485 



Cymene. 



The analytical results suggested the presence of cymene, 

 and to determine the identity of this hydrocarbon a portion 

 of the rectified oil, thought to contain the cymene in greatest 

 •quantity, was treated in the cold with a dilute solution 

 of potassium permanganate, and the oil unacted upon re- 

 moved. The oil was then oxidized by an aqueous solution 

 of potassium permanganate (12 grams KMn0 4 in 330 grains 

 water), as suggested by Wallach : about 2 grams of oil at the 

 time were added, and the solution heated on a rapidly boiling 

 waterhath. When the reaction was completed the Mn0 2 was 

 filtered off, the filtrate evaporated to dryness, the salt boiled 

 out by alcohol, evaporated to small bulk, water added, and 

 •acidified with sulphuric acid. The separated acid was purified 

 from alcohol ; it then melted at 155-156 c C. From the 

 method of formation of this substance, and its melting point, 

 there seems little doubt but that the acid formed was 

 p-oxyisopropylbenzoic acid. This result, together with other 

 factors, indicates the presence of p-cymene in the oil of this 

 species. That this hydrocarbon occurs in the oil of E. 

 yostrata in some quantity is thus shown. 



Aromadendral. 



Messrs. Schimmel & Co. have not as yet recognized 

 aromadendral' as an aldehyde differing from cumin aldehyde, 

 and in "Die Atherischen Ole,'' published by this firm in 

 1910, they state that cumin aldehyde occurs in the oils of 

 several Eucalypts, which are there enumerated, page 440. 

 Cumin aldehyde may occur in the oils of some Eucalyptus 

 species, and perhaps does, but as this aldehyde does not contain 

 an asymmetric carbon atom it cannot be active to light, and 

 consequently, on theoretical grounds alone, cannot be identi- 

 cal with the laevorotatory aldehyde which occurs in so many 

 Eucalyptus ©ils ; often, as in the case of E. rostrata and E. 

 sahibris, with a very high specific rotation. 



As this aldehyde occurs in some quantity in the oil of 

 E. /(/strata, as well as the oils of several other species here 

 dealt with, it was thought advisable to isolate it in a pure 

 condition from the oil of a Kangaroo Island tree and deter- 

 mine the properties of the aldehyde from this source. 



Aromadendral appears to be a dihydroaromatic aldehyde 

 having the formula C ](l H u O. This formula was originally 



