132 



METHODS FOR THE ANALYSIS OF BLOOD 



pipette is under atmospheric pressure and the volume of the gas 

 is read on the scale. 



Calculation. By means of the table on page 133 the readings 

 on the apparatus can be directly transposed into c.c. of carbon 

 dioxide chemically bound by 100 c.c. of plasma. The barometer 

 reading and room temperature are taken at the time of the deter- 

 mination. For convenience in the calculation values are given. 



D 



below for the ratio ^ - over the range usually encountered. (In 

 7oO 



order to have the column in the pipette exactly balanced by that 

 outside, the surface of the mercury in the leveling bulb should be 

 raised until it is level with the mercury meniscus in the pipette, 

 and then, for entire accuracy, raised above the latter meniscus 

 by a distance equal to 1/14 the height of the column of water 

 above the mercury in the pipette. As the water column is as a 

 rule, only about 10 mm. high, the correction that has to be esti- 

 mated is less than 1 mm. of mercury, i.e., the entire correction for 

 the water column is not enough to influence results appreciably. 



In case the volume of plasma taken for estimation of carbon, 

 dioxide content was 0.5 c.c. the observed volume of gas is multi- 

 plied by 2 before it is used to calculate the volume per cent of car- 

 bon dioxide bound. 



The temperature figures at the heads of columns represent the 

 room temperature at which the samples of plasma are saturated 

 with alveolar carbon dioxide and analyzed. It is assumed that 

 both operations are performed at the same temperature. The 

 figures have been so calculated that, regardless of the room tern- 



