393 
Gouty and Urinary Concretions. 
combined with more or less of marine acid, according to the 
degree of heat applied. If the proportion of the earth is wished 
to be ascertained, acid of sugar will separate them most effec- 
tually, by dissolving the phosphorated magnesia, and forming 
an insoluble compound with the lime. 
(14.) Caustic vegetable alkali has but little effect upon the 
entire stone; but if heated upon the stone in powder, a strong 
effervescence takes place from the escape of alkaline air, 
and the menstruum is found to contain lithic acid precipitable 
by any other acid. Some phosphoric acid also, from a partial 
decomposition of the triple crystals, is detected by nitrated 
quicksilver. 
(15.) The triple crystals alone are scarcely fusible under the 
blow-pipe; phosphorated lime proves still more refractory; but 
mixtures of the two are extremely fusible, which explains the 
fusibility of the calculus. 
The appearance of the lithic strata, and the small proportion 
they bear to the other ingredients, shews that they are not an 
essential part, but an accidental deposit, that would be formed 
on any extraneous substance in the bladder, and which pro- 
bably in this instance concretes during any temporary inter- 
val that may occur in the formation of the crystals. 
I come now to what has been called 
Mulberry Calculus. 
This stone, though by no means overlooked, and though 
pointed out as differing from other species, has not, to my 
knowledge, been subjected to any farther analysis than is given, 
in the Second Volume of the Medical Transactions, by Dr. 
Dawson, who found that his lixivium had little or no effect 
j 
