116 PROCEEDINGS OF THE AMERICAN ACADEMY 



and did not succeed in obtaining his ciircumiri crystallized. In view 

 of these facts we feel no hesitation in rejecting all the previous analy- 

 tical results except those of Daube. 



Daube gives curcumin the formula Cj,jTIj,j03, but our results, and 

 for that matter his, agree much better with the formula C^JI^^O^, as 

 appears from the following comparison : — 



We have therefore adopted the formula Cj^H^^O^, which is also con- 

 firmed by the analyses of derivatives of curcumin to be given later 

 in the papier. 



Properties of Curcumin. 



Curcumin crystallizes from alcohol in stout needles, which under 

 the microscope appear as well-formed prisms with square ends, or 

 spindle-shaped crystals, often arranged in radiating groups ; iu color 

 i*t is orange to yellow, according to the size of the crystals, with a 

 beautiful blue reflex ; its solution in ether exhibits a very strong 

 green fluorescence ; when pure it has no odor ; it melts at 178'^, appar- 

 ently with decomposition.* It is nearly insoluble in water, somewhat 

 soluble in cold, more readily in hot alcohol and methyl alcohol, more 

 soluble in glacial acetic acid than in alcohol, less so in ether, very 

 slightly soluble in benzol f and carbonic disulphide, and essentially 

 insoluble in ligroine. Strong sulphuric acid dissolves it with a fine 

 reddish-purple color, which changes to black from charring after some 

 time ; strong hydrochloric acid produces the same effect, but with more 

 difficulty. It is readily soluble in alkalies and alkaline caibonates, and 

 is even dissolved to a slight extent when boiled with precipitated 

 calcic carbonate and water. The solution in amnionic hydrate loses 

 ammonia when boiled, and deposits unaltered curcnmin. A solution 

 of baric hydrate converts it into a blackish-red powder, but lime-water 

 gives a red solution like that obtained from calcic carbonate. It is not 

 affected by acid sodic sulphite. 



* Daube found 1G4° ; Gajewsky, 172^ or 140^. 

 t Compare Daube, Ber. d. eh. G. 1870, p. G09. 



