1888.] Electro-chemical Effects on Magnetising Iron. 161 



Ferric Chloride and Chlorine Water, Col. 4, Divisions I and II. — 

 This solution consisted of 250 fluid grains of a concentrated solution 

 of Fe 2 Cl 3 and 750 fluid grains of saturated chlorine water. In these 

 experiments the electro-negative position assumed by the magnetised 

 bar formed an exception to the general rule, which, I think, may 

 probably to some extent be explained on the supposition of the dia- 

 magnetic properties of the dissolved chlorine; the magnetised bar 

 being somewhat less attacked by the free chlorine than the unmag- 

 netised rod. When the chlorine had exhausted its action on the 

 metal, the electro-chemical reaction became gradually reversed, and 

 the magnetised bar then assumed the electro-positive position (see 

 Col. 4, Division II), as in the case of normal ferric chloride solution 

 only. To show that the above negative effect was due only to mag- 

 netic influence, various experiments with Fe 3 Cl 3 and chlorine water 

 were made, in which it was found that on ceasing to magnetise the 

 bar A for a few moments, the E.M.F. decreased, and the magnetised 

 bar A assumed a less negative position, but on again connecting the 

 battery to the coil, the magnetised bar therein assumed a more 

 electro-negative position. 



Nitric Acid, sp. gr. 1*42, and Potassium Chlorate, Cols. 5, 7, 8, and 

 9. — These experiments made with apparatus, fig. 4, with solutions 

 containing varied proportions of HN0 3 and K 2 C10 3 , are confirmatory 

 of the results obtained in Part I, and also indicate that these magneto- 

 chemical effects are greater in stronger solutions. On ceasing to 

 magnetise the bar A, in course of any of these experiments, the 

 needle of the galvanometer fell to zero, and on remagnetising the bar 

 A its electro-positive position was re-asserted. 



Ferrous Sulphate, Col. 10, Divisions I, II, III, and IV, a saturated 

 solution of the salt. 



Division I — This set of experiments was conducted on the large 

 polished wrought-iron bars, j-inch diameter, with apparatus fig. 3, 

 the magnetisation of bar A being continuous to the end of each 

 observation. 



Division II. — These experiments were made with small iron bars in 

 apparatus, fig. 4, the solution containing the unmagnetised bar being 

 maintained at a temperature of about 5° to 10° F. above the tempera- 

 ture of the solution in which the magnetised bar was immersed. 



Division III. — In these observations large steel bars f-inch diameter 

 were employed in the arrangement of apparatus delineated in fig. 3. 

 The bar A in the coil was magnetised for a few minutes only at the 

 commencement, and, as the metal was steel, it retained a permanent 

 residual magnetism, which was allowed to complete tbe result. The 

 magneto-chemical effect was not so great in these instances, owing to 

 the magnetism of the bar being less than when the action of the 

 powerful coil w T as prolonged thereon, as in the other experiments 



