POTASSIUM CYANIDE 327 



2. To stop coughing. 



3. To allay itchiug by means of its local, sedative action 

 upon the cutaneous sensory nerve-endings. 



It is mainly useful in veterinary practice as a cough 

 remedy, when the symptom is of reflex origin, or is caused 

 by chronic bronchitis ; and the acid is often conjoined with 

 chloroform, or opium, in some form. Prussic acid is a dan- 

 gerous remedy to apply to the skin, as absorption may 

 occur, or the acid may be lapped off by the patient. 

 Solutions containing, of the diluted acid, 3 ss.-i. to ^ i- 

 of water, are, however, sometimes employed to relieve 

 pruritus. 



PoTASsn Cyanidum. Potassium Cyanide. K C N. 

 (U. S. & B. P.) 



Synonym.^Cjanure de potassium, Fr.; cyankalium, G. 



Derivation. — Made by heating together potassium ferro- 

 cyanide and carbonate. 



Properties. — White, opaque, amorphous pieces ; or a 

 white, granular powder, odorless when perfectly dry, but 

 in moist air exhaling the odor of hydrocyanic acid. Taste 

 sharp and alkaline, and in moist air the salt deliquesces. 

 Reaction very strongly alkaline. Solutions stain and destroy 

 clothing. Soluble in about 2 parts of water ; sparingly 

 soluble in alcohol. 



Dose.—R., gr.i.-ii. (.06-.12); D., gr.-jV (.006). 



Action and Uses. — Potassium cyanide is transformed, in 

 the stomach and blood, into prussic acid, and resembles the 

 latter in its action, but is much slower. Death has been 

 caused in man by 5 grains of the salt. 



Argentum Cyanidum. Silver Cyanide. Ag C N. 



A white, insoluble, tasteless, odorless powder, used for 

 making prussic acid. 



