343 
formerly supposed to be Zeolite , &c. 
as to dissolve what adheres to the neck and cavity of it, a fur- 
ther solution is effected, but differing in some measure from 
the solution of the sublimate collected from the neck of the 
vessel. This latter solution is found to contain lead. If nitric 
or muriatic acid be poured into the retort, so as to dissolve 
what still remains adhering to it, the presence of lead becomes 
more evident. Whence does this metal arise ? I have reason 
to believe that it arises from the glass retort, which is corroded 
by the acid of the fossil extricated by heat. But what acid is 
it? It does not seem to be either the phosphoric or fluoric 
acids, the latter of which became the first object of my sus- 
picion. 
The opinion which Mr. Davy suggested to me seems more 
probable, that it is of vegetable origin. Oxalic acid, on the 
authority of Bergman, may be volatilized ; yet some of its 
properties are very extraordinary and do not accord with this 
idea. 
I decomposed the watery solution of the scales by nitrat of 
lead, and after a sufficient edulcoration of the subsided precipi- 
tate, I dropped upon it some sulphuric acid. No fumes were 
perceptible. The sulphat of lead was separated by the filter, 
and the dear fluid, which passed through it, was gradually 
evaporated ; small crystallizations were formed, the figure of 
which I could not ascertain ; some of them were exposed to 
the flame of th,e blowpipe in a gold spoon ; they did not burn 
to coal, nor give out any empyreumatic smell nor fuse, but 
they assumed an earthy appearance.* 
* I subjected some of the Barnstaple mineral, with which Mr. Rash lei ch kindly fur- 
nished me out of his cabinet, to experiment, with a view of ascertaining whether it 
would produce the same volatilized saline crust, as the Stenna Gwyn fossil, and I 
found that it aid. 
