When the ingredients are mixed, take a bundle of quills or a fork, and beat the whole into a perfect froth. As the froth forms, it is to be skimmed off and placed in a flat dish to subside. The success of the operation depends entirely upon the manner in which this part of the process is conducted; if the albumen is not thoroughly beaten, flakes of animal membrane will be left in the liquid, and will cause streaks upon the paper. When the froth has partially subsided, transfer it to a tall and narrow jar, and allow to stand for several hours, that the membranous shreds may settle to the bottom. Pour off the upper clear portion, which is fit for use. Albumenous liquids are too glutinous to run well through a paper filter, and are better cleared by subsidence.

A more simple plan than the above, and one equally efficacious, is to fill a bottle to about three parts with the salted mixture of albumen and water, and to shake it well for ten minutes or a quarter of an hour, until it loses its glutinosity and can be poured out smoothly from the neck of the bottle. It is then to be transferred to an open jar, and allowed to settle as before.

The solution, prepared by the above directions, will contain exactly ten grains of salt to the ounce, dissolved in an equal bulk of albumen and water. Some operators employ the albumen alone without an addition of water, but the paper in that case has a very highly varnished appearance, which is thought by most to be objectionable.

The principal difficulty in albumenizing paper is to avoid the occurrence of streaky lines, which, when the paper is rendered sensitive, bronze strongly under the influence of the light. The writer believes these to be caused by a commencing decomposition of the animal matter composing the cells in which the albumen is retained and the best remedy appears to be to use the eggs quite fresh; the same object may sometimes (but not invariably) be attained by allowing the albumen to stand for several weeks until it has become sour; after which it will be sufficiently limpid to run through a filter.

In salting and albumenizing photographic paper by the formula above given, it was found that each quarter sheet, measuring eleven by nine inches, removed one fluid drachm and a half from the bath; equivalent to about one grain and three quarters of salt (including droppings). In salting plain paper, each quarter sheet took up only one drachm; so that the glutinous nature of the albumen causes a third part more of the salt to be retained by the paper.

Selection of the Paper.—The English papers are not good for albumenizing; they are too dense to take the albumen properly, and curl up when laid upon the liquid; the process of toning the prints is also slow and tedious. The thin negative paper of Canson, the Papier Rieve, and Papier Saxe, have succeeded with the writer better than Canson's positive paper, which is usually recommended; they have a finer texture and give more smoothness of grain.

To apply the albumen; pour a portion of the solution into a flat dish to the depth of half an inch. Then, having previously cut the paper to the proper size, take a sheet by the two corners, bend it into a curved form, convexity downwards, and lay it upon the albumen, the centre part first touching the liquid and the corners being lowered gradually. In this way all bubbles of air will be pushed forwards and excluded. One side only of the paper is wetted: the other remains dry. Allow the sheet to rest upon the solution for one minute and a half, and then raise it off, and up by two corners. If any circular spots, free from albumen, are seen, caused by bubbles of air, replace the sheet for the same length of time as at first.

The paper must not allowed to remain upon the salting bath much longer than the time specified, because the solution of albumen being alkaline (as is shown by the strong smell of ammonia evolved on the addition of the chloride of ammonium), tends to remove the size from the paper and sink in too deeply; thus losing its surface gloss.

Albumenized paper will keep a long time in a dry place. Some have recommended to press it with a heated iron, in order to coagulate the layer of albumen upon the surface; but this precaution is unnecessary, since the coagulation is perfectly affected by the nitrate of silver used in the sensitizing; and it is doubtful whether a layer of dry albumen would admit of coagulation by the simple application of a heated iron.

To render the paper sensitive.—This operation must be conducted by the light of a candle, or by yellow light. Take of

Prepare a sufficient quantity of this solution, and lay the sheet upon it in the same manner as before. Three minutes' contact will be sufficient with the thin negative paper, but if the Canson positive paper is used, lour or five minutes must be allowed for the decomposition. The papers are raised from this solution by a pair of bone forceps or common tweezers tipped with sealing-wax; or a pin may be used to lift up the corner, which is then taken by the finger and thumb and allowed to drain a little before again putting in the pin, otherwise a white mark will be produced upon the paper, from decomposition of the nitrate of silver. When the sheet is hung up, a small strip of blotting-paper suspended from the lower edge of the paper will serve to drain off the last drop of liquid.

