514 



Messrs. Carnelley and Haldane. 



bottom of the experimental sewer, the sides of which were also 

 moistened before each experiment. By estimating the micro-organisms 

 in the air at the month of the tube and in the box, the difference 

 caused by passage of the air along the tube could be determined. 

 The rate of the current of air through the long tube was in all the 

 experiments 5 feet in six seconds. The determinations were made 

 simultaneously, after the draught had been established for a short time. 



No. of 

 experiment. 



i. 



2 

 3. 

 4, 

 5. 

 6. 

 7. 



Quantity of 

 air aspirated 



through 

 Hesse's tube. 



i litre . 

 i litre . 

 5 litres 

 5 litres 

 5 litres 

 i litre . 

 I litre . 



Average 



Air of laboratory (before 

 passing through tube). 



Total micro- 

 organisms. 



200 

 205 

 4 

 9 

 1 



344 

 221 



141 



Moulds 





 

 1 

 47 

 67 



23 



Air of box (after passing 

 through tube). 



Total micro- 

 organisms. 



100 

 141 

 3 

 2 

 1 



139 

 175 



80 



Moulds. 



1 

 1 

 



42 

 73 



23 



In Nos. 1, 2, 6, and 7 the air was rendered dusty by shaking mats 

 in the room. Nos. 3, 4, and 5 were made with the air of the labora- 

 tory in its ordinary condition. 



