting experiments, chiefly made by Her-
schel, on the action of different portions of the spectrum, have
been tabulated, and will be found in Hunt's valuable Researches
on Light.

As respects the silver haloids, the action of light commences
far beyond the visible rays, and extends some distance into the
visible spectrum. Bromide of silver is very faintly affected by
green rays, which do not act upon iodide. It has, therefore, a
slightly wider range of sensitiveness than iodide.

Below the green come those brighter rays which form the
principal illuminating part of white light. These are without
effect upon sensitive films of the silver haloids that have never
been exposed to light. But Ed. Becquerel has shown that these
less refrangible rays have a " continuing" power, that is, that
although incapable of themselves to commence an impression upon
a sensitive surface, even by a very prolonged action, yet if that
action be set up by the more refrangible rays, these less re-
frangible ones can continue and increase it. Thus, if paper pre-
pared with iodide of silver be exposed to the spectrum, the im-
pression ends with the blue rays. But if it be but exposed for
a second or two to light, and then to the spectrum, and if a de-
veloper be applied, an impression is found to have been made
extending to the very end of the visible spectrum.

414 PHOTOGRAPHIC MANIPULATIONS.

What is also remarkable in this very interesting investigation
is, that the bodies which act as a support to the silver compound
may exercise an important influence on the effects produced.
Thus the iodide and chloride of silver in collodion or paper, or
on a metallic film, are subject to this "continuing" power.
Bromide of silver, when formed on a daguerreotype plate, is not;
formed on collodion or on paper, it is. The image of the spectrum,
when formed on bromide of silver on a plate, is much longer
than the image upon chloride or iodide also on a plate, whereas
bromide in collodion or on paper gives a spectrum no longer
than iodide or chloride.1

These results are as important in their relations to photo-
graphy as they are interesting in themselves, and their bearing
on the negative process is too evident to need that the writer
should dwell on it. Only it may be remarked that they explain
in part some of Mr. Eutherfurd's results in photographing spectra
on collodion ; they seem, however, to indicate that in his ex-
periments the spectrum was not wholly purified from white light,
for in these experiments impressions of many of the less refran-
gible portions of the spectrum were obtained in collodions con-
taining the silver haloids.

Heliochromy.

It has been long known that the various colors of the spectrum
had the power of impressing themselves upon certain sensitive
surfaces, especially upon sub-chloride of silver. So that if a piece
of paper be impregnated with chloride of silver and then be ex-
posed to light till it darkens somewhat, it may in this condition
be exposed to daylight under colored glasses, and after a certain
amount of exposure, will be found to assume the color of the
glass under which it was exposed. Becquerel has varied the ex-
periment by using metallic plates, on which a coating of chloride
of silver was formed. Poitevin discovered that bichromate of
potash aided chloride paper in reproducing natural colors.

But neither have the results so far obtained been at all beauti-
ful, nor has it been found possible to render them permanent.
At the same time, the experiments above referred to are curious
and interesting, and there is no doubt that it is in the power of
photography to reproduce all the colors of nature.

1 Becquerel, La Lumiere, II. pp. 89-92.

PART Y.

CHAPTER I.
PHOTOGRAPHY IN ITS RELATIONS TO HEALTH.

§ 1. — Poisons.

In adopting a pursuit, whether simply with a view to interest
and amusement, or with the design of serious study and investi-
gation, or as a business enterprise, every one should attentively
consider its relations to his health. Permanent injury to bodily
health is an evil so serious that its full magnitude is appreciated
by none who have not learned by their own bitter experience.
The writer, therefore, appeals to the good sense of every one
who may adopt this manual as his guide through the study of
photography, in the first place to neglect none of the general
precautions which will be here recommended ; and in the second,
should he find his health in any way suffer, to ascertain at once
to what that injury is ascribable, and to lose no time in taking
such special action as the case may need. Speaking from per-
sonal experience, and having witnessed evil results in others, the
writer earnestly desires to induce the habitual adoption of effec-
tive precautions.

It is not that photography is necessarily a hurtful art, but its
practice brings its votaries into contact with several very strong
poisons, which, if used without great care, and still more, if used
with the heedlessness that is only too common, are liable to pro-
duce the very worst effects. These substances are principally
ether, collodion, cyanide of potassium, corrosive sublimate, chloride of
gold, nitric acid, acetic acid, and ammonia.

Ether, whether swallowed or inhaled as vapor, has a remark-
able effect, which, like that of many other active agents, is
twofold, stimulating and sedative. The first tendency is to pro-

416 PHOTOGRAPHY IN ITS RELATIONS TO HEALTH.

duce a species of imperfect intoxication, soon followed by more
or less prostration ; this sedative effect has led to its being used
in medicine under the name of " Hoffmann's Anodyne." The
effect of its continued use is to produce languor, depression of
spirits, and bodily prostration.

Collodion, from the large quantity of ether which it contains,
produces the specific effects characteristic of that substance, but
also other effects, the precise source of which is not well under-
stood. When collodion becomes much ripened, and especially
when it takes on a deep color, it is found to give off a very irri-
tating vapor, which attacks the face, and especially the eyelids,
producing severe inflammation. Cases have been cited in which
photographers have been in this way obliged to interrupt their
pursuit for times varying from a few days to many months.
"When the photographer perceives a disposition to irritation and
inflammation in the face, he may at once suspect his collodion of
being the cause.

Cyanide of potassium is, of course, the most dangerous chemical
with which the photographer comes into contact. For clearing
both positives and negatives, especially the former, it keeps its
hold upon photographers, particularly amongst careless manipu-
lators, through two causes. First, if by mismanagement the nega-
tive is a little fogged, cyanide, which has a stronger solvent action
than hyposulphite, tends to clear it up. Second, the transfer of
small portions of cyanide to other solutions by dirty fingers, has
not the absolutely disastrous results that follow such transfers of
hyposulphite. These considerations are not in the least credit-
able to the photographer who is influenced by them.

Cyanide of potassium is a compound of prussic acid with
potash. In this compound it retains all the dangerous proper-
ties that characterize it in the free state. In fact, a solution of
cyanide slowly but continually decomposes, absorbing carbonic
acid from the air and giving off prussic acid in the form of gas.

