280 EIGHTH REPORT — 1838. 



other bodies, not only metals, but even wax or baked earth. 

 3rd. Diffuse daylight, or the weakened rays of a winter sun, 

 neither retard nor assist oxidation, provided they are accom- 

 panied by no change of temperature. 



II. In experiments made with magnetized wires, the results 

 were the same ; no difference of oxidation occurred at the poles 

 or other parts. 



III. In experiments on the reduction of metals by the humid 

 process, as in the Arbor Dianae, no influence of terrestrial mag- 

 netism could be observed. The crystallization took place in 

 both branches of the syphon tube, and without reference to 

 their direction. 



IV. In repeating the experiments with the additional power 

 of a very large magnet, its poles proved not to have the slightest 

 power over the formation or disposition of the crystal within. 



V. Numerous salts were made to crystallize slowly in vessels 

 placed over the poles of magnets, with every care that their 

 power as conductors of heat should not interfere. The mag- 

 netism exerted not the slightest influence over the crystal- 

 lization. In chemical actions, where gas was evolved, no 

 difference in the rapidity of evolution, or quantity of gas pro- 

 duced, occurred, when magnets were present or absent. 



VI. No evidence of the influence of the magnetic poles over 

 the colours of vegetable solutions could be obtained. — {Bib. 

 Univ., xlii. p. 96.) 



67. These apparently satisfactory experiments of Professor 

 Erdmann are, however, again laid open to discussion by some 

 curious results stated by M. Levol {Annal. de Chim. vol. Ixv. 

 p. 285), in a paper " On the phenomena which accompany the 

 precipitation of a metal in the metallic state by another, in 

 presence of a third metal, exercising no chemical action ; and 

 on the circumstances which may modify the results." In this 

 the following statement occurs : — 



" I found a circumstance which appeared to me very curious. 

 It is, that the position of the iron, during the precipitation (all 

 other things being equal), is by no means indifferent as regards 

 the separation of the copper (viz. from its solution). 



" In varying in different ways the experiments which were 

 requisite, I have observed that the results, which were accordant 

 when I plunged the iron horizontally, ceased to be so when 

 (making a double experiment) I placed in one the iron hori- 

 zontally, and vertically, or nearly so, in the other. 



" In the first case I have constantly moi-e copper on the 

 platina {i. e. the passive metal), less iron dissolved, and delay 

 of the complete precipitation. 



