26 Mr. Levy on some newly-discovered 



cult of metal ; tlie former was completely exploded, but the 

 latter substance was scattered only. When the water tube 

 formed a part of the circuit, every other part arranged as be- 

 fore, the gunpowder ignited, but the gold leaf was undisturbed 

 by the discharge of the jars. 



Similar experiments were made with gunpowder and needles, 

 gunpowder and aether, gunpowder and tow, prepared as above. 

 When the circuit was completely metallic, the needles were 

 magnetized, or the aether, the tow, &c. were fired: but the 

 gunpowder was in no instance ignited. When the water tube 

 formed a part of the circuit, the gunpowder was, in every case, 

 ignited ; but the other substances remained unaffected. 



Hence we may conclude, that in order to magnetize pieces 

 of steel, to explode metals, to ignite aether, or tow, with resin, 

 &c. by electricity ; quantity and velocity, or momenttim of the 

 fluid is required. But to ignite gunpowder, quantity and time 

 are indispensable. That is, when the quantity is constant : to 

 produce the former effects requires velocity, to produce the 

 latter effect, time. I remain Sir, 



Your obedient servant, 

 Artillery Place, Woolwich, W. STURGEON. 



Nov. 24th, 1826. 



VIII. On some neisoly discovered Siberian Minerals. By 

 A. Levy, Esq., M.A. F.G.S. 



IVTR. MENGE has lately discovered in Siberia several rare 

 -'-"-*- species of minerals, which hitherto had not been found 

 in that country, ah'eady so rich in that department of natural 

 history. Among the newly discovered species are mentioned 

 Tantalite, Gadolinite, and Zircon. However, from the charac- 

 ters of the specimens of these, which Mr. Heuland has just 

 received and added to his private collection, it appears that 

 the uncommonly well defined and detached crystals, which 

 had been thought to belong to the first, present a form quite 

 incompatible with those of that species, but agree perfectly 

 with the description given by Professor Mohs of the substance 

 he has called Axotomous iron ore, which is isomorphous with 

 specular iron *. The form of the crystals from Siberia, in 

 Mr. Heuland's collection, offer only two varieties; one of them 

 is represented by fig. 1, and the other differs only from it by 

 the absence of the faces marked e^ 



* I believe that the suggestion of Professor Mohs, that Crichtonite and 

 Axotomous iron ore belong to the same species, will prove to be the truth ; 

 and I hope soon to be able to give the results of the comparative exami- 

 nation I have made of the two minerals. 



This 



