( 719 ) 



the said liydrocarbons, these were not considered as identical in the 

 provisional communication. A second point of difference was the 

 obtainment of a crystalline bromide from dihydro-ocimene. When, 

 afterwards, I repeated Semmler's experiments, I found the boiling 

 point of dihydromyrcene to be the same as that of dihydro-ocimene, 

 whilst the other constants (as far as could be ascertained) agreed 

 with those of Semmler ; I found the following values : 



sp. gr.jj nd.,j b.p. at 761 mm. 



0,7852 J, 45 J 4 166°— 168° 



Like Semmler, I found that myrcene and its hydro-product have 

 the same boiling point so that, probably, Semmler's statement is 

 based on a mistake ; for other investigators also state 166° as being 

 the boiling point of myrcene. 



The now probable identity of the hydro-products became a certainty 

 by the bromination of dihydromyrcene. As stated, dihydro-ocimene 

 had given me on bromination a crystalline bromide; from the oil 

 obtained at iirst, it crystallises to the extent of 12 — 147» • After 

 repeated crystallisations from methyl alcohol it forms snow-white 

 crystals which melt, sharply, at 88°. Analysis and determination of 

 molecular weight pointed to the composition CioHigBr^. In most of 

 the organic solvents, this bromide is readily soluble, but in methyl 

 alcohol only to the extent of 1,2%; on boiling with sodium hydroxide 

 and also with silver oxide and water an oil smelling of peppermint 

 is obtained. From diliydromyrcene I now obtained the same bromide. 

 The oil obtained by Semmler soon solidifies when, after being purified, 

 it is put away to crystallise in a cool place; by applying a little 

 artifice I succeeded in instantly inducing the crystallisation. The 

 identity was proved by the fact that this bromide like all its mixtures 

 with dihydro-ocimenetetrabromide, melted, sharply, at 88° and also 

 that the solubility of dihydro-ocimenebromide was practically not 

 affected by addition of this substance. 



This now completely proves : 



1. that both ocimene and myrcene are aliphatic terpenes. 



2. that the dihydroproducts of these terpenes are identical. 

 From this it follows — and this is probably of more importance 



still — that we may now deduce the structural formulae of ocimene 

 and myrcene from the obtained data. 



As regards myrcene, owing to its connection with citral and 

 dipentene '), it was already fairly certain that, like all aliphatic 



1) Power and Kleber, 1. c. 



