TIU-: i)i-:srj<i'CTio\ OF BACTERIA BY CHEMICALS 115 



Chloroform.- This substance, even in pure form, does not destroy 



spores, but it does bacteria in vegetative form, even in 1 per cent, solu- 



I tion. Chloroform is used practically in sterilizing and keeping sterile 



j blood serum, which can be used later for culture purposes by driving 



i off the chloroform. 



lodoform. This substance has but very little destructive action upon 

 bacteria; indeed, upon most varieties it has no appreciable effect what- 

 ever. When mixed with putrefying matter, w r ound discharges, etc., 

 the iodoform is reduced into soluble iodine compounds, which partly 

 act destructively upon the bacteria and partly unite with the poisons 

 already produced. 



Carbolic Acid (C 6 H 5 OH). A solution having 1 part to 1000 inhibits 

 i the growth of bacteria; 1 part to 400 kills the less resistant bacteria, 

 and 1 part to 100 kills the remainder. A 5 per cent, solution kills the 

 less resistant spores within a few hours and the more resistant in from 

 one day to four weeks. A slight increase in temperature aids the destruc- 

 tive action; thus, even at 37.5 spores are killed in three hours. A 3 

 | per cent, solution kills streptococci, staphylococci, anthrax bacilli, etc., 

 within one minute. Carbolic acid loses much of its value when in solu- 

 ition in alcohol or ether. An addition of 0.5 HC1 aids its activity. Car- 

 bolic acid is so permanent and so comparatively little influenced by 

 'albumin that it is rightly widely used in practical disinfection even in 

 [places of more powerful substances. 



Cresol. Cresol [C fi H 4 (CH 3 )OH] is the chief ingredient of the so- 

 (Called "crude carbolic acid." This is almost insoluble in water, and 

 | therefore of restricted value. Many methods are used for bringing it into 

 i solution so as to make use of its powerful disinfecting properties. With 

 'equal parts of crude sulphuric acid it is a powerful disinfectant, but 

 it is, of course, strongly corrosive. An alkaline emulsion of the cresols 

 jand other products contained in "crude" carbolic acid with soap is 

 I called creolin. It is used in 1 to 5 per cent, emulsions. It is fully as 

 [powerful as pure carbolic acid. Lysol is similar to creolin, except that 

 it lias more of the cresols and less of the other products. It and creolin 

 pre of about the same value. 



Tricresol. Tricresol is a refined mixture of the three cresols (meta- 

 rcresol, paracresol, and orthocresol). It is soluble in water to the 

 extent of 2.5 per cent., and is about three times the strength of carbolic 

 acid. 



Aniline Dyes. Some of these colors possess marked germicidal 

 [qualities. According to observers, methyl violet (pyoktanin) and 

 (malachite green destroy the typhoid bacillus in bouillon cultures in 

 jthe proportion of 1 : 200 in two hours' exposure, and the pyogenic cocci 

 in less. In 1: 100,000 solutions they are said to retard the development 

 [of bacteria. 



Oil of turpentine, 1 : 200, prevents the growth of bacteria. 

 Camphor has very slight antiseptic action. 



(Yen-ore in 1:200 kills many bacteria in ten minutes; 1:100 failed 

 to kill tubercle bacilli in twelve hour-. 



