Chemical Science. 213 



hydrogen passed through it; when the substances had acted on 

 each other for some time, the pigment became of a dull white co- 

 lour, whilst the fluid became opalescent from the deposition of sul- 

 phur. The liquid was separated from the solid matter, and the 

 sulphuretted hydrogen separated by exposure to air ; it was then 

 acid and precipitated salts of iron blue, so that, at the same 

 time that the gas reduced the deutoxide of iron to protoxide, the 

 excess of acid required for its neutralization in that state was 

 liberated as ferro-prussic acid. The whole mass exposed to the 

 air became blue, and at the same time partly soluble in water ; 

 but when again treated with sulphuretted hydrogen, the solution 

 did not become acid, nor did it precipitate salts of iron blue, and 

 the insoluble part became black : so that there are evidently two 

 blue combinations, the one composed of three atoms of hydro- 

 cyanate of protoxide, and four atoms of hydrocyanate of deutox- 

 ide, in which theacid and oxygen of the second part is double 

 that of the first ; and another apparently composed of one atom 

 of hydrocyanate of protoxide and two atoms of hydrocyanate of 

 deutoxide. 



" It appears," says M. Berzelius, " from the experiments men- 

 tioned, that the cyanurets of highly electro-positive radicals, as 

 the alcaline metals, do not decompose water, or form hydro- 

 cyanates. The more feeble bases, as glucine, ammonia, and 

 most of the metallic oxides, on the contrary, produce hydro- 

 cyanates, which, when heated, either do not produce cyanu- 

 rets, or, in producing them, are in part decomposed by the 

 action of the oxygen of the bases on the cyanogen, and the forma- 

 tion of carbonic acid, ammonia, and metallic carburets. "With 

 the exception of the hydrocyanate of iron and ammonia, it ap- 

 pears, that when one base is in the state of hydrocyanate, the 

 other is also, so that there is no combination of a cyanuret with 

 a hydrocyanate. When the cyanurets combine with an addi- 

 tional quantity of base, they appear to be changed into hydro- 

 cyanates, and the whole become sub-hydrocyanates; such is pro- 

 bably the state of the combination of cyanuret of mercury with 

 oxide of mercury." 



M. Berzelius then speaks of the nature of the ferro-prussic 

 acid. This combination is produced by the action of a strong 

 acid on the second base of the ferro-prussiates, which being re- 

 moved by it, all the hydrocyanic acid unites with the protoxide 

 of iron, so that it is combined with thrice as much acid as in 

 the neutral compound. This substance was prepared by dif- 

 fusing the moist cyanuret of iron and lead through water, 

 passing sulphuretted hydrogen gas through, decomposing what 

 portion of that gas remained in solution by adding a small 

 quantity more of the salt, filtering, and evaporating under the 

 air-pump-receiver. It left a white opaque uncrystallizable sub- 



