. Annals of Philosophy. 114 Mr. Brooke on Baryto-Calcite. [Aug. Fig. 1, represents the rain gauge in perspective. Fig. 2, is a vertical section. G the body of the gauge, F its funnel, L the lid or cover, v the valve, hinged to the lower orifice of the funnel, s the spring to close the valve, w a wire to conduct the drainings of the funnel into the body of the gauge. Article VIII. On Baryto-Calcite. By H. J. Brooke, FRS. &c. (To the Editors of the Annals of Philosophy.) GENTLEMEN, July 15, 1824. Mr. Broughton, before he left. London, favoured me with specimens of a mineral from Cumberland w
. Annals of Philosophy. 114 Mr. Brooke on Baryto-Calcite. [Aug. Fig. 1, represents the rain gauge in perspective. Fig. 2, is a vertical section. G the body of the gauge, F its funnel, L the lid or cover, v the valve, hinged to the lower orifice of the funnel, s the spring to close the valve, w a wire to conduct the drainings of the funnel into the body of the gauge. Article VIII. On Baryto-Calcite. By H. J. Brooke, FRS. &c. (To the Editors of the Annals of Philosophy.) GENTLEMEN, July 15, 1824. Mr. Broughton, before he left. London, favoured me with specimens of a mineral from Cumberland which had been con- sidered to be carbonate of barytes, but it was very evident that the crystals did not resemble the ordinary figures of carbonate of barytes, and the substance was, therefore, regarded by Mr. Broughton as something new. The external surface of the specimens is coated with sulphate of barytes ; but the internal mass frequently contains cavities which are lined, and / nearly filled with crystals. The primary / form of these is an oblique rhombic prion, as f\^ j shown in the annexed figure, the cleavage being parallel to the planes P, M, and M'. P on M, orM' 102° 54' Pona 147 34 P on h 106 8 MonM' 106 54 M on h 143 27 All the crystals I have seen are modified on some of the edges and angles, and are lengthened in the direction of the edges of the modifying planes, presenting the character of prisms termi- nated by the bright, planes Y, a, M, and h, of the figure. The modifying planes are, however, so numerous, irregular and dull in my specimens, that I have not obtained sufficiently good or corresponding measurements to enable me to ascertain their character, anti they are, therefore, omitted in the drawing. The mineral is translucent with a slight tinge of a yellowish- brown colour. Its lustre rather more waxy than carbonate of barytes. Its hardness is between that of carbonate and filiate of lime. Its specific gravity, as ascertained by Mr. Children, is 3*66.
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Keywords: ., bookcentury1800, bookdecade1820, bookpublisherlondon, bookyear182
