ON CALCULUS VESICLE 155 



tion, a circumstance which is generally observed when two 

 acids are combined ; but both the acids unite with the 

 alkali, according to the law of their attraction. The red 

 mass obtained after desiccation is, however, very different 

 from the concentrated acid, such as is contained in the 

 calculus ; for it is of a darker colour, and very diliquescent ; 

 the least particle gives to a considerable quantity of water a 

 rose colour ; it is attacked by the muriatic and other strong 

 acids with violence, which sooner or later produce a quite 

 colourless solution. Such a remarkable change depends, as 

 much as I have hitherto been able to ascertain, more 

 on the action of the nitrous acid upon the inflammable 

 part than upon anything remaining behind. Such red 

 spots as are produced upon the skin by the solution 

 are likewise produced upon bones, glass, paper, and other 

 substances; but then more time is required before they 

 become visible, which, however, may be a little accelerated 

 by heat. 



I pass over a number of other experiments, made partly 

 in a different manner from those of Mr. Scheele, which, 

 however, prove no more than may be learned from his 

 excellent paper. I was also prevented from finishing some 

 of them by other engagements. I have been these several 

 years collecting the different stony concretions of animal 

 bodies, in order to investigate their component parts ; I have 

 been promised still more of them, and hope to be assisted in 

 this matter, so interesting to medical science, by such as 

 have collections of this kind. The only thing from which 

 we may reasonably expect the discovery of proper remedies 

 for the relief of people labouring under this complaint, is the 

 just knowledge of the nature of the calculus. Did we not 

 already know from experience that lime-water and the 

 caustic lixivium are among the best remedies against the 



