40 H. G. SMITH AND A. R. PENFOLD. 



ON THE MANUFACTURE OP THYMOL, MENTHONE, 

 AND MENTHOL, PROM EUCALYPTUS OILS. 



By Henry G. Smith, p.c.s., and A. R. Penfold, f.c.s., 

 Technological Museum, Sydney. 



[Read before the Royal Society of N. 8. Wales, June 2, 1920.'] 



Although a large number of crude Eucalyptus oils contain 

 a crystallised phenol, yet this is not thymol, but quite a 

 different substance, and thymol, as such, does not occur in 

 any of them, although it may be readily prepared from the 

 peppermint ketone, piperitone. 



The individual constituents already determined as 

 existing in the oils derivable from the various species of 

 Eucalyptus number about 40, and among these are found 

 numerous alcohols, esters, aldehydes, terpenes, etc., but 

 only one ketone. 



This constituent of peppermint odour was first isolated 

 by one of us, (H. G. Smith), and the results of a preliminary 

 chemical investigation presented to this Society in a paper 

 read October, 1900. 



In the Museum publication, "A Research on theEucalypts 

 and their Essential Oils " (Baker and Smith), 1902, p. 233, 

 this ketone was recognised as new, and there named 

 piperitone. 



That the leaves of certain Eucalypts bad an odour of 

 peppermint was noticed soon after the first settlement in 

 Australia in 1788, and in the "Journal of a Voyage to New 

 South Wales," by John White, Surgeon General to the 

 Settlement, published in 1790, the statement is made (p. 

 227) that the essential oil drawn from the leaves had a 



