Report on the Bacteriology of Water. 



299 



Experiments with Oxygenated {Aerated) Thames Water. 



In order to test the action of combined movement and aeration, we 

 employed the following means : — A flask of litre capacity, and 

 with a side arm tubulure, was half filled with the water to be 

 experimented on, and its neck fitted with a caoutchouc stopper 

 through which passed a long, narrow glass tube ; the lower end of 

 the tube was drawn to a point and passed to the bottom of the flask ; 

 the upper end was curved back on itself and carefully packed with 

 successive plugs of sterilised cotton wool, and the end covered with a 

 large tuft of the same. Preliminary trials convinced us that if this 

 apparatus is properly sterilised, and carefully used, air may be 

 drawn through the cotton- wool filter for two or three weeks without 

 contamination of the contents. The accompanying figure represents 

 the apparatus. 



A, lateral tubulure plugged with cotton wool and attached to pump : _B, curved 

 tube plugged at intervals with cotton wool to filter air which passes into 

 liquid below ; C, large wad of cotton wool, tied on to air tube at D ; JS, water 

 containing bacteria to be experimented with. 



In the following series of experiments, one flask was aerated in the 

 manner described for six days, and an exactly similar flask kept 

 standing quietly by its side under exactly similar conditions other- 

 wise. Both flasks contained Thames water, from the same collection, 



