16 
ORIGINAL COMMUNICATIONS. 
cyanoferric acid. Even admitting the correctness of the 
hypothetical impression, to which I have alluded, agreeably to 
which such compounds are acids with a double radical, I 
urged that the appellations of such compounds should be so 
altered as to give precedency to the electro-negative ingre- 
dient. Hence the one would be called cyanohydroferric 
acid; and the other, fluohydrosilicic acid. But in my letter 
to SiLLiMAN, already cited, I advanced a new hypothesis 
respecting the constitution of the fluohydrosilicic, and fluo- 
hydroboric acids. I suggested that they should be considered 
as compounds in which the fluorides of silicon or boron acted 
as acids, the fluoride of hydrogen as a base. Consistently 
with that doctrine, I would consider the protocyanide (or 
'^cyanure^^) of iron in the alleged ferroprussic acid, as acting 
as cyanoferrous acid, the cyanide of hydrogen {prussic 
acid) as a cyanohase forming, by their union, a cyanoferrite 
of hydrogen. 
As compounds, consisting of a basacigen body, hydrogen 
and a radical, do not, when presented to bases, enter into 
combination; but are, on the contrary, decomposed so as to 
allow another radical to take place of their hydrogen, it is 
inconsistent with chemical law, as stated by Berzelius,* or 
my definition of acidity, (page 9,) to designate them as acids. 
I have called the electro-negative protocyanure''^ of iron 
of Berzelius, cyanoferroi^^ acid, because there is " sesqui- 
cyanure" in the cyanureferrico-potassiqiie^^ of that author, 
which, by analogy with the nomenclature of the oxacids, is 
entitled to the appellation of cyanoferric acid. 
* Traite, page 41, vol. ii. 
