Part 6

§ 53.

ALKALI FOSSIL, only in part ſaturated with a peculiar acid is called tinkal; after depuration, borax. It is dug out of the earth in the kingdom of Thibet. Borax takes nearly an equal weight of acid before the alkaline properties entirely diſappear.

I believe no one has yet found the acid of borax united either to the vegetable or volatile alkalies.

§ 54.

ALKALI VEGETABILE aeratum (mild vegetable alkaly) is hardly ever found native, unleſs in the neighbourhood of woods deſtroyed by fire.

In the year 1774, at Douai in Flanders, a ſpring was diſcovered ſurrounded by a wall, whoſe waters, beſides other impregnations, contained 11 grains of vegetable alkaly in a pint.

§ 55.

ALKALI MINERALE aeratum (mild foſſil alkaly, natron, the nitre of the ancients) is found plentifully in many places, particularly in Africa and Aſia, either concreted into chryſtallized ſtrata, or fallen to a powder; or effloreſcing on old brick walls, or laſtly, diſſolved in ſprings. It frequently originates from decompoſed common ſalt. I am not ignorant that the acid of common ſalt adheres ſtrongly to its baſis ſo as not to be expelled by fire; but perhaps the viciſſitudes of the atmoſphere continually acting for ages, may be more powerful. In immenſe plains covered over with this alkaly, ſcarcely any common ſalt is found upon the ſurface, but the deeper you dig the more it is contaminated by it, the common ſalt being yet undecompoſed for want of acceſs of air.

§ 56.

ALKALI VOLATILE aeratum (mild volatile alkaly) has been found in pump waters in London, in Lauchſtadt, at Frankfort on the Mayne, and copper immerſed therein is ſaid to have been diſſolved into a blue liquor.

The three alkalies mentioned above as ſaturated with aerial acid, differ greatly from cauſtic alkalies, in the mildneſs of their taſte, in their property of chryſtallizing, and in their efferveſcing with acids which expel the aerial acid, but they ſtill change vegetable blues to greens, though not ſo powerfully as the cauſtic alkalies do. Therefore, although the ſubtil aerial acid in other reſpects gives them neutral properties, yet in this it does it but imperfectly.

§ 57.

The compounds of earths and acids which poſſeſs ſolubility mentioned at § 20, are decompoſed and precipitated by mild, but not by phlogiſticated alkalies.

§ 58.

TERRA PONDEROSA vitriolata, (heavy ſpar, marmor metallicum, calk) is placed with the earths (§ 89.) Terra ponderoſa nitrata i. e. terra ponderoſa united to the nitrous acid, perhaps exiſts ſomewhere, but has never been met with; neither has the terra ponderoſa united to the aerial acid, yet been found. Terra ponderoſa ſalita i. e. terra ponderoſa with the muriatic acid Mr. HIELM ſays is diſſolved in the waters of the lake Vettern and its neighbourhood.

§ 59.

CALX vitriolata (gypſum, ſelenite) is not only found diſſolved in various waters, but alſo in many places forms immenſe ſtrata. It is placed by all mineralogiſts amongſt the earths, but I think improperly. When burnt it generates heat with water, but in a leſs degree than lime does.

§ 60.

CALX nitrata (nitre of lime; terrene nitre) is ſometimes found in water, but very ſparingly. It is ſaid that the chalk hills in ſome parts of France become ſpontaneouſly impregnated with nitrous acid, which may be waſhed out, and after a certain time they will become impregnated with it again.

§ 61.

CALX Salita (fixed ammoniac) occurs very frequently in waters.

§ 62.

CALX aerata (marble, limeſtone, chalk, ſpar) is very commonly found diſſolved in waters in conſequence of an exceſs of the aerial acid. When it greatly abounds, the water is ſaid to be hard (cruda). By boiling, or by evaporation, it depoſits ſtreaks or cruſts of calcareous matter.

Calx aerata is not ſoluble in water without an exceſs of the ſubtil acid, and therefore might properly be referred to the earths (§ 21).

§ 63.

MAGNESIA vitriolata (Epſom ſalt) is not unfrequent in the waters of England, Bohemia, and other countries. This ſalt is preſently decompoſed by lime water, which circumſtance readily diſtinguiſhes it from the alk. min. vitriol. or Glauber’s ſalt.

§ 64.

MAGNESIA nitrata (magneſia and nitrous acid) is uſually found together with nitre.