48ft Miscellaneous Intelligence, 



Pilated vegetable acids dissolve this principle ^ith great facility; 

 the mineral acids, on the contrary, precipitate these solutions, 

 forming slightly acid and nearly insoluble compounds. If, when 

 thus precipitated, heat be applied, the substance disappears; but 

 on cooling the liquor becomes a gelatinous mass, resembling paste, 

 which, by the application of heat, again liquefies. These precipi- 

 tates, or pure legumine, heated wjth a little of a vegetable acid, 

 the tartaric for instance, produces a thick mucilaginous liquid, 

 which, being diluted, is scarcely sour to the tongue. Infusion of 

 galls precipitates this solution; alcohol does not alter it. The 

 mineral, acids produce precipitates : earthy and metallic salts with 

 mineral acids precipitate it. 



The feeblest alkalies and the alkaline earths dissolve legumine, 

 or its insoluble acid compounds. In order to confirm the suspi- 

 cions which were entertained of the analogy between the legumine 

 and alkaline substances, the insoluble compound of the substance 

 with nitric acid was well washed in boiling alcohol; it was then 

 put into water rendered slightly alkaline by a little ammonia, after 

 which alcohol was added to precipitate the legumine. When well 

 washed, it resembled paste: it retained no ammonia; and yet, 

 when brought into contact with litmus paper reddened by acid, it 

 restored its blue colour. Being spread upon paper, it dried and 

 produced a brilliant varnish : exposed to heat, it liquefied without 

 coagulating. Iodine, mixed with it in water, appeared to dissolve 

 it ; a yellow precipitate was produced by heat, unchanged by the 

 action of alcohol or by drying. It was insoluble in boiling water, 

 and produced a deep blue colour with starch. Being exposed in a 

 glass tube to a careful heat raised above 212° Fahr., violet vapours of 

 iodine were produced, and the legumine remained unchanged. — 

 Ajm. de Chimie, xxxiv. 68. 



26. Substances contained in Essential Oils. — Many of the essen- 

 tial oils become changed by exposure to air, and an acid is formed in 

 them, which, crystallizing in acicular needles, may be separated, and 

 has been considered as benzoic acid. M. Bizio finds that oil of 

 cassia affords the largest quantity of this substance, a few days only 

 being sufficient to cause its formation. He collected the crystals 

 together and separated them from the adhering oil, either by means 

 of bibulous paper ; or else by warming them in a weak solution of 

 carbonate of potash, filtering the solution of the salt formed from 

 the insoluble oil, boiling it with animal charcoal, afterwards decom- 

 posing the purified and crystallized salt by muriatic acid, and sepa- 

 rating the acid in question by dissolving it in alcohol. 



This acid, although it agrees with benzoic acid in some 

 qualities, differs from it in others. It has no odour or taste, is 

 heavier than water, fuzes and sublimes by means of heat, con- 

 densing in brilliant crystals ; burns in the air with flame; dissolves 

 in very small quantity in cold water, but far more readily in boiling 

 water, the acid crystallizing as the solution cools. It dissolves in 



