542 Progress in Scien.ce. [October, 



Much light appears to be thrown upon the probable origin of certain native 

 metals by some researches by Mr. W. Skey, of the Geological Survey of New 

 Zealand.* These experiments show the powerful reducing action which 

 ordinary metallic sulphides exert upon most salts of gold, silver, and 

 platinum. For example, a single grain of iron pyrites was found competent 

 to reduce 8£ grains of gold. The author concludes that although organic 

 matter, as commonly supposed, has probably played some part in effecting the 

 reduction of certain native metals, yet most gold and silver deposits — especially 

 those deposits which occur in the deeper-seated rocks — owe their origin 

 entirely to the deoxidising effects of metallic sulphides upon solutions of salts 

 of the precious metals. 



The mineralogist not less than the physicist is interested in the elaborate 

 researches on the pyro-electric properties of the topaz which have been under- 

 taken by Herr W. Hankel. No fewer than sixty-four crystals from Saxony, 

 Siberia, Brazils, and Asia Minor have been subjected to examination. The 

 frequent association of pyro-electric properties with hemimorphic forms of 

 crystal led Hauy to suppose that the topaz, like tourmaline, must be 

 hemimorphic. Such is not, however, the case, and Hankel's studies point to 

 the general conclusion that pyro-electricity is by no means necessarily correlated 

 with hemimorphism, but appears to be a general property of all crystals. At 

 the same time it is found that the distribution of electricity in a crystal varies 

 according as it is hemimorphic or not. In hemimorphic crystals the opposite 

 extremities of the principal axis are crystallographically dissimilar, and hence 

 assume opposite polar conditions ; whilst in crystals which are not hemi- 

 morphic the two ends are physically similar, and consequently exhibit the 

 same polar condition. In the latter case the distribution of electricity depends 

 in great measure on the external form of the crystal, and may be modified by 

 altering its shape ; but in hemimorphic crystals the distribution appears to 

 depend essentially on the asymmetry of the molecules, and therefore suffers 

 no alteration by any change in the external form of the crystal. 



Another physico-mineralogical paper claims a brief notice here. Professor 

 Dove has examined the behaviour of different kinds of native silica when 

 freely suspended in the magnetic field. Sections were cut from pure and 

 colourless rock-crystal, from smoky quartz, and from agates composed of 

 alternating layers of chalcedony, jasper, amethyst, and other varieties of 

 quartz. The sections were successively suspended between the poles of a 

 powerful electro-magnet, and their deportment completely established the 

 diamagnetic character of silica in all its varieties. 



Professor How, of Windsor, Nova Scotia, continues his researches on the 

 mineralogy of this part of the Canadian Dominion, and has published the 

 description of another new borate found in the gypsum quarries of Wink- 

 worth, in Hants County. Winkworthite, as he terms the new species, is 

 found in nodular masses, more or less crystalline on the exterior, and 

 breaking with a flat fracture which presents irregular glistening facets. 

 Scrapings, viewed under the microscope, appear as transparent oblique-angled 

 plates. Two specimens yielded slightly different results ; the one containing 

 11CaO.SiO2.9SO3.3BO3.20HO, and the other 11CaO.SiO2.8SO3.4BO3.20HO. 

 Winkworthite is consequently intermediate in composition between selenite 

 and Howlite, or silico-borocalcite, and may have originated from the reaction 

 of the elements of these two bodies, either during deposition or subsequently. 



Under the name of Ccernleolactine, Petersen describes a new species of 

 hydric-aluminium phosphate found in the mine of Rindsberg, near Katzen- 

 ellnbogen, in Nassau. The mineral occurs in a deposit of brown iron ore, 

 which, however, is not worked in the neighbourhood of the caeruleolactine in 

 consequence of the presence of phosphorus. The new species presents a 

 bluish milk-white colour, whence the name, and appears to stand between 

 Wavellite and Kalaite — approaching to the former in its chemical, and to 

 the latter in its physical characters. It is instructive to compare the formulae 

 of these three species: — 



* Chemical News, vol. xxiii., p. 232. 