This poison may act in three ways. . Leaning over a bath of it,
or even remaining in a room containing a solution of it exposed
on a considerable surface to the air, a small quantity of prussic
acid is continually inhaled.

In manipulating with its solutions, the hands come into contact
with it. IIow far chemical solutions are taken up by a perfectly
sound skin has been a matter of considerable discussion among
physicians, but recent careful experiments made in Paris leave

poisons. 417

no doubt that the skin continually absorbs liquids which remain
in contact with it.

If, however, the continuity of the skin be broken by a scratch,
cut, pimple, or otherwise, cyanide is readily absorbed at such
places, and a considerable amount of local inflammation may be
produced. In some cases paralysis of the limbs has been affirmed
to have resulted, and even paralysis of the whole side.

For several years past the photographic journals have pub-
lished numbers of letters from photographers who have had
their health injured, or, in many cases, ruined by the action of
their chemicals, and especially by cyanide. Paralysis is the most
common result, attacking most frequently an arm, but sometimes
the entire side. One describes his hands as for months continu-
ally exuding some anomalous secretion, sticking them fast to his
gloves, and interfering with their use. Another complains of
intense pains in the fingers, only to be rendered endurable by
keeping them for hours in cold water. Others find the whole
bodily health broken down, and no help to be obtained from
medicine. One photographer (M. Davanne), after having had his
hands wet with cyanide solution, moistened them with acetic
acid, and was almost instantly struck down insensible with symp-
toms of violent poisoning. His friends barely saved him by long-
continued pouring of cold water on the head.

It should always be remembered that when any substance or
compound having an acid reaction comes into contact with cyan-
ide of potassium, the dangerous tendencies of the latter are greatly
increased — in fact, prussic acid is at once set free.

A very painful class of casualties are those resulting from care-
lessness with cyanide. Solutions are left about ; sometimes the
incredible carelessness of leaving them in drinking tumblers is
committed. For all lives lost in this way (and there have been
many), he who left the solution about is morally responsible.
Once for all, the use of this chemical should be abandoned totally
by photographers. If any insist on using it, the least such can
do is to keep it exclusively in vessels marked conspicuously,

POISON.

Corrosive suhlimate is another dangerous chemical, but not
capable of acting by inspiration through the lungs. Accidents
with sublimate arise either from absorption or internal adminis-
tration.

Absorption through the skin takes place slowly, and the fingers

418 PHOTOGRAPHY IN ITS RELATIONS TO HEALTH.

may be occasionally wetted with sublimate solution without any
noticeable bad results ; the danger lies in this, that there is no safe
line that can be drawn, and that the photographer can form no
conception as to the point to which he may go with impunity.
Evil must be done before its danger can be recognized.

Administered internally, sublimate is a powerful corrosive
poison.

Chloride of gold acts as a poison by causing deep and severe
ulcerations upon the fingers of those who are continually working
in toning baths. Such manipulation should be managed by means
of spatulas and forceps of glass or whalebone.

Nitric acid acts toxically through the lungs. It stains the skin
a deep yellow, which lasts until the epidermis is worn off, but no
other evil seems to result from contact. It is possible that it is
not absorbed, but that it kills the skin too quickly for such an
effect. Nitric acid diffused through the atmosphere and inhaled,
acts as a direct poison. Some years since, Mr. Stevens, together
with an assistant, undertook to sop up a quantity of nitric acid
spilt by the breaking of a large vessel, an act which resulted
fatally to the one and nearly so to the other.

In less quantities, and inhaled over a longer time, it may pro-
duce irritation of the lungs and chest diseases.

Acetic acid acts similarly to nitric, but in a less degree. Its
fumes are very irritating to the lungs, especially to weak ones.
The quantity of acetic acid used in photographic operations is
often very large, so that in many professional establishments
there is alwavs a strong smell of this acid. Such a state of affairs
must be hurtful to every one connected with the place, and ought
to be done away with at any cost.

Pyrogallic acid has been stated lately to be an active poison,
having, in its action on the system, certain analogies with phos-
phorus.

$ 2. — Remedies.

General. — It is evident that all poisons which are liable to be
carried upon the atmosphere should, as far as possible, be kept in
closed vessels. Cyanide should never be left in open pans or
baths. Nitric acid baths used for cleaning (for which purpose
bichromate and sulphuric acid is far preferable; see article on
cleaning plates) should never be left exposed to the atmosphere,

REMEDIES. 419

but the pans or baths should be protected, and be kept under a
chimney or a draught of some sort.

Next to avoiding the production of fumes, the best thing is
ventilation. In the case of ether and collodion, this is the only-
efficient means, as the fumes of collodion cannot be kept out of
the air. For this reason plates should be collodionized, not in the
open air of the dark room, but in a sort of closet partitioned off
and provided with a vent above and below. The operator is
outside of such a closet, and the fumes are not inhaled as the
plate is coated. This is a very important precaution.

When acid fumes have got into the air, their removal can often
be expedited by pouring out ammonia. This, though efficient,
has the disadvantage of causing thick white clouds, which sub-
side by degrees only. Still, its use is occasionally valuable.

Special. — Poisons taken internally must be treated with specific
remedies ; the object is always to bring the poisonous matter into
some inert compound.

Cyanide of potassium has the remarkable property of taking
up iron and forming a perfectly innocuous substance known as
yellow prussiate of potash, ferrocyanide of potassium. Proto-
sulphate of iron may, therefore, be taken internally in consider-
able quantity. Cyanide of potassium, in presence of a mixture
of a protosalt and persalt of iron, is converted instantly into
Prussian blue, a substance not at all injurious to the system.
Those who use cyanide habitually, will do well to keep the mix-
ture of proto and persulphate of iron in readiness for accidents to
others, if not to themselves. Common sulphate of iron in solu-
tion, by continued exposure to air, peroxidizes, and may be used
for this purpose.

For corrosive sublimate when taken internally, white of egg is
usually administered. The quantity of the remedy must be con-
siderable— the raw white of one egg to each three or four grains
of the poison swallowed.

Poisons in cuts and scratches should be immediately treated with
the same remedies as those advised where the poison has been
taken into the stomach. For injuries occasioned by the continuous
absorp>tion of poisons, no satisfactory remedies can be recom-
mended, recourse must be had to the advice of an educated and
intelligent physician.