The solution of nitrate of silver becomes after a time discolored by the albumen, but may be used for sensitizing until it is nearly black. The color can be removed by animal charcoal,[M] but a better plan is to use the "kaolin" or pure white china clay. The writer has also tried the common "pipe-clay," which answered perfectly, but appeared to injure the sensitiveness of paper subsequently floated upon the bath (?).

Sensitive albumenized paper, prepared as above, will usually keep for several days, if protected from the light, but afterwards turns yellow from partial decomposition.

Comparison of British and French Weights and Measures.

WEIGHTS.

MEASURES OF CAPACITY.

MEASURES OF LENGTH.

In weighing solids, few weights are really necessary if they are properly assorted; nothing less than half a grain is likely to be useful, and the series following will weigh any quantity from the half grain to two thousand one hundred and ten and a half grains, by differences of only a single grain.

The numbers are in grains, but the same principle may be carried out with any other denomination, whether ounces, pounds, or tons.

½, 1, 2, 3, 4, 10, 20, 30, 40, 100, 200, 300, 400, 1000, &c.

The artist should be provided with not less than three glass measures—one of a pint, graduated to ounces—one of two ounces, graduated to drachms—and one of two drachms, graduated to minims.

Lewis's Patent Glass Baths for Nitrate of Silver Solutions.—Since the foregoing pages have been in print this new article of Baths has been introduced, and will probably supersede all others now in market. They are encased in a box made expressly to hold them, and form a valuable and important improvement in the apparatus used in the various Glass processes.

INDEX.

Aberration, chromatic, 23;
spherical, 22.
Acetic acid, 66.
Albumen, 63;
preparation of positive paper with, 206.
Alcohol, 70;
used in sensitizing paper, 201.
Ammonia, 71.
Ammonio-nitrate of silver, preparation and use of, 152.
Animal charcoal, 74.

Barium, chloride of, 77.
Baths, glass, 211;
gutta-percha, 34.
Bichloride of mercury for whitening positives, 159.
Bromide and iodide of potassium and silver, 60.
Bromide of potassium, 73.
Bromine, properties of, 72.
Bromo-iodized collodion for positives, (ambrotypes), 58, 59;
for negatives, 60.

Camera boxes, 28.
Camera, construction of, 28.
Camera stands, 31.
Carbonate of soda, 73.
Chemical and visual focus, 21.
China clay, 75.
Chloride of ammonium, 77.
Chloride of barium, 77.
Chloride of gold, preparation of, 83;
for toning, 155
Chloride of sodium, 78.
Chlorine, 75.
Chromatic aberration, 22.
Citric acid, 78.
Cleaning glass plates, 129.
Coating large glasses with collodion, 160.
Collodion, manufacture of, 53;
iodized for positives, 58, 59;
for negatives, 60;
mode of coating glasses with, 131;
vials, 38.
Collodio-Albumen process, Dr. Taupenot, 190.
Color-boxes, 38.
Cutting's patents and correspondence, 173.
Cyanide of potassium, 79;
use of, 63.

Decomposition of light, 16.
Developing solution for positives, 62;
for negatives, 144, 145.
Dippers, glass and gutta-percha, 34.
Double iodide of potassium and silver, 61.

Ether, preparation of, 79.

Fixing positives on glass, 134;
negatives on glass, 146;
positives on paper, 155.
Fluoride of potassium, 81.
Fogging of collodion positives, 137.
Formic acid, 81.
Fulminating gold, 84.

Gelatine, properties of, 82;
for mounting photographs, 157.
Glass, cementing, 158.
Glass plates, cleaning of, 129;
coating with collodion, 131;
coating with albumen, 193.
Glass rods, bending of, 158.
Glycerine, its properties, 82.
Gold, chloride of, preparation of, 85;
for toning, 155.
Grape sugar, 86.

