Proceedings of the P hotogbaphical Section. 979 



pared by precipitating the silver by means of caustic potash, and, 



after thorough washing, dissolving in a saturated solution of nitrate 



of ammonia, then saturate with oxide of silver, and reduce to the 



strength desired. 



Adjourned. 



November 7, 1871. 



Mr. H. J. Newton in the chair ; O. G. Mason, Esq. , Secretary. 



After the usual preliminary business, Mr. C Wager Hull explained 

 his recent experiments in the use of albumen as a substratum for wet 

 and dry plates. He believed that the results obtained by him may 

 have differed from those by Mr. Newton, from the fact of his having 

 used a much heavier body of albumen. 



Mr. H. J. Newton stated that the more complete the solution of 

 albumen (in an alkaline condition), the more compact or harder it 

 became, when dry, on the plate. He proposed albumen. for this pur- 

 pose made as follows : The white of one egg dissolved in ten ounces 

 of water, afterward mixed with eight ounces of water, containing 

 one ounce of alcohol, ten grains of iodide of ammonium, and five 

 grains of bromide of potassium. The solution is improved by keep- 

 ing it two or three weeks in a vessel tightly corked. 



Mr. II. T. Anthony said he had been the first to use albumen as a 

 substratum. At first he had experimented with a view of producing 

 & sensitive film of albumen ; but he found that the salted albumen 

 dissolved, and mixed with the bath or sensitizing solution. He after- 

 ward found that by using collodion over the albumen, a very sensi- 

 tive film was produced, and the action was much more uniform. 



Mr. II. J. Newton stated that the fresh albumen of one egg mixed 

 with six ounces of water, to which three or four drops of aqua 

 ammonia had been added, made the best substratum for collodio- 

 chloride plates. He believed that many photographers had discarded 

 the collodio-chloride, when the real fault was in the albumen which 

 they used. 



Mr. J. B. Gardner preferred plain albumen, without the addition 

 €»f ammonia. For the final cleaning of his plates, he used alcohol, 

 acidulated by the addition of a small quantity of acetic acid. He 

 flows the plate with albumen when perfectly dry, and thus avoids 

 any liability to injure his silver bolution from albumen on the back of 

 the plate. 



