FORMALDEHYDE 355 



Resorcinol is chiefly used in skin diseases to cure itching^ scaling and 

 induration in subacute and chronic eczema and psoriasis. It may be 

 combined with zinc ointment (1 to 8). 



Resorcinolis. 



Zinci oxldl aa 31. 



Unguenti aquae rosae 3x. 



M. (and heat to melt resorcinol crystals). 

 S. Apply to skin twice daily, 

 or is used in solution with glycerin and lime water, as follows : 

 To relieve itching in erythematous eczema. 



Resorcinolis gr.xxx. 



Glycerin! 3ss. 



Liquoris calcis 5ii. 



M. 



S. Apply externally. 



Internally, resorcin is of worth in diarrhea and fermentation. 

 FoBMAij>EHYDE. C Hj O. ( Non-ofScial. ) 



Synonym. — Formic aldehyde. 



Derivation. — Obtained by partial combustion of wood alcohol, without igni- 

 tion, by evaporation of the spirit in contact with a hot, platinized, asbestos plate. 

 2 C H. O H+Oj = 2 C H O H-|-2 HjO. 



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 was the commercial 

 name for an aqueous solution containing 40 per cent, of formaldehyde gas, but 

 is now official. 



FREFABATIOX. 



Liquor Formaldehydi. (U. S. P.) 



Synonym. — ^Formol, formalin, E.; forraaldehydum solutum, P. G. ; solute 

 d'aldfihyde f ormique, Fr. ; f ormaldehydlosung, G. 



Solution of formaldehyde. Containing not less than 37 per cent, of formalde- 

 hyde gas. 



Action and Uses. — Formaldehyde and formalin are slowly acting 

 microbicides. A 1 per cent, solution of formalin will kill Staphylococ- 

 cus 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. cholerae in 

 less than 15 minutes. Clothes soaked in cultures of B. typhosus, S. 

 cholerae and Staphylococcus pyogenes aureus, and then for 24 hours in a 

 1 per cent, solution of formalin, were found to be completely sterile 

 (Slater). Trillat and Robinson have found that formaldehyde gas has 

 wonderful disinfectant and penetrating properties, destroying all patho- 

 genic bacteria in ordinary rooms containing the microorganisms buried 

 under mattresses, between blankets, in clothing and other articles, in the 

 air, dust, and morbid secretions. Harrington proved, however, that the 

 penetrating power of formaldehyde is nil in the case of moist substances, 

 and that sterilization is not always complete when microorganisms are 

 imbedded in, or covered by, dry pervious material. Still, formaldehyde 

 is the best gaseous disinfectant now known for the sterilization of infected 

 premises. It does not kill insect pests, animal parasites or rats, but 



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