APPENDIX. 283 
time, fome of it is reduced to a fixed State, 
by being ftrongly united in the Operation to 
Particles which are capable of being thrown 
into permanently elaftic Air. This is very fre- 
quently obferved in the making of Char- 
coal ; the Dull which covers the great Pile of 
burning Charcoal, being covered with the 
white volatile Salt which arifes from the Wood ; 
while at the fame time another part of the vo- 
latile Salt which is found in the Form of Sal 
T^artar in the A(hes of the Charcoal, is re- 
duced to fo fixed a State, that it is very difficult 
to volatilize it, unlefs it be mixed as in this Ex- 
periment with a Calx, 
Experiment III. 
I. TN Experiment XCVI. Fol I. p. 224. I 
X obferved, when I let freffi Air into the 
glafs Veflel, ay Fig, 34. p. 16S, that the fuL 
phureous Vapours which arofe from the Mix- 
ture of Spirit of Nitre and vitriolic Walton 
Mineral, did abforb the freffi admitted Air fo 
fall as to make the Water rife very vifibly in 
the inverted Glafs ay but I did not then pur- 
fue the Experiment any farther, which I have 
fmee done. 
z. For 