The writer feels that he cannot leave this subject without again
advising photographers to pay more attention to the conditions

420 CHEMICAL MANIPULATIONS.

of health than is generally done. Those who have the direction
and management of establishments, should never forget that
those whom they employ are often much more exposed to these
dangers than themselves, without having the opportunity or the
privilege of introducing better arrangements and precautions.
And that, however employers may feel disposed to risk their own
health, they are not justified in causing others, either ignorantly
or knowingly, to share such dangers. Many a man, when he has
found his nervous system permanently injured, or his lungs
weakened, commences care-taking when it is too late. The need-
ful precautions are neither many nor troublesome ; they should
be taken from the outset, and steadily persevered in.

CHAPTEK II.
CHEMICAL MANIPULATIONS.

Some of the simpler chemical manipulations are frequently
needed in photography, and deserve a brief description here.

§ 1. — "Weighing and Measuring.

No operations are commoner or seem easier than these, and yet
in none are mistakes more frequent.

Weighing. — For the operations of photography, a small bal-
ance like that on page 421, having a nine or ten inch beam, will
be the most suitable, using a heavier and commoner pair of scales
for weights over one or two ounces. Fig. 142 represents the
French pattern of " trebuchet" or tilting scale, now largely manu-
factured here. The pans rest on the box until the lever is
pressed, when they swing loose.

In weighing, it is necessary always to beware of "sticking."
When the pans are nearly equally loaded, but not exactly, the
needle may point at the centre by reason of the beam not moving
with entire freedom. By making the pans oscillate a little, it
will be easy to see if the needle moves on each side to the same
distance from the centre.

WEIGHING- AND MEASURING,

421

Fig. 142.

Inattention to reckoning the weights is another common source
of mistakes, especially with our defective system.

The following are the details of the weights as now used. The
grain is the same always.

Avoirdupois.
1 drachm = 54. 7 grains nearly.
1 ounce = 437£ grains.
1 pound = 16 ounces = 7000 grains.

Apothecaries.

1 drachrn = 60 grains.
1 ounce = 480 grains.
1 pound = 12 ounces = 5760 grains.

Troy.
1 pennyweight = 24 grains.
1 ounce = 20 dwt. = 480 grains.
1 pound = 12 ounces =5760 grains.

Decimal Weights authorized by Congress.
A thousand milligrammes make one gramme.
A thousand grammes " " kilogramme.

One grain corresponds to 65 milligrammes nearly (64.8).
One drachm apothecaries' weight to 3.882 grammes.
" ounce • "

" " avoirdupois
pound "

" apoth. or troy

" 31.1035
" 28.349

" 453.59

" 373.242

1 gramme = 15.43234 grains.

1 kilogramme = 2 lbs. 3 oz. 119.85 grs., or 15,432.35 grains.

422

CHEMICAL MANIPULATIONS.

Fig. 143.

Measuring is still more liable to error
than weighing. The vessel must be kept
carefully perpendicular, and be examined
by a level light. The surface of the liquid
is always curved, being higher at the edges.
The lower level is that to be used, that is,
the lower part of the curved surface must
correspond with the lines ruled on the
glass, as shown by the dotted line on the
figure, which represents a "minim glass."

Liquid Measure.
1 fluidrachm = 60 minims.
1 fluidounce = 8 fluidrachms.
1 pint= 16 fluidounces.
1 gallon = 8 pints.

§ 2. — Heating.

The alcohol lamp was for a long time the favorite source of heat
when needed on a small scale ; its advantage lies in its high tem-
perature and freedom from smoke. As alcohol both evaporates
and absorbs water from the air, the wick should be kept covered.
If the wick-tube is passed through a cork, this should always
have a groove to permit escape of vapor, or it will be liable to
be driven out with a dangerous explosion.

But whenever gas can be had, the Bunsen burner (see Fig. 14-i)
conveniently and economically replaces alcohol.

The sand-bath is an excellent means of applying a gentle heat
to large surfaces.

A very simple and convenient form of sand-bath is to have a
circular rim on top of a stove, filled with clean building sand.
The heat is thus applied much more evenly than if the vessel were
set directly on the stove without the interposition of the sand, and
the danger of breakage is greatly diminished.

A sand-bath may also be established over a Bunsen burner.
Get a worker in sheet-iron to make a cylinder of stout galvanized
iron, about twelve inches in diameter, and ten high. The top
and bottom are turned over heavy iron wire, and curved pieces
are cut out at top and bottom, to serve as air-passages. A circular
piece of sheet-iron is hammered into a basin thirteen inches
across, and this, filled with sand, rests on the top of the cylinder.
Such a cylinder will support a very heavy weight.

EVAPORATION.

423

Fig. 144.

§ 3. — Evaporation.

In evaporating, two important points are to be borne in mind.
First, the heat should not be contracted to a single point ; and
second, it should not be so diffused as to strike that part of the
vessel that is above the liquid. In either case fracture is apt to
occur ; in the latter case, almost certainly.

For large operations the sand-bath will be proper; that is, for
evaporating negative baths, and such work. For small operations
the following arrangement is capital.
Procure a lampstand, with a strong
ring about five inches in diameter ;
take a piece of strong but fine and
close-meshed brass wire gauze, six
inches square, lay it on the ring and
press the corners down under the ring,
so as to fix it firmly to it. This
wire gauze forms a support which will
carry anything from a capsule an inch
in diameter to a basin of twelve or
fifteen inches, provided the lampstand
be strong and stout as it should be, as

well as flasks, beakers, or, in fact, any utensil whatever. The
Bunsen's burner stands under this, always ready for service at a
moment's notice. The wire gauze stops the
flame, and permits only the hot air to pass
through, thus giving a great protection against
accident, whilst scarcely interfering with the
heating.

A tripod, if made strong and stout, is also
a good support, but far less convenient than
the foregoing, inasmuch as it cannot be raised
and lowered, and is never so strong as the lampstand. In this
case, also, a piece of wire gauze should be interposed between
the vessel and the source of heat.

Fi°r. 145.

§ 4. — Filtration.

