852 BENZOYL. 



a boiling and dilute solution of an alkaline benzoate with nitrate 

 of silver, and allowing the liquid to cool. 



HYDRURET OF BENZOYL, OR ESSENCE (VOLATILE OIL) OF BITTER 



ALMONDS. 



Formula C 14 H 5 O 2 + H=Bz,H. The crude oil obtained by 

 distilling laurel leaves or bitter almonds with water, contains 

 hydrocyanic acid, benzoic acid and some benzoine (a solid oil) ; 

 it is purified by a new distillation with water, protochloride of 

 iron and hydrate of lime in a thin liquid. The oil which 

 distils over may be dried perfectly by digestion with chloride of 

 calcium. 



Pure hydruret of benzoyl is a transparent colourless liquid, 

 of high refracting power ; its odour is strong and peculiar hav- 

 ing some resemblance to that of hydrocyanic acid, its taste 

 burning. It is poisonous. The density of the oil is 1 .043, its 

 boiling point 356 ; its vapour may be transmitted through a 

 tube heated to redness without being decomposed. It inflames 

 easily in air, and burns with a white smoky flame. It is soluble 

 in 30 parts of water, and may be mingled in all proportions 

 with alcohol and ether. Nitric acid dissolves hydruret of 

 benzoyl, but converts it with difficulty into benzoic acid. 

 Hydruret of benzoyl is gradually converted in air into benzoic 

 acid by absorbing 2 atoms of oxygen, an atom of water being 

 formed at the same time which combines with the benzoic acid 

 formed. In. presence of an alkali it absorbs oxygen rapidly 

 and is transformed almost immediately into a benzoate. When 

 mixed with dry hydrate of potash, and distilled at a high tem- 

 perature out of contact with air, it forms benzoate of potash, 

 by the decomposition of water, and pure hydrogen gas is dis- 

 engaged. Submitted to a moderate heat with an alkali it gra- 

 dually produces, according to Fremy, an alkaline benzoate arid 

 a volatile oily liquid very rich in hydrogen. Dilute solutions of 

 the alkalies, barytes, or lime-water, dissolve hydruret of benzoyl, 

 but do not alter it, even when kept for 24 hours at 1 40 or 

 160, provided air is excluded. But all these solutions furnish 

 a notable quantity of the solid benzoine, when after having 

 added to them some drops of hydrocyanic acid they are exposed 

 to a temperature of 158. On treating hydruret of benzoyl 



