Gn the Benzott Acid In the Urine of Horsea. 1 5% 



which, as none appeared by pouring muriatic acid into the 

 urine evaporated to the consistence of syrup, must have ex- 

 isted in the urine in a free state. The w^eightof it amounted 

 to fifteen grains. 



Experiment IV. 



Five pounds of urine were evaporated to diyness, and a 

 fourth part of alcohol being added, the whole was exposed 

 to heat. The alcohol, which after some time had acquired 

 a dark colour, was again filtered and evaporated^ No traces 

 of benzoic acid, however, were perceptible. 



Experiment V. 



Qf four pounds of urine a small part was subjected to 

 •previous proof by msriatic acid : a riebuIou3 precipitate im- 

 mediately took place, but on the additioji of more muriatic 

 acid it again disappeared. The rema.ining urine not decom- 

 posed with muriatic acid I evaporated to the consistence of 

 syrup, by which means a great quantity of pure calcareous 

 earth was separated ; to the discovery of which I was con- 

 ducted by dissolving the residuum in muriatic acid, which 

 was very easily done, and without effervescence. Having 

 dropped sulphuric acid into this solution, sulphate of limw 

 was immediately formed. The urine separated from the 

 calcareous earth was decomposed by sulphuric acid : there 

 was formed a perceptible precipitate, which being digested 

 with alcohol had lost none of its weight, and which wajj 

 merely sulphate of lime. The precipitate then, first pro^ 

 duced in the unevaporated urine by muriatic acid, did not 

 by any means arise from benzoic acid. 



It appears from these experiments, that In consequence 

 of the great difference observed in them it is not possible 

 to determine the proportions of the component parts of tho 

 yrine. 



In the many experiments which I made with the urine 

 of different horses, I always found deviations in those which, 

 ^ontanied benzoic acid. In general, I found none of this 

 acid ; in some cases, but very seldom, I found a considera- 

 ble quantity of it ; calcareous earth I found only once. 



Whence then arises this great difference ? The answer 

 to this question will, perhaps, make us better ac(juainte4 

 with the cause of these differences. To accomplish this 

 fnd, it was, in the first place, necessary to examine into th^ 

 origin of this acid, whether it was formed from the vege- 

 tables on which the horses fed, and conv&yed into the urine, 

 Vr whether it was created iu, the aniuia! body by the mutuaj 

 ' actioa 