Hadow, Mr., Researches and Formula for making soluble cotton, 46;
on iodizing collodion, 54.
Head rests, 33.
Helio, collodion process for positives and negatives, 164.
Honey, 86.
Humphrey's collodion gilding, 63.
Hydrochloric acid, 87.
Hydriodic acid, 87.
Hydrosulphuric acid, 88.
Hypo bath, 203.
Hyposulphite of gold, 85.
Hyposulphite of silver, 17.
Hyposulphite of soda, preparation and properties of, 89.

Instantaneous positives, 159.
Iodide of ammonium, preparation of, 91;
for iodizing collodion, 58, 59.
Iodide of cadmium, 92.
Iodide of iron, preparation of, 93;
its uses and acceleration, 159.
Iodide of potassium and silver, preparation of, 61;
use in sensitizing collodion, 58, 60.
Iodide of potassium, properties and preparation of, 94.
Iodide of silver, preparation and properties of, 112;
its use in the nitrate bath, 65, 147.
Iodine, preparation and properties of, 90.
Iodized collodion, 58, 59, 60, 131.
Iron, perchloride of, 98.
"  protonitrate of, 97.

Jenny Lind stands, 32.

Kaolin, properties of, 75.

Lenses, double-convex, concavo-convex, double-concave, 19.
Lenses, forms of, 19, 20;
combination of, for portraits, 27;
chromatic aberration of, 23;
spherical aberration of, 22.
Leveling stands, 35.
Light, decomposition of, 16.
Litmus, 98.

Manipulations of the positive collodion process, 129;
negative process, 143.
Measures and Weights, 210.
Milk, 99.
Mounting positives on paper, 157.

Negatives for printing positives, 151, 169.
Nitrate of potash, 102.
Nitrate of silver, 116.
Nitrate of silver bath, mode of preparing for positives, 64;
for negatives, 147;
for negatives and positives in Helio's process, 164.

Nitrate of silver used in developing negatives, 145.
Nitric acid, preparation and properties of, 100;
use in nitrate bath, 65, 147;
use in making soluble cotton, 46.
Nitro-sulphuric acid used in preparing soluble cotton, 42, 51.

Oxide of silver, preparation of, 109.
Oxygen, 109.
Oxymel, preparation of, 105.

Paper, sensitive, for printing, 152;
alcohol used in, 201.
Patent for the use of camphor in combination with iodized collodion, 176;
for sealing photographic pictures, 177;
for the use of alcohol as a desiccating agent, 178;
for the use of bromide of potassium in collodion, 178;
for the use of japanned surfaces for taking positives, 179;
for photographic pictures in oil, 181;
for making transparent borders, 183;
coloring positives, 185, 187;
for albumenized collodion, 186.
Plate-Holders, Lewis's patent, solid glass corners for, 137.
Plato vices, 64.
Portrait lenses, combination of, 27.
Positives, (ambrotypes,) process for producing, 129;
by the Helio process, 164;
printing on albumenized paper, 192, 206;
ammonio-nitrate of silver used in, 152;
use of chloride of gold in toning, 155;
fixing, 155;
fixing and brightening, (ambrotypes), Humphrey's collodion gilding
used in, 63;
printing frames for, 36;
collodion for, 58, 59;
mica used for, 136.
Positives, enlarging from negatives, 199.
Potash, 105;
carbonate of, 106.
Practice of the positive collodion process, 129;
negative process. 143;
Helio's positive and negative process, 164;
printing on paper, 151.
Prism, 14;
refraction of light by, 14.
Protosulphite of iron used in developing positives. 62;
negatives, 144.
Pyrogallic acid, preparation of, 107.

Sensitizing paper, use of alcohol in, 201.
Silver, properties of, 107;
removal of stains from the nitrate of, 161;
recovery of from waste solutions, 203.
Solar spectrum, 14.
Soluble cotton, 42;
Hadow on, 46.
Spherical aberration, 22.
Spots upon positives, 139.
Stains and lines upon positives, 139.

Taupenot, M., his Collodio-albumen process, 190.
Test-paper, use of, 205.
Toning bath for positives on paper, 155.

Weights and Measures, 210.

CORRECTIONS.

[Transcriber Note: Corrections have been applied to text.]

On Page 61 and 16th line from the top, for "Iodide of Silver," read Iodide of Potassium.

On Page 167 and 2nd line, for "32 ounces," read 64 ounces.