82 PHYSIOLOGICAL CHEMISTRY. 



tration (the amount of coloring matter in grams in 1 c. c.) by C, 

 then C = A.E. 



Different apparatus have been constructed (VIERORDT and 

 HUFNER) for the determination of the extinction coefficient which 

 is equal to the negative logarithm of those rays of light which 

 remain after the passage of the light through a layer 1 cm. thick 

 of an absorbing liquid. In regard to these apparatus the reader is 

 referred to other text-books. 



As control the extinction coefficients are determined in two different 

 regions of the spectrum, namely, D3&ED51E and DZED%E. The 

 constants or the absorption ratio for these two regions of the spectrum are 

 designated by HEFNER by A and A'. Before the determination the blood 

 must be diluted with water, and if the proportion of dilution of the blood be 

 represented by V, then the concentration or the amount of coloring matter in 

 100 parts of the undiluted blood is 



C= 100. V.A.E and 

 6'= 100. V.A'.E'. 



The absorption ratio or the constants in the two above-mentioned regions 

 of the spectrum have been determined for oxyhaemoglobiu, haemoglobin, 

 carbon monoxide haemoglobin, and methaemoglobiu. 



The figures for the above coloring matters obtained from canine blood are 

 as follows : 



Oxy hemoglobin ............. A 0.001330 and A ' 0.001000 



Hemoglobin ................. A r = 0.001091 " A r ' = 0.001351 



Carbon monoxide hemoglobin A c 0.001130 " A e ' = 0.001000 

 Methsemoglobin .............. A m 0.003696 " A m ' 0.002798 



The quantity of each coloring matter may be determined in a mixture of 

 two blood-coloring matters by this method, which is of special importance in 

 the determination of the quantity of oxyhaemoglobin and haemoglobin present 

 in blood at the same time. If we represent by .Z^and E' the extinction co- 

 efficients of the mixture in the above-mentioned regions of the spectrum, by 

 AO and AO and A r and A r ' the constants for oxyhaemoglobin and reduced 

 haemoglobin, and by Fthe degree of dilution of the blood, then the percentage 

 of oxyhaemoglobin H and of (reduced) haemoglobin H r is 



and 



H r = 100 V. 



Among the many apparatus constructed for clinical purposes 

 for the quantitative estimation of haemoglobin the haemometer of 

 FLEISCHL is to be preferred. The determination by this apparatus 

 is made by comparing the color of the blood diluted with water 

 with the color of a wedge-shaped movable prism of red glass. If 

 the blood shows the same color as the glass prism, then the amount 

 of haemoglobin in the blood may be directly read from the scale. 



