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the protoxide, to a subphosphate of the peroxide. 

 With the greatest diffidence of myself, I have re- 

 peatedly tried the experiments of those Chemists, 

 the most celebrated of all Europe : and by finding' 

 my results invariably disagree with theirs, I have 

 been compelled to consider their statement as a 

 mistake, and to declare, that, in regard to the 

 manner in which iron is united to the colouring 



o 



matter of the blood, we know as little now, as 

 when iron was first discovered in it- I have en- 

 deavoured to shew, that the colouring matter, 

 much as it resembles albumen, cannot itself be 

 albumen; and that as LEEUWENHOEK and 

 HARTSOEKER proved long ago, by microscopical 

 observations, it is not dissolved in the blood, but 

 floats in it in a suspended state ; for if the coagu- 

 lated cruor is triturated in serum, part of the co- 

 louring matter is thereby separated, and the se- 

 rum assumes a red colour ; but if it is suffered 

 to settle in a cylindrical glass, the colouring 

 matter slowly precipitates itself to the bottom, 

 and the serum above becomes clear, as before. 



I have proved, that metallic oxides, particu- 

 larly those of iron, may, in a certain degree, be 

 dissolved by the serum, and thereby, more or less, 

 Change its colour; but that none of them imparts 



