VII.] 



ESTIMATION OF HAEMOGLOBIN. 



6i 



In practice it will be found that, during 6 or 8 degrees of dilution, 

 it is difficult to distinguish a difterence between the tint of the 

 tubes. It is therefore necessary to note the degree at which the 

 colour of the dilution ceases to be deeper than the standard, and 

 also that at which it is distinctly paler. The degree midway 

 between these two will represent the haemoglobin percentage." 



ADDITIONAL EXERCISES. 



8i Fleischl's Haemometer.— This apparatus (fig. 36) consists of a horse-shoe 

 stand with a pillar bearing a reflecting surface (S) and a platform. Under 

 the table or platform is a slot carrying a glass wedge stained red (K), and 

 moved by a wheel (R). On the platform (M) is a small cylindrical vessel (G), 



Fleischl's Haemoraeter. 



divided into two compartments (a and a') by a vertical septum. In one 

 compartment is placed pure water, and in the other the blood to be investi- 

 gated. A scale (P) on the slot of the instrument enables one to read off 

 directly the percentage of h?emoglobin. .,.,..„, 



{a.) Fill with a pipette the compartment (a') over the wedge with distilled 

 water, and see that the surface of the water is quite level with the top of the 

 cylinder. Fill the other compartment (a), that for the blood, about one- 

 quarter with distilled water. 



