Prof. Page on Electro-Magnetism as a Moving Power. 161 



Pholerite. By Dr. J. Lawrence Smith. 



[Silliman's American Journal, Januarj' 1851.] 

 This mineral, which resembles 2>holerite in composition, has 

 been found with the emery of Naxos associated with emerylite. 

 It is white, lamellar, and somewhat crystalline, sometimes gray. 

 It is soft to the touch like steatite, infusible before the blowpipe, 

 and when heated with nitrate of cobalt becomes strongly coloured 

 blue. It is scratched with the nail, and has a specific gravity of 

 2*j64'. Its composition is identical with the pholerite of Guil- 

 lemiu, also with the mineral forming the gangue of the diaspore 

 of Schemnitz. It Mas decomposed with carbonate of soda. It 

 afforded — 



This corresponds to the following formula, Al-O^ SiO'^ + 2H0 ; 

 but it is a question whether or not wc should consider the water 

 as existing in any definite proportion, and whether or not they 

 did not all contain more water when first taken from their loca- 

 lities. These hydrated silicates of alumina are numerous, and 

 bear various names, but it is doubtful if many of them are en- 

 titled to much consideration as distinct species. 



XXI. On Electro-Magnetism as a Moving Power. 

 By Prof. Chas. G. Page*. 



Note. — [As no description has yet been published by Prof. Page 

 of his new electro-motive engine, we gladly avail ourselves of the 

 following brief explanation which Prof. Silliman has given of its 

 fundamental principle. — Eds. Phil. Mag.^ 



IT is well known that when a helix of suitable power is con- 

 nected with the poles of a battery in action, that an iron bar 

 within it will remain held up by the induced magnetism although 

 the helix be put in a vertical position : and if the bar be partly 

 drawn out of the helix by the hand, it goes back with a spring- 

 when the hand lets go its hold. This power — the action of the 

 liclix u])on the metallic bar within it, — is the ])ower used in his 

 engine. The ])ower, when a single coil is used, has its points of 

 greatest and weakest force, and in this condition is objectionable. 

 Ijut })y making the coil to consist of a series of short independent 

 helices, which are to l)e brought hi action successively, the me- 

 tallic rod is made to pass through the coil and back again with 

 * From Silliman's American Journal for November, 1850. 

 Phil. Mag. S. 4. Vol. 1 . No. 2. Feb. 1851. M 



