188 Dr. Hare on Chemical Nomenclature. 



prussic acid, iron, and potassa. As the prussic acid was 

 viewed at the same time as a compound of hydrogen and cy- 

 anogen, the ferroprussic acid was considered as a compound 

 of cyanogen, hydrogen, and iron. According to Berzelius, 

 the supposed ferroprussiate is a compound of a " protocyanure" 

 of iron, and a " cyanure of potassium'" each being a simple 

 haloid salt, and the aggregate a double " cyanure." Agreeably 

 to my nomenclature, the "protocyanure" of iron is considered 

 as cyanoferrous acid, and the "cyanure" of potassium as a 

 cyanobase ; the aggregate being a cyanoferrite of the cyano- 

 base of potassium, but designated briefly as a cyanoferrite of 

 potassium. 



I infer that the "ferroprussic" acid is analogous in consti- 

 tution to the triple compound of fluorine, silicon and hydro- 

 gen, improperly called hydrofluosilicic acid ; and that, consist- 

 ently with the hypothetical views under which the latter re- 

 ceived its name, the former should be called hydrocyanoferric 

 acid. Even admitting the correctness of the hypothetical im- 

 pression, 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 ingredient. Hence 

 the one would be called cyanohydroferricacid ; 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 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, 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 cyanobase, 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 in- 

 consistent with chemical law, as stated by Berzelius*, or my 

 definition of acidity, (page 183,) to designate them as acids. 



I have called the electro-negative "protocyanure" of iron 

 of Berzelius, cyanoferrows acid, because there is " sesquicy- 

 anure" in the " cyanureferrico-potassique" of that author, which, 

 by analogy with the nomenclature of the oxacids, is entitled 

 to the appellation of cyanoferric acid. 



* TraitCj page 41, vol. ii. 



