Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/253

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Nothing having been said in my papers on the oxide of tin, and the sulphate of barytes and quartz, on the mode of cleaving them, they are now placed in the following table at the head of the ten substances forming the particular objects of this communication, chiefly to allow the opportunity of saying a few words on the subject of splitting them.

Measurements.
Substances Primitive Crystal. Reference to Plate 12 According to Haüy According to Bournon By the
Reflecting Goniometer
Oxide of Tine An obtuse octohedron of which the common base of the pyramids is square Fig.1 P on P 67° 42′ 67° 50′
Haüy
P on the opposed plane over the apex 112° 50′
Sulphate of Barytes A right prism, with rhombic bases. Fig. 2. M on M 101° 32′ 13 101° 42′
Haüy
M on the adjacent plane, over the edge A 78° 27′ 47 78° 18′
Quartz A slightly obtuse rhomboïd Fig. 5. P on P 94° 24′ 94° 15′
Haüy
P on P' 85° 36′ 85° 45′
Zircone An obtuse octohedron; the common base of the pyramid is square. Fig. 1. P on P 82° 50′ 84° 20′
Haüy
P on the opposed plane over the apex 95° 40′
Staurotide A right rhomboidal prism Fig. 2. M on M 129° 30′ 129° 20′
Haüy
M on the adjacent plane over the edge A 50° 40′
Anatase An acute octohedron; the common base of the pyramid is square. Fig. 4. P on P 137° 10′ 136° 47′
Specular Iron A slightly acute rhomboid. Haüy Fig. 3. P on P 87° 9′ 86° 10′
92° 51′ 93° 50′
Diopside An oblique rhomboidal prism. Haüy Fig. 6. M on M 87° 42′ 87° 5′
M on the adjacent plane, over the edge A 92° 55′