104 



the stone from the bladder of a tortoise ; from 

 which it appears, that man is not the only animal 

 in whose body this acid is generated. 



The Kidneys, in which the urine is formed, 

 have not been examined, and the chemical proper- 

 ties of their parenchyma are not known. The uri~ 

 nary bladder and its channels are similar in their 

 composition to the intestines ; but the mucus of 

 the bladder, such as it is deposited with the urine, 

 is very unlike the mucus in other places. It is 

 almost completely pellucid, forming 1 small grains, 

 which, when gathered on a filter, leave a slip- 

 pery and colourless mucus, which, however, often 

 becomes red in drying, and shows signs of con- 

 taining uric acid. After being moistened with 

 water it does not aofain become viscid. 



The concretions, which are formed in the urine, 

 have, from the remotest times, been the object of 

 conjectures and experiments. From GALEN to 

 PARACELSUS, the ideas relative to these concre- 

 tions were absurd. VAN HELMONT compared 

 them to tartar; and after him, they were vari- 

 ously described by a great number, among whom, 

 HALES, BOYLE, BOERHAAVE, and SLARE, de- 

 to be mentioned. At last, some calculi 



