Royal Society. 229 



XXVII. Proceedings of Learned Societies, 



ROYAL SOCIETY. 



[Continued from p. 151.] 



June 18, 1874. — Joseph Dalton Hooker, C.B., President, in the 



Chair. 

 ^HE following communication was read : — 

 -*- " On Coniferine, and its Conversion into the Aromatic Prin- 

 ciple of Vanilla." By Ferd. Tiemann and Wilh. Haarmann. 



The sap of the cambium of coniferous trees contains a beautiful 

 crystalline glucoside, coniferine, which was discovered by Hartig 

 and examined some years ago by Kubel, who arrived at the formula 



- H - O„+aaq. 

 A minute study of this compound leads us to represent the mole- 

 cule of coniferine by the expression 



C ]G H 22 8 + 2aq, 

 the percentages of which nearly coincide with the theoretical values 

 of Kubel's formula. 



Submitted to fermentation with emulsine, coniferine splits into 

 sugar and a splendid compound, crystallizing in prisms which 

 fuse at 73°. This body is easily soluble in ether, less so in alcohol, 

 almost insoluble in water ; its composition is represented by the 

 formula 



C 10 H 12 O 3 . 

 The change is represented by the equation 



C M H 22 0, + H 2 = C 6 H 12 6 + 10 H 12 O,. 



Under the influence of oxidizing agents the product of fermen- 

 tation undergoes a remarkable metamorphosis. On boiling it with 

 a mixture of potassium bichromate and sulphuric acid, there passes 

 with the vapour of water, in the first place ethylic aldehyde, and 

 subsequently an acid compound soluble in water, from which it 

 may be removed by ether. On evaporating the ethereal solution, 

 crystals in stellar groups are left behind, which fuse at 81°. 

 These crystals have the taste and odour of vanilla. An accurate 

 comparative examination has proved them to be identical with the 

 crystalline substance which constitutes the aroma of vanilla, and 

 which is often seen covering the surface of vanilla-rods. 



On analysis, the crystals we obtained were found to contain 

 C 8 H 8 3 . 

 This is exactly the composition which recent researches of Carles 

 have established for the aromatic principle of vanilla. The trans- 

 formation of the crystalline product of fermentation into vanilline 

 is represented by the following equation : — 



C 10 H 12 O 3 + = C 2 H,0 + C 8 H 8 O s . 



To remove all doubt regarding the identity of artificial vanilline 

 with the natural compound, we have transformed the former into 



