504 



HjEMATOSINE. 



Caroonate of soda, with traces 



of phosphate 0.3 



Phosphate of lime 0.1 



Caustic lime 0.2 



Subphosphate of iron 0.1 



Sesqui-oxide of iron 0.5 



Carbonic acid and loss 0.1 



1.3 



The ultimate analysis of haematosine ap- 

 proaches very nearly to that of fibrine. Mi- 

 chaelis declares to have found a difference of 

 ultimate constitution between the colouring 

 matter of arterial and venous blood : his ana- 

 lyses are as follows : 



Arterial. Venous. 



Nitrogen 1 7.253 1 7.392 



Carbon 51.382 53.231 



Hydrogen 8.354 7.711 



Oxygen 23.011 21.666 



It will be observed, on examining these ana- 

 lyses, that the difference of constitution is so 

 small that we may reasonably conclude it has 

 been produced by a difference in manipulation 

 or some other extraneous cause capable of 

 modifying the result: indeed, ultimate ana- 

 lyses of identical substances have, when in the 

 hands of different chemists, often yielded re- 

 sults far more discrepant than these, and that 

 too when each operator stood high as an ana- 

 lyst. Berzelius, in remarking on these expe- 

 riments, observes that it is impossible for the 

 chemist to fix the state of blood whether arterial 

 or venous; for it will lose its condition with 

 respect to the colouring matter long before the 

 chemist can procure its haematosine for analysis. 

 Thus the venous clot becomes of a bright red 

 colour when exposed to air, and arterial blood 

 soon loses its vermilion hue. A great con- 

 trariety of opinion exists as to the cause of the 

 red colour of haematosine, some chemists sup- 

 posing that the iron contained in it takes an 

 active part in its coloration, while others 

 maintain that though iron is present it cannot 

 be considered as the cause of colour. Win- 

 terl imagined he had discovered the secret 

 when he formed sulphocyanic acid (blut saure) 

 by carbonizing blood with carbonate of potash 

 and precipitated salt of iron with the lixivium 

 an experiment quoted by Treviranus ; but we 

 are unable to detect the sulphocyanic acid in 

 blood, so this formation of a ferruginous co- 

 louring matter must not be considered as in 

 any way assisting in the inquiry, although it 

 simulates the tint of blood most completely. 

 Fourcroy asserted that subphosphate of iron 

 was capable of imparting a red colour to serum, 

 which is not the case, and went so far as to 

 declare that the colourless globules of the 

 chyle contained neutral phosphate of iron, 

 which, when mixed with the blood, was de- 

 composed by the alkali present into a sub- 

 phosphate, which on reaching the lungs be- 

 came a per-salt and imparted colour to the 

 fluid. This idea is quite hypothetical, and in 

 discordance with facts as observed by other 

 jchemists. 



Engelhart's experiments on haematosine tend 

 to shew that iron is in some way influential 

 in producing the red colour of the blood. He 

 showed that, though albumen and fibrine 

 yielded no iron on incineration, the metal ex- 

 isted in considerable quantity in hsematosine. 

 He found that a solution of red particles im- 

 pregnated with sulphuretted hydrogen became 

 of a violet colour and then passed to a green, 

 it being impossible to restore the original red 

 tint. Chlorine when passed through the solution 

 bleached it, having previously produced a 

 green colour; when decolorization was com- 

 plete, white flocculi were observed to fall, 

 which on being examined yielded no appre- 

 ciable ash, while the clear solution gave evi- 

 dence of iron by the usual reagents. The 

 white flocculi were supposed by Engelhart to 

 be the colouring matter changed to white by 

 the abstraction of its iron. It is evident that 

 even if the colour of the blood were owing to 

 some peculiar animal matter and not to iron, 

 we should still expect decolorization by chlo- 

 rine ; but yet the change of colour from red to 

 green which that re-agent produces previous to 

 decolorizing the solution, renders it probable 

 that its action is on iron in some form of com- 

 bination as yet unknown. Rose has shown 

 that many organic matters interfere with the 

 action of the tests for iron when present in 

 solution with that metal, and quotes this to 

 account for the failures in procuring the re- 

 actions of iron from the blood in a fluid state. 

 Some experiments of Berzelius, however, have 

 proved that the artificial combinations of iron 

 with albumen which Rose formed, can be pre- 

 cipitated by ferrocyanate of potassa if they 

 are previously treated with acetic acid : as this 

 does not happen with blood, it is very pro- 

 perly contended that Rose's experiments are 

 not to be looked upon as an explanation of the 

 difficulty. In a paper published by Mr. 

 Brande in the Philosophical Transactions for 

 1812, that gentleman proposes to consider 

 haematosine as an animal dye, which like co- 

 chineal is capable of uniting with metallic 

 oxides ; thus the oxides of mercury and tin are 

 active precipitants of this colouring matter, 

 and woollen clothes previously impregnated 

 with a solution of bichloride of mercury have 

 been permanently dyed by steeping them in a 

 solution of hsematosine. The question as to 

 whether or not iron be really necessary to the 

 existence of the red colour of the blood can- 

 not be considered as determined, and it is 

 difficult to imagine any line of experimenting 

 which could afford results sufficiently satis- 

 factory to settle the point. Mr. Brande's ex- 

 periments, by which he concluded that hsema- 

 tosine contained iron in no greater proportion 

 than fibrine or albumen, would have placed the 

 matter beyond doubt if other chemists had 

 confirmed" his observations; but the expe- 

 riments of Dr. Engelhart published in 1825, 

 and which have received very general con- 

 firmation, show that fibrine and albumen 

 when pure contain no iron, and that the metal 

 exists in considerable quantity in hasmatosine. 

 (G.O. Rees.) 



