AND THE PARACYANIC ACID. 43 



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

 mercury, and probaUy pai-acyanate of potash. Such a reaction is thus explained. 



2 (C,N,0 + HgO) + SKI = (Hgl, + KI) + Hg + 2 (CN.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, of cyanogen absorbed by alcohol, 

 33.5 — carbonic acid — — caustic potash, 

 17.0 — nitrogen, remaining. 



57.6 

 A black residue remains behind, which, by fiirther 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 31.5. A portion of a 

 beautifully yellow (HgO + C8N4O) gave a gas, of which 88.5 left 30 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 imder 

 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 grs. 7.74 grs. of carbonic acid, and 1.32 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 = 11.933 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 



Experiment. 

 Calculation. (1.) (2.) 



Ce = 611.496 = 9.150 . . . 9.402 



N4 = 708.144 = 10.599 . . . 10.888 



0, =. 100.000 = 1.499 . . . 1.529 



2HgO = 5263.288 = 78.752 . . . 78.181 . . 79.200 



6682.928 100 100 



The water amounts only to about 1.7 atoms. 



