I fear your correspondent underrates the power of the human body in enduring torture. I have seen a similar account of the execution of Damiens, with which I will not shock your readers. The subject is a revolting one, but the truth ought to be known, as it is (most humanely, I fully believe) questioned.
G. W. R.
Oxford and Cambridge Club.
PHOTOGRAPHIC CORRESPONDENCE.
Difficulties in making soluble Cotton.—In making soluble cotton according to the formula given by Mr. Hadow in the Photographic Journal, and again by Mr. Shadbolt in "N. & Q.," I have been subject to the most provoking failures, and should feel obliged if Mr. Shadbolt or any other of your correspondents could explain the causes of my failures, which I will endeavour to describe.
1st. In using nitrate of potash and sulphuric acid, with a certain quantity of water as given, I have invariably found that on adding the cotton to the mixture it became completely dissolved, and the mass began to effervesce violently, throwing off dense volumes of deep red fumes, and the whole appearing of a similar colour. I at first thought it might be the fault of the sulphuric acid; but on trying some fresh, procured at another place, the same effects were produced.
Again, in using the mixed acids (which I tried, not being successful with the other method) I found, on following Mr. Hadow's plan, that the cotton was also entirely dissolved.
How is the proper temperature at which the cotton is to be immersed to be arrived at? Are there any thermometers constructed for the purpose? as, if one of the ordinary ones, mounted on wood or metal, was used, the acids would attack it, and, I should imagine, prove injurious to the liquids.
At the same time I would ask the reason why all the negative calotypes I have taken lately, both on Turner's and Sandford's papers, iodized according to Dr. Diamond's plan, are never intense, especially the skies, by transmitted light, although by reflected light they look of a beautiful black and white. I never used formerly to meet with such a failure; but at that time I used always to wet the plate glass and attach the paper to it, making it adhere by pressing with blotting-paper, and then exciting with a buckles brush and dilute gallo-nitrate. But the inconvenience attending that plan was, that I was compelled to take out as many double slides as I wished to take pictures, which made me abandon it and take to Dr. Diamond's plan of exciting them and placing them in a portfolio for use. I imagine the cause of their not being so intense is the not exposing them while wet.