ESTIMATION OF THE AMOUNT OF HAEMOGLOBIN 177 



with the diluted blood, wipe it off carefully on to the top, so as to 

 avoid loss. 



The remaining steps are again like those in Gowers' haemo- 

 globinometer, but with this difference : that you are comparing 

 two solutions of the same substance. These are very easy to match, 

 and the exact quality of the light does not matter, so that the 

 method may be used by any artificial light. 



I find it convenient to saturate the water in a bottle with 

 CO by bubbling coal-gas through it for some minutes. The 

 haemoglobin is then converted into CO haemoglobin in the process 

 of dilution, no further gassing is necessary, and the procedure is 

 exactly like Gowers' in all respects. The solution will keep for a 

 day or two if well stoppered. 



Oliver's H^moglobinometer differs from that of Gowers in 

 that the degree of dilution is constant and the colour of the diluted 

 blood is read off by comparison with a seriesof care fully graduated 

 standards. It consists of (i) a capillary glass tube with thick 

 walls and ground ends, one of which is flat and the other pointed : 

 this tube is mounted in a metal handle, the other end of which 

 serves as a stirrer (Fig. 43, c) ; (2) a small cell with an opaque 

 white bottom, and provided with a cover-glass which has a slight 

 bluish tint («) ; (3) a series of twelve coloured glass discs mounted 

 over an opaque white background (a) ; (4) certain small pink glass 

 discs used as riders ; (5) a short glass pipette with an indiarubber 

 nipple at one end and a short length of indiarubber tubing at the 

 other (d) : the latter fits over the pointed end of the capillary tube 

 mentioned first ; and (6) a small wax candle such as is used for 

 Christmas-trees. A camera-tube lined with a green material 

 is used to screen the eyes whilst the comparison is being 

 made. 



Method of Use. — Prick the patient in the usual way. Apply the 

 polished end of the capillary tube to the drop of blood ; this will 

 completely fill the tube, being drawn up by capillary attraction. 

 When quite full, wipe both ends of the tube with the fingers, and 

 apply the end of the glass pipette (previously filled with water) to 

 the pointed end of the capillary tube. Now squeeze the nipple 

 gently, so as to force the blood and (subsequently) the water drop 

 by drop into the cell. Interrupt the process occasionally, and stir 

 the contents of the cell with the metal handle of the measuring- 

 tube. Continue to add water until the cell is exactly full : this is 

 the first step which presents the slightest difficulty. Apply the 



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