1074 Transactions of the American Institute. 

 December 7, 1869, 



Professor Chakles A. Jot, Vice-President of the Section, in the cliair'; Mr. O. G. 

 Mason, Secretary. 



Mr. Newton exhibited a sample of alkaline negative solution 

 made from nitrate of silver crystals wliich liad been exposed to the 

 snn, and a negative which he had made on a plate sensitized in the 

 solution exhibited. He used a number of test papers before the Sec- 

 tion, which made the condition of the solution apparent to all'present. 



Professor S. D. Tillman remarked that the discovery made by Mr. 

 Newton was singular, and likely to lead to important results. Assum- 

 ing the proof positive that crystals of pure nitrate of silver, when 

 exposed to direct sunlight for a given time, will be changed in appear- 

 ance and, it seems, in character also, since an aqueous solution of 

 this neutral salt after such treatment has been shown to be decidedly 

 alkaline, the nature of this change becomes a question of great inter- 

 est, because it diifers from any chemical action before observed. He 

 did not believe that the alkalinity of the compound was due to a 

 single element, but was the result of the unusual combination oT two 

 ■elements, resembling somewhat the action by which the volatile 

 alkali ammonia is produced by the union of three atoms of hydrogen 

 with one atom of nitrogen, neither of which in a separate state 

 exhibits any characteristics which would lead us to suppose tha{ any 

 alkaline compound would result from their combination. The body 

 Tinder consideration contains nitrogen, which, as regards its atomicity, 

 is generally a triad, its least quantivalende or saturating power being 

 tri-atomic, and as seen in the case of ammonia, one atom of it is 

 capable of holding three atoms of the monad element, hydrogen. The 

 strongest reason for supposing that silver may play the same part as 

 hydrogen is that both are monatomic. Only nine other elements are 

 usually classed among monads, namely, fluorine, chlorine, bromine 

 >and iodine among the electro-negatives ; and lithium, sodium, potas- 

 sium, rubidium, and coBsiuni among the electro-positive simple 

 bodies. 



If we suppose that the presence of water is necessary to the con- 

 summation of this change, we may represent the new combination 

 by following the example of Berzelius, who regarded even an aqueous 

 solution of ammonia as the oxyd of ammonium, the latter being a 

 hypothetical compound consisting of four atoms of hydrogen and one 

 atom of nitrogen. A molecule of water and of nitrate of silver 



