Part 13

CRONSTEDT Min. § 124. 2. b. Minera aluminis romani.

Alum ore.

It certainly contains vitriolic acid, and perhaps, alſo, a ſmall portion of ſulphur. The vegetable alkaly ſufficiently ſhews its volcanic origin.

§ 118.

ARGILLA (argillaceous earth) contaminated by ſiliceous matter, pyrites, and petroleum.

CRONSTEDT Min. § 124. 2. c. Schiſtus aluminaris.

Alum ſlate.

§ 119.

ARGILLA (argillaceous earth) intimately united with leſs than half its weight of ſiliceous earth, and a ſmall quantity of mild calcareous earth.

CRONSTEDT Min. §§ 43–48. Gemma.

The Gems ſuffer no change under the blowpipe, with foſſil fixed alkaly, but are diſſolved by microcoſmic ſalt and borax.

To this head belong Rubinus, the ruby; Saphirus, ſapphire; Topazius, topaz; Smaragdus, emerald.

The tourmaline holds a kind of middle place betwixt the gems and the ſcherle. The colour, in all of them, is owing to iron.

§ 120.

ARGILLA (argillaceous earth) intimately united to half its weight of ſiliceous earth (or more), and a little mild calcareous earth. Scherle.

CRONSTEDT Min. §§ 68–71. Granatus et Baſaltes, which I call Scherle.

The remote varieties of theſe are eaſily diſtinguiſhed, the near ones difficultly.

§ 121.

ARGILLA (argillaceous earth) looſely united to half its weight, or more, of ſiliceous earth, and a little calcareous earth.

CRONSTEDT Min. §§ 108–112. Zeolithus. Zeolite.

There is a great affinity betwixt this and Scherle; but in the zeolite, the component parts cohere ſo looſely, that acids attach and ſeparate them without their being previouſly treated with alkalies; but this is not the caſe with the ſcherles.

Zeolite, contaminated by magneſia, I have not yet examined.

§ 122.

ARGILLA (argillaceous earth) intimately united to a large proportion of ſiliceous earth, and a ſmall proportion of magneſia.

CRONSTEDT Min. §§ 93–96. Mica. Talcum. Glimmer. Talc.

SILICEOUS EARTH, OR TERRA SILICEA.

§ 123.

This, like the other primitive earths, is ſeldom found pure. In order to have it ſo, reduce clear quartz chryſtals into powder; melt it with four times the weight of fixed alkaly; diſſolve the whole in water; precipitate by a large quantity of ſtrong acid; carefully waſh and dry the precipitate.