396 Dr. Wollaston’s Analysis of 
lamina is striated in a direction perpendicular to the surface, 
as from an assemblage of crystallized fibres. 
This calculus dissolves entirely, though slowly, in marine or 
nitrous acid, and, consisting of the same elements as earth of 
bones, may undergo a similar analysis, which it cannot be ne- 
cessary to particularize. 
By the blow-pipe it is immediately discovered to differ from 
other urinary calculi : it is at first slightly charred, but soon 
becomes perfectly white, still retaining its form, till urged with 
the utmost heat from a common blow-pipe, when it may at 
length be completely fused. But even this degree of fusibility 
is superior to that of bones. The difference consists in an ex- 
cess of calcareous earth contained in bones, which renders them 
less fusible. This redundant portion of lime in bones renders 
them also more readily soluble in marine acid, and may, by eva- 
poration of such a solution, be separated, as in the last experi- 
ment upon mulberry calculus. The remaining phosphorated 
lime may be re-dissolved by a fresh addition of marine acid ; 
and being now freed from redundant lime, will, upon evapo- 
ration of the marine acid, assume a crystalline form. As the 
laminated calculus contains no excess of lime, that will at once 
yield such crystals : their appearance will be described in the 
succeeding experiment. 
Calculus from the Prostate Gland. 
There is still another calculus of the urinary passages, though 
not of the bladder itself, which deserves notice, not from the 
frequency of its occurrence, but from having been supposed 
to give rise to stone in the bladder. I mean the small stones 
which are occasionally found in the prostate giand. Those 
