358 LIQUID PARTS OF ANIMALS. 



I. The number of constituents discovered in blood, not reckon- 

 ing water, which constitutes a considerable portion of it, amount 

 at least to 22. The following table exhibits the names of these 

 substances : 



1. Albumen. 12. Common salt. 



2. Hematosin. 13. Chloride of potassium. 



3. Yellow colouring matter. 14. Sal-ammoniac. 



4. Fibrin. 15. Sulphate of potash. 



5. Extractive matter. 16. Carbonate of soda.* 



6. Serolin. 17. Carbonate of lime. 



7. Cholesterin. 18. Carbonate of magnesia. 



8. Cerebrote. 19. Phosphate of soda. 



9. Iron. 20. Phosphate of lime. 



10. A volatile fatty acid salt. 21. Phosphate of magnesia. 



II. Soap of margaric and 22, Lactate of soda. 



oleic acids. 



Let us take a view of these different substances in succession. 



1. Albumen. It has been already observed, that when heal- 

 thy blood is drawn from an animal and left at rest, it gradually 

 separates into two portions ; namely, a gelatinous looking sub- 

 stance, containing all the red globules, and called the crassamen- 

 tum or clot, and a liquid portion of a greenish yellow colour, 

 which floats on the surface, called the serum. 



It was first observed by Dr Harvey, that when the serum is 

 heated it coagulates and becomes as firm as the white of an egg, 

 though not so white, f The point of coagulation, as measured by 

 my thermometer, is 159. It had been long known that the 

 white of an egg coagulates when heated to the same point. 

 Rouelle and Bouquet about the year 1776, first compared serum 

 of blood and white of egg together, and concluded that both con- 

 tained a similar substance, which from the white of egg, which con- 

 tains it in the state of greatest purity, has got the name of albumen. 



The albumen of eggs was examined with some care by Neu- 

 mann, who ascertained its property of being coagulated by heat, 

 alcohol, and acids, found that in a gentle heat it might be evapo- 

 rated to dryness, constituting a yellowish translucent substance 

 resembling amber in appearance, and still capable of dissolving 



* Dr Davy is of opinion that the soda in blood is in the state of sesquicar- 

 bonate. See Phil. Trans. 1838, p. 291. 

 | De Generatione Auim. p. 161. 



