in solid and in gaseous species, upon which several chemists have in late years insisted.

The question of heterogeneous and of homogeneous differentiation or disintegration in gases is also discussed at length, as well as several other related problems, all of which have been previously noticed in the author's lately-published volume, entitled "A New Basis for Chemistry," to which the present paper is a supplement.-T. Sterry Hunt.

I

Miscellaneous.-By subjecting mixtures of zinc salts and sulphates of sodium or potassium to a high temperature Alex. Gorgeu has succeeded in obtaining little hexagonal prisms and plates of zinc oxide with the hardness and density of the natural zincite. By the addition of a small quantity of manganese sulphate to the mixture before heating, the crystals obtained possessed the pink color of the natural mineral. Willemite was produced by calcining a mixture of one part zinc sulphate, onehalf to one part sodium or potassium sulphate, and one-thirtieth part hydrated silica. The crystals obtained were in the form of hexagonal prisms, terminated by an obtuse rhombohedron. They corresponded in all their properties with the naturallyoccurring willemite. Bourgeois has effected the syntheses of several crystallized carbonates by heating their corresponding amorphous carbonate precipitates to a temperature of 100° in glass tubes containing a solution of some ammoniacal salt. Calcium, strontium, and barium carbonates crystallized as calcite, strontianite, and witherite. The first was accompanied by some aragonite. Lead carbonate crystallized as cerussite and hydrocerussite, and cadmium carbonate formed little crystals corresponding to calcite. The same results were reached by heating solutions of the saline salts with ammonium carbonate at 140°.

2

-Brazilian topaz possesses an electrical axis which does not correspond to any crystallographic axis.3-E. Cohen has described pseudomorphs after the concretionary markasite occurring in the chalk at Rügen, Pomerania. The pseudomorphs are composed of a mixture of 9.88 per cent. silica, 11.93 per cent. copiapite, and 78.19 limonite.

Comptes Rendus, civ., 1887, p. 120; Bull. d. 1. Soc. Chim. d. Paris, xlvii., Feb. 1887, p. 146.

2 Ib., ciii., 1886, p. 1088; Bull. d. 1. Soc. Chim. d. Paris, xlvii., Jan. 1887, p. 81. 3 K. Mack, Pogg. Annalen, 1886, No. 6, p. 153.

4 Sitzb. d. Naturw. Ver. f. Neuvorpommern u. Rügen, 1886.

June 6, 1887.