316 Mr. Take Sone on the Magnetic Suscejrtibilities 



of these results was used according to the kind o£ gases 

 under examination. Thus the mass of carbon dioxide was 

 always determined by the weighing method, and that of 

 hydrogen chiefly by the volumetric method. The mass of 

 air sealed in the measuring tube at the atmospheric pressure 

 and temperature was obtained by calculation, the conditions 

 of the atmospheric air and the volume of the tube in which 

 it was sealed being; known. The volume of the measuring 

 tube was accurately determined by filling it with mercury. 



(c) Method of filling the Measuring Tube with Gas. 



The measuring tube is connected with the neck of the 

 compressing cylinder E by means of a screw D (fig. 7). 



Fig. 7. 



The lower end of the glass cylinder E is bent upward, and 

 connected by a short rubber tube with a glass tube coming 

 from a three-way-cock T. One of the three ways com- 

 municates with a Gaede auxiliary pump and another with 

 the gas generator or reservoir. The lower part of the 

 cylinder E is dipped in a mercury bath as shown in fig. 7 . 

 By means of the three-way-cock, the cylinder is first con- 

 nected with the pump, evacuated, and then the cock is 

 turned, the gas is introduced into the cylinder. Next the 

 cylinder is again evacuated and the gas introduced ; these 

 processes are usually repeated four or five times. Then the 

 air previously contained in the cylinder is removed, and 

 the cylinder now contains the pure gas at a pressure of abou ^ 

 one atmosphere Then the cylinder E and the glass tube i 

 disconnected under the surface of the mercury in the bath^ 



