Scheele,[198] with whom the inquiry originated, conceived that every calculus consisted of a peculiar concrete acid, soluble in alkaline lixivia, and which Morveau denominated the _Lithic Acid_; but the subsequent researches of Fourcroy, Vauquelin, Wollaston, Pearson, Henry, Brande, Marcet, and Prout, have demonstrated the existence of _several_ bodies in the composition of urinary calculi, viz. _Lithic Acid_; _Phosphate of Lime_; _Ammoniaco-magnesian Phosphate_; _Oxalate of Lime_; _Cystic Oxide_;[199] and _Xanthic Oxide_;[200] to which may be added an _animal cementing ingredient_. The varieties of calculi produced by the combination or intermixture of these ingredients, are represented in the following Tabular Arrangement. ┌─────────────────────────────────────────────────────────────────────┐ │ A TABULAR VIEW OF THE DIFFERENT SPECIES OF URINARY CALCULI. │ ├───────────────┬─────────────────┬─────────────────┬─────────────────┤ │ SPECIES OF │ EXTERNAL │ CHEMICAL │ REMARKS. │ │ CALCULI. │ CHARACTERS. │ COMPOSITION. │ │ ├───────────────┼─────────────────┼─────────────────┼─────────────────┤ │1. LITHIC or │_Form_, a │It consists │It is the │ │ URIC. │ flattened oval;│ principally of │ prevailing │ │ │ _Specific │ _Lithic Acid_; │ species; but │ │ │ gravity_, │ when treated │ the surface │ │ │ generally │ with nitric │ sometimes │ │ │ exceeds 1·500; │ acid, a │ occurs finely │ │ │ _Colour_, │ beautiful pink │ tuberculated. │ │ │ brownish or │ substance │ It frequently │ │ │ fawn-like; │ results. This │ constitutes the│ │ │ _surface_ │ calculus is │ _Nuclei_ of the│ │ │ smooth, texture│ slightly │ other species. │ │ │ laminated. │ soluble in │ │ │ │ │ water, │ │ │ │ │ abundantly in │ │ │ │ │ the pure │ │ │ │ │ alkalies. │ │ ├───────────────┼─────────────────┼─────────────────┼─────────────────┤ │2. MULBERRY. │_Colour_, │It is _Oxalate of│This species │ │ │ dark-brown; │ Lime_, and is │ includes some │ │ │ _texture_, │ decomposed in │ varieties which│ │ │ harder than │ the flame of a │ are remarkably │ │ │ that of the │ spirit lamp, │ smooth and pale│ │ │ other species; │ swelling out │ coloured, │ │ │ _Sp. grav._ │ into a white │ resembling a │ │ │ from 1·428 to │ efflorescence, │ _hemp seed_.