EXAMINATION OF WATER II7 



the special methods will be tried other than those used in the 

 laboratory for pathogenic bacteria. 



173. Collecting Water — if the water is collected from a 

 spigot or pump, allow it to flow for 2 or 3 minutes first, and 

 then collect the desired quantity, 100-200 c.c, in a sterile 

 bottle and cork tightly ; orj if near at hand, absorbent cotton 

 plugs may. be used. 



If from a stream or river, withdraw the stopper and immerse 

 the sterile bottle, mouth ddwnward, to the depth desired and 

 allow it to fill. There are several mechanical devices for col- 

 lecting water from considerable depths from the surface. 



