Materials for a History of the Prussiates. 351 



bined with charcoal. The rest is pure charcoal, one of the 

 elements of the acid destroyed. The two others, the hy- 

 drogen and azote, are employed in producing ammonia. As 

 to the carbonic acid and the gaseous oxide, it is equally evi- 

 dent that these are the two oxidations, major and minor, of 

 the charcoal furnished by the oxygen of the two oxides which 

 we have ascertained to exist in Prussian blue. 



This decomposition takes place with such a moderate heat 

 that it has appeared- to me very convenient when we wished 

 to procure gaseous oxide.. There is not the least ground for 

 suspecting any oil to be present : it is very surprising to see 

 that in the course of a destruction where charcoal and hy- 

 drogen abound, there is not a single particle of these com- 

 bustibles which proceeds to constitute itself in any of the 

 respects which can form oil. 



The oily and aromatic character assumed by the hydrogen 

 during the solution of the residue, also demonstrates that 

 the combination of iron with charcoal does not require a 

 very high temperature. The charcoal of the blood when it 

 is obtained by a very inferior heat, also contains iron in a 

 carbure t ted state ; for with muriatic acid it also gives aro- 

 matic hydrogen, I think Priestley has somewhere noticed 

 the bituminous smell of the hydrogen furnished bv the fluxes 

 of charry substances. 



Distillation of the triple Prussiute of Potash. — This salt 

 loses ten per cent of water, and its colour also, for it be- 

 comes bleached; it does not become soft without a red heat 

 being applied. Some chemists have thought they discovered 

 in the roasting or flux of it a method of taking away the 

 oxide. The following results will show that these processes 

 lead to nothing useful : 



When this salt enters into fusion, there escapes a little 

 prussic acid, which is seized by the ammonia formed at the 

 same instant. There afterwards passes over a nebulous va- 

 pour, which is condensed like farina in the neck of the re- 

 tort. This vapour is not continued after, when the flux is 

 finished, and the sublimate so formed has the alkaline $nd 

 bitter taste of the simple prussiate. 



Alcohol dissolves a part of it^ and what is. separated from 



it 



