CH. XXVI.] ILEMOGLOBINOMETER. 437 



diluted up to the graduation 50. the amount of haemoglobin is only half what 

 it ought to be 50 per cent, of the normal and so for other percentages. 



Von Fleischl's Hsemometer. The apparatus (fig. 369) consists of a 

 stand bearing a white reflecting surface (S) and a platform. Under the 

 platform is a slot carrying a glass wedge stained red (K) and moved by a 

 wheel (R). On the platform is a small cylindrical vessel divided vertically 

 into two compartments, a and a'. 



Fill with a pipette the compartment a' over the wedge with distilled water. 

 Fill about a quarter of the other compartment (r) with distilled water. 



Fig. 369. FleischPs Htemoglobinometer. 



Prick the finger and fill the short capillary pipette provided with the 

 instrument with blood. Dissolve this in the water in compartment a, and 

 fill it up with distilled water. 



Having arranged the reflector (S) to throw artificial light vertically through 

 both compartments, look down through them, and move the wedge of glass 

 by the milled head (T) until the colour of the two is identical. Read off the 

 scale, which is so constructed as to give the percentage of haemoglobin. 



Dr. Georgre Oliver's Method consists in comparing a specimen of blood 

 suitably diluted in a shallow white palette with a number of standard tests 

 very carefully prepared by the use of Lovibond's coloured glasses. These 

 standards are much better matches for blood in various degrees of dilution 

 than in the other colorimetric methods. The yellow tint of diluted hemo- 

 globin is very successfully imitated. 



Tests for Blood. These may be gathered from preceding 

 descriptions. Briefly, they are microscopic, spectroscopic, and 

 chemical. The best chemical test is the formation of hsemin 

 crystals. The old test with tincture of guaiacum and hydrogen 

 peroxide, the blood causing the red tincture to become green, 



