in different chemical Processes on Fluor Spar. 413 
spirit lamp; and by inverting this in a tray of platina filled 
with liquid fluoric acid, [ contrived to submit the fluid to 
the agency of electricity in sach a manner, that in succes- 
sive experiments it was possible to collect any elastic fluid 
that might be produced. Operating in this way, with a very 
weak Voltaic power, and keeping the apparatus cool by a 
freezing mixture, I ascertained that the platina wire at the 
positive pole rapidly corroded, and became covered with a 
chocolate powder; gaseous matter separated at the negative 
pole, which I could never obtain-in sufficient quantities to 
analyse with accuracy ; but it inflamed lke hydrogen. No 
other inflammable matter was produced when the acid was 
"pure. 
In a case in which the acid had been condensed in a tube 
of lead, joined by a sojder containing tin, a large quantity 
of powder separated at the negative surface of a dark co- 
lour, and which appeared to be tin mixed with a subfluate ; 
the powder burnt when heated in the air, and gave fluoric 
fumes when treated by potassa and sulphuric acid. 
_ L attempted to electrize the liquid fluoric acid, by making 
plumbago the positive surface; but the plumbago was 
quickly destroyed, a subfluate of iron was deposited on the 
negative surface, and the liquid became turbid and black. 
When a point of charcoal attached to a wire of platina was 
made positive, the effects were similar to those produced by 
a platina wire alone; for the acid speedily penetrated through 
the pores of charcoal, and the platina, in consequence, be- 
came a point of contact with the fluid. 
I applied the power of the great Voltaic batteries of the 
Royal Institution to the liquid fluoric acid, so as to take 
sparks in it. In this case, gas appeared to be produced 
from both the negative and the positive surfaces; but it 
was probably only the undecompounded acid rendered 
gaseous, which was evolved at the positive surface, for du- 
ring the operation the fluid became very hot, and speedily 
diminished. The manner in which the surrounding atmo- 
sphere became filled with the fumes of the fluoric acid, 
rendered it, indeed, very difficult to examine the results of 
any of these experiments; the dangerous action. of these 
fumes has been described by MM. Gay-Lussac and The- 
nard, and [ suffered considerable inconvenience from their 
effects during this investigation. By mere exposure to 
them in their uncondensed state, my fingers became sore 
beneath the nails, and they produced a most painful sensa- 
tion, which lasted for some hours, when they came in cun- 
tact with the eyes, 
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