196 CLINICAL BACTERIOLOGY AND HiEMATOLOGY 



' 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 

 hsemoglobin 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. 



Sahli's HyEMOGLOBiNOMETER. — Here the standard consists of 

 a solution of acid haematin in glycerin and water, and has a 

 brown colour. To use it it is necessary to convert the haemo- 

 globin of the blood to be tested into acid haematin, so that (as in 

 Haldane's method) two solutions of the same substance are com- 

 pared. A dilute solution of HCl (about i per cent., the exact 

 strength being immaterial) is required. This is placed in the 

 graduated tube, and the measured amount of blood added : this 

 soon turns brown, but half an hour or so should be allowed to 

 elapse before the final step is carried out, as the solution gradually 

 darkens. Then the further dilution is carried out, with water or 

 dilute acid, until the depth of the colour exactly matches the 

 standard. 



This method is the most convenient for clinical work, and is 

 sufficiently accurate. 



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 series of carefully 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. 40, c) ; (2) a small cell with an opaque 

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

 bluish tint {e) ; (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 



