PRUSSIC ACID. 377 



Ferrocyanogen, like all other compound radicals, con- 

 ducts itself, under ordinary circumstances, as an ele- 

 mentary substance. 



WJiatisfcrri- 946. On tne removal of one atom of 

 cyanogen? potassium from two molecules of this salt, 

 a coalescence of the ferrocyanogen of the two mole- 

 cules seems to be the result, and a new compound radi- 

 cal is formed. This radical is called ferricyanogen. 

 It combines with the three remaining atoms of potas- 

 sium, to form ferricyanide of potassium. 

 Give the ro - ^^ ' P RUSSIC ACID. Hydrocyanic acid 

 erties of prus- i s made from cyanide of potassium, by the 

 its mode of same method employed for producing hy- 

 preparation. drochloric ac id f rom common salt. The 



ferrocyanide of potassium is more commonly employed 

 in the process. Prussic acid is intensely poisonous. A 

 drop or two of the concentrated liquid, placed upon the 

 tongue of a dog, produces immediate death. On ac- 

 count of its extremely dangerous properties, the prepa- 

 ration of the acid should never be attempted except 

 by a professional chemist. The odor of the acid is 

 somewhat similar to that of cyanogen, and may be fre- 

 quently detected in the vicinity of establishments where 

 galvanic gilding is conducted. Ferrocyanogen and fer- 

 ricyanogen, like simple cyanogen, have their hydrogen 

 acids and series of salts. The acid of the former is 

 bibasic, and that of the latter tribasic, as already shown 

 by the composition of their potassium compounds. 

 What is said ^48. OTHER ORGANIC ACIDS. Tartaric 

 of citric, ma- acid, before mentioned, is found in the 



lie, lactic, ox- 

 alic, and for- grape. The acid tartrate of potassa or 



mie acids ? crea m of tartar, which deposits in wine 



