258 _ An Analysis of Fluor- Spar. 
the charge of the jar. The battery represents muriatic 
acid, the | positive jar represents sulphuric acid, and the’ne- 
gative jar represents soda. The powers are reversed j but it 
Goes not atiect the conclusion. These experiments may 
be made also by employing Jarge and small conductors. 
Conclusion. 
If I have been thus free in stating my objections to the 
opinions of one of the most distinguished philosophers of . 
the age, | was encouraged to proceed, when | reflected that, . 
as the establishment of truth was the object of research, 
the discovery of error as a preparation, would be to no one 
more highly pleasing, than to the illustrious framer of this 
ingenious hy pothesis. 
XLV. An Analysis of Fluor-Spar. By Tuomas Tuom- 
son, M.D. F.R.S.E.* 
Tae mineral ‘called Fluor-Spar has been long known, 
and valued on account of its- beauty and the ease with 
which it can be turned on the lathe into various ornaments 
and useful utensils. It occurs chiefly in veins, and very 
frequently apcompanige lead-ore. Some of its properties 
have been described more than a century ago 3 as, for ex- 
ample, its phosphorescing when heated, and its corroding 
glass when mixed with sulphuric or nitric ‘acid. But itis not 
forty years sinceits composition was discovered by Scheele, | 
who demonstrated that it is composed of lime and a_pecu-- | 
liar acid called fluoric. Chemists now distinguish it by = ~~ 
the name of fluate of lime. 
Hitherto, no chemical analysis of this salt has been pub- 
lished, except a very incorrect one by Kirwan and Gren, * 
a arabs has been ascribed to Scheele, though I cannot find 
it in any of his dissertations on fiuor-spar. By that analysis, { 
itis made to contain 27 per cent. of water,—a proportion 
very inconsistent with the properties of native fluate of 
lime, which, when strongly heated in a wind furnace, loses 
at an average only akodlth part of its weight. The obvious 
inaccuracy of the analysis given by the authors just men- 
tioned induced me to make a set of experiments on it last 
-summer (1807). I selected the purest transparent colour- 
-less crystal, which I found by repeated trials to be very 
nearly pure fluate of lime. When reduced toa fine pean, 
a eS 
* From the Wernerian Transactions, 
and 
