Art. XXXVII.–On the Production of a Mono-hydrate of Chloride of Barium.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 3, 1870, Page 220

Art. XXXVII.–On the Production of a Mono-hydrate of Chloride of Barium. By W. Skey, Analyst to the Geological Survey of New Zealand; with Notes on its Crystallization, by E. H. Davis. (With Illustrations.) [Read before the Wellington Philosophical Society, September 17, 1870.] In testing a mineral from the Thames gold-field containing baryta, I observed that the chloride of this base deposited crystals from its hydrochloric acid solution, differing considerably in shape from those described as belonging to the common bi-hydrate; they also differ in lustre, which inclined to pearly. I therefore analyzed these crystals, and the results of this give the following formula: Ba Cl + HO. This is then a mono-hydrate of chloride of barium, which is the lowest hydrate yet obtained. Like the bi-hydrate, it effloresces in the air at common temperatures. The action of hydrochloric acid in determining the production of this variety, is no doubt referable to its affinity for water, this being superior to that of the monohydrated salt. This salt has been microscopically examined by Mr. Davis, and the accom panying drawings of the crystals, and notes thereon, have been furnished by him. On the Crystallization of Ba CI HO. The crystals are white and pearly, and effloresce rapidly; they are exceedingly small, requiring a high magnifying power to make them at all distinct. The system is tetragonal, the same as the bi-hydrate of barium, but, unlike that compound, all the crystals are ditetragonal forms, or at least have a combination of the ditetragonal and first kind of tetragonal, or of the first and second kinds. The relations of the parameters could not be deter mined for certain, for want of a proper instrument. Pl. XXVI., fig. 1, is a ditetragonal pyramid, very perfect, having the parameters as 1 : 1 : 2 as nearly as possible. Fig. 2, is a ditetragonal spheroid or ocalenohedron, its parameters are nearly 1 : 1 : 2.5.

J. New Crystalline form of Iron Pyrites. 2 to 9. Crystals of Monohydrated Chloride of Barium.

Fig. 3, is a ditetragonal prism, broken at one end, and terminated at the other by an obtuse pyramid. Fig. 4, is similar to Fig. 3. Fig. 5, is a combination of a primary prism with a prism of the second kind, apex being the pyramid of the first kind. Fig. 6, is interesting, as it presents the curious marking hitherto (I believe) peculiar to chiastolite, which is a rhombic crystal. Fig. 7, is a normal prism terminated by a pyramid, having its angles replaced by a more acute pyramid of the second kind. Fig. 8, is a combination of a primary prism having an acute pyramid capped by one more obtuse, which is again terminated by a pinacoid; this crystal is either one which has lost its water of crystallization, or, what is more probable, it has absorbed one equivalent from its neighbour, which was quite opaque to polarized light. Fig. 9, represents two crystals, both perfect, consisting of combinations of primary and secondary prisms and pyramids. All these were carefully examined and drawn while under the microscope; they present no features by which they could be certainly recognized from some other salts, but as a new compound, it is interesting to observe the com plete change in the style of the crystallization which one equivalent of water can cause.