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to it the colour of blood, and that the serum, thus 

 impregnated with iron, is entirely destitute of the 

 intrinsic characters of the colouring* matter. As 

 none of our most delicate tests of iron discover 

 its presence in the colouring matter, I thought 

 myself entitled to conclude, that iron cannot 

 be found in it in a saline form ; ancl, as we find 

 it impossible, even with the strongest acids, to 

 extract from the blood, or from its charcoal, 

 either the iron or the earthy phosphate, which are 

 so abundantly contained in the ashes of blood, 

 it follows of course, that neither of these sub- 

 stances exists there in the state of a salt ; from 

 which it is very probable, that blood contains the 

 elements of these salts, united in a manner different 

 from their combination in the salts. From this 

 circumstance, I further concluded, that the sub- 

 phosphate, or bone earth, which was supposed to 

 be contained in the blood, did really not exist 

 there, for I found that it could not be extracted 

 from dried blood with any diluted acid ; on the 

 contrary, that bone earth must always be a pro- 

 duction of the decomposition of the immediate 

 constituent parts of the blood, and that it is gene- 

 rated just on the very spot where its presence is 

 required. 



c 2 



