112 PROCEEDINGS OF THE AMERICAN ACADEMY 



oxidation (yielding valeric and caproic acids) and action with phos- 

 phoric pentachloride studied. He also prepared and analysed roso- 

 cyanin, but was unable to find a satisfactory formula, for it. 



Finally, in 1873, he published the last paper* we have been able to 

 find on this suliject, in which he states that curcumiu yields on oxida- 

 tion with potassic dichromate terephthalic acid, and that rosocyanin con- 

 tains no boron, and, fused with potassic hydrate, yields jmraoxybenzoic 

 acid. 



In brief, the following facts had been established in regard to cur- 

 curain at the time that we began our research upon it: — Its formula 

 was either C^Jrl^^O^ or CjgHjgO^ ; the highest melting-point observed 

 was 172° ; with alkalies it formed reddish-brown salts; with boric and 

 sulphuric acids rosocyanin ; it was susceptible of reduction, and gave an 

 oil with zinc dust ; by oxidation it yielded oxalic acid or terephthalic 

 acid, and by fusion with caustic potash protocatechuic acid. 



Accordingly we first turned our attention to the determination of 

 its formula. 



Extraction and Purification of Curcumiu. 



After several experiments we have adopted the following method 

 as the best and most convenient : — The turmeric oil is first removed 

 from the ground root by treatment with ligroine ; | then the curcurpin, 

 mixed with a large quantity of resin, is extracted with ether, and 

 finally purified by crystallization from alcohol. 



The turmeric v;sed by us has been principally Bengal turmeric, 

 bought of Messrs E. and F. King, of Boston; we have, however, also 

 extracted enough of the Madras turmeric, the only other brand occur- 

 ring in the Boston market, to assure ourselves of the identity of the 

 curcumiu obtained from both. 



For a full description and history of turmeric, which consists of the 

 root-stocks of the Curcuma longa^ a plant of the ginger family, grow- 

 ing in India and other parts of the East, we would refer to Fliickiger 

 and Hanbury's Pharmacographia,$ and to a full botanical article 

 recently published by A. Meyer § in the Archiv der Pharmacie. 



* Ber. d. ch. G., 1873, p. 196. 



t In our first experiments we followed Ivanow-Gajewsky, and used carbonic 

 disulphide for this purpose ; but we liave found that hgroine is not only much 

 cheaper and more agreeable to work with, but yields a purer oil. 



I Macmiilan and Co., London, 1879. 



§ Arch, riiarm. Ser. 3, xviii. p. 401. 



