ON CALCULUS VESIC/E 149 



would, however, be a necessary consequence if vitriolic 

 acid were a constituent part of the calculus ; and since 

 the acid of sugar (Sec. in. (h)) does not produce any pre- 

 cipitation, which certainly would take place if lime were 

 a constituent part of it, I conclude, I say, that calculus 

 is neither calcareous nor gypseous, but consists of an oily, 

 dry volatile acid united with some gelatinous matter. The 

 calculus is an oily salt, in which the acid prevails a little, 

 since it is soluble in pure water (Sec. VL), and imparts 

 to the tincture of lacmus a red colour. That it contains 

 phlogiston, appears by its solution in caustic alkalies and 

 lime-water (Sees, iv., v.), but especially from the effects 

 produced by means of nitrous acid, from which it acquires 

 quite different properties than from being dissolved in 

 alkalies, nor can it be precipitated from this solution 

 (Sec. in. (/)). The animal gelatinous substance appears on 

 distillation, by which a liquor is obtained resembling spirit 

 of hartshorn, and a fine coal is left behind. 



SECTION VIII. 



I have found calculus dissolved in all urine, even in 

 that of children. If four cans of limpid fresh urine 

 be evaporated to 2 oz., a fine powder is deposited as it 

 cools, and a part firmly adheres to the glass. This 

 powder dissolves very readily in a few drops of caustic 

 alkali, and has moreover all the properties of a calculus 

 vesicse. The lateritious sediment, which is deposited from 

 the urine of those who labour under an ague, is of the 

 same nature. I suspected in the beginning that there 

 was an unknown menstruum in this urine, which, being 

 volatile in the open air, was the cause of such a large 

 quantity of this powder being kept suspended in the 



