ECONOMETER. 



149 



v', 0.4 inch in diameter leads to the inside of the flue before the 

 damper; a second pipe, v" , communicates with the interior of 

 the same flue beyond the damper. In the interior, the tube i' 

 is connected to the upright pipe/, which leads the gas to bell 

 /, and the tube i' to the tubulure g. i' and i" are of rubber. 



FIG. 37. ECONOMETER. 



The balance is very sensitive, the beam carrying at one 

 end the gas-holder e' , open below and containing about 30 

 cubic inches, and at the other end a second holder of similar 

 size and weight as the first. Attached to the bottom of this 

 one is a pan to hold the balancing weights. 



The tube f conducts the gas to the balloon /, which, open 

 below, is freely movable in the cylinder g y by which it pro- 

 duces suction in the tube i" . 



Carbonic acid being heavier than common air (1.96 to 

 1.29) as well as the other associated gases, it follows that the 

 density of the gases passing through the tubes depends on the 

 carbonic acid content. The scale is divided so that each 

 division shows one per cent of CO 2 in the gases. 



