BLOOD. 



the reading with the small cell is correct, the reading with the large 

 one should be 52.5, since 42 Xf 52.5. The mean of the two 

 readings is taken as approximately correct. 



Each instrument is supplied with a corrected scale of haemo- 

 globin values. Comparing the figure, obtained above, with the 

 scale, it is found to correspond to a solution containing 400 milli- 

 grams of haemoglobin in 1000 c.c. of solution. The dilution which 

 was employed was i to 200, i to 300, or i to 400, according as to 

 whether the pipette was filled to the mark ^, f , or y. To find the 

 actual amount of haemoglobin in a given volume of blood, the re- 

 sult obtained would have to be mutliplied by 200, 300, or 400. In 

 the example taken above with a dilution of i to 200 there would be 

 8 grams of haemoglobin in 100 c.c. of blood. 



4. Estimation of Specific Gravity. It was first demon- 

 strated by Hammerschlag that the specific gravity of blood bore a 

 sufficient relation to the haemoglobin content to make it of value in 

 estimating the same. Variations in haemoglobin ordinarily cor- 

 respond quite closely to variations in specific gravity. With this 

 in view Hammerschlag devised the following table showing the re- 

 lation between specific-gravity changes and variations in haemo- 

 globin percentage: 



Specific Gravity. Per cent Haemoglobin 



.033-1 .035 25-30 



.035-1 .038 30-35 



.038-1.040 35-40 



.040-1 .045 40-45 



.045-1 .048 45-55 



.048-1.050 55-65 



.050-1 .053 65-70 



-053-! -055 7-75 



-OSS" 1 -57 75- 8 5 



.057-1.060 85-95 



The most convenient method for obtaining the specific gravity 

 is through the use of two fluids with which the blood will not mix, 

 one of a high density and the other of a lower density, such as 

 chloroform and benzol. 



[71] 



