982 Transactions of the American Institute. 



those to which the iodides were first added ; in which statement Mr. 

 D. Chapman and Mr. II. J. Newton concurred. 



The photographs of supposed hieroglyphics exhibited by Mr. New- 

 ton at the last meeting were then further discussed by Dr. Boynton 

 and others ; after which the Section adjourned. 



January 2, 1872 



Mr. Henry T. Anthony in the chair ; Mr. O. G. Mason, Secretary. 



Most of the evening was taken up by a discussion upon the chemi- 

 cal composition and permanency of photographic impressions on 

 albumen paper ; in the course of which it was stated that sensitized 

 paper, which had become discolored by keeping, could be restored to 

 whiteness by merely passing it through pure water. 



Mr. H. T. Anthony narrated the circumstances under which he was 

 led to originate the process of fuming sensitized paper with ammonia. 

 He had been experimenting with ammonia in fuming sensitized 

 plates. While walking on Broadway the thought came to him that 

 any acid condition of the sensitized paper must, in toning, produce 

 an unnecessary reduction of golcl, and that, consequently, there would, 

 be great economy in removing any such acidity, or, at least, in 

 reducing it to a minimum. He immediately returned to his photo- 

 graphic room and tried the fuming of paper, in which he met with 

 complete success. 



Mr. O. G. Mason stated that, by a series of experiments which he 

 had tried during the last year, he was led to believe that the chloride 

 or iodide salts commonly used would, remain permanently sensitive 

 to light if rendered sufficiently acid to neutralize the effects of the 

 atmospheric alkalies. He attributed the rapid deterioration of sensi- 

 tized paper during the prevalence of warm, damp weather, to greater 

 amount of alkaline vapor then present in the atmosphere. He had 

 been able to keep sensitized albumen paper nearly two years without 

 any apparent change, by merely rendering it slightly acid and 

 excluding the continual contact of air by keeping it in a tin case. 

 On such paper he had produced first-class prints after neutralizing the 

 acid by ammonia fumes. He believed that a simple apparatus might 

 be constructed for fuming tannin and other dry plates just previous 

 to exposure in the camera ; and that they might thus be rendered 

 very nearly, if not quite, as sensitive as the ordinary wet plates. 



Adjourned. 



