426 Miscellaneous Intelligence. 



consists of 87.28 acid, and 12.72 lime. A neutral, and a sub-salt 

 of lead may be formed; the former, by mixing- a hot solution of a salt 

 of lead with a hippurate, will be obtained, as the mixture cools, in 

 nacerous plates : these are anhydrous, and consist of 64.38 acid, 35.62 

 oxide. Other salts have been formed with other bases. 



When the dry hippuric acid is decomposed by heat, there is found, 

 as already stated, a crystalline sublimate, which condenses in the 

 neck of the retort, and has a yellow or rosy colour ; if much hip- 

 puric acid has been used, this substance ultimately obstructs the 

 neck of the retort. This substance dissolves in hot water easily, 

 and contains ammonia; when combined with lime, filtered, and 

 separated again by muriatic acid, it has all the properties of benzoic 

 acid ; it forms salts hke the benzoates, and, in fact, it is benzoic acid. 

 Hence Fourcroy and Vauquelin were right when they said they had 

 obtained benzoic acid from the urine of horses ; but it had not 

 existed there ready formed. 



If the hippuric acid be mixed with four times its weight of quick 

 lime and distilled, it is entirely transformed into a yellow oily liquid, 

 with an agreeable odour, containing ammonia, and resembling the 

 fixed oils. If the hippuric acid be mixed with sulphuric acid, and 

 heated only until sulphurous vapours begin to appear, if then the 

 black mass be mixed with water, boiled with lime and then muriatic 

 acid used, benzoic acid may be separated, being formed in this way as 

 well as by heat alone. When the hippuric acid is boiled with nitric 

 acid, a little nitrous acid is evolved, and then water precipitates pure 

 benzoic acid. 



M. Liebeg remarks, that he has not been able to extract the 

 smallest trace of benzoic acid from the food of horses of which he 

 has examined the urine ; the crystalline form makes him doubt 

 whether the substance which M. Vogel found in the anthoxanthum 

 odoratum, and holcus odoratus, is really benzoic acid, as announced. 



25. On the Decomposition of Urea and Uric Acid, at high Tem- 

 peratures, by M. Wohler. — Most chemists have remarked the sin- 

 gular property of urea as an organic body, of leaving no charcoal 

 when decomposed by heat ; but with the exception of observing the 

 formation of a large quantity of carbonate of ammonia, the products 

 have not been closely examined. Fourcroy and Vauquelin have 

 remarked, that during the ebullition which it undergoes, occasioned 

 by the evolution of much carbonate of ammonia, a dry infusible 

 substance is formed, which, at a higher temperature, sublimes and 

 forms a white crystalline crust which they conclude to be uric acid. 



The urea used by M. Wohler was obtained from urine, and was 

 in fine large regular crystals. If only in small plates, or not regu- 

 larly crystallized, it cannot be trusted, usually then containing a 

 little alkali. There are two precautions in its preparation which 

 must not be neglected : first, when precipitating it from evaporated 

 urine, the nitric acid used must be free from nitrous acid, for the 

 latter destroys urea; and, secondly, the nitrate of urea must be 



