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XXXIV. Chemical Researches on the Blood, and some other 

 Animal Fluids. By William Thomas Brande, Esq, , 

 F.R.S. Communicated to the Society/ for the Improve- 

 ment of Animal Chemistry, and by them to the Royal 

 Society, 



[Concluded from p. 117.] 



SECTION VI. 

 Researcfies on the colouring Matter of the Blood. 



I. J. o procure this substance for experiments, I generally 

 employed venous blood which had been stirred during its 

 coagulation ; the fibrina is thus removed, and the colouring 

 matter diO'used ttirouch ihe serum, from which it gradually 

 subsides, being difficultly soluble in that fluid j on decanting 

 ofT the supernatant serum, the colouring matter remains in 

 a very concentrated form. When other modes ci" procur- 

 ing it were employed ihev will be particularly mentioned; 

 hut as 1 have not found the serum which is retained inter- 

 fere much with the effects of various agents upon the co- 

 louring principle, the method just noticed was commonly 

 adopted. 



2. When the colouring matter thus collected is micro- 

 scopically examined, it seems, as Lewenhoeck first ob- 

 served*, to consist of minute globules. These are usually 

 described as soluble in water, a circumstance which my 

 own observations led me to doubt, and which the more ac- 

 curate experiments of Dr. Young, an account of which, 

 intended for publication, he has kindly permitted me to 

 peruse, have completely disproved. 



3. Theeffect of water upon the red globules, is todbsolve 

 their colouring matter, the globule itself remaining colour- 

 less, and, according to Dr. Young, floating upon the surface. 



This aqueous solution is of a bright red colour, and not 

 very prone to putrefaction. When heated, it remains un- 

 altered at temperatures below igo** or 200^ Fahrenheit; at 

 higher temperatures it becomes turbid, and deposits a pale 

 brown sediment : if in this state it be poured upon a filter, 

 the water passes tlirough without colour, so that exposure 

 to heat not only destroys the red tint, but renders the co- 

 louring matter insoluble in water. 



Alcohol and sulphuric ether added to this solution also 

 render it turbid, and when these mixtures were filtrated, a 

 ColourlesB and transparent liquor was obtained. 



• Hallcr Elcm. Physlolog, vol. i. p. 5). 



M 3 4. The 



