38 CHEMICAL PHYSIOLOGY. 



1. W.L. of Absorption Bands of Oxy-Haemoglobin. 



(a.) Arrange the apparatus as shown in Fig. 6. A is 

 the telescope through which the observer looks and sees the 



Fig. C. Arrangement of the spectroscope for determining wave-lengths. 

 A, Telescope ; B, collimator tube ; C, scale tube ; D, hsematinometer. 



spectrum obtained by the light passing through B, and dis- 

 persed by the flint-glass prism in the centre of the apparatus. 

 In C is fixed a scale photographed on glass and illuminated 

 by a fan-tailed burner. D is the heematinometer containing 

 the dilute blood. 



(b.) Throw a piece of black velvet cloth over the prism ; 

 light both lamps ; look through B ; adjust the slit in A and 

 the telescope in B, so as to get a good view of the spectrum, 

 and over it the image of the scale. D is supposed not to be 

 in position at first. In a loop of platinum wire burn some 

 common salt in the flame to get the bright yellow sodium 

 line D. Adjust the scale so that this line corresponds to the 

 figures 58-9 on the scale, and fix the spectroscope tubes (A 



