LIQUID PARTS OF ANIMALS. 



Bucquet about the year 1776 * made some interesting experi- 

 ments on blood. He found that the crassamentum might, by 

 means of water, be divided into two distinct substances ; namely, 

 the colouring matter, which was soluble in water, and which, if 

 we except its red colour, possesses nearly the characters of the 

 serum ; and a white fibrous portion, which he distinguished by 

 the name of tiiejibrous part of blood, j This substance coagu- 

 lates when blood is allowed to cool, and then becomes insoluble 

 in water. When dried in a very moderate heat it becomes hard 

 and brittle, assumes a dirty grey colour, and contracts as parch- 

 ment does when exposed to the same heat 



Fourcroy and Vauquelin turned their attention to animal sub- 

 stances at an early period of their chemical career ; and in 1790 

 announced the discovery of bile and gelatin in ox blood. They 

 affirm that, if the serum of blood mixed with the third of its 

 weight of water be coagulated by heat, and the albumen separat- 

 ed, the residual liquid, when sufficiently concentrated, assumes 

 the form of a jelly. J 



Fourcroy assures us that blood coagulates when cooled down 

 to 77, and that in the act of coagulation the thermometer rises 

 ll-25, making the coagulating point 8825. The serum, ac- 

 cording to him, coagulates at 155*75. These and many other 

 observations on the blood, made about the same time (1790) by 

 Fourcroy, are so inaccurate that it seems unnecessary to detail 

 them. 



Nearly about the same time a chemical examination of the 

 blood, with observations on some of its morbid alterations, was 

 published by Parmentier and Deyeux. || 



In 1797, a paper was published by Dr Wells on the colouring 

 matter of the blood.1F In this paper he explained the reason of 

 the change of colour which blood experiences by the action of 

 air, and showed, contrary to the opinion at that time universally 

 prevalent, that the colouring matter of blood is not iron, but an 

 organized substance of an animal nature. 



* See Dictionnaire de Chirnie, par Macquer, 2d edition, article Sang des Ani- 

 maux. 



j- It is the substance now called fibrin. This name, I presume, was con- 

 trived by Fourcroy. 



\ Ann. de Chim. vi. 181. Ibid. vii. 146. 



(| Jour, de Phys. 1794, p. 372, 438. 



1 Phil. Trans. 1797, p. 416. 