Of filtration, all that need be said is, make the filter always a
little smaller than the funnel, and always wet it before pouring
in the liquid to be filtered. Select a good paper, which filters

42-i

CHEMICAL MANIPULATIONS.

clean and quickly, and when that which exactly suits is found,
a good supply should be laid in. Nothing is more vexatious
than to wait for a slow filtration.

Fi?. 146.

§ 5. — Pouring.

In transferring liquids from one vessel to another, there are

two contrivances bv which the clean
performance ot^ the operation Avithout
sa may be greatly facilitated. These
are greasing and rod-pouring.

Greasing is the application of a little
tallow on the linger under the lip over
which the liquid is to be poured. For
pouring valuable liquids out of large
vessels, especially if nearly full, this
mode is very useful.

In rod-pouring, the glass rod is first
wetted with the liquid, and is then held
to the lip of the vessel, which is so in-
clined as to pour slowly, the stream following the rod (Fig. 146),
Both methods may be combined.

§ 0.— Fusing.

For reducing chloride of silver in the dry way, a Hessian cru-
cible may be used. The chloride is intimately mixed with twice
its weight of dry carbonate of sodium; this mixture is rammed
tightly into the crucible, which is by degrees raised to a white
heat. As the Hessian crucibles are porous, some of the silver
may sink in. To obviate this, fuse a little borax in it. or use a
Paris '. crucible, which is not liable to this objection.

For fusing nitrate oi' silver, a Berlin or Meissen porcelain basin
will be required; none other can be depended upon. The Ber-
lin are the best, and are stamped in blue; some with the letters
K P M. some with a Prussian eagle inside of a circle. Both of
these sorts are excellent. With care, the operation is perfectly
and fracture need not be feared. The Bunscn burner will
give the necessarv heat tor small quantities, or combined burners
for larj

N hi'TKA LIZ ATI ON. 425

\ 7. — Neutralization.

Where the object is merely to render an alkaline liquid acid, or
an acid one alkaline, it will be sufficient to add the appropriate
reagent, until blue litmus-paper, by turning red, indicates acidity ;
or red, by becoming blue, shows alkalinity, as the case may be.

But an exact neutralization, as where an acid or an alkaline
liquid is to be rendered exactly neutral, is an operation requiring
some circumspection. Jf, Cor example, an acid liquid is to be
neutralized with ammonia, and the latter liquid is added a few
drops at a time, the operation will be very tedious, and will be
almost certain to fail, an excess of ammonia will almost certainly
beat last introduced. The operator, therefore, feels his way. Ee
pours off a part, say a third, of the acid liquid, and add.-; boldly
enough ammonia to make it quite alkaline. Be then add,- enough
of the remainder of the original liquid to render the mixture
decidedly acid. Repeating this several time , he gets a pn
clear idea ofthe proportion of ammonia, unknown at first, which
is required. Towards i be end he diminishes the quantity of each
successive addition, till with the last drops, with care, he obtains
an exact neutralization.

There are some cases in which the neutralization is effected
by the addition of a substance which, even if added in exo
produces a precipitate, and so leaves the solution neutral, so that
the addition el' an <• of the precipitant is without, much im-

portance. An example of this is presented in the neutralization
of an acid negative hath with carbonate of sodium. I fan e :c<
of carbonate of sodium be added beyond what is necessary to
neutralize the free acid, carbonate of silver is formed, and this
being but \>:iy sparingly soluble in water,1 is precipitated. The
addition, therefore, of a slight excess of carbonate of sodium docs

not render the liquid more than very faintly alkaline.

In other cases, the neutralization is effected by a substance
insoluble in the solution after neutralization. This is the simplest

e of all: it is sufficient to add the neutralizing substance in

. and then to remove that excess by filtration. An example

of t, his. is afforded in the preparation of a neutral gold toning-

bath. The acid solution of perch loi ide of gold is agitated with

688 of precipitated chalk ; as much chalk dissolves as is neees-

1 Soluble in 81,978 parts of water at 12° 0. (Kremers.)

426 CHEMICAL MANIPULATIONS.

sary to neutralize the excess of hydrochloric acid, and the rest
is got rid of by filtration.

Negative baths requiring neutralization must always be treated
with bicarbonate of sodium, never with chalk.

| 8. — Decantation.

Fig. 147. In call cases where a precipitate is to subside, that ope-

ration takes place best in vessels larger at the bottom
than at the top, tolerably well in vessels with straight
sides, and very badly in conical vessels, widening
towards the top. Those of this last shape should, there-
fore, never be employed for decantation. The shape
shown in the margin is the proper one.

\ 9. — Cleaning Glass and Porcelain Vessels.

The bichromate mixture already recommended for cleaning
glass plates is most excellent for vessels. It should be pretty
strono-. A most useful plan is to take cold saturated solution of
bichromate of potash, and add about one-eighth its bulk of sul-
phuric acid (or one-fourth its bulk of the dilute acid that comes
from the drying-box). If the ordinary acid is used, it must be
mixed in a porcelain or thin glass vessel ; a bottle will probably
break by the sudden heat evolved. For a few moments a corro-
sive vapor is thrown off; after cooling, however, this trouble
disappears.

About a quart of this mixture is to be kept on hand and poured
into vessels needing cleaning, which it does very effectually. It
may be used again and again until it takes a brownish-violet
color, when it should be rejected as spent.

$ 10. — Marking Negatives.

The photographer will often desire to mark his negatives, es-
pecially landscapes, with the name of the place, the lens used, or
other note of interest. With portraits there are always places
convenient for either marking with black varnish, or marking
with a sharp point through a dense place, on portions not to be
used in the print. But with a landscape negative, good to the
very edge, one is not disposed to sacrifice a place for marking.

BENDING GLASS.

427

An excellent plan is to use a writing diamond, which is quite dif-
ferent from a glazier's, and may be had of the philosophical
instrument makers. With one of these one may write legibly
on the back, over a very thin or a very thick portion, without
the marks showing in the print, as is the case when a glazier's
diamond is used. These writing diamonds are sparks set in steel
tubes much like everpoint pencils. They are mostly made in
Amsterdam, the great centre of diamond-cutting.

§ 11. — Bending Glass.

