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 laminæ. 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."
"The oxalate of lime, or mulberry calculus, is generally of a very dark brown colour, approaching to black. Its surface is very rough and tuberculated (hence the epithet of mulberry.) It is usually hard, and when cut through exhibits an imperfectly laminated texture. This species of calculus seldom surpasses the medium size, and is rather common. There is a variety of it remarkably smooth, and pale coloured. These are always of small size; and from their colour and general appearance, have been termed the hempseed calculus.—Chemical characters. Before the blow-pipe, this species of calculus expands into a kind of white efflorescence, which, when moistened and brought into contact with turmeric paper, stains it red. This white alkaline substance is the caustic lime deprived of its oxalic acid."
"The triple phosphate of magnesia-and-ammonia calculus is always nearly white; its surface is commonly uneven, and covered with minute shining crystals. Its texture is not laminated, and it is easily broken and reduced to powder. In some rare instances, however, it is hard and compact, and when broken exhibits a crystallized texture, and is more or less transparent. Calculi composed entirely of the triple phosphate of magnesia-and-ammonia are rare; but specimens, in which this salt constitutes the predominant ingredient, are by no means uncommon.—Chemical characters. Before the heat of the blow-pipe, this calculus gives off the odour of ammonia, and at length melts with difficulty. It also gives off ammonia, when treated with caustic potash. It is much more soluble than the preceding species in dilute acids, from which it is again readily precipitated by ammonia in its original crystallized form.
"The calculus composed of a mixture of the phosphate of lime and triple phosphate of magnesia-and-ammonia, or the fusible calculus, is commonly whiter and more friable than any other species, resembling sometimes a mass of chalk, and leaving a white dust on the fingers. This species is generally not laminated. Occasionally, however, it separates readily into laminæ, the interstices of which are often studded with sparkling crystals of the triple phosphate. The variety of this species which is not laminated often acquires a very large size, and assumes the form of a spongy friable whitish mass, evidently moulded to the contracted cavity of the bladder in which it has been formed. This species of calculus occurs very frequently.—Chemical characters. It may be readily distinguished by the ease with which it melts before the blow-pipe. It also dissolves readily in acids, and particularly in dilute muriatic acid; and if to the solution, oxalate of ammonia be added, the lime is precipitated alone, and the magnesium may be afterwards separated by the addition of pure ammonia.