An Analysis of Fluor-Spar. 259 
and digested in nitric acid, I found in the acid only a little 
lune, owing doubtless to the partial decomposition of the 
flauate, and minute traces of iron and lead: these two me- 
tals I detected by evaporating the nitric solution to dry- 
hess, heating it to redness, and then dissolving the residue 
in muriatic acid. The colour of the solution showed the 
presence of iron, and a few needle-form crystals’ of muriate 
of lead were deposited after the solution had stood for some 
days. The fluate which I-used bad been dug out of a 
lead-mine in Northumberland, and small crystals of sul- 
phuret of lead were here and there to be seen in it. * Pro- 
bably some one of these had escaped my attention, and, by 
being mixed with the fluate which I used, occasioned the 
appearance of the lead, which, however, did not amount to 
sipdth part of the salt, and therefore could not occasion 
any sensible error in the subsequent analysis. 
I first tried to decompose the fluate of lime, by fusing it 
with twice its weight of carbonate of potash in a platinum 
crucible.» On'y a small portion of the fluate was decom- 
posed. I was therefore obliged to repeat the fusions very 
often, washing off the alkali after each operation, by 
means of water, and then dissolving the carbonate of lime 
formed, in muriatic acid. Fatigued with the tediousness 
of this method, and despairing of an accurate result from 
the great number of successive solutions, I abandoned it 
altogether, and adopted the following method, much more 
expeditious and equally precise. 
From a mass of fluor-spar which I had ascertained to 
contain no sensible portion of foreign matter, [ separated 
100 grains, which I reduced to powder, and digested for 
some hours in a platinum crucible, with rather mere than 
an ounce of pure concentrated sulphuric acid. The mix- 
ture was then evaporated to dryness, and the crucible ex- 
posed for an hour to a strong heat, in a wind-furnace. To 
ensure the complete decomposition of the fluor, the mass __ 
was reduced to powder, and treated a second time in the 
/ game manner with another ounce of sulphuric.acid. The 
residue, which was white with a slight shade of red, proved 
on examination to be pure sulphate of lime. It weighed 
156°6 grains. 
- Now it has been ascertained by the most careful ex- 
periments, that sulphate of lime thus violently heated con- 
tains 43 per cent. of lime. Of consequence, the whole 
quantity of lime in 156°6 grains of sulphate is 67°34 grains. 
This is obviously the whole lime contained in 100 grains 
of fluor-spar; and since that mineral contains no sens ble 
Re portion 
