Page:Proceedings of the Royal Society of London Vol 1.djvu/146

Rh iron, mixed with a portion of argill. Its appearance altogether might easily induce mineralogists to refer it to that kind which has been distinguished by the name of Arragonite : but various reasons are here assigned for considering them as distinct substances. Chemical analysis has not yet afforded any criteria for distinguishing this species either from the arragonite or the common carbonates of lime. And it is lastly thrown out, merely as a conjecture, whether its greater degree of hardness and speciﬁc gravity may not be owing merely to its constituent particles being more minute and more closely connected

The second part of this paper, which treats of a new species of oxide of iron, is prefaced by a short survey of the different appear- ances of the oxides of iron. according to their various degrees of combination with oxygen : and it is here suggested, that not only the proportion of oxygen, but also the mode of combination, may contribute to produce varieties which cannot by any other means be accounted for. The new species here described is thought to hold its place between the slightly attractable oxide of iron called Specular ore, or, by Abbé Hauy, fer oligiste, and that kind which no longer crystallizes except in a very indeterminate form. Its surface is of a gray colour, and has a specular appearance : it is not at all acted Upon by the magnet, and seems to be the last degree of oxidation in which iron retains the property of ctystallizing in a regular form. This form is a perfect cube; its fracture is conchoidal; its hardness is rather inferior to that of the slightly attractable oxide of iron; its speciﬁc gravity only 3961.

To this species it seems ought to be referred the Eisen-glimmer of the Germans, when it is not attractable. When at all acted upon by the magnet, it ought to be numbered among the slightly attractable oxides of iron. Specimens of this new species have been brought from Lapland, and are often found mixed or embodied in other oxides of the same metal.

The author, lastly, points out how, by the red colour of the powder and by scratching. this species may be, in a general way, distinguished from the others; an object of no trivial importance, since the products of metal from the ores may be inﬂuenced by this discrimination.

After some general observations on the various discoveries lately made, which have contributed to extend our knowledge of the construction of the heavens, Dr. Herschel assumes as a possibility, that among the multitude of the stars in the ﬁrmament, there may be instances of pairs of stars of the same or different relative magnitudes, which may revolve, either; in circles or ellipses, round their common