THE PHOTOGRAPHIC NEWS. November 9, 1860. p.329
Read at the Meeting of the Photographic Society of London, on the 6th [illegible]
I HAVE, from the first announcement of M. Niepce de St. Victor's alleged discovery of a new property of light, taken a constant interest in the controversy to which it has given rise. I have ever been sceptical as to its truth, thinking it might be explained by a reference to known physical laws. Although I had formed several opinions as to the cause of the result, I took no experimental steps until after the appearance of Mr. Crookes's demonstration that the heat and moisture of the tube, joined to the tartaric acid used, were sufficient to account for of the result of Niepce's main proof experiment. M. Niepce, [illegible] apparently set right, replied to Mr. Crookes by making the same experiment under a freezing mixture arrangement. He still got the result he had all along insisted upon; but he owned and other agents could simulate his original results. Not observing any reply from Mr. Crookes--who I believe was then much occupied determined to read M. Niepce's original papers, in the Comptes Rendus of the French academy. I there found that M. Niepce set out in a manner dangerous for most experimenters namely, with the notion that light might be absorbed icy bodies in such a way as to be given out again; the action to be made manifest by photographic papers. A great number of experiments made in a variety of ways convinced him that he was right in his conjecture. Disregarding, for the present, his earlier forms of experiment, I decided on examining most scrupulously his latest result, given in reply to Mr. Crookes. I read carefully his note, and was at once struck with the form of his experiment. He places between the vessel containing the alleged stored-up light a piece of paper, having impressed upon it what he calls "gros caracteres," which by some odd association of ideas I interpreted to mean the heading of a newspaper. I came upon this thought by recollecting that the French printers use an ink which is very offensive to an English taste, and it at once occurred to me that the tarry ink might be at the bottom of M. Niepce's result. I had found it to act upon nitrate of silver. Whatever these notions were worth, they induced me to resolve to try at once M. Niepce's experiments minus the chief agent--the light. I took advantage of the opportunity the London Institution newspaper-room affords to secure a freshly-arrived copy of the Indépendence Belge. the bituminous odour of which was unmistakable. it was the evening edition, and arrived here early in the morning. I at once placed it in a dark room with its title-page in contact with a paper washed over with a neutral solution of nitrate of silver. I left the whole in the copying frame for an hour. M. Niepce names six hours. After that time, just as I anticipated, I got, by a wash of gallic acid, a positive, but on looking at the paper against the light, I found this appearance to be mainly due to the penetration of the gallic acid wherever the letters had been in contact: a differential action was evidently at work, and accounted for all the appearances. No light was used by me during the experiment. A copy of the Times newspaper, similarly treated at the same time, gave only the faintest indication of its title; only that I looked for it, it would have escaped notice. The other paper was distinct in its action. Upon drying the result a curious appearance was observed: the surface became faintly negative as though the printing ink had suspended on the surface, the reduction of the silver salt. The back of the paper now presented an appearance well known to Talbotype photographers, namely that of a negative become positive at its back. This I think due to the penetration of the gallic acid, and consequential internal spontaneous deposit. These differential actions will doubtless now be made clear in all their relations. Upon informing Mr. Hardwich of my results, he reminded me of a paper by Mr. Busk, who proved that almost any engraving without exposure to light, could be shown to have the power of suspending the photographic properties of chloride of silver; but as he uses light at one stage of his experiment, his result differs from mine, and is not accepted by M. Niepce's advocates as a solution of the controversy. My experiment is, I take it, a simple repetition of M. Niepce's, minus the disputed agent, the light. I am still investigating further the exact physical and chemical causes of the varied phenomena which have so long perplexed us. I may perhaps be permitted to say that I regret that I have not been able to confirm the conclusions of one to whom we are so much indebted for the introduction of albumen into photography.
PRINTING AND TONING OF ALBUMENIZED PRINTS.
[[NB APPEARS TO BE INCOMPLETE --wh]]BY J. STUART.
Read at the Meeting of the City of Glasgow and West of Scotland Photographic Society, October 4, 1860.
THE question is often asked by those who are about to supply themselves with photographic mementos of the living: "Are they permanent?" I have no doubt as to the permanency if proper precautions be taken to free them from the chemicals used in the fixing. I am sorry that so many think a few hours' washing will do for the freeing of the print from the hyposulphite. It has always been my opinion that mere soaking is not sufficient if they are intended to be permanent. To my mind a certain amount of friction is requisite to force a union between the water and the soda left in a newly-fixed print. Tepid water is an excellent substitute for pressure, as the soda dissolves much more rapidly in it than in cold water. I should not consider that prints floated in cold water would be at all permanent. It is the duty of all who are engaged in supplying the public with paper prints to do all in their power to make them permanent; if not, it will quickly tell upon them-selves. The public will soon find out that they are not getting lasting mementoes, but "dissolving views."
[[nb I assume there is more that we don't have --wh]]