CONSTITUENTS OF BLOOD. 41 



when the latter is purified from all foreign mat- 

 ters. 



The second principal ingredient of the blood is 

 contained in the serum, and gives to this liquid all 

 the properties of the white of eggs, with which it is 

 identical. When heated, it coagulates into a white 

 elastic mass, and the coagulating substance is 

 called albumen. 



Fibrine and albumen, the chief ingredients of 

 blood, contain, in all, seven chemical elements, 

 among which nitrogen, phosphorus, and sulphur are 

 found. They contain also the earth of bones. The 

 serum retains in solution sea salt and other salts of 

 potash and soda, in which the acids are carbonic, 

 phosphoric, and sulphuric acids. The globules of the 

 blood contain fibrine and albumen, along with a red 

 colouring matter, in which iron is a constant ele- 

 ment. Besides these, the blood contains certain 

 fatty bodies in small quantity, which differ from 

 ordinary fats in several of their properties. 



Chemical analysis has led to the remarkable re- 

 sult, that fibrine and albumen contain the same 

 organic elements united in the same proportion, so 

 that two analyses, the one of fibrine and the other 

 of albumen, do not differ more than two analyses of 

 fibrine or two of albumen respectively do, in the 

 composition of 100 parts. 



In these two ingredients of blood the particles 

 are arranged in a different order, as is shewn by the 

 difference of their external properties ; but in die- 



