112 Mr. W. Brande’s Chemical Researches on the Blood , 
of the coagulum of chyle in dilute, than in concentrated acids, 
points out a strong analogy bet\veen those two bodies. 
The sweet taste of chyle naturally suggested the idea of its 
containing sugar ;* but I am not aware of any direct experi- 
ments which have demonstrated its existence, and have there- 
fore detailed minutely such researches as I have been enabled 
to make upon the subject, hoping at some future period to 
render them more complete. 
The experiments to prove the non-existence of gelatine in 
the serum of blood, will, I trust, be deemed sufficiently deci- 
sive : they shew that that abundant proximate principle of 
animals is not merely separated from the blood, in which it 
has been supposed to exist ready formed, but that it is an 
actual product of secretion. 
The proportion of iron afforded by the incineration of seve- 
ral varieties of animal coal, is much less considerable than we 
have been led to expect, and the experiments noticed in the 
fifth section, shew that it is not more abundant in the colour- 
ing matter of the blood, than in the other substances which 
were submitted to examination ; and that traces of it may be 
discovered in the chyle which is white, in the serum, and in 
the washed crassamentum or pure fibrina. 
The inferences to which I have alluded, in the first section 
of this paper, are strongly sanctioned by these facts, and co- 
incide with the opinion which has been laid before the Royal 
Society, by Dr. Wells, •f respecting the peculiar nature of the 
colouring principle of the blood, and support the arguments 
which are there adduced. 
That the colouring matter of the blood is perfectly inde- 
pendent of iron, is, I conceive, sufficiently evident from its 
* Forbyce on Digestion, 2d Edition, p. 52 5. f Phil. Trans. 1797, 
