468 Electrochemical Effects on Magnetising Iron. [June 16, 



chemical effect appeared to be less marked when using aqua regia 

 containing excess of HCl. The relative electrochemical position of 

 the two bars in such case being less divergent, the HCl appearing 

 to act somewhat as a strong diluent. 



Hydrochloric Acid and Sulphuric Acid, Columns 9 andlO. — Singular 

 to say, the previously described magnetochemical effects were com- 

 paratively small when using such a powerful reagent as hydrochloric 

 acid alone, either concentrated (sp. gr. 1*16) or diluted. When this 

 acid was employed in conjunction with concentrated solution of 

 potassium chlorate (Table A, column 3), the effects there recorded 

 appeared due rather to the oxidising agency of the evolved chloric 

 compounds ; in the presence of magnetism, the reactions with this 

 electrolyte were occasionally irregular, the excess of HCl appearing 

 sometimes to interfere. Sulphuric acid, cone, also seemed to behave 

 abnormally, though this acid does not ordinarily act strongly on iron. 

 The experiments with both the above acids in course of a large 

 number of observations, proved exceptions to the general rule. The 

 magnetised bar in the sulphuric acid, cone, and also in the hydro- 

 chloric acid, diluted, became the electronegative metal, not only in 

 the case of H 2 S0 4 , when using the apparatus fig. 1, but also when 

 experimenting with the modified form, fig. 2. Occasionally, with 

 sulphuric acid, cone, the magnetised bar was, on first magnetising it, 

 slightly electropositive for a few minutes only; but afterwards 

 became steadily negative. 



Under the conditions of experimentation, the magnetised bars in 

 the powerful oxidising reagents used almost inva.riably assumed the 

 electropositive position, the presence of H.N0 3 appearing essential 

 to the full development of the positive position of the bar under the 

 influence of magnetism. On the contrary, the magnetised bar 

 seemed to be the electronegative metal in H 2 S0 4 , cone, and also in 

 the HCl (diluted), as electrolytes. The two latter reagents by their 

 action on the metal generate gases of a reducing character. These 

 exceptions are not, however, averse to the principle that magnetisa- 

 tion exerts an influence on the relative electrochemical position of a 

 pair of iron bars, varying according to the nature of the solution and 

 the extent to which one of them is magnetised. In the above excep- 

 tions, it is possible that the magnetised bar assumed the negative 

 position consequent on its being the one more attacked, under 

 magnetic influences, by the reagent; thus producing a greater evolu- 

 tion of reducing gases in the tube A containing the magnetised bar 

 than in the other tube ; this may perhaps explain the negative effect. 

 The observations of this memoir therefore indicate that, under the 

 powerful and rapidly oxidising conditions described, a magnetised 

 bar becomes metal positive to an unmagnetised one, whereas in the 

 exceptional instances above alluded to, the electronegative effect 



