would, if carefully and honestly stated by some twenty or thirty photographers, be extremely valuable. Of this there can be little doubt, and we hope that our scientific photographic friends, will respond to this suggestion. We for our parts are ready to receive any such communications, and will, at the end of the month, collate and arrange them in such form as may best exhibit the results. It is obvious that, in a matter of such a nature, we at least should be furnished with the names of our correspondents.
The Céroléine Process.—The unfavourable state of the weather has prevented me from making many experiments as to the value of the process given in your 234th Number, but I have seen enough to convince me that it will effect a great saving of trouble, and be more sensitive than any modification of Le Gray's process that has yet been published. It will, however, be rather more expensive, and, in the hands of persons unaccustomed to chemical manipulations, rather difficult; but the solutions once made, the waxing process is delightfully easy.
William Pumphrey.
On preserving the Sensitiveness of Collodion Plates.—The Philosophical Magazine of the present month contains a very important article by Messrs. Spiller and Crookes upon this great desideratum in photographic practice. We have heard from a gentleman of considerable scientific attainments, that, from the few experiments which he had then made, he is convinced that the plan is quite feasible. We of course refer our readers to the paper itself for fuller particulars as to the reasoning which led the writers to their successful experiment, and for all enumeration of the many advantages which may result from their discovery. Their process is as follows:
"The plate, coated with collodion (that which we employ contains iodide, bromide, and chloride of ammonium, in about equal proportions), is made sensitive by immersion in the ordinary solution of nitrate of silver (30 grains to the ounce), and after remaining there for the usual time, is transferred for a second solution of the following composition:
Nitrate of zinc (fused)
2 ounces.
Nitrate of silver
35 grains.
Water
6 ounces.
The plate must be left in this bath until the zinc solution has thoroughly penetrated the film (we have found five minutes amply sufficient for this purpose, although a much longer time is of no consequence); it should then be taken out, allowed to drain upright on blotting-paper until all the surface moisture has been absorbed (about half an hour), and then put by until required. The nitrate of zinc, which is still retained on the plate, is sufficient to keep it moist for any length of time, and we see no theoretical or practical reason why its sensitiveness should not be retained as long: experiments on this point are in progress; at present, however, we have only subjected them to the trial of about a week, although at the end of that period they were hardly deteriorated in any appreciable degree. It is not necessary that the exposure in the camera should be immediately followed by the development, as this latter process can be deferred to any convenient opportunity, provided it be within the week. Previous to development, the plate should be allowed to remain for a few seconds in the original thirty-grain silver-bath, then removed and developed with either pyrogallic acid or a protosalt of iron, and afterwards fixed, &c. in the usual manner."
| Nitrate of zinc (fused) | 2 ounces. |
| Nitrate of silver | 35 grains. |
| Water | 6 ounces. |
Replies to Minor Queries.
Tippet (Vol. ix., p. 370.).—P. C. S. S. cannot help thinking that tippet is nothing more than a corruption, per metathesia, of epitogium. Such, at least, seems to have been the opinion of old Minsheu, who, in his Guide to the Tongues, 1627, describes it thus:
"A habit which universitie men and clergiemen weare over their gownes. L. Epitogium, ab ἐπὶ and toga."