Natural-Philosophical Collections. 231 



Separation of Lead and Manganese from the Substances in wMeh they occur. 

 At a late meeting of the Academy of Sciences, M. Becquerel read a notice on 

 the means of separating lead and manganese from the compounds in which they 

 occur. M. Becquerel employs electricity as a very delicate re-agent, not only for 

 discovering the presence of manganese and lead in solutions, but also for extract- 

 ing them with ease, in such a manner as to leave no trace of them, and without 

 the apprehension of their bringing over other metals with them. A solution of 

 acetate of iron and manganese is poured into a capsule, and there are immersed 

 in it two platina plates in communication each with one of the poles of a voltaic 

 pile. Decomposition of the water and disengagement of gas immediately take 

 place. The oxygen, by going over to the positive pole, superoxidizes the man. 

 ganese, which then abandons the acetic acid, and is deposited upon the positive 

 plate of platina. A thousandth part of a grain of acetate of manganese is render- 

 ed sensible by this procedure. Nitrate and sulphate of manganese and iron lead 

 to the same result, because the peroxide of manganese is insoluble in acetic, ni- 

 tric, and sulphuric acids, while the peroxide of iron easily dissolves in them. 

 Whatever metals may be combined with the manganese, they are easily separated 

 from it. The author mentioned, among others, manganese and zinc, the separa- 

 tion of which is difficult by the ordinary chemical means. 



The separation of lead from other metals requires a modification of the above 

 method ; because the oxide of lead being easily reduced, the metal immediately 

 goes over to the negative plate of platina, as well as the other bases which occur 

 in the solution. With the low tension piles the same inconvenience is not experi- 

 enced, because the oxide of lead is not transported to the negative pole. This ob- 

 servation has induced M. Becquerel to adopt an apparatus which allows the lead 

 to be super-oxidized, without there remaining in the solution any trace that can 

 be rendered sensible by the most delicate re-agents. 



Non-interference of different Electric Currents Professor Marianini has 



been led to examine what might take place when electric currents are so directed 

 as to cross each other, with a view of ascertaining whether there might be any in- 

 terference ; but he finds none, and in this respect, draws a strong analogy between 

 electricity and light ; the rays of the latter, as is well known, crossing each other 

 in almost all directions, as if quite indifferent. 



At first, by attaching two zinc and two copper plates to the sides of a cube of 

 wood, and connecting them into cross pairs by wires, and plunging them into a 

 vessel of acid, it was found that whether one or both pairs were connected, not 

 the slightest difference resulted in the strength of the current in the wires when 

 examined by a magnetic needle : here, therefore, was no interference. 



Whether the currents were equal, or unequal ; of one, or of many hundred 

 pairs of plates ; put in action together, or successively ; when three currents were 

 used in place of two ; when they were made to intersect each other at acute an- 

 gles, or to pass parallel to each other ; even when they were made to pass through 

 the same metallic communication — still no interference or alteration was observed. 



M. Marianini considers these effects as favourable to the Franklinian theory of 

 electricity. In a note, he also quotes other effects, which he thinks far more ea- 

 sily explained by the theory of one electric fluid. In an electro-motive pair, if 

 the negative plate be more deeply immersed in the fluid, the effect is greater than 

 if the positive plate be immersed. If a plate of tin, or some other metal, 18 or 

 20 square centimetres in surface, be formed, at one side, with a narrow projecting 

 band, and then placed so that the plate is in one vessel of water (a), and the band in 

 another (6) — if then, a plate of zinc be placed in the vessel (6), and a plate of 

 copper in (a), neither of them touching the metal — if then a galvanometer be con- 

 nected with the zinc and copper plates, a feeble deviation will be obtained ; but 

 if the zinc and copper plates be reversed, a much stronger effect will be procured. 



" It is in vain that I endeavour to explain this fact by the theory of two elec- 

 tric fluids, since, if on the one hand, when the plate of zinc is in (6), the passage 

 is rendered difficult for the vitreous fluid, and facilitated for the resinous fluid ; 



