182 Chemical Researches on the Blood, 



4. The matter remaining upon the filter was insoluble irt 

 water, in alcohol, and in sulphuric ether; but when digested 

 in dilute muriatic or sulphuric acid, a portion was taken up 

 formini]!; a brown solution. I regard this soluble portion, 

 as a modification of the colouring matter produced by the 

 operation of heat : the insoluble residuum had the properties 

 of albumen. 



5. Fffects of Acids on the colouring Matter. 



A. Muriatic acid poured upon the colouring matter of 

 the blood, render? one portion of it nearly insoluble and of 

 a bright i)ro\\ n colour : another portion is taken up by the 

 acid forming a dark crimson solution when viewed by re- 

 flected liglii ; but when examined by transmitted light, it 

 has a greenish hue. 



Tliis solution remains transparent, and its colour is un- 

 impaired bv long exposure to light, either in contact with 

 the air, or when kept in close vessels. At its boiling tem- 

 perature the colour is also permanent. 



Infusion of galls produces no change in this muriatic 

 solution, nor is its colour affected by carbonated alkalies, 

 even when added in considerable excess. 



It is rendered brown red bv supersaturation with caustic 

 potash, but not wi*|i soda, nor ammonia: these, and espe- 

 ciallv tlie latter, rather heighten its colour. 



\A'^ben cnns.dtrablv diluted with water its original colour 

 is much impaired, and ihe creen hue, which it always e^- 

 hibus by tiansnutted light, becomes more evident. 



In preparing this si)luUon, [ frequently employed the 

 coagulum of blood cut uno pieces, and digested in equal 

 parrs of muriatic acid and water, at a temperature between 

 130 and vOO"". In three or four hours the acid was poured 

 ofl", and nitrated. The clear solution was in a'l respects 

 siniif.r to ihat aiiove described, although before fiUration it 

 appeals of a diriv brown colour. 



I evaporaietl a portion of this muriatic solution in a wa- 

 ter-baib, to drvness; it reia;ned its colour to the last, and 

 left a transparent pellicle upon the evaporating bason, of a 

 dirtv red colour : this when rcdissolved in muriatic acid 

 acQiured its former tuit, but the colour of its aqueous solu» 

 tion vva>j nearer brown than red. 



B. Sulphuric acid, diluted with eight or ten parts of 

 water, forms an excellent solvent of the colouring principle 

 of the blood. 



It 



