ON THE TREATMENT AND UTILIZATION OF SEWAGE, 73 



ing of the bellows drawing in about 50 cubic inches of air. A quantity of 

 this air was passed through plugs of clean cotton-wool which had been heated 

 from 110° to 120° C, and these were sent to Mr. Cooke for examination. One 

 specimen of the wool, through which about 5000 cubic inches of the sewer air 

 had been transmitted, was put into distilled water with a little white sugar 

 to see if any germs similar to those lately described by Professor Heisch 

 would become visible. The liquid was examined in a week's time, but none 

 of the germs found. The experiments were made about 11 o'clock a.m. 



The next experiment was made on the same day, about 2 hours later, on 

 the air in the Ranelagh sewer, the largest in the Paddington district. The air 

 was taken from an opening in Gloucester Terrace, and was drawn out by 

 means of an air-pump. Some of the air was passed through cotton-wool, and 

 some collected for analysis gave the following results : — 



cub. centims. 



Volume of gas taken 14-86 



Volume after absorption of carbonic acid . . 14-80 



Volume after absorption of oxygen 11-71 



per cent. 



Carbonic acid 0-40 



Oxygen 20-79 



Nitrogen 78-81 



100-00 



The air was also allowed to pass over acetat«-of-Iead paper for 5 minutes 

 but no blackening took place. 



Another experiment was made at the drain in the back kitchen of 34 

 Upper Hamilton Terrace, St. John's Wood. The beU-trap was taken up and 

 a glass tube was put down the drain. The air was blowing up the drain at 

 the time, and had a disagreeable smell. A specimen of this air gave the fol- 

 lowing results ; it will be seen that it was quite free from any combustible 

 gases : — 



vols. 



Volume of air taken 229-65 



After addition of explosive gas 346-43 



After explosion 229-65 



After absorption of carbonic acid 229-37 



After addition of hydrogen 348-44 



After explosion 204-40 



per cent. 



Combustible gases 0-00 



Carbonic acid 0-12 



Oxygen 20-91 



Nitrogen 78-97 



100-00 



The following experiments were made on the air in a drain from a sink 

 in a room iu St. Mary's Hospital. This drain was selected as being the 

 nearest to the main drain passing from the hospital into the Cambrid"'e 

 Place sewer. The bell-trap of this drain was taken up ; a glass tube passing 

 about a foot down it was firmly corked into it, and by means of the air-pump 

 the air drawn out of it. First, a specimen of the air was passed throuo-h 

 cotton-wool, one specimen sent to Mr. Cooke, another treated with distilled 

 water and sugar ; the result of this experiment, as in the former case, was 



