130 A CHEMICAL SIGN OF LIFE 



Description of Apparatus III. As shown in Fig. 5, 

 the main part of this apparatus consists of only one glass 

 bulb A, which serves the combined purposes of respira- 

 tory and analytical chambers of the biometer. Its 

 capacity is about 30 to 40 c.c., but can become smaller 

 by introducing mercury in the same way as we managed 

 in the other apparatus. The barium hydroxide tube d 

 is inserted through its wall, and the three-way stopcock 4 

 is attached to the bottom of the chamber. Just opposite 

 the top of the barium hydroxide tube d there is another 

 three-way stopcock 2, one arm of which is connected to 

 the nitrometer C and the other arm of which is con- 

 nected to tube B, into which the respired air is to be 

 drawn for a subsequent analysis. This tube B is 

 attached to a mercury burette G, by which the pressure 

 in the tube and the chamber can be adjusted. The 

 similar mercury burette H is attached to the chamber 

 proper for the same purpose as well as for the means of 

 driving air into the tube B. The remaining parts of the 

 apparatus are exactly the same as in the biometer and 

 are shown in the figure with dimensions. 



Method for quantitative determination of carbon dioxide 

 with apparatus III. The detailed method is as follows : 

 Open stopcocks 2 and 3 in such a way as to connect the 

 chamber A and the tube B only. Fill the tube B with 

 mercury by raising the mercury burette G. Close stop- 

 cock 2 when a little excess of mercury is pushed over into 

 the space in the capillary tube between the chamber A 

 and the tube B and when the tube B is known to be 

 absolutely free from any bubble of air. The closing of 

 the stopcock must be done in such a way that there 

 is a connection made between the chamber A and 



