182 



CHEMICAL RESEARCHES ON THE ANIMAL FLUIDS. 



with nitric ; 



with acetic 



and uncertain. Either the sediment of the colouring matter 

 from the serum, or the crassamentum of the blood, may be 

 indifferently employed in forming these solutions. 



When dilute sulphuric acid is added to the colouring mat- 

 ter, it renders it slightly purple ; and, if no heat be applied, 

 the acid, when poured off and filtered, is colourless ; so that 

 dilute sulphuric acid, when cold, does not dissolve this colour- 

 ing principle. 



One part of the crassamentum of blood cut into pieces was 

 put into a matrass placed in a sand heat, with about three parts 

 of dilute sulphuric acid. It was kept for twelve hours in a 

 temperature never exceeding 212^ nor below 100°. After 

 twenty-four hours the acid was filtered oflf, and it exhibited a 

 beautiful bright lilac colour, not vciy intense, and tainted with 

 green when viewed by transmitted light. 



This solution is nearly as permanent as that in the muriatic 

 acid. Some of it, which has been kept for a month in an open 

 vessel, often exposed to the direct rays of the sun, is very little 

 altered. 



When diluted with two or three times its bulk of water, 

 the lilac tint disappears, and the mixture is only slightly green. 



When exposed to heat, the colour gradually changes as the 

 acid becomes more concentrated by evaporation, and when re- 

 duced to about half its bulk, the lilac hue is destroyed. 



The solutions of pure and carbonated alkalis, when added in 

 excess, convert the colour of this sulphuric solution to brownish 

 red ; but in smaller quantities they merely impair it by dilution. 



C. Nitric acid, even much diluted, is inimical to the colour- 

 ing matter of the blood. 



A few drops added to the muriatic or sulphuric solutions 

 gradually convert their colour to a bright brown, and larger 

 quantities produce the same change immediately. 



The action which this acid exerts upon the colouring matter 

 under other circumstances is nearly similar, and always at- 

 tended with its decomposition, so that my attempts to procure a 

 red solution in this menstruum uniformly failed of success. 



D. Acetic acid dissolves a considerable quantity of the co- 

 louring matter of the blood j the solution is of a deep cherry 

 red colour. When somewhat diluted, or when observed in 

 tubes of about a quarter of an inch bore, this solution appears 



per- 



