181S.] Chemical Properties of Animal Fluids. 203 



I washed the albumen well in this experiment, digested it in 

 muriatic acid, and then burnt it to ashes, which were almost 

 exactly equal in quantity to the ashes produced by the combus- 

 tion of the same weight of colouring matter. But the ash of 

 the albumen was white, and did not show a particle of iron. I 

 found a trace of soda, but the greatest part was phosphate and 

 carbonate of lime, with a little magnesia. It is clear, therefore, 

 that the earthy salts found in the ashes of coloured blood had not 

 been dissolved in the blood, nor even existed as salts in the blood, 

 from which they were obtained by means of combustion. Hence 

 we may conceive, how the blood can produce and deposit, in the 

 animal economy, the earthy phosphates, which, however, are 

 not soluble either in pure water or in the blood ; and hence too 

 we may infer, that the production of bone cannot be considered 

 as a simple crystallization of a salt, conveyed by the blood in a 

 state of solution, but requires us to suppose the decomposition of 

 the animal matter of the blood, as well as in any other secretion. 

 All the authors who have written on the blood, assert that 

 gelatine is one of its component parts. This, however, is a 

 mistake, and arises from the gelatinous appearance of the albu- 

 men, as I have never been able to detect a particle of gelatine 

 in blood ; and, as far as my researches extend, I have found 

 gelatine to be a substance altogether unknown to the economy 

 of the living body, and to be produced by the action of boiling 

 water on cartilage, skin, and cellular membrane, substances 

 which are totally distinct from fibrin and albumen. 



On Human Blood. 



The blood of man perfectly resembles in composition that of 

 the ox, but the coagulum of human blood is more easily decom- 

 posed by water, and the fibrin thus obtained is more transparent. 

 When dried, it amounts to no more than 0*75 from 1000 parts. 

 Human fibrin has the same chemical properties with that of the 

 ox, but is more readily incinerated : the white ash consists of 

 the phosphates of lime and magnesia, a little carbonate of lime, 

 and soda. 



The colouring matter of human blood is also chemically the 

 same with that of ox blood, but is much more easily reducible 

 by fire to the same yellow ash, which seems to show that it con- 

 tains less azote or ammonium. A hundred parts of dried colour- 

 ing matter of human blood gave 15- parts of ash, of which 3 

 porta dissolved in water, and were alkaline, and when saturated 

 with acetic acid, and mixed with muriate of barytcs, it left a 

 copious precipitate of phosphate of barytcs, soluble in an excess 

 ot mu ri a t ic acid. 1 found in this acetic solution no traoe either 

 <it muriatic acid or of potash. It appears, therefore, that soda 

 and phosphoric acid, as well as the earthy phosphates, are pro- 



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