trated vitriolic acid, from which it again feparates entire and 
unchanged upon the affufion of water, C. 1. 2. 
4thly, That it cannot be decompofed (via humida), by roll 
fixed alkaly, C. 4. 
sthly, That it may be Netomsgesi (via ficca) by the vege- 
table fixed alkaly, D. E. G. H. 
6thly, That it may be decompofed by inflammable matter, 
uniting to its acid, and forming fulphur ; but that it cannot be 
decompofed by heat alone, A. 1. 
“thly, From experiments I. 1.2. it appears, that 100 pas 
of this fubf{tance contain 
306 «=Dr. WituErRine’s Experiments and Obfervations 
Vitriolic acid pure “ 32,8 ‘ 
‘Terra ponderofa pure 67,2 
YOO 
For the 100 parts of terra ponderofa aérata made ufe of in the 
experiment I. 1. would lofe during the folution 20,8 of fixed 
air (§ 1ft, A.); then, deduting 0,6 for the marmor metalli; 
cum contained in the terra ponderofa aérata (§ 1ft. A. 1. 2), 
there remains 78,6 of pure terra ponderofa. This, when fa- 
turated with vitriolic acid, and made perfectly dry, weighed 
1173 confequently it had taken 38,4 of vitriolic acid. 
OBSERVATIONS 




The apparent infolubility of terra ponderofa aérata in the 
diluted vitriolic acid (I. 2.) can be accounted for by remarking, 
that the moment the furface of the lump was ated upon by 
the acid, an infoluble coat of marmor metallicum was formed 
upon it, which effectually precluded any further operation of 
the acid. 
Profeffor 
_— ; 
