226 Miscellaneous Intelligence. 



specific lyravity of the native alloys of gold and silver when com- 

 pare<l with calculation, or with the results obtained from an alloy 

 similar in composition prepared by fusion ; thus the native gold 

 of Marmato has a specific gravity of 12.666, whereas, by calcu- 

 lation, it ought to be 16.931. The gold of Malpaso, by experi- 

 ment, is 14.706, by calculation, 18.223, and by fusion, 18.1. The 

 gold of Santa Rosa, -by experiment, is 14.149, and by calculation, 

 16.175. This difference, M. Boussingault says, is not due to 

 porosity in the native gold, as he has observed it in the granular 

 and fine varieties, but a peculiar character of the metal in this state. 

 Such an enormous difference, however, is one that can be admitted 

 only upon repeated experimental proofs, made in the most unex- 

 ceptionable manner ; and, considering that it is only in some of the 

 metals that any permanent difference in specific gravity can be 

 established, and even with them to but a small extent, would be a 

 fact so important as to be worth extreme trouble in the verifica- 

 tion. — Annales de Chimiej xxxiv. 408. 



8. Protheelte — d new Mineral. — This mineral was discovered in 

 1826, at Rothenkoph, in the valley of Zillerthal, Tyrol. It occurs 

 in rectangular prisms, generally without distinct summits, and 

 rough at both ends. The angles are very seldom truncated, the 

 faces are striated longitudinally. The crystals are of various sizes, 

 some being very small, but they have occurred 5 inches in length, 

 and two in width "; the longitudinal fracture is lamellar, the cross- 

 fracture conchoidal. The substance is usually fissured, nearly 

 opaque in large specimens, translucent or' diaphanous in small 

 masses. Its colour is crysolite green or' white, or between the 

 two ; its lustre between that of glass and the diamond ; it is heavy; 

 a good conductor of heat ; hard enough to scratch glass ; in- 

 fusible before the blowpipe; highly electric by friction. The white 

 crystals have a fibrous texture, which, as well as the colour, seems 

 the result of decomposition. When cut and polished, the mineral 

 assumes a great variety of aspects ; the green parts then resemble 

 the finest crysolites, but the fibrous white parts, when cut of a round 

 form, present one or two reflections on a transparent ground which 

 move as the stone i^ moved, just like those from the cat's eye ; these 

 reflections are very brilliant, and are accompanied by numerous iris 

 colours, which move like those on the opal. This phenomenon is 

 often observed in the rough stone, which, when exposed to light, 

 exhibit certain deep red tints of a cupreous colour, and metallic 

 lustre on all the faces. — Bull. Univ. B. xi. 42. 



9. Volcanic Bisulphuret of Copper. — M. N. Covelli, during hish 

 examinations of Mount Vesuvius, has observed some particular" 

 actions gwng on, especially in the fumeroles on the eastern side 

 of the mountain, -and within the crater. Speaking of the fornier, 

 he says, ** Here there are fumeroles in which pure chloride of lead 



