404 RESPIRATION 



the glass in the pump, I obtained the following results, using a large- 

 sized Bohr pump with every precaution. 



B. Determination of Oxygen Capacity of Blood Haemoglobin 

 by Haemoglobinometer 



Colorimetric methods of estimating the relative concentrations of 

 haemoglobin in blood have been used for long; and in 1878 the late 

 Sir William Gowers introduced his well-known and extremely con- 

 venient "haemoglobinometer" for clinical purposes. 5 In this apparatus 

 there are two tubes A and B (Figure 102) of equal diameter; A is 

 sealed and contains picrocarmine jelly of such strength and composition 

 that when 20 cubic millimeters of normal human blood are diluted with 

 water in the tube B to the mark ioo, the tints of the liquid in the two 

 tubes are the same. If the blood contains abnormally little or much 

 haemoglobin, the quantity of water required to produce the tint of the 

 standard picrocarmine solution will be correspondingly less or more, 

 so that the percentage of the normal proportion of haemoglobin can be 

 read off on the tube. The diameter of the tubes and strength of the 

 picrocarmine or haemoglobin solution are so chosen that any variation 

 from the normal strength can be perceived with the maximum of readi- 

 ness. A solution much stronger or weaker would not be suitable. The 

 design is thus not only extremely convenient, but also thoroughly cor- 

 rect in principle. 



When it was discovered that the coloring power and oxygen capacity 

 of haemoglobin are strictly proportional to one another it became evident 



5 Gowers, Trans. Clinical Soc., XII, p. 64, 1878. 



