258 INORGANIC AGENTS 



disinfect these parts. More recently Burnham (1912) has cast doubt on this 

 treatment by failing to find formaldehyde in germicidal amount in any of the 

 secretions (except urine) after ingestion of urotropin. It can now be bought 

 more cheaply under its official name than by its trade name urotropin. It should 

 be given in solution thrice daily. 



Doae.—H. & C, 3ii-iv, (8-15); D., gr.v-x, (.3-.6). 



Class 7. — Miscellaneous Carbon Compounds 



ACIDUM HyDEOCYANICUM DlLtTTUM. 



Diluted Hydrocyanic Acid. H C N. (U. S. & B. P.) 



Synonym. — Prussic acid, acidum hydrocyanatura, s. borussicum, E.j* acide 

 cyanhydrique, s. hydrocyanique, Fr. ; cyanwasserstonsaure, blausaure, G. 



Derivation. — An aqueous solution containing not less than 1.9 per cent, nor 

 more than 2.1 per cent, of HCN, and not more than 0.1 per cent, of HCl. Pre- 

 serve in small, dark, amber-colored, well-stoppered bottles. Obtained by distil- 

 lation of potassium ferrocyanide, 20; sulphuric acid, 8; and water, 65 j into 

 distilled water. The following reaction first occurs: K, Fe Co Nj-|-2 Hj S O, = 

 2 Kj S O. + H, Fe Ce Ne; then on the application of heat, the hydroferrocyanic 

 acid resulting in the first reaction reacts with the remaining potassium ferro- 

 cyanide and sulphuric acid, as follows: H4 Fe Co Na-|-Ki Fe Co N8-I-H2 S 04=: 

 6 H C N-I-K2 S O4-I-K, Fe Cs No). 



Diluted hydrocyanic acid can also be made by mixing hydrochloric acid, S; 

 with distilled water, 55; silver cyanide, 6. Shalce together in a glass-stoppered 

 bottle. AgCN-FHCl=:HC N-f-Ag CI. When the precipitate of silver chlo- 

 ride falls, pour off the clear, supernatant fluid. 



Properties. — A colorless liquid, of a characteristic odor, resembling that of 

 bitter almond. It is very unstable and is apt to be inert as obtained from ordi- 

 nary drug stores. 



Incompatibles. — Salts of iron, copper and silver; sulphides and red mercuric 

 oxide. 



Dose.—H. & C, 111.XX-X1, (1.3-2.6); Sh., TTLx-xv, (.6-1); Sw., TTlii-v, (.12-.8) ; 

 D., Tn,i-iii, (.06-.2). 



Action External. — Prussic acid is absorbed to some extent through 

 the unbroken skin; paralyzes the peripheral sensory nerves, and acts as 

 a local anesthetic. If the finger is held over a bottle containing the 

 acid, it soon becomes anesthetized. Upon mucous membranes, or raw 

 surfaces, prussic acid is rapidly absorbed and exhibits its usual consti- 

 tutional action. 



Action Internal. — Alimentary Canal. — Hydrocyanic acid exerts a 

 sedative effect upon the mucous membrane of the stomach and upper por- 

 tion of the digestive tract. It is absorbed into the blood, but we are 

 ignorant of its fate or mode of elimination. 



Blood. — In poisoning, the blood becomes first of a bright arterial 

 hue, and later assumes a dark, venous color. The first condition is due 

 to the fact that the tissues do not absorb oxygen owing to changes which 

 interfere with cell respiration, or, in other words, to inhibition of the 

 oxidizing ferments, oxidases, of the cells which enables them to utilize 

 the oxygen of the blood. The dark color of the blood is probably owing 

 to asphyxia and accumulation of carbonic dioxide, following the paralytic 

 action of prussic acid upon the respiratory centre. A substance called 

 cyanohemoglobin is formed outside the body by hydrocyanic acid when 

 shaken with blood. The acid appears to deoxydize the normal oxyhemo- 



•Scheele's prussic acid contains 4 to 5 per cent, of the pure hydrocyanic acid. 



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