RED GLOBULES OF THE BLOOD. 181 



ture becoming of a fine transparent red, and the process takes 

 place almost immediately. On the contrary, when the globules 

 refuse to be dissolved, a muddy mixture is formed. When they 

 are dried in serum, and afterwards soaked again in it, they do 

 not resume the globular form. They have more substance than 

 the coagulating lymph, for they do not lose so much of their 

 bulk by drying. 



Notwithstanding the doubts that have been raised on the sub- 

 ject, it seems now to be very well ascertained, that iron is the 

 colouring principle of the red globules of the blood, though it 

 cannot be detached in the coloured state, owing to the absolute 

 necessity of using strong heat, or concentrated acids to destroy 

 the substance with which it is combined. The iron is an oxide 

 with a small quantity of the sub-phosphate, but a knowledge of 

 this fact does not enable the chemist to imitate red globules by 

 mixing these chemical substances with albumen. The process 

 by which Berzelius obtains iron from the biood, consists in 

 placing a clot of the latter upon blotting paper, whereby its se- 

 rum is absorbed. The clot being afterwards put into water, its 

 colouring matter is dissolved, while the lymph remains entire; 

 by removing then the lymph, and evaporating the water, the co- 

 louring matter -is obtained, which, on being reduced to ashes, 

 renders about one two-hundredth part of its weight in iron. 



The chemists also inform us, that fibrine, albumen, and the 

 colouring matter, all resemble one another so closely, that they 

 are only modifications of one and the same substance; and that 

 each of them yields, upon decomposition, phosphate and car- 

 bonate of lime, though these ingredients cannot be detected by 

 tests applied to the entire mass of blood. 



11 It is difficut to determine by what means the iron, or the 

 sulphur, or the elementary principles of calcareous earth, ob- 

 tain an existence in the blood. If these materials were equally 

 diffused throughout the surface of the earth, we might easily 

 "conceive that they were introduced through the medium of 

 food. But as this is not the case, as some regions, like New 

 South Wales, at least, on this side the Blue Mountains, contain 

 no limestone whatever, and others, no iron or sulphur, while all 

 these are capable of being obtained apparently as freely from 

 the blood of the inhabitants of such regions, as from that of 

 those who live in quarters where such materials enter largely 



VOL. II. 17 





