DESTR UCTION OF BA CTEEIA B Y CHEMICALS. 165 



forms about one-third the strength of pure carbolic 

 acid. 



Chloroform. This substance, even in pure form, does 

 not destroy spores, but it does bacteria in vegetative 

 form, even in 1 per cent, solution. Chloroform is used 

 practically in sterilizing and keeping sterile blood-serum, 

 which can be used later for culture purposes by driving 

 off the chloroform. 



lodoform. This substance has but very little destruc- 

 tive action upon bacteria; indeed, upon most varieties 

 it has no appreciable effect whatever. When mixed 

 with putrefying matter, wound 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 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 destructive 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 solution in alcohol or 

 ether. An addition of 0.5 HC1 aids its activity. 

 Carbolic 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 [C 6 H 4 (CH 3 )OH] is the chief ingredient of the 

 so-called " crude carbolic acid." This is almost in- 



