— 126 — 



As mentioned in our last Report 1 ), the ultra-violet rays have the power 

 of liberating odoriferous bodies which occur in plants in the form of 

 glucosides. This peculiar property of the ultra-violet rays has recently 

 again been observed by J. Pougnet 2 ) in the case of immature vanilla-pods. 

 It was necessary to expose quite green fruit to the light for about 6 hours, 

 but almost ripe pods only required 20 minutes exposure before the vanilla 

 odour became perceptible. 



On the formation and consumption of hydrocyanic acid in the growth 

 of the sweet and* the bitter almonds, see under the heading <( Almond 

 Oil", p. 17. 



Chemical. 



For the purpose of completing our previous reference to the 105 th 

 paper of Wallach 3 ) on Terpenes and Essential oils, of which we have 

 already made previous mention, based upon the abstract of the paper 4 ) 

 which has appeared in the Nachrichten der K. Ges. d. Wissenschaften zu 

 Gottingen, October 1910, page 517, we quote the following further details 

 from the original paper: Carvenolide 5 ), the lactone obtained when carvone 

 tribromide is reduced by Paal's method, absorbs one molecule hydrogen, 

 with formation of dihydrocarvenolide (m. p. 36 to 38°; b. p. 260 to 261°). 

 This dihydrocarvenolide is most probably identical with pulegenic acid 

 lactone, and, if so, carvenolide would be an unsaturated lactone of 

 pulegenic acid. 



Pulegenolide, which was obtained by Wallach 6 ) many years ago by 

 acting with sodium hypobromite upon pulegenic acid, was at the time 

 regarded as a saturated compound, owing to the difficulty with which it 

 absorbs halogen. But in the course of the reduction of pulegenolide with 

 hydrogen in the presence of palladium it was found that it does absorb 

 one molecule of hydrogen, and, in the process, yields dihydropulegenolide 

 (m. p. 49 to 50°; b. p. 260 to 261°). 



a-Fenchonitrile absorbs 2 atoms of hydrogen, giving rise to dihydro- 

 a-fenchonitrile (b. p. 214 to 215°) a substance which is also obtainable 

 from fencholenic acid amide. For this purpose the latter is reduced by 

 Paal's method, the resulting dihydro-a-fencholenic acid amide (m. p. 133 

 to 134°) being distilled with phosphorus pentoxide, dihydro-a-fenchonitrile 

 resulting. The reduction of /^-fencholenic acid amide proceeds decidedly 

 more slowly than that of the «-amide. Dihydro-^-fencholenic acid amide 



*) Comp. Report April 1911, 160. 



2 ) Compt. rend. 152 (1911), 1184. 



3 ) Liebigs Annalen 381 (1911), 51. 

 *) Report April 1911, 164. 



5 ) Liebigs Annalen 305 (1899), 249. Comp. Report April 1899, 56. 



6 ) Liebigs Annalen 300 (1898); Report October 1898, 52. 



