434 Professor BerzeUus on [Jui^E, 



sures placed in contact with caustic potash were reduced to 45*4 

 measures; but 45*4 x 3 = 136*2; which gives, as exactly as 

 can be expected in experiments of this nature, two volumes of 

 carbonic acid gas for one orf azote. Thus this experiment proves 

 that the carbon and the azote, in these salts, are in the same 

 proportions as in cyanogen. No water was formed, except a 

 shght and unimportant trace of moisture.* The whole quantity 

 of gas obtained consisted of 102 volumes of carbonic acid and 51 

 of azote ; the former weighed 3*1 grains, and the azote 0*99 gr. 

 which give for 100 parts of salt, 11-05 .of carbon, and 12*84 of 

 azote ; or together, 23*89 of cyanogen. This quantity, added 

 to the other element of the salt employed, exceeds its weight by 

 6*19, if the bases exist in it in the state of oxide; but if the 

 prussiate be composed of one atom of cyanuret of iron with two 

 atoms of cyanuret of lead, the sum of the cyanogen, iron, and 

 lead, obtained, gives almost exactly its weight. 



It appeared to me very easy to verify this idea by acting on 

 the ferruginous prussiate of lead by sulphuretted hydrogen gas : 

 18*84 grains of the anhydrous salt were introduced into a small 

 weighed glass ball, blown by the lamp. 1 caused a current of 

 sulphuretted hydrogen gas to pass through the ball, which, on 

 quitting it, traversed a tube filled with muriate of lime. While 

 cold, the prussiate of lead was not altered by the gas, but on 

 heating the ball by a spirit-lamp, it was immediately blackened, 

 and hydrocyanic acid evaporated with the sulphuretted hydrogen 

 that passed off in excess. No trace of moisture was perceived 

 during the operation, not even when the mass in the ball was 

 red-hot in the sulphuretted hydrogen gas. The remaining mass 

 weighed 17*06 grs. and was composed of sulphuret of iron, at the 

 minimum, and sulphuret of lead. The tube containing the 

 muriate of lime had only gained 0*0077 of a grain in weight, a 

 part of which was sulphur. Thus this experiment proves that in 

 the anhydrous ferruginous prussiate of lead the metals are not in 

 the state of oxide ; for even if we suppose in this experiment that 

 no water is obtained, '\n consequence of the sulphur seizing the 

 oxygen of the metalhc oxides, the sulphuric acid, so produced, 

 ought to have combined with a part of the oxides, and have occa- 

 sioned a much more considerable increase of weight than was 

 obtained in the experiment ; on the other hand, if the salt be 

 really composed of one atom of cyanuret of iron with two atoms 

 of cyanuret of lead, its decomposition by sulphuretted hydrogen 

 should give for 18*84 grains of metallic cyanuret, 17 grains of 

 sulphuret; which agrees, as nearly as possible, with the result 

 of the experiment. The composition then will be 



The original has been shortened.— £ii^ 



