THE BIOMETER: HOW TO USE IT 135 
of carbon dioxide produced by 10 mg. of the tissue 
during ten minutes will be 
I.OoX10—7 gxS= 16.6X1I0—7 g. 
of carbon dioxide. 
In order to test the accuracy with which our new 
method can be used for the estimation of the exceedingly 
minute quantities of the carbon dioxide, a series of 
determinations was made on the samples whose con- 
centrations were unknown to the experimenters at the 
time of analysis. 
The results are given in Table IT: 
TABLE II 
VotumE of SAMPLE WEIcHT oF CO: IN I C.c. 
REQUIRED TO GIVE A 
PRECIPITATE Found Taken 
DOC sG emia se sim Sass susie oink 1.0 X1077 g.| 0.92X107 7g. 
OLS Cc Ohavscaunciaew duady dake 2.0 X10~7g.| 2.3 X10 7g. 
OSS. C:Chsi sce ....| 1.82X1077 g.| 1.83 X10—7g. 
Tis! (C.Craiverdinies den eteas% 0.67 X10—7g.| 0.62X107 7g. 
Dig BSNCl Cis: x ecasceseiaeaes 0.45 X10 7g.| 0.45 X107 7g. 
One disadvantage of this apparatus III is that we 
must take into consideration temperature and pressure 
variation, which was entirely unnecessary for the 
biometer proper. If the respiration and analysis are 
carried out at different temperature and pressure, 
the ratio between the minimum volume which gives 
the first precipitate and the original volume of the 
chamber will not be rigid. In that case the minimum 
volume should be translated to the volume at the 
temperature and pressure at the time of respiration. 
Such correction, however, will not be necessary if the 
