230 CLINICAL BACTERIOLOGY AND H^MATOLOGY 



jelly tinted to represent the colour of normal blood of a cer- 

 tain degree of dilution. The other is graduated into a hun- 

 dred parts, the graduation being such that when 20 cubic 

 millimetres of normal blood are diluted with water up to 

 the loo mark, the colour of the two tubes should be exactly 

 the same. A pipette measuring 20 cubic millimetres and a 

 dropping-bottle (which is to be filled with water) are also 

 provided. 



Method of Use. Place a few drops of water (preferably, 

 but not necessarily, distilled) in the graduated tube. Draw 

 the blood in the usual way. Apply the tip of the measuring 

 pipette to the drop, and suck gently until the blood reaches 

 up to the mark. Now put the tip of the pipette into the small 

 quantity of water in the bottom of the graduated tube and 

 blow out the blood; this will sink to the bottom of the tube; 

 now raise the tip of the pipette into the supernatant layer of 

 clear water; suck water up the pipette until it reaches above 

 the mark, and blow it out; repeat this process until the blood 

 is thoroughly washed out from the pipette. Take great care 

 not to withdraw any of the diluted blood when removing the 

 pipette. Finally shake the tube so as to mix the blood and 

 water thoroughly. 



Place the two tubes side by side on a sheet of white paper 

 in front of a well-lighted window which is not exposed to 

 direct sunlight; look at them by the light which is reflected 

 from this paper and add water from the pipette belonging 

 to the dropping-bottle, drop by drop, until the colour in the 

 two tubes is exactly the same. Read off the height of the 

 column of diluted blood; this gives the percentage amount 

 of haemoglobin. 



HALDANE'S H^MOGLOBINOMETER is similar in principle, 

 but here the standard tint consists of a sealed tube contain- 

 ing a solution of carboxy-haemoglobin. The rest of the 

 apparatus is exactly like Gowers', and the method of use is 

 similar, except that, after the 20 cubic millimetres of blood 

 have been diluted with the few drops of water in the com- 

 parison-tube, it is to be converted into CO haemoglobin by 

 saturation with ordinary coal-gas. To do this, take the 

 curved tube supplied with the apparatus, fit it to an ordinary 

 gas-burner, and insert the other end of the tube in the com- 

 parison-tube, taking care not to touch the solution of blood : 



