( 718 ) 



that in llio oxidation in acetone solution no acids liiglier tlian acetic, 

 acid were formed and besides not a trace of oxalic acid Avith hydrogen- 

 peroxide. I am therefore of opinion that those substances owe their 

 origin to migration of double links during the oxidation. All 

 this causes that, I, for one, consider the structural formulae based 

 on oxidation experiments with such very changeable substances as 

 very untrustworthy. One should also be very careful in drawing 

 conclusions from the isolation of small quantities of the more typical 

 decomposition products, as these may have been yielded by impurities. 



Notwithstanding the beautiful researches of Tiemann and Semmler ') 

 on geranial, citral, etc, the structural formulae of none of the mem- 

 bers of the aliphatic terpene group seems to have been sufficiently 

 established as was only recently shown by Harries oxidations with 

 ozone "). 



Meanwhile I had ti-ied, whether ocimene could be hydrogenised 

 like myrcene by means of sodium and alcohol. This proved to be 

 the case. Ocimene, therefore, also contains a conjugate system of 

 double links. The iiydro-product, which I obtained, had the compo- 

 sition Ci„H,g ') (I will call it in future dihydro-ocimene) ; it is a 

 very mobile liquid of an agreeable odour. For its constants I found 

 the following values : 



sp. gr.,5 nd.j, b.p. at 761 mm. 



0,7792 1,4507 166°— 168° 



whilst Semmler '') states for dihydromyrcene : 



sp. gr. nd. b.p. 



0,7802 1,4501 171°,5— 172°,5. 



The temperature, at which the specific gravity was determined, 

 and the barometric pressure at the boiling ]ioint are not stated ; at 

 770 mM., the boiling point of dihydro-ocimene is, however, "but 

 little higher. Owing to this dilference of 6° in the boiling point of 



1) Ber. 28, 2126 (1895). 



2) Ber. 36, 1933, 2998, 3001, 3658; and 37, 012, 839, also H.^RRIES und 

 ScHAüwECKER, Ber. 34, 2987 (1901) and Harries, Lehrbuch der Org. Cham, by 

 V. Meyer und P. Jacobson, II, 754. The above-standing was written before the 

 latest publication of Harries on this subject appeared (Lieb. Ann. Jan. 1906). 



S) In the combustion of these substances with copper oxide in an open tube 

 the carbon is often found a good deal too low, but in the closed tube Nvith lead 

 chromate the exact values are always obtained. On the strength of his analyses, 

 Chapman also concluded at first to the presence in oil of hops of a hydrocarbon 

 G10H18 which by further investigation proved to be myrcene. 



*) I. c. 



