254 » ^- CHIKASHIGE. 



them. Beyond the well known fact that the mixed solutions are 

 intensely green, no sign of any action was ohserved. When the solid 

 salts, a little damp, were heated together, nlso as recommended by 

 Johnstone, watery fusion occurred and the wnter boiled off without 

 o'as beinof o-enerated. When, however, the water being' Sfone, the 

 residue got much hotter, there occurred, as might have been an- 

 ticipated, an explosive reaction in which torrents of gases escaped. 

 These gases, collected over water and gradually mixed with oxygen, 

 proved to consist of nitric oxide to the extent of about two-thirds 

 of their volume, the rest being prin('i])ally nitrogen. Carbon dioxide 

 and ammonia were also freely given off. and condensed together to 

 form a sublimate, and a cloud, and a sohition in the trough-water, of 

 ammonium carbonate or carbamate. The residue smelt strongly of 

 ammonia and was black from the presence of cobalt sulphide, but did 

 not contain the sulphur and the carbon which eJohnstone supposed are 

 formed, at least not in quantities which I (^ould detect. 



It is a matter of common experience that potassiiun thiocyanate 

 boiled with dilute nitric acid is decomposed with evolution of nitric 

 oxide and other gases, being partly oxidised and partly converted into 

 the insoluble yello\^' perthiocyanogen. N<3w, only a small cjuantity 

 or, rather, only a weak concentration, of nitric acid is needed for this 

 reaction, and the presence or absence of cobalt nitrate makes, I find, 

 no difference. Pi'obably, therefore, Johnstone's laboratory solution of 

 the latter salt contained nitric acid in some quantity, as Schertel, 

 indeed, has suggested. 



