1869.] Physics. 319 



with mining may be dispensed with when gun-cotton fired by the 

 new system is employed. 



Electricity. — M. Becquerel, in his sixth memoir ' On Electro- 

 Capillary Actions/ describes the processes which he employed to 

 obtain a great number of hydrated oxides in the crystalline state. 

 In a vessel containing a solution of nitrate of copper, a smaller 

 vessel, one side of which was composed of parchment paper, was 

 placed, containing aluminate of potash. Nitrate of potash was 

 produced, but in the place of aluminate of copper in the porous 

 vessel, crystals of hydrated alumina presented themselves ; and on 

 the outside, crystals of hydrated oxide of copper formed. By re- 

 placing the aluminate of potash by silicates, M. Becquerel obtained 

 hydrated sihca sufficiently hard to scratch glass. 



A new arrangement for furnishing currents of electricity has 

 been made known by M. Ney. It is composed as follows : — (1) a 

 vessel filled with solution of chloride of ammonium, containing a 

 plate of amalgamated zinc ; (2) a porous cylmder filled with car- 

 bonate of copper, into which a plate of copper plunges. To main- 

 tain the battery in action, it is only necessary to add solid chloride of 

 ammonium irom time to time. In mihtary telegi'aphy, where the 

 pile should be capable of transport, the outer vessel might be filled 

 with sand saturated with a solution of cliloride of ammonium in the 

 place of the solution. This arrangement recommends itself on the 

 score of cheapness, for native carbonate of copper answers suffi- 

 ciently well, and it likewise only requires attention while in actual 

 use. Carbonate of copper is insoluble in a solution of chloride of 

 ammonium, but upon closing the current, the chloride is decom- 

 posed into hydrochloric acid and ammonia ; the hydrochloric acid 

 collects at the zinc jDole, the ammonia at the copper. The carbonate 

 of copper becomes soluble, and its reduction gives rise to a secondary 

 current having the power of a DanielFs element. This form of 

 battery is perfectly constant. 



Mr. Gore has recorded some experiments on the electrolysis of 

 hydrofluoric acid, both anhydrous and hydrated. They are in- 

 teresting as showing the extreme energy and refractory character of 

 that almost unknown element fluorine. With the anhydrous acid 

 he has used anodes of gas carbon, carbon of lignum-vitae, and of 

 many other kinds of wood, of palladium, platinum, and gold. The 

 gas-carbon disintegrated rapidly ; aU kmds of charcoal flew to 

 pieces quickly, and the anodes of palladium, platinum, and gold 

 were corroded without evolution of gas. The acid with a platinum 

 anode conducted electricity much more readily than pure water ; 

 but with one of gold it scarcely conducted at all. These electro- 

 lytic ex]X'riments presented extreme difficulties, and were conducted 



