PREVENTIVE MEDICINE 213 



yielding first some resinous bodies, then homologues of phenol 

 (cresols, &c.), and lastly pure phenol. 



The phenol is washed with a little water and then distilled, the 

 portion coming over between 180 and 190 C is collected separately. 

 On cooling phenol crystallises out, and is separated from the liquid 

 portion (cresols). 



CRESOL OR CRESYLIC ACID. Cresol is a slightly yellow or 

 colourless fluid with a tarry odour obtained from coal tar. 



There are three isomeric cresols (ortho-, meta-, and para-cresol), 

 but the principal constituent of the " crude carbolic acid " of 

 commerce (the source of commercial cresylic acid) is para-cresylic 

 acid with more or less of its isomers. A mixture of the three was 

 introduced under the name of Trikresol. Cresol is the basis of the 

 numerous disinfectants of the lysol class. 



Compound Solution of Cresol. There are various formulae for 

 this preparation under different names. Liquor Cresolis Sapon- 

 atus, B.P., contains 50 per cent, cresol rendered soluble with castor 

 oil and caustic potash. Liquor Cresolis Compositus, U.S. P., also 

 contains 50 per cent, cresol, but linseed oil is used instead of castor 

 oil. The B.P.C. formula is similar to the latter, but has in addition 

 a little alcohol. The German Pharmacopoeia gives equal parts of 

 cresol and pale soft soap. This is said to be 3 to 5 times more 

 powerful as a bactericide than carbolic acid and much less 

 poisonous. All these preparations form a clear solution with water 

 and are imitations of lysol, in place of which they may be used. 

 Similar preparations are Sapocresol, Crelium, Phenolin, and 

 Kresapol. 



LYSOL. Lysol is a dark alkaline liquid containing about 50 per 

 cent, of cresols. It is miscible with water. It is prepared by 

 mixing linseed oil (or a fat) with oil of tar and saponifying with 

 caustic potash and alcohol. The Lysol Patent specification 

 (expired) gives this formula : Tar oil 100, linseed oil 100, caustic 

 potash solution (1 in 2) 75, and alcohol 65. Boil under a reflex 

 condenser until saponified, sp. gr. 1-047. A transparent brown 

 syrupy liquid, forming a clear solution with water. It is a solution 

 in neutral soap of tar oils distilling between 187 and 200 C, which 

 are present to the extent of about 47 per cent. 



CREOLIN. Artmann's Creolin (German patent) is prepared by 

 sulphonating tar oil freed from carbolic acid and extracting with 

 water. The milky liquid is separated into two layers by means of 

 hydrochloric acid or brine, the upper layer being removed for use. 

 Pearson's (English) is a soluble preparation of 20 per cent, cresylic 

 acid rendered soluble by means of soap. It is similar to Jeyes 



