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January 17, 1868.] THE PHOTOGRAPHIC NEWS. 33 Evon engravings, would change by tho discolouration of the paper. The whole question was one of degree, as there wore the elements of destruction in everything. The presenc: of silver in tho whites of the print where it was not required was one of their chief troubles, as it was there ready at once to register the action of any agency acting injuriously on silver, and show it in the most delicate part of the picture. Mr. Johnson said that the question existed as to whether the silver in tho whites was more sensitive than tho reduced silver which formed the shadows of tho print. Mr. Hart thought the great drawback to photographs was the lowering of tho tone of tho whites arising from tho presence of silver there ; and that if it could be removed the chief cause of fading would bo got rid of. Tho reduced silver which formed the dark parts of tho print were coated with gold, which would resist the action of tho deteriorating agencies to which Mr. Johnson referred. Mr. Frank Eliot said, that having already communicated the results of some experiments to the PHOTOGEAPIIIC News Almanac, he would not enter further into the question than to remark that tho print which Mr. Spiller exhibited, in which ho had removed tho silver from tho whites by cyanide, but had also injured tho brilliancy of tho print, had been too perfectly toned with gold to commence with. Probably, had it been less toned, loft in a rodder state, tho result of tho cyanide treatment would not have been so injurious. Ho would ask Mr. Spiller if ho had tried tho effect of a littlo cyanide mixed with tho hypo fixing bath. Mr. Spiller had not, bat thought tho suggestion worth trying. After some conversation, Mr. Spiller, referring to tho remarks of Mr. Johnson, said that tho gold toning upon tho silver print was an inportant element not to bo overlooked, and if a silver coin wore coated with a very slight deposit of gold it would bo effectually pro tected from tho action of sulphur. Ho quite agreed with Mr. Johnson, however, that silver prints would always bo subject to deteriorating influences. Tho Chairman, in proposing a vote of thanks to Mr. Spiller, remarked that in his practice with tho photographic registra tion at tho Observatory they adhered now to tho practice of twenty years ago, in using plain paper, in which tho insoluble salt of silver formed in tho albumen was avoided, and a better chance of permanency obtained. After a vote of thanks, Tho Chairman, in calling attention to Mr. Goodo’s casol for touching negatives, described a similar one ho had in use at Greenwich. Ho also mentioned a curious fact, to tho effect that having, in order to secure uniform temperature, removed their apparatus for photographic registrations into a room with littlo ventilation, they found that when tho fire and gas had consumed tho oxygen in the room, tho action on tho paper became much loss perfect. It was then announced that at tho next mooting, besides tho annual business, Mr. Johnson would reail a paper on a now system of landscape photography. Tho proceedings then terminated'. Gorrespondeute. REMARKS UPON THE CHEMISTRY OF PHOTOGRAPHY. Sir,—Photography may be compared to gambling, the prizes being few and tho blanks many. Yet there arc good and bad photographers, just as there arc good and bad card players. Games of chance, by tho observance of certain Jaws, often bring success. Photography has its “ lucky ” ones; so has the turf. A friend of mine has j ust told mo of a person whom he sup- plied with instruments and chemicals; and, although he had never done anything before in the art, I am assured that he has taken in the first fortnight a number of very fine photo graphs. But my friend is afraid, as I am, that his success will ultimately turn out to be his ruin, for he is determined at once to commence professionally. No advice can prevail on him to wait; and, unless a bad case of fogging, followed by other photographic diseases, immediately afflict him, a hundred to one ho will be ruined. “ Tips ” arc not confined to the turf, for you can obtain photographic information that will relieve you of all your difficulties for 2s. Gd. in postage stamps. If that be too much to believe, why, you have only to send for that collo dion and developer which never fail to give perfection. I need not say that if this were so, photographic failures would be almost unknown. Before proceeding with any further remarks, I think it just to myself to state that this is a subject that I have un dertaken to write upon only at the request of a number of friends. There were many weighty reasons for my diffi dence, not the least of which was a reluctance to differ very materially with the first chemists and photographers of tho day. This feeling amounted almost to a relinquishment of any publication whatever of the results of my experience. Selfish reasons have also had their weight; for I admit that it took some time toconsider whether I would be just to myself by giving to the world what has cost me so mneh in money and time. But, after taking everything into serious consi deration, I have determined to freely publish all that I know, on certain conditions—which conditions, if acted upon, will accomplish more in every way than a discussion, which would probably end in nothing of real value. The wet collodion process has been practised by me pro fessionally since its first introduction by Archer, and what I am willing to communicate has been known to me and tested for two years. I have read nearly all that has been published in English on the subject; but in no publication can 1 get an insight into the principles of photography, only a list of the different materials affected by light, and the numerous different formulae for putting them together— some better and some worse, but all very imperfect, inasmuch as the very best seldom give the highest possible result, and when they do they cannot be depended on for any length of time. The same failures which were inherent in the process on its first introduction belong to it yet. Whatever success some have attained can only bo attributed to good manipu lation, long practice, and, perhaps, quite as much as any thing else, to an almost unlimited choice of material to mix and doctor as experience points out will suit different cir cumstances. This much is admitted by the majority of leading photographers, as they tell us they have nothing new to communicate. Photography, as an art, has made giant strides; as a science, it lags behind. Better knowledge of its laws would enable us to enter new fields and gather richer harvests than any yet reaped. From my first connection with photography I have striven earnestly and constantly, sacrificing wealth, health, and comfort—in fact, most things a man values have have I counted as nothing in comparison to success in realis ing an idea of certain chemical combinations that, in my opinion, would throw a new light on the foundations of tho science, which idea I had formed before I was in practice twelve months. Reason told me that what I was working for was quite possible, yet my innumerable experiments so disappointed me, as to often take away all hope of success; but still I perse vered, and in time a certain success has rewarded my efforts. But there is much to be done yet, and the knowledge I have already gained has given me the master-key that is certainly destined to unlock every secret. I will now endeavour to distinctly state what I have and what I can accomplish. First,—I can prepare my chemicals so that I can with certainty produce, consecutively, a great number of the highest class of negatives entirely free from every kind of imperfection ; their production can be abso lutely relied upon for a lengthened period, and quite out of all proportion to what can be accomplished by any pub lished formula. For instance, I have (produced from two ounces of nitrate of silver four hundred half-plate negatives. The chemicals were not altered in any way by me; worked