ON CHEMICAL NOMENCLATURE. 
15 
acids formed by the halogen bodies with hydrogen, as halo- 
hydric acids; those formed with that radical by the amphigen 
bodies, as amphydric acids. As the same radical will in other 
cases be found to form acids with several of the halogen bo- 
dies, platinum for instance, the acids thus produced, may be 
called haloplatinic acids ; or if gold were the radical, they 
would be called haloauric acids. These examples will sug- 
gest to the chemical reader a series of names, as for instance 
haloargentic, halocupric, halostannic, halopalladic. 
I consider prussian blue as a cyanoferrite of the cyanobase 
of iron, or briefly a cyanoferrite of iron. The diversity of pro- 
perties which enables two cyanides of iron to exist in 
combination in this cyanoferrite, 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 dif- 
ferent properties, and are said in consequence to be isomeric, 
or to afford cases of isomerism. 
The salt designated by Berzelius as the " cyanure 
ferroso-potassique,^^ is the well known test for iron hereto- 
fore 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 compound of hydrogen 
and cyanogen, the ferroprussic acid was considered as a com- 
pound of cyanogen, hydrogen, and iron. According to 
Berzelius, the supposed ferroprussiate is a compound of a 
^'protocyanure^^ of iron, and a ''cyanure Oii potassium 
each being a simple haloid salt, and the aggregate a double 
''cyanure.'^'' Agreeably to my nomenclature, the ''proto- 
cyanure'''' of iron is considered as cyanoferrous 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 called hydrofluosilicic acid ; and that, 
consistently with the hypothetical views under which the 
latter received its name, the former should be called hydro- 
