5 
some Minerals of the ZeoUie Family. 
There it deposited silex abundantly : the neck of the retort was 
not corroded, and it shewed only slight traces of silex deposited 
by the gas. The alkaline liquid, when evaporated to dryness, 
and redissolved in water, left 19 parts of undissolved Silex. 
The alkaline solution, when supersaturated with muriatic acid, 
in a platinum dish, and heated slightly for some hours, to drive 
off the carbonic acid, was afterwards neutralised by the ammo- 
nia, of which a small excess was added, but no precipitate was 
formed. By adding muriate of lime, Fluate of Lime wasTorm- 
ed, which, when washed and dried, weighed 65.67 =: 18.26 parts 
of Fluoric Acid. The residue in the retort being exposed to 
the fire, to deprive it of its excess of sulphuric acid, left 150 
parts of Gypsum, equivalent to 62.25 parts of pure Lime. The 
precipitate thus analysed, was therefore composed of 
Lime, 
62.25 
or 
63.75 
Silex, 
19.00 
17.80 
Fluoric Acid, 
- 18.26 
18.45 
99.51 
100 0 
as calculated from the formula CS^ -f %CFl. 
The 4.82 parts precipitated from the solution of apophyllite 
by the caustic ammonia, were therefore a true Fluo-silicate of 
Lime, and contained 3 parts of Lime, 0.95 of Silex, and 0.87 
of Fluoric Acid. 
In order that nothing might be neglectecl which could contri- 
bute to a perfect knowledge of the composition of Tesselite^ I 
repeated the preceding analyses upon 312 millegrammes which 
still remained of the mineral. I shall here compare the results 
of the analyses of the Apophyllite and of the Tesselite ^y\xh one 
another, and with the result obtained by the old analyticab me- 
thod ; that is to say, where the fluoric acid was partly disen- 
gaged in evaporating the solution to dryness^ and partly cpm- 
bined with the lime. 
Silex, - . , 
Tesselite. 
51.76 
Apophyllite of Uto. 
51.18 
Fluo-silicatc of Lime, 
3.53 
4.82 
Lime, - - 
22.73 
21.71 
Potash, , . . 
5.31 
5.27 
Water, - - . 
16.20 
16.20 
99.53 
99.18 
A 2 
