44 Gas Analysis. V 
acidified diluted blood. This correction for any temperature may 
be obtained from Curve 1| in Fig. 4. 
A typical calculation of the results obtained is as follows. 
Volume of air at 18°C. (compressed) in dif- 
fusion tube before removing stopper......... 10.9" tce-eae) 
Volume of air (at atmospheric pressure) in dif- 
fusion tube after removing stopper...... a= [ds ee eee 
Volume taken for analysis... video a = TS eo 
Gas remaining after absorption o of CO). Ne ee = 7.506 “ (4) 
CO, absorbed, 7.e., (3)—-(4).. Soese SS O68 es 
2 
Total CO, in air in tube, 7.e., (5) X x, Re Ree = 038.40 wo) 
CO, in solution in acidified blood, 7.e., volume 
of liquid (2.75 cc.) X solubility coefficient 
(1.0) X COs in air in tube a Re APE ee oe Sy: = 0 00653. aa) 
Total GO, from blood, tel, (6) =P (7) ace. ae ae == 01479" eas) 
CO, reduced from barometric pressure 762 and 
: 760 
temperature 26° to 760 and 0°, 2.e., (8) X 762 
273 
Se i Se = 0.448“ (9) 
(273 + 18) 
Volumes per cent CO, in blood, 7.e., (9) X 100 = 44.8 
Comparison of the results obtained with the original Barcroft- 
Haldane method and with our modification shows in every case 
that the latter gives figures 2 to 3 volumes per cent higher than . 
those obtained with the older method. This is due to the fact that 
the heavy precipitate produced by adding both ferricyanide and 
acid to blood renders it extremely difficult in the Brodie appa- 
ratus to shake the last trace of CO, out of the thick coagulum. 
Semultaneous Determination of Oxygen and COs. 
There appears no reason (except that just mentioned) why 
both gases should not be determined on a single sample of blood 
by first liberating the oxygen and then the COs. We have found 
that this can in fact be done (using half quantities of blood and 
reagents or in diffusion tubes of 20 cc. capacity) if a small glass 
rod or some lead shot is put into the tube to assist in breaking . 
up the heavy masses of the precipitate formed by the addition 
