54 HYrONlïillTES ; PIIOPERÏIES ANt> PRËPAÉATION BY 



Effects of heating silver hyponitrite. 



In my first paper it is stated that silver hyponitrite is de- 

 composed by a moderate heat into nitric oxide, metallic silver, 

 and a little silver nitrate — in this resjDect resembling silver ni- 

 trite, and that it does not fnse or exhibit any other change except 

 that from a bright yellow to a silver-white colonr. That is still 

 a correct statement, so far as it goes, but it is imperfect. In 

 1887 van der Plaats stated that silver hyponitrite decomposes 

 explosively Avlien heated ; presumably his preparation contained 

 acetate. Timm, who properly denied its explosive character in 

 1893, observed that in decomposing by heat, the l)right yellow 

 salt becomes dark brown before assuming the svliite colour of 

 silver, while Kirschner found (1898) that the salt becomes tem- 

 porarily black. Tlium's observation was due, I think, to tlie 

 very dense red, almost opaque, hot nitric peroxide which then 

 pours forth and through wldcli at times the solid mass does 

 look very dark. Kirschner's observation may Ije due also to 

 this cause or to his hyponitrite having contained sulphite. How- 

 ever this may be, the salt decomposes with only the change of 

 colour I have described and in a lump of the precipitate the 

 change can be followed by movement of the sharp boundary 

 line between the bright yellow salt and bright white metal, just 

 as it can be followed in calcium oxalate decomposing by heat ; 

 there is no brown or black intermediate stage. Thum seems to 

 have found no silver nitrate, but observed the production of 

 dense red fumes even when the salt was heated in an atmosphere 

 of carbon dioxide and at a temperature not much (?) above 100°. 

 From the important observation of the generation of nitric 2)er- 

 oxide he concluded that the decomposition of silver hyponitrite 