An ordinary gas flame is sufficient for bending glass tubes up
to half-inch diameter. No particular care is necessary except to
apply the heat equally by slowly turning the tube round, and to
avoid commencing to bend until the glass is quite soft, otherwise
the tube will almost certainly break. The black from the flame
will easily wipe off. Lay the bent tube on some non-conducting
surface to cool slowly.

§ 12. — Piercing Holes in Corks.

This is best done with borers FiS- 148.

consisting of tubes of brass or
tinned iron. The former are to
be had of the instrument makers,
in sets of different sizes sliding
into each other. The tin tubes
can be made by any tinsmith, and
should have a cross-piece as a
handle across one end. This end-
piece has a hole cut into it of the
same size as the tube, in order

that the pieces of cork punched out may pass freely through.
Several sizes will be wanted, say T3S, T*g, f%, J, f, 1 inch. A set
of a dozen comprising other intermediate sizes is still more satis-
factory. The edges should be occasionally sharpened with a rat-
tail file.

428 CHEMICAL MANIPULATIONS.

§ 13.— Softening Corks.

All corks are the better for softening. The cork-pressers
usually sold are next to worthless. To roll the cork under the
foot, with a piece of clean paper above and below it, is not a bad
way, but the circular cork-pressers, consisting of a notched wheel
and excentric band, are most excellent. A cork should be soft-
ened before boring, not after.

§ 14. — Blackening Brass and Wood Surfaces.

Brass. — Dissolve a drachm of bichloride of platinum in one
ounce or one and a half ounce of water, and add a grain of nitrate
of silver. Clean and polish the brass surface, warm it, and apply
the solution with a small tuft of cotton. Eub till dry, and then
finish off with a little dust of graphite, avoidiug to put on any
polish, which would convert the surface into a reflecting one,
and enable it, though black, to send back white light.

Brass surfaces are cleaned for these purposes, either by rubbing
with sand and polishing powder, or by applying nitric acid. The
fumes that rise should be carefully avoided, and the acid be only
.left on till a bright surface is obtained.

Wood. — Take five parts of lampblack, two of finely pulverized
gum-arabic, and one of brown sugar ; mix to a thick paste with
water, and rub on with a piece of flannel. This is excellent for
the insides of cameras and drying-boxes ; it does not come off on
the fingers. A second coat aids in obtaining a perfect blackness.
If it soils the finger when rubbed on it, there was too much
lampblack; if there show itself any reflection, there was too little.

§ 15.— Paste.

Paste is far preferable to mucilage for attaching labels. If
Avell boiled, and then mixed with a little carbolic acid (one
drachm to eight or ten ounces of paste), and placed in a bottle
with a cork pierced to carry a brush, it will keep in excellent
condition for a year or more. When gum mucilage is used, the
addition of a very little glycerine will make it hold better, and
diminish its tendency to separate or "scroll."

buckle's brush.

429

Fig. 149.

§ 16. — Filtration of Viscid Liquids— the Percolator.

Solutions of gum, of gelatine, and other viscid liquids, are best
filtered through a percolator. This is a porcelain
funnel without a neck, and pierced with twelve
oval openings. It is so set into a jar that all
the openings shall be below the upper rim of
the jar. A paper or other filter is placed inside.
When paper is used, it is best to make the
lower part of the paper double, by putting in a
second and smaller filter to prevent bursting at
the bottom. The facility of filtering through
the percolator greatly exceeds that of an ordinary filtering
funnel.

§ 17.— Buckle's Brush.

A string is passed over a tuft of cotton, and the end of the tuft
is pulled by the string into a glass tube. This sort of brush has

Fig. 150.

been largely used for extending solution of nitrate of silver, and
other solutions, over paper. When soiled, it is easy to change
the cotton for a fresh piece.

NOTES AND ADDENDA.

Permanent Silvered Paper (see p. 277).— At the time when the article on the
author's new process in the body of this manual went to press, there had been
so far time only for testing its keeping qualities about seven weeks. Since then,
the paper has been used after keeping it for over three months, with entire success,
and the great value of the method has been fully confirmed. As already men-
tioned, when the paper is long kept, it acquires a slight yellowish tinge on the
face, and a light brownish coloration on the back ; but as these disappear in
the operations of toning and fixing, when carried through precisely in the ordi-
nary manner, they have no importance. The prints executed on paper kept
over this long period are not to be distinguished from those made immediately
after sensitizing.

The object of this process is not, however, so much to keep paper over these
long periods, as to enable those who work on a small, or even on a moderate
scale, to avoid the trouble of daily, or almost daily, preparation of small quantities
of paper ; even, however, for those who operate more largely the process has its
advantages in the avoidance of waste such as constantly results from miscalcula-
tion and from unexpected changes of weather, by which vexatious losses are a
common experience. It should be remarked that the experiments here described
were made during the moderate weather of spring, and that in hot summer
weather the time during which the paper can be kept may not reach so great a
length.

The writer desires also again to call attention to the fact, that all paper prepared
by any process with the intention of long keeping, should be sensitized with much
more careful exclusion of light than is necessary for paper intended for immediate
use. Similar care is necessary when the box containing it is opened to take out
part of the paper, in order that what remains over shall not have been exposed
to light. It is best to do this in the dark room.

Water-proof Negative Varnish.— -Since the remarks on p. 375, &c, went to
press, there has been time to extend the observations on the resistance of these
varnishes over a longer period. After the plates had been left for three months
under water, they were in the following conditions : —

The bleached lac varnish (No. 1), and one of the orange lac varnishes
(No. 3), were in good condition, and exhibited no signs of injury except that each
had a small pucker or fold at one corner, so slight as to have no real importance.

The other orange lac varnish (No. 2) was in an entirely perfect condition.

Sandarac varnish (No. 4) was badly torn, about one-third the film was off the
plate.

The resisting powers of all these four varnishes cannot be considered as

432 NOTES AND ADDENDA.

otherwise than very remarkable, for even the Sandarac stood for a long time,
and though inferior to the other three in its resistance to moisture, excelled
them in resistance to heat and to mechanical injuries.

The observation has been often made, that out of a lot of negatives made at
the same time, and varnished -with the same varnish, and kept under identical
conditions, some will be ruined with honeycomb cracks and others escape, and
this fact has occasioned much surprise, and has remained unexplained. The
writer is satisfied, from his examination, that the explanation is very simple.

