BLOOD 271 



of 18.5 per cent, it is of course easy to express 

 the results in terms of oxygen capacity. The 

 exact percentage of haemoglobin corresponding to 

 18.5 per cent oxygen capacity is still uncertain. 

 According to Hufner's latest results it would be 

 13.8 per cent. 



In using the haemoglobinometer, place 15-20 

 c.c. water in the graduated tube, for dilution of 

 the blood. Draw 20 cb. mm. of blood into the 

 pipette, with the necessary precautions. 1 Gently 

 blow the blood out of the pipette on to the sur- 

 face of the water in the graduated tube. Before 

 mixing the blood with the water introduce into 

 the free part of the tube a narrow glass tube con- 

 nected with the gas-tap, turn on the gas, and 

 push the gas-tube down to near the level of the 

 water, so that the air may be instantly displaced 

 from the tube. Avoid any loss of liquid. If 

 the upper part of the tube, or the liquid itself, 

 is warmed by the fingers while the solution is 

 being mixed or saturated with carbon monoxide, 

 a little liquid is apt to spurt out. This can be 

 avoided by holding the tube in a cloth. With- 

 draw the gas-tube while the gas is still flowing. 

 Close the top of the graduated tube with the 

 finger and invert the tube about a dozen times, 



1 See page 264 ; remember not to use blood squeezed from 

 the ear. 



