240 



Domestic Science 



vessel, replace the latter, and at once re-start the out- 

 flow of water. Should the aspirator be of less than 

 10 litres capacity, disconnect it when empty, rapidly 

 refill it, and replace it. Repeat this refilling till the 

 requisite quantity has been run out. 



The volume of water collected is equal to the volume 



Fig. .77. 



A = large aspirator fitted with stopcock. 

 C = large U-tube filled with pumice-stone moistened with pure 



sulphuric acid. 



T, T'= small U -tubes filled similarly to C. 

 K, K...= tight-fitting rubber stoppers. 



R, H = retort stands. 

 /. J, J = close-fitting rubber joints. 



of air which has passed through the drying- tubes. 

 Disconnect the latter, and quickly re- weigh each 

 separately. 



The increase in weight of C is the weight of the 

 moisture present in the volume of air passed through it. 

 Any increase in the weight of T beyond, say, -005 g., 