Varnish penetrates but slowly through a collodion film, and if it is poured off
too soon, the negative may appear to be all right, and yet the varnish have
really no sufficient hold upon the glass. The importance of this point has, the
writer believes, never before been pointed out. In the directions for varnishes
given in this manual, it is advised to wait ten or twelve seconds after the plate is
completely covered, before commencing to pour off. This gives the varnish time
to completely saturate the film and to cover the glass under the film with an even
stratum. Attention to these directions is important, especially for those who wish
to feel that their negatives are safe for a long period of years.

It seems scarcely necessary to say that if the hyposulphite has not been
thoroughly washed out, the dangers to the negative are thereby much aggra-
vated. Experience is also constantly accumulating to show that when negatives
have been carelessly varnished, or where a poor varnish has been used, any
sudden change of hygrometric condition may cover the negative with honey-
comb cracks. A case has been cited in which a negative in good condition was
taken from a warm, dry room and carried for half an hour through a damp
atmosphere, at the end of which time it was covered with cracks. With any of
the above four varnishes properly applied, it is safe to say that such a trial might
have been repeated a score or perhaps a hundred times without evil results.

When this trouble occurs, the writer would advise to revarnish with a thin
spirit varnish, leaving it in for twenty or thirty seconds before commencing to
pour oft'. In his own work he has never met with a single case of cracking.

Reducing Residues. — Lately the plan of precipitating silver as oxalate and
reducing by heat, has been brought forward again. The idea is ingenious, and
as oxalate of silver is easily resolved into metallic silver by the simple application
of beat, the method would be convenient enough, were it not so dangerous. The
oxalate of silver, when heated, is liable to explode with tremendous violence ; an
accident of this sort happened some years ago in the laboratory of M. Wurtz, in
Paris.

New Developer. — It is stated that the action of pyrogallic acid as a developer is
greatly heightened by the addition of sulphate of copper. A three-grain solution
of pyrogallic acid is mixed with one-third of its bulk of a cold saturated solution
of sulphate of copper just before throwing it over the plate.

INDEX.

Aberration, 58, 59
Accessories, 203

arrangement of, 189
Acceleration of exposures, 220
Acetate toning, 290
Adapting flanges, 224
Admission, centre of, 69
After-intensification, 171
Alabastrine positives, 189
Albertype, 394

Albumen positives on glass, by de-
velopment, 387

by sun printing, 391
Albumenizing glass, 155

paper, 270
Alcohol, influence of, 131
Alkaline carbonate toning, 2S9

development, 358
Alum in the printing bath, 274
Ambrotypes, 42, 188
Aniline process, 396
Animals photographed, 349
Annatto for backing, 356
Anthony, H. T., alum in printing
bath, 274

fuming, 279
Aplanatic lens, 10, 81
Apparent size of objects, 10(!
Architectural photography, 208
Arrangement of accessories, 191
Arrowroot paper, 272
Astigmation, 61
Atmospheric effect, 244

Backgrounds, 203
canopy, 204
conical, 205

Backgrounds —

crayon, 208

inclined, 204

pictorial, 208

rotating, 206
Backing dry plates, 356
Balance, 421
Bar frame, 45
Barrel distortion, 65
Bases in collodion, 134
Bath, fixing, 46

negative, 19, 155

positive, 44

printing, 273, 274

swinging, 158

toning, 46
Bending glass, 427
Benzoate toning, 290
Berlin portraits, 194, 283
Blackening brass and wood sur-
faces, 428
Blistering in dry plates, 352

silver prints, 341
Blotting off silvered paper, 274
Blue stippling, 121
Blurring, 27, 315
Brass surfaces, to blacken, 428
Brilliancy, how obtained, 231
Bromide of ammonium, 134

of cadmium, 136

of lithium, 135

of potassium, 134

of sodium, 135
Bromides in collodion, 137, 168
Buckle's brush, 429

Calcio-chloride toning, 289
Camera, landscape, 147
levelling the, 147

434

INDEX.

Camera —

red lining to, 221

reversing of, 148

selection of, 12, 147, 221

solar, printing by, 268

tested, 13

for transparencies and opalo-
types, 384, 385

Van Monckhoven's, 266

Woodward's solar, 266
Canopy background, 201
Carbon printing, 298, 402

on glass, 403
Carbonate of silver, printing on,

282
Carriers, 14
Centre, admission and emission, 69

optical, 68
Chemicals, 15

in fault, 304
Chemical focus, 95
Chloride of iron, printing with, 398

of silver, development on, 160
Chlorine, intensifying by, 172
Chromatic aberration, 59
Cleaning, 35

glass, 426
Cleanliness, 17
Clouds, 219, 239

printed in, 184

reflected, 185
Clove process, 373
Coating the plate, 23
Coffee process, 371
Collo-developers, 164
Collodio-bromide process, 365
Collodio-chloride process —

failures in, 242

on glass, 388

on paper, 391
Collodion, 131, 231, 305

decanting, 145

dry plate, 365

filtering, 146, 367

formulas for, 142, 143

injurious to health, 416

keeping of, 146

salting, 132, 134

thinning, 25
Colors obtained in photography,
414

Coma, 63

Comets, 324

Combination prints, 182

Composition, 234

Conical background, 204

Conjugate foci, 75

Contact printing on glass, 386

Contrast, causes of, 165, 313

in composition, 243
Contrasts, 213
Copying, 251

camera, 253, 255

cone, 253
Corks, to pierce, 427

to soften, 427
Corrosive sublimate for intensify-
ing, 172
Corrosive sublimate, poisonous ef-
fects of, 417
Cotton, negative, 126
Crapy lines, 310
Crayon portraits, 194
Cross-lights, 193
Creamy negatives, 161
Curvature of the field, 63
Cut-off, 15
Cyanide for intensifying, 173

poisonous nature of, 416

Daguerreotypes, copying of, 254
Dark room, 109

arrangement of, 111

temperature, 113
Decantation, 426
Defects in the image, 313
Developers, Collo-, 164

strong and weak, 162

sugar, 164
Developing boxes, 346
Development, 30, 132, 162, 305

aids to, 162, 163

alkaline, 358

of dry plates, 358

management of, 165, 166, 19S,
200, 214, 318, 432

on paper, 260
Diagonal line, the, 236
Diaphragms, 64, 92

inclined, ^>G, 219

INDEX.

