ox the ‘Terra Ponderofa, &c. 
EXPERIMENTS, 
A. roo grains expofed to a red: heat for one hour in. ablack . 
Jead' crucible, loft five grains in: weight ; but as a fulphuteous 
fmell was perceptible, I fufpeéted that a decompofition had 
taken place, and therefore expofed: another portion to a fimilar 
heat for the fame fpace of time in a tobacco-pipe. This had’ 
no fmell of fulphur, nor wasit diminithed in: weight. 
2. Tt ts barely fulible under the blow-pipe ; ; but with borax 
fluxes readily into. a. white opake glafs. 
B. roo: grains, ground in a mortar, and wafhed' over ex- 
tremely fine by repeated-additions of water, were boiled in the 
fame water,.and, after fettling, the water was poured off. The 
powder, when dried, had‘ not fenfibly loft weight. 
2. To feparate portions of the wafhing water, were added 
mild vegetable and: mild foffil alkaly; but without any appear- 
‘ance of precipitation. Nutre of mercury gave a very flight 
brownifh cloud, barely difcernible ;. and nitre of filver an. ex= 
tremely flight bluifh appearance. 
- 3. The fame powder, boiled’ again: in frefh water, did: not 
affect the water at all; for it {tood the teft of nitre of filver 
without any change.. : : 
AS, Portions. of the powder B: were boiled in vitriolic, ni- 
trous, and’ muriatic acids, of the ufual ftrength, for feveral: 
minutes.. The acids were then faturated with vegetable fixed’ 
alkaly, but without any appearance: of precipitation, 1 nor had! 
the portions of powder loft any weight. | 
2. But when boiled in. vitriolic acid, unti! that acid became: 
very much concentrated and nearly. red-hot, the whole of it 
diffolved ; but, feparated again upon theraddition of water, was: 
Bus 2g not 
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