S02 On GraveUif and Calculous Concreiiornf, 



weakest acids, and still possessing its original crystalline 

 form and properties. That, from these circumstances, witlt 

 that of turning the vegetable blues red, it was of an acid 

 rature, soluble in nitrous acid with effervescence: this so- 

 lution lingcing the skin and other animal ntatters red, and, 

 upon evaporation to dryness, assuming a red rose colour: 

 this last property being peculiarly characteristic o-f this sub- 

 stance; subliming in part by distillation, without any al- 

 teration in its properties, and affording carbonate of am- 

 monia, and other usual animal products, partly from the 

 admixture of animal matter, and probably some adhering 

 urea. To these distinguishing chemical properties of the 

 Swedish chemist, Fourcroy has since added the following: 

 When triturated with a lixivium of either of the fixed al- 

 kalies, it forms a matter of a saponaceous consistence, very 

 soluble with excess of alkali, but little so without it. The 

 saturated urates of potash and soda are little sapid, soluble, 

 or cn-stailizable. Bv precipitating their dilute solution by 

 ■muriatic acid we obtain the lithic acid in brilliant needle- 

 like crystals, very voluminous, a little coloured, tending to 

 the yellow, or fauve, as he calls it. An)monia exerts liitle, 

 if any, solvent power upon it ; lime water takes up a little. 

 The alkaline carbonates have no action upon it: and this 

 last circmiistance, I would beg leave to observe, has con- 

 tinued to be the opinion to this day ; but how far founded, 

 ■H'ill appear in the sequel. To this matter Scheele gave the 

 name of liihk acid; by which it continued to be known, 

 until our countryman, Dr. Pearson, has latterly proposed 

 that of nr'c; a change greedily adopted by the French che- 

 mists, as being more particularly indicaiive of its origin. 

 Jn compliance with the philosophers of both nations, I 

 shall, in future, term it nric acid, and the concretions of 

 that nature, calculi of the uric acid kind. The publication 

 of Scheele's Essay excited the experimental inquiries of both 

 chemists and physicians. His experiments were, accord- 

 ingly, repeated by several of our countrymen in particular; 

 but with various, and in many instances different, results. 



It was already cursorily observed, that Bergmart's analysis 

 differed from Scheele's in some circumstances, which he, 

 even at that period, was disposed to attribute to a difference 

 in the nature of the calculi which they respectively exa- 

 mined ; and this conjecture has been fully establislwd by 

 every subsequent inquiry since that time. We accordingly 

 find a paper of Dr. Dawson's, in the London Medical 

 Transactions for the year ]76y, showing these concretions 

 to be of very different and opposite kinds, and, of cd/rse, 



soluble 



