Medical zoology and mineralogy. Or, Illustrations and descriptions of the animals and minerals employed in medicine, and of the preparations derived from them; including also an account of animal and mineral poisons, with figures coloured from nature / [John Stephenson].

  • Stephenson, John, 1790-1864
Date:
1832
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Licence: Public Domain Mark

Credit: Medical zoology and mineralogy. Or, Illustrations and descriptions of the animals and minerals employed in medicine, and of the preparations derived from them; including also an account of animal and mineral poisons, with figures coloured from nature / [John Stephenson]. Source: Wellcome Collection.

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    213. Before the blow-pipe it becomes soft and friable, and loses weight. It is soluble in sulphuric, nitric, and muriatic acids. Ac- cording to Dr. Bruce, it consists of pure magnesia 70, water 30, in 100 parts. Native magnesia has hitherto been found only in small veins that traverse a rock of serpentine, at Hoboken, in New Jersey. Genus III.—BARYTES. Baryte, Pr.; Barite, It.; Baryterde; Schwerde, Ger.. The earth called Barytes exists in nature in combination either with sulphuric or carbonic acid, forming two distinct species of minerals, the Sulphate and Carbonate of Barytes. It is the heaviest of all earthy minerals, except Zircon. Both species are used in pharmacy for preparing the muriate. Sp. 1. Sulphate of Barytes, or Heavy-Spar.—(Pl. XLV. fig. 2.)—Baryte sulphate crystalizee, Hauy; Schwerspath, Werner. —It occurs generally crystalized, also lamellar, fibrous, granular, compact, or earthy. The prevailing colours are greyish, yellowish- white, blueish-white, and red. The crystals are frequently colour- less and transparent, and have a shining vitreous lustre, inclining to pearly. The secondary crystals are generally fiat prisms, or tables, and they often occur of considerable size. The specific gravity varies from 4‘30, to 4-37. It is brittle, and easily frangible. Its constituents are barytes 67, sulphuric acid 33. Very fine crystals of this variety are found in the lead-mines of Cumberland, Durham, and Westmoreland. Compact Sulphate of Barytes occurs in amorphous masses, which have a lamellar structure; also dis- seminated, reniform, semi-globular, with cubic impressions, and also in curved lamellar concretions. It is found in the mines of Staffordshire and Derbyshire, where it is named Cawk. Sp. 2. Carbonate of Barytes, or Witherite.—Baryte car- bonatee, Hauy. Witherit, Werner.—This mineral is rarely crys- talized; but most frequently occurs in irregular masses, or in distinct