PHOTOGRAPHIC NOTES AND QUERIES.
Portable Camera for Travellers.—Your correspondent E. S. asks for a clear description of a camera that will supersede the necessity of a dark room. Mr. Stokes has invented one; and in the early part of the photographic exhibition at the Society of Arts it was exhibited. The weight of the camera is only nine pounds, including focussing-glass, lens, shutter, &c. The shutter is so arranged that it will contain from twelve to twenty pieces of prepared paper, each piece between separate sheets of blotting-paper. Light and air are completely excluded, by the paper being pressed by the front portion of the shutter. When required for use, the first piece of paper is placed at the back of the glass. By the assistance of a small hood, the impression is then taken; and, by removing the millboard, the paper will fall back into its place. At the same time another piece can be brought forward, ready for a second picture, before focussing, and so on to the end. The hood is made of India rubber cloth, and answers the purpose of a focussing cloth, without the trouble of removing it from the camera throughout the day. The size of the pictures that can be taken by it is 9½ by 12 inches. It has been tried during the latter part of the last year, and proved most successful.
Philip H. Delamotte.
Bayswater.
The Albumen Process.—I shall be greatly obliged to Dr. Diamond, or any other photographer, by their kindly communicating through your medium their experience with albumenized glass. I have Thornthwaite's Guide to Photography.
I should like answers to the following Queries:
Must the albumen be poured off from the plate after it is spread over the surface, in the same manner as collodion?
Is the plate (while roasting, according to the process of Messrs. Thompson and Ross) nearly perpendicular in the process?
Will the iodized albumen, for giving the film, keep; and how long?
How long will the plate retain its sensitiveness after exciting?
May the same sensitive bath be used for a number of plates without renewing, in the same way as silver bath for collodion?
In conclusion, what is the average time with single achromatic lens, six or seven inch focus, to allow to get a good picture?
Will photographers who are chemists turn their attention to obtain sensitive dry glass plates? for I think there can scarcely be any doubt of the advantage of glass over paper for small pictures (weight, expense, &c., are perhaps drawbacks for pictures larger than 5 × 4 inches); but the desideratum is a sensitiveness nearly equal to collodion, and a plate that can be used dry.
Thos. Lawrence.
Ashby-de-la-Zouch.
Black Tints of French Photographers.—Can you inform me, through the medium of your valuable periodical, how those beautiful black tints, so much prized in the French prints from photographic negatives, are obtained? By so doing you will give great pleasure to several excellent amateur photographers, and especially your constant reader,
Philophotog.
Originator of the Collodion Process.—As some think the credit of the invention of the collodion process a matter of dispute, will you allow me to remind your correspondents that the truth will be much easier to discover if they will confine themselves to actual facts?
In No. 167., p. 47., G. C. first recklessly accuses Mr. Archer of untruth, and then tests his own claim to truth by quoting from Le Gray's edition of 1852, to prove Le Gray's edition of 1850. Why did he not go back at once to the 1850 edition; and if that contains anything like an intelligible process, why is it altogether omitted from Le Gray's edition of 1851, which was the one Mr. Archer spoke of, and correctly?
The history of collodion is (as far as I know) this. In September, 1850, Dr. Diamond invited me to meet Mr. Archer at his house, and for the first time Mr. Archer produced some prepared collodion, a portion of which identical sample Dr. Diamond now has in his possession.
Mr. Archer had then been trying it some five or six weeks. His experiments then went on, and in March, 1851, he published it in the Chemist. Let any of your readers procure that Number, and compare Mr. Archer's claim with Le Gray's, who, in 1852, states that he published it in 1850, and gave "the best method that has been discovered up to the present time;" and yet, singularly enough, in his edition of 1851, leaves out this best method entirely.
W. Brown.
Ewell.
Developing Paper Pictures with Pyrogallic Acid, &c.—Have any of your photographic correspondents tried developing their paper negatives with pyrogallic acid? If so, perhaps he would favour the readers of "N. & Q." with the result of his experiments.
In Dr. Diamond's process for paper negatives, he says the paper, after the iodizing solution has been applied, must be dried before soaking in water. I wish to ask whether it may be dried quickly by the fire, or must it be dried spontaneously by suspension, &c.? Again, how long must the paper remain on the sensitive mixture: must it be placed on the sensitive solution, and immediately taken off and blotted, or placed on the sensitive solution, and after some time (what time?) taken off and immediately blotted?
Have any of your readers substituted iodide of ammonium for iodide of potassium, in preparing paper, collodion, &c., and with what success? And have they substituted nitrate of zinc for glacial acetic acid, as recommended in a French work, with any success?
R. J. F.