435

Difficulties in portraiture, 198

Dippers, 25

Direction, line of, 234

Dispersion, 54

Distance in landscape composition,

238
Distance of position, 191
Distortion, 65
Double portraits, 181
Drawings, copying of, 251
Dress, effect of, 196
Dry plate photography, 351, 365

plates, to dry, 353
backing of, 356
development of, 358
failures in, 360
Drying box, the author's, 354
Drying dead, 330
Drying plates by heat, 353

spontaneously, 356

by sulphuric acid, 354
Dust, 160

Edging plates, 352
Emission, centre of, 69
Enamels burned in, 392
Encaustic paste, 300
Engravings, copying of, 251
Enlargements, 177, 265
Equivalent focus, 70
Ether, influence of, 131

injurious effects of, 415
Evaporating, 423
Exposure, 30, 195

acceleration of, 220

of dry plates, 361, 363

Failures in dry plate work, 360
in photographic operations, 301
in silver printing, 337
in varnishing, 40, 330

Faults in spherical lenses, 58

Feathery markings, 330

Fennemore's glass room, 118

Ferrotypes, 42, 188

Field work, 222

Figure, relative size of, 192

Figures in landscapes, 241

Filtering collodion, 146, 367

Filtration, 423

Fixing the print, 293

Fixing bath, 46

Flanges, 96, 224

Flare, 91

Flat pictures avoided, 199

Focal lengths of lenses, 66

determined, 70, 72, 73, 74
Foci, conjugate, 75
Focus, chemical, 95

equivalent or absolute, 70
Focussing, 28, 224
Fogging, 302

of dry plates, 362

sources of, 112, 113
Foliage, 219

Foreground in landscapes, 219, 237
Fuming, 279
Fusing residues, 424

Gallate of lead, 261
Ghost in the camera, 91
Ghosts, 181
Glass, cleaning of, 17, 155

for glass house, 115

ground, 48, 121

preparing of, 155

selection of, 154
Glass room, 115
Globe lens, 85

Glycerine and honey process, 350
Gold, chloride of, a poison, 418
Gold residues saved, 3S1
Groups, 120, 192, 248
Granularity in negatives, 310
Green color, its actinic value, 139
Ground glass, printing under, 180,

283
Gum in dry plate work, 365
Gum-gallic process, 374
Gurney's glass room, 119

Halation, 315

Half-tone, how obtained, 167, 315

436

INDEX.

Harsh pictures avoided, 199
Health, 415

Heat in development, 359
Heating, 422
Heliochromy, 414
Holders, pneumatic, 159, 160
Horizon in landscapes, 242
Hyposulphite of sodium, testing
for, 297

Illumination, 201
Image defective, 313

nature of, 97
Inclined backgrounds, 203, 204
Index of refraction, 54
Instantaneous photography, 347
Intensifying negatives, 171, 172, 173
Intensity, falling off of, at edges, 65
Iodides in collodion, 137
Iodine for intensifying, 171
Irregularity of film, 310
Iron, printing with salts of, 397
Ivory, miniature effects on, 390

Jamin lenses, 80

Landscape lenses, 9, 91

photography, 11, 51, 208, 224
Legray's process, 264
Lenses, aplanatic, 10, 81

Blunt's hemispherical, 88

care of, 96

centering of, 93

comparison of, !>2

focal lengths of, OG

general remarks on, 90

globe, 8o

images of, 97

Jamin, 80

nature of, 56

orthoscopic, 87

Pantascope, 88

Lenses —

portrait, 79

quickness of, 95

rapid rectilinear, 9, 81

rectilinear, 88

Ross's doublet, 87

selection of, 9, 93

triplet, 83

view, 9, 78

Zentmayer, 86
Levelling the camera, 29, 209
Liesegang, toning formula, 291
Light, exclusion from lens, 120

influence of, 250

insufficient, 202

management of, 193, 200

regulation of, 109, 124
Line engravings, copying of, 251
Lines in the negative, 326
Lithographs, copying of, 251
Local redevelopment, 169

reduction of negatives, 176
Loescher & Petzch's glass room,

119
Lumps in the film, 311

Magnesium light, negatives by, 185
Management of light, 193
Manipulations, 420
in the field, 222
Marbled stains, 327
Materials for landscape work, 221
Measuring, 422
Meicke's experiments, 275
Melainotypes, 189
Mercury for intensifying, 172, 174
Metrical weights, 421
Mezzotint prints, 194, 2S3
Mezzotints, copying of, 251
Microphotography, 258
Microscopic photography, 259
Miniature effects on ivory, 390
Minim glass, 422
Miscellaneous faults, 333
Moonlight effects, 181
Morphia process, 374
Mottling in the negative, 312
Mounting prints, 299

INDEX.

437

Negative, the, 147, 158

artifices with, 181

bath, 19, 155, 304

development on paper, 263

drying of, 37

for enlargement, 177

influences on, 167

intensifying of, 171, 172, 173, 174

by magnesium light, 185

marking of, 426

paper pasted on, 180

printing of, 280

reducing of over-developed, 176
locally, 176

retouching, 178

reversed, 400

scarlet, 173

storing of, 186

thin, how printed, 281

varnished, to intensify, 175

varnishing of, 37, 375, 431

washing of, 36
Neutralization, 425
Nitrate of silver, fused, 157, 305
Nitric acid, poisonous effects of,

418
Nitroglucose, 268
Notman, toning formula, 290

Objectives, 9

Oil paintings, copying of, 251
Opalotypes, 383
Optical centre, 68
Orthoscopic lens, 87
Out-door photography, 344
Oxalotype, 398
Oyster-shell markings, 327

