BLOOD. 1G9 



Lecanu's method of analysing tlie blood is very similar to 

 tliat of Berzelius. 



Denisi adopts a method of analysing this fluid which involves 

 considerable time and manipulation; and, after all^ does not 

 give results of very great accuracy. 



Fresh blood is received into two vessels of known capacity, 

 one of which is narrow and high. One portion is used for the 

 determination of the water, the carbonate of soda, and the 

 chlorides of sodium and potassium; the other for the estunation 

 of the other constituents of the blood. 



I. The first portion is evaporated to dryness in the water- 

 bath, pulverized in an agate mortar, again heated on the water- 

 bath, and the quantity of evaporated water estimated. 



The residue is incinerated, digested in water, and filtered; the 

 filtered solution is evaporated to dryness, and the residue is 

 weighed, dissolved in water, and treated with nitrate of silver ; 

 chloride of silver, and oxide of silver (?) are precipitated. This 

 precipitate is dissolved in nitric acid, the solution is evapo- 

 rated and crystallized ; the crystals are dissolved, decomposed, 

 and neutralized by carbonate of soda. The solution which is 

 thus obtained (of nitrate of soda) is filtered, evaporated to dry- 

 ness, and incinerated with animal charcoal in a platinum cru- 

 cible. It is then digested in water, and the carbonate of soda 

 ascertained. Upon deducting the weight of the salt from that 

 of the whole ash of the blood, we obtain as a residue the weight 

 of the chlorides of sodium and potassium. 



II. The other portion is allowed to stand for twenty-four 

 hours, in order to permit of the thorough separation of the clot 

 from the serum. 



The latter is removed with a pipette, and the separation is 

 continued until incipient signs of decay present themselves. 

 The water is removed from the serum, in vacuo, at a tempera- 

 ture of from 120° to 140°. The clot is placed in a small bag 

 and washed with water until all the colouring matter is removed. 

 The residue, consisting of fibrin, is then placed in the water 

 that has been used for the washing of the clot. The fibrin 

 is separated by decantation, the solution of colouring matter 

 being carefully poured off. It is then washed with fresh water. 



' Recherclies experimentales sur le Sang humain, considers a I'etat sain, par S. 

 Denis : Paris, 1830, p. 121. 



