1822.] Decomposition of Metallic Salts hy the Magnet, 41 



The next experiment, related by Mr. Murray, which I shall 

 notice is the following : *^ A portion of platinum wire that 

 suffered no change in nitrate of silver in solution, was made the 

 uniting wire between the poles of a powerful horse-shoe magnet 

 (that supported 12 lbs. weight). When this was immersed into 

 nitrate of silver, it soon became discoloured and acted upon." 



I immersed a platina wire in a solution of nitrate of silver, 

 the opposite the ends of the wire being connected with the two 

 poles of a pretty strong horse-shoe magnet. After remaining 

 about 30 hours in the solution, the surface of the platina wire 

 was not in the sHghtest degree tarnished. The solution was a 

 portion of the same as that employed in the other experiments. 

 I conclude, therefore, that magnetism has no power whatever in 

 influencing the action of platina on nitrate of silver. 



The last statement of Mr. Murray's which I shall allude 

 to is, that ^' two magnetic bars were left for two days ia 

 phosphorous acid. The acid was decomposed; the north pole 

 of one of the bars was scarcely affected, but the north pole of 

 the other was corroded half an inch deep, and developed the 

 fasciculated structure described by Mr. Daniel." 



1 arranged some magnetic and unmagnetic bars in phosphoric 

 acid in the same mode as described with respect to nitrate of 

 silver. The north pole of one and the south of the other were 

 immersed in separate glasses, and at first were not connected, 

 but were afterwards by a smaller magnet, south and north poles 

 being respectively in contact with north and south poles of the 

 immersed magnets. The action of the phosphoric acid upon the 

 magnets was not in the slightest degree increased by the 

 contact. 



The circumstances which I have now detailed, I think, justify 

 me in concluding, that Mr. Murray's experiments are fallacious, 

 and his inferences unwarranted by facts. 



I am, Sir, your obedient servant, B. M. 



Article X. 



On the Properties of Peroxide of Hydrogen or Oxygenated Water, 

 By M. Thenard. (Extracted from the last Edition of his 

 Traite de Chimie.) 



Water is combined with a large quantity of oxygen, by dis- 

 solving peroxide of barium in muriatic acid, and adding sulphuric 

 acid to the solution. These tv/o operations are to be several 

 times repeated with the same liquor ; then adding sulphate of 

 silver, and at last barytes, and separating the precipitates suc^ 

 cessively by the filter. Muriatic acid readily dissolves the peiv 