Pads, 45

Pad fuming, 279

Panoramic'camera, 88

Paper, albumeniziug, 270
arrowroot, 272
enlargements, 265

Paper-
negatives, 263
for positives, 269
sensitizing of, 273
Papyroxyline, Liesegang's, 129
Paraffining, 264
Paste, 428

encaustic, 300
Pencil drawings, copying of, 251
Percolator, 429

Permanence of silver prints, 300
Permanganate of potassium, 174
Perspective, atmospheric, 244

incorrect, 103

photographic, 97
Photogalvanography, 395
Photography, architectural, 208

landscape, 208
Photographs, copying of, 254
Photolithography, 394
Pinholes, 321
Plans, copying of, 255
Plate boxes, 187
Plates, preserved, 350

sensitive, keeping of, 344
Pneumatic holders, 159, 160
Poisons, 415
Portrait lenses, 10, 79
Portraiture, 90, 106, 190, 247
Posing the sitter, 197
Position of background, 206

in landscape work, 240
Positive bath, 44, 273
Positive paper, new method of pre-
paring a paper that will keep,
277,431

paper, washed, 275

printing, 269, 280
Positives, alabastrine, 189
Pouncy's carbon process, 402
Pouring, 424
Preservatives for dry plates —

clove, 373

cochineal, 370

coffee, 371

gum gallic, 374

morphia, 374

pyro gallic, 369

resin, 373

tannin, 371

tea, 371

438

INDEX.

Pressure frame, 283
Printing, 280, 284
Printing bath, 273

new, for permanent paper,
277, 431
Printing in the camera, 384
Printing in clouds, 184
Printing, failures in, 336

frames, 45, 283

on glass by development, 383

silver, 269
Prints, combination, 182

finishing the, 298

mounting of, 299
. rolling the, 300

silver, permanence of, 300

tested if well washed, 297 .
Projection, panoramic, 108

plane, 106
Pyrogallic preservative for dry

plates, 369
Pyroxyline, 126

alcoholic, 130

influence of, 130

treatment with alkali, 132

variable character of, 168

Rapid rectilinear lens, 9, SI
Red lining to camera, 220
Redevelopment, 32

local, 169
Reducing over-developed nega-
tives, 176
Reflectors, 124
Reflection, 52
Refraction, 52

Relievo process, "Woodbury's, 396
Rembrandt effects, 194
Remedies for poisoning, 418
Repeating back, 191
Repetition in composition, 243
Residues, treatment of, 379,432
Resin process, 373
Retouching the negative, 178
Retouching, use of resin in, 379
Revarnishing, how to do, 41
Reversed negatives, 400
Ridge roof, 115

inclination of, 117,

Rolling prints, 300
Ross's doublet lens, S7
Rotating background, 206
Rubber varnish, 352
Rules, general, 47

Salomon's glass room, 120
Sarony's glass room, 119
Scarlet negatives, 173
Schlippe's salt, 173
Seasons, influence on landscape

work, 227
Sensitizing paper, 44, 273

new method, 277, 431
Serum of milk, 264
Shade printing, 2S0
Shadows, 216
Sharpness, want of, 317
Shepard, Dr., toning formula, 291
Silver, bromide of, 410

chloride of, 406

iodide of, 406

prints, permanence cf, 300

pure, value of, 157
Sizing the film, 177
Skies, management of, 210, 219, 230
Sky shade, 219
Slides, 221
Sliding front, 29
Slipping of film, 317
Smeariness of film, 320
Snow landscapes, 215
Softness, 231

how obtained, 165
Solar cameras, 266
Sore hands, to heal, 37
Specks in the film, 160
Spherical aberration, 58
Splitting of film, 316
Spots, hazy, 323

opaque, 324

transparent, 321
Stains, 14, 43, 327
Stand, 15

Steinheil aplanatic, 10, 81
Stereopticon slides, 386
Stereoscope, 256
Storing negatives, 1S6
Stopping out, loO

INDEX.

439

Stops, 92, 211, 223

Streaks in the negative, 31, 320

Sugar in development, 165

Sulphide of potassium for intensi-
fying, 172

Sun printing, 280

Sunlight in glass room, 122

Surface stains, 327

Swan's carbon process, 399

Swing-back, 148, 223, 225

use in landscape work, 151
portraiture, 130

Swinging bath, 158
lens, 131

Syrup for keeping negatives moist,
347

Tank, washing, 295

Tannin process, 371

Tea process, 371

Temperature of glass room, 123

Tents, 34(3

Theoretical considerations, 404

Thinness of film, 310

Tissue, carbon, 399

Toning, 232, 288

bath, 46

formulae, 289, 290, 291

and fixing baths, 292
Top-light, excess of, 201
Transparencies, 386
Triplet lens, 83
Tripod, how made, 221

chemical, 423
Tunnel system, 124
Two-bath system, 155

Uranium intensifying, 174
Unsatisfactory results in portrait-
ure, 200

Varnish, 37

effects of too thin, 41,432

Varnish —

India-rubber, 352

negative, 375, 431
Varnishing, 37, 38,431

failures in, 40, 41, 330,432
Veiling, 302

Velvet drapery, 194, 197
Ventilation, 28, 110, 121

box, 111
View lens, 9, 78
Vignetting with cotton, 286

by development, 287

with a frame, 285

glasses, 285

with a lens, 287

on the negative, 287

with paper, 286

by a screen, 2S8
Viscid liquids, to filter, 429

Washed sensitive paper, 275

Washing the negative, 36, 169
prints, 46, 295

Washing tank, 295

Wax-paper process, 264

Weakening of negatives in fixing,
330

Weather, indications of, 229

Weighing, 420

Weights, 421

Wenderoth's glass room, 118

Willis's aniline process, 396

Wind, the, 226, 229

Wood-cuts, copying of, 251

Wood surfaces, to blacken, 428

Woodbury's relievo process, 396

Woodward, Dr., microscopic pho-
tography, 259

Woodward's camera, 266

Xyloidine, 130

Zentmayer lens, S6

THE NEW YORK PUBLIC LIBRARY

THE REFERENCE DEPARTMENT

ircuinstances to be
taken from the Building

This book is under no circa

WIT^

form 4M

Internet Archive Audio

Featured

Top

Images

Featured

Top

Software

Featured

Top

Books

Featured

Top

Video

Featured

Top

Mobile Apps

Browser Extensions

Archive-It Subscription

Save Page Now

Full text of "A manual of photography: intended as a text book for beginners and a book of reference for advanced photographers"

See other formats