BACTERIOLOGICAL STUDY OF WATER. 599 



Where it is not convenient, however, to make the 

 analysis on the spot, the sample of water should be 



taken and packed in ice and kept on 



FIG. 93. 



ice until the plates can be made from 

 it, which should in all cases be as soon 

 after its collection as possible. 



For the collection of samples from 

 the deeper portions of streams, lakes, 

 etc., a number of convenient devices 

 have been made. A very satisfactory 

 apparatus has been made for me by 

 Messrs. Charles Lentz& Sons, of Phila- 

 delphia. It consists of a metal frame- 

 work, in which is encased a bottle 

 provided with a ground-glass stopper. 

 To the stopper a spring clamp is at- 

 tached, and this in turn is operated by 

 a string, so that when the weighted 

 apparatus is allowed to sink into the 

 stream the stopper may be removed 

 from the bottle at any depth by simply 

 pulling upon the string. When the 

 bottle is filled with water the stopper 

 is allowed to spring back into position 

 by releasing the string. The whole 

 apparatus (depicted in Fig. 93) is pro- 

 vided with a weight that insures its 

 sinking, and a heavy cord by which it may be lowered 

 and raised. It should be sterilized before using. After 

 collecting the sample the bottle should be wiped dry 

 with a sterilized towel. Before removing the stopper 

 the mouth of the bottle should be rinsed with alcohol 



rz&soMS. 



