1887.] 



Electrochemical Effects on Magnetising Iron. 



467 



The records in the above table under divisions I were experiments 

 made with apparatus, fig. 1, the records entered under divisions II, 

 relate to observations made with apparatus, fig'. 2. 



The records of the effects in the stronger solutions do not indicate 

 the full extent of the electric action compared with that of the weaker 

 solutions ; because in the former case the tubes could only be par- 

 tially filled, so as to prevent boiling over. 



General Remarks. 



Potassium Chlorate and Nitric Acid Solutions, Columns 1 and 2. — 

 At the termination of some of these experiments, the depth of colour 

 of the solution surrounding the magnetised iron was perceptibly of a 

 darker shade than the colour in the tube surrounding the un- 

 magnetised bar, this was confirmed by Eggertz's carbon coloration 

 test, 



Ferric Chloride and Nitric Acid, Column 5. — At forty minutes from 

 the commencement of one experiment in apparatus fig. 1, the record 

 was an E.M.F. of 0*023 volt, the magnetised bar being positive; the 

 battery was then attached to a smaller coil surrounding the other 

 bar B, which was then magnetised instead of the bar A, and in 

 course of five minutes a reduction in the positive position of bar A 

 to an extent of 0'021 volt occurred. At forty-five minutes the 

 battery was reconnected to the coil surrounding the bar A, producing 

 a steady increase of positive position in that bar as recorded in 

 Table A, column 5. 



Aqua Begia, undiluted. — With this reagent in fig. 1 no very 

 decided galvanic reaction took place until the bar had remained 

 magnetised for some ten minutes, when violent effervescence occurred 

 accompanied by evolution of dense reddish-brown fumes, the magne- 

 tised bar then becoming rapidly electropositive to an extent yielding 

 an E.M.F. of about 0*110 volt. This position was subsequently more 

 or less maintained for some ten minutes, the galvanometer, however, 

 gradually falling to zero as the ebullition in both tubes subsided. 

 This was a difficult experiment to make, owing to the very violent 

 effervescence. 



Aqua Begia, diluted, Column 8. — Up to the commencement of the 

 effervescence no perceptible difference in the colour of the solution 

 in the respective limbs of the U-tube was noticed ; but immediately 

 on the violent ebullition occurring, which took place generally about 

 ten minutes from commencement, the solution surrounding the mage- 

 tised bar frequently became of a very much darker tint. This 

 marked difference between the colour of the respective solutions in 

 the two tubes was maintained for some time, afterwards the two 

 solutions became apparently nearly chromatically equal. The electro- 



