CHAPTER XIII. 



BACTERIOLOGICAL EXAMINATION OF WATER, 

 FILTERS, MILK, AIR, SOIL, ETC. 



The bacteriological examination of water — The nature and number 

 of the organisms found in water — Determination of the number of 

 micro-organisms in water — ^Regulations of Imperial German Health 

 Department — Examination for sewage bacteria — Isolation of the 

 typhoid bacillus from water — Inhibition by phenol — Resistance of the 

 typhoid and colon bacillus to phenol— Eisner's method — Stoddart's 

 method — Isolation of the cholera bacillus from water — Examination 

 of filters — Examination of milk — Number of bacteria found in milk 

 — Milk diseases — Blue, red, yellow, bitter, stringy, soapy milk, etc. 

 — The organisms producing these diseased conditions — Necessity for 

 improved sanitary control of dairies — The sterilisation and pasteurisa- 

 tion of milk — Detection of the tubercle bacUlus — Examination of 

 air — Number of bacteria in the air — Sewer air — Filtration of air — 

 Examination of air by Hesse's and other methods — Examination of 

 soil — Number of micro-organisms found in the soil — Methods of 

 bacteriological examination of soU. 



THE BACTERIOLOGICAL EXAMINATION OF WATER. 



All natural waters necessarily contain micro-organisms, as 

 they are constantly being carried into it by air-currents, 

 and by the drainage from land-surfaces. It is only in water 

 from deep artesian wells and deep-seated springs that 

 organisms are very few in number, and it is very rare even 

 in these to find them entirely absent. The number and 

 variety of the bacteria in water depends upon several 

 conditions, such as the amount of organic matter in the 



