in the Year IS 35, in reference to the Physiology of Plants. 159 



easily dissolved in alcohol are considered as sub-resins, with 

 two of which we are already acquainted as possessing a cry- 

 stalline nature, those from the Elemi and Euphorbium, which 

 are isomeric or have the same elementary composition, and 

 consist of 2 (C 10 H 16 ) 4- O*. The resin discovered by Boussin- 

 gault in the wax-like covering of Ceroxylon andicola before 

 cited, possesses a similar fundamental composition ; it was of a 

 bright white colour and crystalline, melts at above 100° centig., 

 is soluble in aether, aethereal oils, and alcohol. Nees von 

 Esenbeck and the author found also in the bloom of the Be- 

 nincasa fruit a white crystalline resin soluble in alcohol, and 

 of a bitterish taste. 



Th. Martiusf showed some time back how to prepare, 

 free from colour, the brown resin from the jalap root, by 

 treating the spirituous solution with animal charcoal; accord- 

 ing to his more recent experiments this decolorated resin, 

 having been wrapped in paper, resumed after three years its 

 brown colour. This colouring process appears in the course 

 oi' time to change the resin in the root to the state in which 

 we receive it ; as according to the experiments of Nees von 

 Esenbeck and the author, mentioned in last year's report 

 (p. 220), the resin which had been extracted from jalap roots 

 cultivated in Germany, and preserved only a short time, was 

 scarcely coloured yellow. 



During the past year chemists have directed their attention 

 particularly to the cethereal oils of the black mustard-seed, and 

 were occupied partly on methods of preparing it, as MM. 

 Hesse J, Hoffmann §, Faure ||, Wittstockf, and Aschoff**. 

 According to most of the observers, a great quantity of aethereal 

 oil may be obtained from the meal of the black mustard-seed 

 when it has been left for some time in cold water; from which 

 it appears that, as in bitter almonds, not the aethereal oil but 

 the radical is contained in the seed. Faure observed that 

 tincture of galls and chlorine prevented the evolution of the 

 oil ; and Aschoff found that by mixing the mustard meal with 

 water ammonia was evolved. The produce amounted in general 

 to 0*9 — 1 per cent, of a colourless oil, which is heavier than 

 water = T002 at 14° Reaum. It is of the class of those con- 

 taining sulphur, and does not explode with iodine; it does how- 

 ever with potassium. Ammonia combines with it, and forms 



* Pogpendorff's Annalen, vol. xxxiii. p. 49. 



f Bnchn. Repert.,vo\. h. part 3. J Geiger's Ann., xiv. part 1. 



§ Pharm. Convers-Blatt. 1835. No. 44. 



|| Journ. de Pharm. Sept. 1835. 



\\ Berliner Jahrbiickcr, xxxv. part 2. p. 256. 



** Erdmanu and Schweigger-Seidel, iv. p. 314. 



