138 INFECTION AND IMMUNITY 



depend upon shallow wells or polluted streams for 

 their supply of drinking water. The liability to 

 dangerous soil pollution in the vicinity of human 

 habitations, or in temporary camps, is so great that 

 sanitarians have long since learned to look with sus- 

 picion upon wells located in towns or in the vicinity 

 of privy-vaults in the country. Numerous examples 

 are upon record of local outbreaks of typhoid fever 

 directly traceable to the drinking of contaminated 

 well-water. 



The typhoid bacillus is promptly destroyed by the 

 various chemical disinfectants named in the pre- 

 vious chapter as germicidal for the cholera spirillum. 

 From a practical point of view, for the disinfection of 

 excreta, we recommend especially milk of lime, carbolic 

 acid (five-per-cent. solution), chloride of lime (four-per- 

 cent, solution), lysol, cresol or creolin (two-per-cent. 

 solution). The quantity of the disinfecting solution 

 used should be in excess of the quantity of excreta 

 to be disinfected, and the time allowed for the action 

 of the germicidal agent should be at least two hours. 



Boiling water in liberal amount (four or five times 

 the quantity of liquid excreta and urine) may also be 

 used with perfect safety and will accomplish the ob- 

 ject in view within a few minutes (ten minutes). 

 For bed linen and soiled underclothing, immersion in 

 boiling water or in a two-per-cent. solution of one of 



