BENZOIC ACID. 81 



Products of its metamorphosis. Oil of bitter almonds is usually 

 regarded as a combination of a hypothetical oxygenous radical 

 (benzoyl) with hydrogen ; it is thus a hydride of benzoyle, 

 C 14 H 5 O 2 .H ; it is a thin, colourless liquid whose specific gravity 

 is 1*043 and whose boiling point is 180; when exposed to 

 the air it oxidises and becomes converted into hydrated benzole acid. 

 It not only occurs in oil of bitter almonds, but is often found as a 

 product of decomposition when albuminous or gelatinous sub- 

 stances are treated with strong oxidising agents (Guckelberger).* 

 The one equivalent of hydrogen of this body may not only be 

 replaced by chlorine, bromine, or iodine, but also by sulphur or 

 cyanogen. 



Benzamide, H 2 N.C 14 H 5 O 2? whose preparation is noticed in 

 the introductory remarks on this group, is a beautifully crystal- 

 lisable body which is soluble in water, alcohol, and ether, and 

 possesses all the known properties of the amides. 



Benzonitrile, C 14 H 5 N, whose formation has also been alluded 

 to, is a colourless oil, which boils at 191, dissolves in 100 parts 

 of boiling water, and in alcohol and ether in every proportion ; 

 as, when treated with potassium, it yields cyanide of potassium, 

 many regard it as cyanide of phenyl, C 12 H 5 .C 2 N. 



If azobenzide, C 12 H 4 N, be dissolved in alcohol, the solution 

 saturated with ammonia, and sulphuretted hydrogen passed 

 throughout, we obtain the organic base, benzidine, C 12 H 6 N. 



Benzoin, C 14 H 6 O 2 , (isomeric with oil of bitter almonds) is 

 formed by the contact-action of the caustic alkalies on oil of bitter 

 almonds containing hydrocyanic acid ; it occurs in prisms which 

 are devoid of colour, taste, and smell, and which may be sublimed 

 without undergoing decomposition ; it dissolves in concentrated 

 sulphuric acid, and in an alcoholic solution of caustic potash, com- 

 municating in each case a blue tint to the mixture ; on passing its 

 vapour through a red hot tube it is again converted into oil of 

 bitter almonds. By the action of chlorine it loses 1 equiv. of hydro- 

 gen, and is converted into benzile, C 14 H 5 O 2 , which is isomeric 

 with the hypothetical radical, benzoyl, crystallises in sulphur- 

 yellow six-sided prisms, and is fusible and capable of sublimation. 



Benzine or benzol, C 12 H 6 , is obtained, as has been already 

 mentioned, on treating benzoic acid with an excess of hydrated 

 lime ; it is a colourless inflammable fluid with an ethereal odour, 

 is solid at 0, boils at 86, is insoluble in water, but dissolves in 

 alcohol and ether. Amongst the many other substances which 



* Ann. d. Ch. u. Pharm. Bd, 64, S. 46 ff. 



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