280 On the Electric Shock and Spark from a permanent Magnet. 



call Jabon, is steatite intermixed with black particles. The 

 steatite contains no silver, but the black matter is rich in man- 

 ganese and iron, and contains by Mr. Johnson's assay 185 

 ounces of fine silver in the ton. 



The processes of reduction in the large way in Mexico 

 gave a larger proportion of silver than that indicated by the 

 samples tried here. 



I am. Gentlemen, yours, &c. 



Chatham Place, March 18, 1837. John Taylor. 



LVIII. On the Electric Spark arid Shock from a permanent 

 Magnet, By the Rev. Wm. Ritchie, LL.D.^ F.R.S., Pro- 

 fessor of Natural Philosophy in the Royal Institution and 

 in University College^ London,^ 



1 N mechanical science it is well known and universally admit- 

 -*- ted, that \)[\q, prime mover can never produce a greater power 

 than that which it possesses; and that action and reaction are 

 perfectly equal and opposite in their effects ; but these great 

 principles are too often lost sight of when we enter on the inves- 

 tigation of the actions of those agents we term imponderable. 

 In the case of a wire conducting voltaic electricity. Dr. Fara- 

 day has shown that it communicates by induction a similar 

 electric state and loses a part of its own power. If measure- 

 ments could be accurately employed there could be no doubt 

 that the quantity gained by the one would be exactly equal 

 to the quantity lost by the other. In the case of a per- 

 manent magnet, or one of hardened steel, there seems still a 

 good deal of obscurity in its mode of action, as if its magnetism 

 arranged by induction were held fast by that property of the 

 steel called by French writers la force coercitive. That this is 

 not the case, and that the electricity in a permanent magnet 

 moves within the limited spaces of the crystalline particles 

 with great facility, may be shown by many examples. If a 

 circle or ring be formed of steel, welded at the junction and 

 rendered very hard, so as to be easily broken with a blow 

 from a hammer, and if it be magnetized by passing one of the 

 poles of a magnet, a north pole for example, round it continu- 

 ally in the same direction as indicated by the arrow, the electri- 

 city will be arranged in a peculiar manner, constituting mag- 

 netism ^without development of poles. If a covered wire be rolled 

 round it, as in the annexed figure, and the ends covered with 

 the cups of a galvanometer, or so connected that the circuit 

 may be broken at the moment the magnet is broken across 



* Communicated by the Author. 



