176 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



in a small stand. One of these tubes is filled with a jelly tinted 

 to represent the colour of normal blood of a certain degree of 

 dilution. The other is graduated into a hundred parts, the 

 graduation being such that when 20 cubic millimetres of normal 

 blood are diluted with water up to the 100 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 tube. 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 heemoglobin. 



Haldane's H^moglobinometer is similar in principle, but 

 here the standard tint consists of a sealed tube containing 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 comparison-tube, it is to be converted into CO haemo- 

 globin 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 comparison-tube, 

 taking care not to touch the solution of blood : turn on the gas, and 

 allow it to run into the tube for some time. When the comparison- 

 tube is filled with gas remove it, close it quickly with the finger, 

 and shake gently for a minute or two ; if you wet your finger 



