1S4 Chemical Researches on the Blood, 



colouring matter of the blood ; the solution is of a deep 

 cherry red colour. Wl^ien somewhat diluted, or when ob- 

 served in tubes of about a quarter of an inch bore, this so- 

 lution appears perffCtly gieen by transmitted light. In its 

 other habitudes it nearly resembles the muriatic solution. 



E. The solution o\ the colouring matter in oxalic acid is 

 of a brighter red than those hitherTo noticed ; that in citrie 

 acid is very similir to the acetic solution, and with tartaric 

 acid the compound somewhat inclines to ecarlet. All these 

 solutions exiiibit the green hue, to which I have so otteii 

 alluded, in a reoiarkablc degree. 



6. E^'ecis of' Alkalies on the colouring Principle of the 

 Blood. 



The caustic and the carbonated alkalies forip deep red 

 solutions of this substance, which art extremely perma- 

 nent. 



J. Solutions of pure potash, and of the s.ibcarbonate, take 

 up a large proportion of the colouring matter of the blood. 

 The intensity o\ the colour of this soluHon, when concen- 

 triitfcl, is such, that it appears opake, unless viewed in >mall 

 m.iSsth, or in a diluted state, when it is of a bright red toy 

 lour. 



2. In Soda and its subcarbonate, the solution has more 

 of ai crimson hue, which colour is extremely bright in its 

 concentrated t»tate. 



3. The solution in liquid ammonia approaches nearer to 

 scarlet than that in which the fixed alkalies are employed. 



4. When these alkaline solutions are supersaUirated with 

 muriatic acid, or with dilute sulphuric acid, they acquire h 

 col'iiir nearly similar to the original solutions in those acid? 

 which have been above described. 



5. iSliiric acid added in small quantities, or even to sa- 

 turation of the alka'. le mensuuiim, heightens the colour of 

 the tliree compounds j but when there is a slight exees-, a 

 tint ot oiange is produced, which soon passes intii bright 

 yellow. 



6. The alkaline solutions may be evaporated nearly to 

 dryness withou'. losing their red colours ; during the eva- 

 poiaiion of tile ammouiacal soUnion, the alkali flies off. and 

 a hroAH-red solution of the colouring matter in waier re- 

 mains. 



Having ascertained the above facts respecting the co» 

 louring piiiK-:j)!e ot the b!ood, I next proceeded to examine 

 how iar it was susceptible of entering into those combiiia^ 



tioij^ 



