10 CHAPTER XXIII. 



BLOOD. 



Composition of Blood (Approximate average, human). 

 Water 77 p -% solids. 23 p - c -. Of the latter haemoglobin 14 

 proteids 7-5, salts 1-5 (urea 0-02, glucose 0-12). 



Colour. Arterial scarlet ; Venous purple. 



Reaction. Alkaline. Due to Na 2 HPO 4 and sodium car- 

 bonate. Place a drop on red litmus paper moistened with 

 normal saline, and after 15 seconds wash with the same. 

 Observe the colour of the stain. 



Specific gravity. 1035-1068. Estimate it by Roy's method 

 (Lloyd-Jones). The following are required : 



(a) A stock of standard solutions (SS) of glycerin and 



water of specific gravities varying from 1030 to 1080 

 by steps of 5 degrees. 



(b) Glass tubes drawn to capillary ends, of which the 



terminal 5 mm are bent at right angles. 



(c) A 3 drachm phial or an 8 cc tube. 



Process : Commencing with SS of a S.G. 1045 in the phial, 

 fill the capillary tube for 2 cm with blood from your 

 finger. Do not squeeze the finger in obtaining it. 

 Plunge the capillary point into the fluid in the phial, 

 holding the bent part horizontally, and expel a small 

 drop. If the drop falls or rises, the S.G. of the SS 



