168 Chemical Hesearches on the Bloody 



The experiments to prove the non-existence of gelatine 

 in the serum of blood, will, I trust, be deemed sufficiently 

 decisive : they show that that abundant proximate principle 

 of animals is not merely separated from the blood, in which 

 it has been supposed to exist ready formed, but that it is an 

 actual product of secretion. 



The proportion of iron afforded by the incineration of 

 several varieties of animal coal, is much less considerable 

 thim we have been led to expect ; and the experiments no- 

 ticed in the fifth section show ihnt it is not more abundant 

 in the colouring matter of the blood than in the other sub- 

 stances which were submitted to examination; and that 

 traces of it may be discovered in the chyle which is white, 

 in the serum, and in the washed crassamentum or pure 

 iibrina. 



The inferences to which I have alluded, in the first sec- 

 tion of this paper, are strongly sanctioned by these facts, 

 and coincide with the opinion which has been laid before 

 the Royal Society, by Dr. Wells*, respecting the pecu/Zar 

 nature of the colouring principle of the blood, and support 

 the arguments which are there adduced. 



That the colouring matter of the blood is perfectly inde- 

 pendent of iron, is, I conceive, sufficiently evident from its 

 general chemical habitudes, and it appears probable that it 

 may prove more useful in the art of dveing than has hitherto 

 been imagined, since neither the alkalies nor the acids 

 (with the exception of the nitric) have much tendency to 

 alter its hue. The readiness, too, with which its stains are 

 removed from substances to which no mordant has been 

 applied, seem to render it peculiarly fit for the purposes of 

 the calico-printer. I have not extended these experiments, 

 nor have I had them repeated on a sutricient scale to enable 

 me to draw more general conclusions respecting the possi- 

 bility of applying them with advantage in the arts: this 

 would have kd me into too wide a field, and one not im- 

 mediatelv connected with the objects of this Society: tlie 

 subject, however, appears important. 



It is not a little remarkable tliat blood is used by the 

 Armenian dyers, together with madder, in the preparations 

 of their finest and most durable reds f, anti that it has even 

 been found a necessary addition to insure the permanency 

 of the colour |. This fact alone may be regarded as de- 



♦ Phil. Trans. 1797. 



•f Tooke's Russian Empire, vol. iii. p. 497. 



J Aikin's Dictionary, art. Dyeing, and Philosoph. Magazine, vol. xviii. 



Djonstratine 



^i 



