404 Dr. A. E. Garrocl. A Contrilution to the StmJu [Apr. 



From the remainder of the original residue alcohol extracted nx 

 pigment, and hot alcohol more still, the liquid assuming a sepia 

 and showing no absorption bands. The hot alcoholic solution 

 posited, on cooling, a dark, pulverulent sediment, which, examine 

 microscopically, was found to be amorphous. A black residue 

 remained which was insoluble in water, alcohol, and dilute acids, 

 scarcely soluble in amylic alcohol, but was readily dissolved by str 

 ammonia (the uromelanine of Thudichum). The alkaline solutic 

 gave no absorption bands. 



After extraction with water the original residue communicated 

 yellow colour to ether, but no substance resembling the omicholic 

 of Thudichum (which is readily soluble in ether with a fine red cole 

 was obtained. 



Frecipitants of the Yellow Pigment. 



In its behaviour towards metallic salts the pigment obtained by 

 process exhibited the closest resemblance to the urochrome 

 Thudichnm. 



The solutions were almost decolorised by the acetates of lead, 

 nitrate of silver, and by phosphotungstic and phosphomolybdic 

 which all threw down precipitates containing the bulk of 

 pigment. 



Mercuric acetate decolorised the solutions completely, a yellow 

 cipitate being formed, from which the colouring matter could 

 readily extracted with alcohol acidulated with hydrochloric acid, 

 apparently not without some change, evidenced by its reddish-1 

 colour. 



Mercurous acetate had not the power of throwing down the 

 ment from its solutions. 



Behaviour of the Pigment toicards Uric Acid. 



If to a solution of colourless urate, obtained from snake's 

 ment, some of the yellow pigment was added, and if the condition! 

 the experiment were so adjusted that crystals of uric acid are si 

 deposited from the solution, these crystals resembled those which 

 compose the yellow or brown variety of uric acid sand, and ha< 

 moreover, the ordinary urinary forms, the familiar whetstone shap 

 preponderating. I have, indeed, specimens of crystals so obtaine 

 which are quite indistinguishable from those of the natural urinar 

 sediments. 



This experiment is difficult to carry out satisfactorily, chiefl 

 owing to the instability of the isolated pigment. If the crystals an 

 too quickly deposited they have the whetstone form, but are onh 





