Benj. Russell.
[Agreeing, as we do most entirely, with the Photographers of Norwich in their estimate of the skill and perseverance exhibited by Dr. Diamond in simplifying the collodion and paper processes, and of his liberality in making known the results of his experiments, we have great pleasure in giving publicity to this recognition of the services rendered by Dr. Diamond to this important Art.]
Simplification of the Wax-paper Process.—At a late meeting of the Chemical Discussion Society, Mr. J. How read the following paper on this subject:—
"The easiest way of waxing the paper is to take an iron (those termed 'box-irons' are the cleanest and best for the purpose) moderately hot, in the one hand, and to pass it over the paper from side to side, following closely after it with a piece of white wax, held in the other hand, until the whole surface has been covered. By thus heating the paper, it readily imbibes the wax, and becomes rapidly saturated with it. The first sheet being finished, I place two more sheets of plain paper upon it, and repeat the operation upon the top one (the intermediate piece serving to absorb any excess of wax that may remain), and so on, sheet after sheet, until the number required is waxed.
"The sheets, which now form a compact mass, are separated by passing the iron, moderately heated, over them; then placed between folds of bibulous paper, and submitted to a further application of heat by the means just described, so as to remove all the superfluous wax from the surface, and render them perfectly transparent—most essential points to be attended to in order to obtain fine negative proofs.
"I will now endeavour to describe the method of preparing the iodizing solution.
"Instead of being at the trouble of boiling rice, preparing isinglass, adding sugar of milk and the whites of eggs, &c., I simply take some milk quite fresh, say that milked the same day, and add to it, drop by drop, glacial acetic acid, in about the proportion of one, or one and a half drachm, fluid measure, to the quart, which will separate the caseine, keeping the mixture well stirred with a glass rod all the time; I then boil it in a porcelain vessel to throw down the remaining caseine not previously coagulated, and also to drive off as much as possible of the superfluous acid it may contain. Of course any other acid would precipitate the caseine; still I give the preference to the acetic from the fact that it does not affect the after-process of rendering the paper sensitive, that acid entering into the composition of the sensitive solution.
"After boiling for five or ten minutes, the liquid should be allowed to cool, and then be strained through a hair sieve or a piece of muslin, to collect the caseine: when quite cold, the chemicals are to be added.
"The proportions I have found to yield the best results are those recommended by Vicomte Veguz, which I have somewhat modified, both as regard quantities and the number of chemicals employed. They are as follow:
| 385 | grains | of iodide of potassium. |
| 60 | " | of bromide. |
| 30 | " | of cyanide. |
| 20 | " | of fluoride. |
| 10 | " | of chloride of sodium in crystals. |
| 1½ | " | of resublimed iodine. |