PnOTOGRAPHICAL SECTION PROCEEDINGS. 1109 



ready for use. I exhibited some plates preserved with this process 

 to the members of the photographic society at one of our meetings 

 last fall, at which Mr. Rockwood was present. He stated that he 

 had used tea for preserving dry plates, and at times produced very 

 fine results, but he had used Oolong tea, and he often found his 

 plates bad where there had been no change except in the tea. If I 

 recollect right, he stated that he published some of his experiments ; 

 «but, as far as I was concerned, I had no recollection of ever 

 seeing any published process for using tea for a preservative. I 

 have used, in experimenting, loaf-sugar and also rock-candy in 

 these solutions, but prefer and would recommend sugar of milk. I 

 made a very sensitive plate by adding a grain and a half to the ounce 

 of acetate of morphia to my tea solution ; it worked in one-fourth of 

 the time ; whether they will keep I am unable to say. I have one, 

 however, which is several months old, that will test that point when 

 used. There was one drawback, however, to its adoption ; the same 

 difficulty presented itself that appeared in the tannin, into which I 

 introduced acetate of morphia ; the tea soon became turbid and unfit 

 for use, except, perhaps, as an anodyne. Whether the morphia 

 could not be introduced into these other solutions, in the same way 

 adopted with the tannin, with the same or still more beneficial 

 results, I have not yet had an opportunity to demonstrate. Since 

 the publication in the Philadelphia Photograj^her^ of Mr. Carey 

 Lea's modified Gordon's gum process, where he claims to have pro- 

 duced dry plates with his bromide of silver collodion, as sensitive as 

 wet ones, I have applied this gum formula to, dry plates made in the 

 ordinary way ; the only change from Gordon's is the substitution of 

 twelve grains to the ounce of sugar instead of five, with the addition 

 of carbolic acid to preserve it. In my experiments last summer with 

 Gordon's process, I used two drops of the solution of carbolic acid to 

 five ounces of the gum solution, to prevent its changing. With this new 

 gum formula I have produced very sensitive plates, requiring from thirty 

 to forty-five seconds exposure with an iron developer ; according to 

 my recollection, that was the time I found necessary for the old for- 

 mula. Those experiments, however, were made in midsummer, 

 which would show increased sensitiveness by the new formula of at 

 least one-third. I have made very beautiful dry plates, about one- 

 quarter more sensitive than the tannin plate, with a strong tea made 

 with white oak bark, I have also used, as a preservative, bisulphate 

 ■ of quinine, peruvian bark, quassia, rhubarb root, sumach leaves, with 



