PHOTOGRAPHIC CORRESPONDENCE.
The Calotype Process.—I have made any first essay in the calotype process, following Dr. Diamond's directions given in "N. & Q.," and using Turner's paper, as recommended by him. My success has been quite as great as I could expect as a novice, and satisfies me that any defects are due to my own want of skill, and not to any fault in the directions given. I wish, however, to ask a question as to iodizing the paper. Dr. Diamond says, lay the paper on the solution; then immediately remove it, and lay on the dry side on blotting-paper, &c. Now I find, if I remove immediately, the whole sheet of paper curls up into a roll, and is quite unmanageable. I want to know, therefore, whether there is any objection to allowing the paper to remain on the iodizing solution until it lies flat on it, so that on removal it will not curl, and may be easily and conveniently laid on the dry side to pass the glass rod over it. As soon as the paper is floated on the solution (I speak of Turner's) it has a great tendency to curl, and takes some time before the expansion of both surfaces becoming equal allows it to lie quite flat on the liquid. May this operation be performed by the glass rod, without floating at all?
Photographers, like myself, at a distance from practical instruction, are so much obliged for plain and simple directions such as those given by Dr. Diamond, which are the result of experience, that I am sure he will not mind being troubled with a few inquiries relative to them.
C. E. F.
Hockin's Short Sketch.—Mr. Hockin is so well known as a thoroughly practical chemist, that it may suffice to call attention to the fact of his having published a little brochure entitled How to obtain Positive and Negative Pictures on Collodionized Glass, and copy the latter upon Paper. A Short Sketch adapted for the Tyro in Photography. As the question of the alkalinity of the nitrate bath is one which has lately been discussed, we will give, as a specimen of Mr. Hockin's book, a quotation, showing his opinion upon that question:
"The sensitizing agent, nitrate of silver in crystals, not the ordinary fused in sticks, is nearly always confessedly adulterated; it is thus employed:
"The silver or nitrate bath.—Nitrate of silver five drachms, distilled water ten ounces; dissolve and add iodized collodion two drachms.
"Shake these well together, allow them to macerate twelve hours, and filter through paper. Before adding the nitric acid, test the liquid with a piece of blue litmus paper; if it remain blue after being immersed one minute, add one drop of dilute nitric acid[[3]], and test again for a minute; and so on, until a claret red is indicated on the paper. It is necessary to test the bath in a similar manner, frequently adding half a drop to a drop of dilute acid when required. This precaution will prevent the fogging due to alkalinity of the bath, so formidable an obstacle to young hands."
Footnote 3:[(return)]
"Dilute nitric acid.—Water fifty parts, nitric acid one part."
Photographic Society's Exhibition.—The Photographic Society opened their first Exhibition of
Photographs and Daguerreotypes at the Gallery of the Society of British Artists, in Suffolk Street, with a soirée on Tuesday evening last. Notwithstanding the inclemency of the weather, the rooms were crowded not only by members of the Society, but by many of the most distinguished literary and scientific men of the metropolis. The Queen and Prince Albert had, in the course of the morning, spent three hours in an examination of the collection; and the opinion they expressed, that the exhibition was one of great interest and promise, from the evidence it afforded of the extraordinary advance made by the art during the past year, and the encouragement it held out to the belief that far greater excellence might therefore still be looked for in it, was a very just one, and embodied that given afterwards by the most competent authorities. We have not room this week to enter into any details, but can confidently recommend our readers to pay an early visit to Suffolk Street.