448 Prof. Beizeliu3 on the Composition of Pnissiates. [June, 



been separated from the cyanuret before the commencement of 

 the experiment, the residual mass is a double carburet, composed 

 of an atom of quadricarburet of iron and two atoms of quadricar- 

 buret of lead, Fe C* + 2 Pb C*. If, on the other hand, the 

 cyanuret contains water, one part of the carbon of the cyanogen 

 is converted into carbonic acid at the expense of the water, and 

 there is a deficiency of carbon in the quadricarburet of iron. It 

 has been supposed that the residual mass, after the decomposi- 

 tion of cyanuret of iron and lead, is a kind of pyrophorus ; this 

 is an error probably derived from the circumstance of the carbu- 

 rets thus obtained taking fire readily at a lower temperature than 

 is sufficient to inflame other bodies ^ so that, if the retort be 

 broken before the contents are cold, they take firek, and continue 

 to burn like amadou. 



6. Prussia ft Blue. — Prussian blue treated with muriatic acid 

 was dried at the temperature of 336 Fahr. and afterwards decom- 

 posed. It gave at first pure water, then a little hydrocyanate of 

 ammonia, and afterwards a great quantity of carbonate of ammo- 

 nia, but always followed by moisture. After the evolution of the 

 volatile bodies, I placed the retort in the middle of burning 

 charcoal, and there was produced a quick and brilliant combus- 

 tion, as with the hydrocyanate of iron and ammonia. 



Fifty parts and 7-lOths of the black mass which remained in 

 the retort were burned in a small capsule previously weighed, 

 54-86 parts of red oxide of iron were left. This relation between 

 the weights of the carburet of iron and that of the oxide, agrees 

 precisely with a tricarburet of iron Fe C' ; for, according to 

 calculation, 50*7 of tricarburet of iron ought to give 54*89 parts 

 of red oxide of the metal. As water accompanies the products 

 of the 'decomposition of prussian blue, from the beginning tathe 

 end, it is evident that the affinity of iron for carbon keeps them 

 in a fixed state of combination, and consequently the proportion 

 - of carbon in the carburet of iron obtained by the decomposition 

 of prussian blue is not an accidental circumstance. 



6. Hydroci/auate of Iron and Copper. — This compound con- 

 tains water, besides that which converts it into hydrocyanate. It 

 gives during decomposition much water, some carbonate, and 

 hydrocyanate of ammonia. The phenomena of combustion may 

 be produced in the mass, but for this purpose, a very high tem- 

 perature is necessary, and yet it is not very brilliant. The resi- 

 dual mass is black, and possesses the external characters of 

 those already described. It inflames readily, and continues to 

 burn by itself; 27-7 parts of carburet yielded 28*9 of the two 

 oxides, both at the maximum of oxidation. The numbers agree 

 with a compound of an atom of quadricarburet of iron and two 

 atoms of bicarburet of copper; that is to say, Fe C* + 2 Cu C^ 



7. H^drocj/anate of Iron andXJobait, — If this hydrocyanate is 

 well dried, it gives only a small quantity of water, carbonate and 

 hydrocyanate of ammpnia, at the boiUng point of mercury. Its 



