74 REPORT — 1870. 



negative. A specimen of the air from this drain was also analyzed, and gave 



the following results: — 



cub. centims. 



Volume of air taken 11'69 



After absorption of carhonic acid 11-63 



After absorption of oxygen 9-21 



per cent. 



Carbonic acid 0-51 



Oxygen 20-70 



Nitrogen 78-79 



100-00 



A large quantity of this air was now drawn through water, and the water 

 tested for ammonia and albumenoid ammonia. The experiment was made as 

 follows : — a measured quantity of water (in this case four gallons) was allowed 

 to run out of a gas-holder ; the air thus drawn out of the drain first passed over 

 acetate-of-lead paper, then through three small flasks, each containing 80 cub. 

 centims. of pure distilled water ; the tubes passing into the water were sur- 

 rounded with platinum gauze, so as to break up the bubbles in the water. 

 The experiment lasted 3^ hours. The 240 cub. centims. of water in the flasks 

 was put into a retort and distilled with a little carbonate of soda ; it gave a 

 trace of ammonia, about yos ^^ ^ milligramme. 



These experiments must be looked upon as simply tentative, but certainly 

 indicate a purer air in these sewers than might have been anticipated. 



Eejjort hy Mr. M. C. Cooke, M.A., Aug. 27, 1870, 



I have examined microscopically the contents of the tubes sent to me, 

 viz. — 



No. 1. Air from Cambridge Place sewer, about 5000 cubic inches of which 

 passed through the cotton-wool. 



No. 2. Air from the same sewer, of which about 7000 cubic inches passed 

 through the cotton-wool. 



No. 4. Air from large sewer in Gloucester Place, about 2950 cubic inches 

 of which passed through the wool. 



No. 5. Air from sink-drain in Hospital, about 2950 cubic inches of which 

 passed through the wool. 



These were all examined separately and without any contact. All utensils, 

 slips of glass, ttc. were quite clean. 



The method adopted in all instances was uniform. 



The plug of cotton-wool was immersed in distilled water (freshly distilled) 

 and well shaken in the water in a clean tube. The water with the organisms 

 in suspension was then examined, drop by drop, till nearly exhausted. 

 Whether this was the best method to adopt I am not certain, but the process 

 was the same for the four samples. 



The results generally indicate comparative freedom from organic bodies; in 

 Nos. 4 and 5 perhaps an insufficient quantity of air was passed through the 

 wool, as compared with Nos. 1 and 2. 



No. 5 contained a very few starch-granules (PL III. fig. 17), a little granular 

 matter, and two or three brownish spores, almost identical with fungi-spores 

 of the genus Macrosporivm. They are club-shaped, -0015 x -0005 inch in 

 size, with three or four septa ; the upper portion coloured, the lower or nar- 

 rower portion (the base) colourless. Species of this genus are common on 



