UIUNAEY CALCULI. 553 



men considered calculi as a peculiar mucilage concocted and pe- 

 trified by the heat of the body. These opinions were ably re- 

 futed by Van Helmont in his treatise De Lithiasi, which contains 

 the first attempt towards an analysis of urine and urinary cal- 

 culi ; and, considering the period when it was written, is certain- 

 ly possessed of uncommon merit. He demonstrates that the ma- 

 terials of calculi exist in the urine. He considers them as com- 

 posed of a volatile earthy matter, and the saline spirit of urine, 

 which coagulate instantaneously when they come in contact; 

 but which are prevented from combining in healthy people, by 

 what he calls scoria, which saturates the salt of urine. * 



Boyle found calculi soluble in nitric, but insoluble in sulphuric 

 acid and muriatic acid and vinegar, f Thus showing the species 

 upon which his experiments had beeen made. Slave attempted 

 a chemical analysis of them. J Hales extracted from them a 

 prodigious quantity of air. He gave them the name of animal 

 tartar ; pointed out several circumstances in which they resem- 

 ble common tartar, and made many experiments to find a solvent 

 for them. Drs Whytt and Alston pointed out alkalies, parti- 

 cularly lime, as the best solvents of calculi. The first attempt at 

 a description of human urinary calculi that I have met with was 

 by Dr Lewis in his notes on Neumann's Chemistry, published in 

 1759. || 



Such was the state of the chemical knowledge of urinary cal- 

 culi when Scheele published a set of experiments upon a collec- 

 tion of them, which he had made; in the Memoirs of the Stock- 

 holm Academy for 1 7 7 6. 1F All that he examined were of the same 

 nature. Scheele showed that they consisted of an acid, to which 

 the name of uric acid was given. He considered calculi as oily 

 salts composed of a mucilaginous matter with uric acid in excess. 

 To Scheele's paper an appendix was added by Bergman. He 

 also had been engaged in examining urinary calculi. Some he 

 found to agree in their nature with those of Scheele, while others 

 consisted chiefly of phosphate of lime. 



Scarcely any addition was made to the discoveries of Scheele 



De Lithiasi, p. 21. Constituting an appendix to Van Helmont's Opera. 



f Shaw's Boyle, iii. 557. J Phil. Trans, xvi. 140. 



Veget. Statics, ii. 189. 



|| Lewis's Neumann's Chemistry, p. 532. 



^ Kongl. Vetenskiaps Acad. Hand. 1776, p. 327. 



