Part 8

Sometimes likewiſe it happens that neutral ſalts join earthy ſalts, and earthy ſalts metallic ones. I generally diſtinguiſh compound ſalts according to the number of their principles, whether the ſame acid be joined to ſeveral baſes, or the ſame baſis to different acids; or laſtly, whether ſeveral menſtrua and ſeveral baſes are joined together. Hence ariſe ſalts triple, quadruple, &c. which the diligence of after times muſt illuſtrate. I ſubjoin the moſt remarkable examples of triple and quadruple native ſalts which have occurred to me.

§ 76.

ALKALI MINERALE SALITUM (common ſalt) contaminated by magneſia ſalita. The common ſalt when pure does not deliqueſce, but this degree of purity is ſeldom found, and in the native foſſil production (ſal gem) never.

§ 77.

MAGNESIA vitriolata (Epſom ſalt) contaminated by ferrum vitriolatum (vitriol of iron.)

§ 78.

ARGILLA vitriolata (alum) native, contaminated by vitriol of iron. In the aluminous ſchiſtus it ſometimes effloreſces in a feathery form. Is this the plumoſe alum of the antients?

§ 78*.

ARGILLA vitriolata (alum) native; contaminated by ſulphur and vitriolic acid.

At the places about Wedneſbury and Bilſton, in Staffordſhire, where the coal pits are on fire, this ſubſtance ſublimes to the ſurface, and may be collected in conſiderable quantity during dry or froſty weather. I cannot be certain that this is a true chemical union, but the eye cannot diſtinguiſh the parts. Perhaps the ſulphur volatilizes the alum and ſo becomes intimately mixed with it. The exceſs of vitriolic acid keeps it in a deliqueſcent ſtate.

I believe a ſimilar compound ſubſtance ſublimes at the Solfaterra near Naples. W.

§ 79.

ARGILLIA vitriolata (alum) native, contaminated by vitriol of cobalt. In the mines of Herregrund and Idra this may be ſeen, ſhooting out into long ſlender filaments. Perhaps this is the trichites of the Greeks. Diſſolved in water it immediately betrays the preſence of vitriolic acid, upon the addition of terra ponderoſa ſalita (muriatic acid ſaturated with heavy earth.) By the addition of phlogiſticated alkali a precipitate of cobalt is thrown down, which makes a blue glaſs with borax or microcoſmic ſalt.

§ 80.

CUPRUM vitriolatum (vitriol of copper) contaminated by iron.

§ 81.

FERRUM vitriolatum (vitriol of iron) contaminated by nickel.

§ 82.

CUPRUM vitriolatum (vitriol of copper) and vitriol of iron contaminated by zinc. Such is found at Fahlune.

CLASS II. EARTHS.

§ 83.

Before we can underſtand the nature of earths, we muſt know their component parts. Thoſe earths which cannot be further decompoſed we call primitive, and thoſe which conſiſt of two or more of theſe intimately united, derivative. By this union we do not mean a mere mechanical diffuſion, at leaſt not ſuch as can be diſtinguiſhed by the eye, as is the caſe in ſtones, (ſaxa.)

§ 84.

It is evident that the primitive earths will conſtitute ſo many natural Genera, and different mixtures of theſe the Species.

They who would make ſeveral Genera out of one primitive earth, muſt ſeparate the glaſſy, red, white, horny ſilver ores, and other different compoſitions into as many Genera, or elſe act inconſiſtently with their own principles.

§ 85.

At preſent we only know five primitive earths. They who reckon fewer, reſt their opinions upon fanciful metamorphoſes unſupported by faithful experiments. As experiments teach us that there are five primitive earths, it is evident that the Species ariſing from the mixture of theſe cannot exceed twenty-four, viz. 10 double (conſiſting of two earths) 6 triple, 3 quadruple, and the 5 primitive.

Although theſe different mixtures are poſſible, and probably do exiſt, they have not yet been all found. The natural compoſitions of acids with the earths, forming ſubſtances not ſoluble in 1000 times their weight of boiling water, and which may be called ſaline earths, muſt be added to the ſpecies, as they are certainly chemical combinations.