112 Rohiqnet on Aroma, 



ascertained that they contain an essential oil, of which they 

 have described several properties, and, among others, that of 

 having a decided odour of prussic acid. I had undertaken, con- 

 jointly with my companion M. Couverchel, some experiments 

 on the changes which are produced during the developement 

 of the kernel in stone-fruits, and the following is one of our 

 observations. We took apricots at the time when the stone 

 contained only a glairy transparent substance, in which the 

 vegetable embryo could be with difficulty discovered. The 

 gelatinous substance gave by pressure a juice slightly milky, 

 having a faint odour resembling that of starch boiled in water* 

 This juice, being filtered, was very liquid, and in time acquired 

 the odour of bitter almonds. If, immediately on its extraction, 

 a fragment of potash be added to it, it will instantly develope 

 an ammoniacal smell ; and what is remarkable, if the experi- 

 ment be repeated at different times, it will be found, that the 

 ammoniacal smell occasioned by the potash is stronger as the 

 odour of the prussic acid increases. We have also observed, 

 that the same juice, when distilled by itself, gives no trace of 

 essential oil, though it affords a considerable quantity, if a 

 small portion of calcined magnesia be added to it before dis- 

 tillation ; a water is then obtained very odorous and slightly 

 ammoniacal, and a very limpid oil. After a time the water 

 becomes milky, because charged with a greater quantity of 

 ammonia, it retains the oil in suspension. This coincidence in 

 the developement of the odour, and the volatile alcali, reminds 

 me of a fact I observed many years since, and which is con- 

 tained in the analysis of tobacco published by M. Vauquelin, in 

 the Annates du Museum. An. infusion of the leaves of tobacco, 

 after having been precipitated by acetate of lead, acted on by 

 sulphuretted hydrogen, filtered, and submitted to distillation, 

 gave a fluid product of an herbaceous odour ; but, on 

 adding potash or ammonia, this odour became so strong and 

 penetrating as to be insupportable. This observation is in 

 accordance with what is practised daily in the manufactories of 

 snuff in order lo give it pungency. It is made to suffer the 

 commencement of fermentation, and ammonia is then deve- 



