120 / Mr. Thomas Richardson on the 



that carbonate of ammonia has the same effect, as those 

 found by that gentleman.* 



2. Colouring matter or Hematosine. 



Various methods have been proposed for obtaining this 

 substance in a state of purity, but all of them are liable to 

 some objections. That which I followed, suggested by 

 Dr. Thomson, affords the hematosine as pure as, perhaps, 

 it can be obtained by any of the methods known. 



The clot cut into very small pieces is agitated with six or 

 seven different portions of water, till as much of the saline 

 matter is washed away as possible. The remaining clot is 

 then digested in the cold, in distilled water, for forty-eight 

 hours, when a strong solution of the hematosine is obtained. 



The solution has the disagreeable smell and taste of 

 blood. It is quite dark coloured, but on adding water its 

 red colour may be seen. 



The solution may be evaporated to dryness without 

 coagulating. When quite dry it is quite black, but in thin 

 layers is deep red ; its lustre is like jet, and the specific 

 gravity in this state 1.2506. 



Berzelius states the coagulating point of the hematosine 

 to be 158°, and Lecanu found the solution to become 

 muddy at 149°, and completely coagulated at 158°. The 

 following experiments were made to determine this point. 

 A wide mouthed phial, filled with mercury, was heated on 

 the sand-bath to 130°, and a glass tube containing the 

 hematosine plunged into the midst of the mercury ; through 

 a cork, which filled the open end of the tube, a thermo- 

 meter was fixed, and the following observations made : — 



