80 Intelligence and Miscellaneous Articles. 



I may, in conclusion, observe that the attraction of two plates 

 lends itself perfectly to the measurement of dielectric constants ; 

 it is simple, rapid, and only requires a sensitive balance, and is 

 preferable to all methods now in use. — Journal de Physique, June 

 1892. _____ 



INVESTIGATION OF THE PROPERTIES OF AMORPHOUS BORON. 

 BY H. MOISSAN. 



Pure amorphous boron, obtained by reducing boric anhydride by 

 means of magnesium, is a bright chestnut-brown dirty powder, of 

 specific gravity 2*45. Even in the electric arc it cannot be melted ; 

 heated for a long time to 1500° it agglomerates, but not to any 

 great extent. The electrical conductivity is small; the specific 

 resistance a = 801 megohms. 



Heated in the air, amorphous boron takes fire at 700°, and burns 

 with production of sparks. It burns in oxygen with a brilliant 

 lustre; with sulphur also it unites at 610°, with incandescence, 

 boron sulphide being formecY Boron takes fire in chlorine at 410°; 

 it burns with bright incandescence, forming chloride : bromine acts 

 in an analogous manner. 



Amorphous boron combines with metalloids more readily than 

 with metals. At a high temperature it combines, however, with 

 magnesium, iron, and aluminium, and more readily still with 

 silver and platinum. 



Very concentrated nitric acid readily acts on amorphous boron 

 and with ignition. Sulphuric acid is reduced to sulphurous ; 

 phosphorus is separated from phosphoric acid at 800°, arsenic 

 from arsenic acid, and iodine from iodic acid. 



Boron is a powerful reducing agent, exceeding carbon and 

 silicon in this respect, for at a red heat it can withdraw oxygen 

 from carbonic oxide and from silica. It cau readily reduce a 

 number of metallic oxides ; CuO, SnO, PbO, Sb0 3 , and Bi 2 3 , 

 even on moderate heating, part with their oxygen to boron, with 

 incandescence. Lead peroxide detonates violently when rubbed 

 with boron in a mortar; and a mixture of sulphur, nitre, and boron 

 detonates under a red heat like gunpowder. 



Amorphoas boron also has a reducing action on a great number 

 of salts ; the sulphates of potassium and sodium, as well as those 

 of calcium and barium, are reduced by boron to sulphides as by 

 carbon. Silver is separated in beautiful crystals from solutions 

 of silver nitrate; and from solutions of palladium, platinum, and 

 gold the corresponding metals. 



Boron unites directly with nitrogen only at very high teinpe-. 

 ratures. 



Amorphous boron shows thus in its chemical relations remark- 

 able analogies with carbon. — Comjrtes Rendus, vol. cxiv. p. 607. 



