12, The Action of Light on Silver Chloride. 
By P. S. MacManon. 
[Read at the First Indian Science Congress on January 15, 1914.] 
the nature of the coloured compound or products obtained by 
the action of light on silver chloride. The results hitherto 
subsequently disclosed, but it is hoped that some explanation 
has been found of certain discrepancies between two of the 
subchloride of silver, secondly, that it is an oxychloride, and 
thirdly, that it is an allotropic form of reduced silver. — 
the scientific foundations to the modern art of coloured pho- 
tography. The experimental basis upon which this hypothesis 
Tests, consists briefly in the fact that the darkening of AgCl in 
Sunlight ig accompanied by an evolution of small quantities 
of chlorine and that the resultant substance obtained contains 
in Consequence more Ag than corresponds to the formula 
AgCl but that no metallic Ag can be dissolved out of it by 
dilute HNO The existence of a subchloride insoluble in HNO, 
ed 
ti © second theory forms the subject to which most atten- 
a sh een given up to the present stage of the investiga- 
» an 
found untenable. The third theory, a modified form of which 
