On Chemical Nomenclature. : 271 
ical reader a series of names, as for instance haloargentic, halocu- 
pric, halostannic, halopalladic. 
I consider prussian blue as a cyanoferrite of the cyanobase of iron, 
or briefly a cyanoferrite of iron. The diversity of properties which 
enables two cyanides of iron to exist in combination in this cyanofer- 
rite, one as an acid, the other as a base, is one among many other 
instances in which compounds constituted of the same elements in 
the same ratio, have different properties, and are said in consequence 
to be isomeric, or to afford cases of isomerism. 
The salt designated by Berzelius as the ‘* cyanure ferroso-potass- 
ique,” is the well known test for iron heretofore called ferroprussiate 
of potassa ; under the idea that it consisted of prussic acid, iron, and 
potassa. As the prussic acid was viewed at the same time as a com- 
pound of hydrogen and cyanogen, the ferroprussic acid was consid- 
ered as a compound of cyanogen, hydrogen, and iron. According 
to Berzelius, the supposed ferroprussiate is a compound of a “pro- 
tocyanure” of iron, and a “cyanure of potassium ;” each being a sim- 
ple haloid salt, and the aggregate a double “ cyanure.” Agreeably 
to my nomenclature, the “protocyanure ” of iron is considered as cy- 
anoferrous acid, and the ‘ cyanure” of potassium as a cyanobase ; 
the aggregate being a cyanoferrite of the cyanobase of potassium, but 
designated briefly as a cyanoferrite of potassium. 
I infer that the “ ferroprussic” acid is analogous in constitution to 
the triple compound of fluorine, silicon and hydrogen, improperly call- 
ed hydrofluosilicic acid; and that, consistently with the hypothetical 
views under which the latter received its name, the former should be 
called hydrocyanoferric 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 ap-. 
pellations of such compounds should be so altered as to give prece- 
dency to the electro-negative ingredient. Hence the one would be ° 
called cyanohydroferric acid ; and the other, fluohydrosilicic acid. 
t in my letter to Prof. Silliman, already cited, I advanced a new 
hypothesis respecting the constitution of the fluohydrosilicic, and 
fluohydroboric 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, 1 
would consider the protocyanide (or “cyanure”) of iron in the alleged 
Serroprussic acid, as acting as cyanoferrous acid, the cyanide of hy- 
en (prussic acid) as a cyanobase forming, by their union, a cya- 
noferrite of hydrogen. 
