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.