8 PROCEEDINGS OP THE AMERICAN ACADEMY 



interesting fact that potassic dichromate and sulphuric acid, and also 

 neutral potassic permanganate, attack this substance only with extreme 

 difficulty, whereas they both act vigorously on curcumin. 



Summary. 



1. Curcumin takes up two atoms of hydrogen when treated with 

 nascent hydrogen. 



2. The dihydride thus formed passes over easily into an anhydride 

 by losing one molecule of water. 



3. The anhydride of diethylcurcumin dihydride is much less easily 

 attacked by oxidizing agents than diethylcurcumin, but the products 

 are the same, — ethylvanillic acid with a trace of ethylvanillin. 



4. Bromine removes two atoms of hydrogen from the dihydride, 

 and replaces four more, forming Cj^Hj^Br^O^. 



5. Only four atoms of bromine can be added to curcumin. 



6. The tetrabromide has a great tendency to form vanillin when 

 treated with substances which remove bromine. 



7. With an excess of bromine a substance, Cj^HgBr^O^, is formed. 



8. The pentabromcurcumindibromide is oxidized in neutral or acid 

 solutions only with great difficulty. 



The observations just described throw some light upon the nature 

 of the side-chain of curcumin, but as the inferences to be drawn from 

 them are at best extremely doubtful, we shall postpone all discussion 

 of the structure of curcumin until our further study of it has put the 

 subject on a more secure basis. 



III. TURMERIC OIL — TURMEROL. 



The oil obtained from turmeric, which amounts to about 11 per 

 cent of its whole weight, has naturally attracted the attention of chem- 

 ists much less than curcumin, the yellow coloring-matter of the root ; we 

 find consequently only a few analyses and some meagre statements about 

 the action of reagents upon the oil, in place of the much fuller study to 

 which curcumin had been submitted. The most important of these will 

 be found in the papers of Ivanow-Gajewsky * and Kachler,t but as 

 they all refer to mixtures, it is not necessary to repeat them here. 

 The oil, however, is not without practical interest, as to it the 

 turmeric (and therefore curry powder) owes its aromatic taste and 

 smell. 



* Ber. d. ch. G. 172, p. 1103. 

 t Ber. d. ch. G. 170, p. 713, 



