quantity of which had become excessive._ This alternation of a principle containing nearly half its weight of azote, with another containing no azote at all, is perhaps, one of the most singular facts occurring in physiology." p. 74. The second subdivision of functional urinary diseases comprises six chapters: _first_, on urinary gravel and calculi; _second_, on the data, showing the comparative prevalency of different forms of urinary deposite, and the order of their succession; _third_, on the lithic acid diathesis in general; _fourth_, on the mulberry or oxalate of lime diathesis; _fifth_, on the cystic oxide diathesis, and _sixth_, on the phosphatic, or earthy diathesis. Under the first chapter, we have an account of I. Pulverulent or amorphous sediments; II. Crystallized sediments, or gravel; and III. Solid concretions, or urinary calculi. Of the latter, our author enumerates thirteen species. 1. The lithic acid calculus. 2. The lithate of ammonia calculus. 3. The oxalate of lime, or mulberry calculus. 4. The cystic oxide calculus. 5. The bone earth, or phosphate of lime calculus. 6. The triple phosphate of magnesia-and-ammonia calculus. 7. The calculus, composed of a mixture of the phosphate of lime, and triple phosphate of magnesia-and-ammonia, or fusible calculus. 8. The alternating calculus. 9. The mixed calculus. 10. The carbonate of lime calculus. 11. The xanthic oxide calculus. 12. The fibrinous calculus. 13. The prostate calculus. Of these, the 2nd, 4th, 5th, 9th, 10th, 11th, 12th, and 13th species are more or less rare, and consequently of less interest. The remaining 5 are of much more frequent occurrence, and are thus described by our author: "_The lithic acid calculus_ is generally of a brownish-red, or fawn colour; but occasionally of a colour approaching to that of mahogany. Its surface is commonly smooth, but sometimes finely tuberculated; and upon being cu t through, it is usually found to consist of concentric laminae. Its fracture generally exhibits an imperfectly crystallized texture, sometimes an amorphous or earthy one, in which case, it usually contains a mixture of other substances. This is one of the most common species of calculi.--_Chemical characters._ Before the blow-pipe, this calculus blackens, emits a smoke having a peculiar odour, and is gradually consumed, leaving a minute quantity of white ash, which is generally alkaline. It is completely soluble in caustic potash, and precipitable again by any acid in the form of a white granular powder. Lastly, if to a small particle, a drop of nitric acid be added, and heat applied, the lithic acid is dissolved; and if the solution be evaporated to dryness, the residue assumes a beautiful pink or carmine colour."