On the Triple Prussiates. 103 



discovery of this acid, considers it as formed of carbon, iron, azote, 

 and hydrogen ; but his experiments do not demonstrate in a satis- 

 factory manner the absence of oxygen, since they have led him 

 to ascribe to iron other degrees of oxidizement, besides those 

 which had been determined by more direct means. M. Robiquet 

 and M. Berzelius are of the same opinion with Mr. Porrett ; M. Ber- 

 zelius found that the precipitate, obtained, by pouring a solution 

 of lead into the triple prussiate of potash, is formed of 



3 atoms of cyanogen ; 



2 „ lead ; 



1 „ iron ; 

 or of 2 ,, cyanide of lead ; 



1 „ cyanide of iron ; 



! of potash and iron ; 

 of barytes and iron ; 

 of lime and iron ; 

 have an analogous composition ; that is to say, they contain each 



1 atom of cyanide of iron. 



2 atoms of the cyanide of the other metal. 



Now since the hydrogen, contained in the acid of the prussiates, 

 has totally disappeared, and since no more oxygen is found in 

 the triple prussiates, and particularly in that of lead, which I shall 

 take as an example, these two bodies must have united to forra 

 water; and, consequently, the acid of the triple prussiates must 

 contain a sufficient quantity of hydrogen to neutralize the two 

 proportions of oxygen contained in the two proportions of oxide 

 of lead. This salt must be composed, therefore, of 



2 atoms of hydrogen; 

 1 ,, iron ; 



3 „ cyanogen ; 



or of 2 ,, hydrocyanic acid ; 

 1 ,, cyanide of iron. 



I consider this acid as a true hydrogen acid, whose radical 

 should be formed of one atom of iron, and three atoms of cyanogen. 



When we combine it with an oxide, its hydrogen forms water 

 with the oxygen of the oxide, and its radical unites with the 

 radical of the latter. The compound is no longer a prussiate. 

 It is a cyanoferruret. Reciprocally, when we decompose a cy- 

 anoferruret by a hydrogen-acid, sulphuretted hydrogen for 

 example, the hydrogen of the latter combines with the cyanides 

 of iron (cyanoferre), and produces the hydro-cyanoferric acid. In 

 other respects, the theory of the cyanoferrurets, and of the hydro- 

 cyanoferrates, would be exactly the same as that of the sulphurcts 

 and the hydrosulphates, of the chlorides and hydrochlorides, Sfc. 



It is undoubtedly premature to give a name, such as cyanoferrc, 

 to a being still hypothetical, or at least which has not been ob- 

 tained insulated ; but on one hand, I regard its existence as very 



