338 INOEGANIC AGENTS 



Externally it is of value in scaly skin diseases, as psoriasis, 

 in solutioii (1-4), in glycerin. Internally, resorcin is of worth 

 in fermentation and indigestion, given in a large amount of 

 water an liour or two after eating 



FOEMALDEHYDE. C H O H. 



(Non-official.) 



Synonym. — Formic aldehyde. 



Derivation.- — Obtained by partial combustion of wood 

 alcohol, without ignition, by evaporation of the spirit in 

 contact with a hot, platinized, asbestos plate. 2 C Hj O H 

 + 0, = 2CHOH^-2 H,0. 



Properties. — Formaldehyde is a pungent gas, having a 

 spec. gr. of 1.6; soluble in water, forming a clear, colorless, 

 stable solution when kept in glass-stoppered bottles, but 

 volatilizing on exposure to the air. Formalin is the com- 

 mercial name for an aqueous solution containing 40 per 

 cent, of formaldehyde gas. 



PREPARATION. 



Liquor Formaldnhydi. (U. S. P. ) 

 Formalin. Containing not less than 37 per cent, of formaldehyde 

 gas. 



Action and Uses. — Formaldehyde and formalin are 

 powerful inicrobicides. A 1 per cent, solution of formalin 

 will kill Staphylococcus pyogenes aureus in about an hour ; 

 B. typhosus in 40 to 50 minutes ; B. coli communis in 30 

 to 40 minutes ; B. anthracis and S. choleras in less than 15 

 minutes. Clothes soaked in cultures of B. typhosus, S. cho- 

 lersD and Staphylococcus pyogenes aureus, and then for 24 

 Tiours in a 1 per cent, solution of formalin, were found to be 

 completely sterile (Slater). Trillat and Robinson have 

 apparently shown that formaldehyde gas has wonderful 

 disinfectant and penetrating properties, destroying all 

 pathogenic bacteria in ordinary rooms containing the micro- 

 organisms buried under mattresses, between blankets, in 

 in clothing and other articles, in the air, dust, and morbid 

 secretions. Harrington has proved, however, that the pene- 



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