39i 
Gouty and Urinary Concretions. 
from which the quicksilver may be expelled by heat, and the 
acid procured separate. By addition of vitriolic acid to the re- 
maining solution, Epsom salt is formed, and may be crystal- 
lized, after the requisite evaporation of the nitrous acid, and se- 
paration of any redundant quicksilver. 
(7.) These crystals require a very large quantity of water 
for their solution, but are readily soluble in most if not all acids; 
viz. vitriolic, nitrous, marine, phosphoric, saccharine, and ace- 
tous ; and when precipitated from them re-assume the crystal- 
line form. 
(8.) From the solution in marine acid, sal ammoniac may 
be obtained by sublimation. 
(9.) Although the analysis is satisfactory, the synthetic 
proof is (if possible) still more so. After dissolving magnesia in 
phosphoric acid, the addition of volatile alkali immediately forms 
the crystalline precipitate, having the same figure and proper- 
ties as the original crystals. 
(10.) If volatile alkali be cautiously mixed with recent urine, 
the same compound will be formed ; the first appearance that 
takes place when a sufficient quantity of alkali has been gradu- 
ally added, is a precipitate of these triple crystals. 
These constitute the greater part of the fusible stone; so that 
a previous acquaintance with their properties is necessary, in 
order to comprehend justly the nature of the compound stone 
in which they are contained. 
The most direct analysis of the compound stone is effected 
by the successive action of distilled vinegar, marine acid, and 
caustic vegetable alkali. 
(11.) Distilled vinegar acts but slowly upon the calculus 
when entire ; but when powdered, it immediately dissolves the 
