AND THE PARACYANIC ACID. 43 



tallic mercury. The solution is yellow or orange coloured, and contains biniodide of 

 mercury, and probably paracyanate of potash. Such a reaction is thus explained. 



2 (CN^O + HgO) + SKI = (Hgl, + KI) + Hg + 2 (CsN.O + KO) 



and it is probable that the haloid salts in general would act in a similar manner. 

 11. Heated to 230° F., these paracyanates are decomposed, and, from the 

 sudden evolution of gas, appear to decrepitate. Mercury is sublimed, and carbo- 

 nic acid, nitrogen, and cyanogen gases may be collected. 67.6 vols, of the mixture 

 collected over mercury gave 



7.1 vols, oi cyanogen absorbed by alcohol, 

 83.5 — carbonic acid — — caustic potash, 

 17.0 — nitrogen, remaining. 



57.6 

 A black residue remains behind, which, by further heating, gives cyanogen 

 only. 



12. Burned with bichromate of potash, it gives also carbonic acid and nitro- 

 gen gases in the proportion of two to one. 



Thus 97.5 vols, left 32.5 of nitrogen, and 95 vols, left 81.5. A portion of a 

 beautifully yellow (HgO + C8N4O) gave a gas, of which 88.5 left 80 vols. 



13. It was not till I came to subject this salt to analysis that I was made 

 fuUy aware of the necessity of attending minutely to the circumstances under 

 which it was prepared, and to the nature of the mercurial solutions employed. 

 I have analyzed only two portions. The first precipitated from a neutral solution 

 of the acid, dried at 212° F., and burned with bichromate of potash, gave from 

 24.08 gi's. 7.74 grs. of carbonic acid, and 1.82 of water = 5.48 per cent. This 

 gives for the composition of the anhydrous salt 



C = 9.402 N = 10.888 = 1.529 HgO = 78.181 



16.57 grs. of the same salt dissolved in muriatic acid, and precipitated by 

 hydro-sulphuric acid, gave 13.83 grs. of bi-sulphuret = 11.988 of metallic mer- 

 cury, or 72.016 per cent. This gives for the anhydrous salt 79.200 of protoxide 

 of mercury. This, therefore, was a basic salt, and its constitution 



Calculation, 



Experiment. 



00 



(2.) 



Cs = 611.496 = 9.150 . 



. . 9.402 . . 





N4 = 708.144 = 10.599 . 



. 10.888 . . 





0, = 100.000 = 1.499 . 



. 1.529 . . 





2HgO = 5268.288 = 78.752 . 



. 78.181 . . 



79.200 



6682.928 100 100 



The water amounts only to about 1.7 atoms. 



