640 A MANUAL OF BACTERIOLOGY 



as much. Commercially they are known as soluble carbolic 

 acid, soluble creosote, etc. Creolin is a type of numerous 

 preparations of the same character. They are all poisonous 

 and sensitive to albuminoids. If naphthalene is present 

 in excess it is deposited in cold weather on standing. Lysol 

 is mainly a solution of the cresols in fat or linseed oil, 

 saponified, with addition of alcohol. It gives a clear 

 solution with water, having slightly less efficiency on naked 

 bacteria than cresol, much superior solvency for grease, 

 and equal sensitiveness to albuminoids. A number of 

 proprietary disinfectants of high germicidal power are 

 now to be obtained. Such are cyllin, McDougalPs M.O.H. 

 fluid, izal, kerol, etc. The active agents appear to be 

 oxidised hydrocarbons without phenol and cresol, in 

 emulsion in glue, soaps, oils, etc., and they are compara- 

 tively non-toxic. The active principle of cyllin is an 

 oxidised hydrocarbon, having a di-phenyl nucleus in place 

 of the single phenyl present in carbolic acid ; it is insoluble 

 in water, hence for the purpose of even distribution in 

 water it is emulsified with a neutral hydrocarbon oil. 

 The finished product contains 50 per cent, of the active 

 principle, and is free from carbolic acid and its homologues. 

 The active principle of kerol consists of oxidised hydro- 

 carbons with a di-phenyl nucleus and contains no phenol 

 or cresol. The germicidal efficiency, expressed as the 

 carbolic- acid co- efficient (p. 645), of a number of substances 

 is given in the Table on page 641. 



Some of the anilin dyes, especially purified methyl violet 

 or pyoctanin, have been claimed to be powerfully antiseptic 

 in solutions of 1-500 to 1-1000. 



Chloroform is a powerful antiseptic, but at least 1 per cent, 

 must be present to act as a germicide ; it is costly, and 

 not much used as a practical disinfectant, but in bacterio- 

 logical and physiological chemistry is a useful antiseptic 

 for preserving solutions which putrefy easily. 



