Apparatus For Estimating Carbon Dioxide 



141 



quantity of carbon dioxide, given by the specimen, may be 

 computed. 



At the suggestion of Dr. F. C. Koch, another apparatus was con- 

 structed, which provides a control drop of the barium hydroxide 

 solution, side by side with the other. The apparatus (Biometer) shown 

 in Fig. 2, although it appears complex, is nothing more than apparatus 

 i, inclined 90, but each of its chambers is provided with a barium 

 hydroxide cup d and f . It is made of glass consisting of two respi- 

 ratory chambers, serving also as analytic chambers, connected by a 

 three-way stop-cock L, the other arm of which is connected to one 

 arm of another three-way stop-cock K. Each of the other two arms 

 of stop-cock K is connected to a nitrometer W and X. The nitro- 



FIGURE 2. Biometer, one-third actual size. 

 The shaded portions of the apparatus indicate the rubber connection which is first 



coated by shellac, and then sealed with a special sealing wax. 

 also sealed with mercury. 



Some parts are 



meter on the right, is connected to a carboy with air free of CO 2 ; and 

 the other, on the left, to a similar reservoir with air free of C0 2 plus 

 any gas which is desired as a medium for conducting the experi- 

 ment. Chamber A is drawn to a capillary stop-cock C; chamber B 

 is drawn to the three-way stop-cock G, one arm of which is con- 

 nected with a mercury burette T, which is used for adjusting the 

 pressure. Both of the chambers have a capacity of 20 to 25 c.c. 

 and are provided with a pair of platinum electrodes n and m, and 

 also with the glass stoppers S and R, which can be sealed as usual 

 with mercury. The pump is connected through J, and the barium 



