1887.] Electrochemical Effects on Magnetising Iron. 459 



killed and pithed immediately after taken from tbe net, may pass into 

 rigor in 30 minutes and be again quite limp 6 hours after death. 

 Sometimes, however, the rigor may not set in for 2 hours after the fish 

 are landed, and it may continue for 17 hours, the difference doubtless 

 resulting partly from the difference in the time the fish were in the 

 trawl net, and partly from the energy expended in attempting to ' 

 escape, or in endeavouring to maintain the respiratory movements 

 under somewhat difficult circumstances. It may therefore be affirmed 

 that though the rigor may persist as long or nearly as long in some 

 trawled fish as in fish caught with a line, in most cases the rigor 

 disappears sooner from trawled than from line- caught fish ; in other 

 words, putrefaction sets in sooner as a rule in fish taken by the trawl 

 than in fish taken by the line, granting, of course, that the line fish 

 are pithed and gutted as soon as they leave the water. 



I have, in conclusion, to express my gratitude to Professor Burdon 

 Sanderson and Mr. Gotch for valuable assistance rendered with the 

 experiments made in the Oxford Physiological Laboratory. I am also 

 indebted to Professor Tait for kindly allowing Mr. Lindsay, of the 

 ^Natural Philosophy Laboratory in the University of Edinburgh, to 

 assist with the electrical experiments. I am further indebted to 

 Mr. Clarkson, B.Sc, of the Natural History Department, Edinburgh, 

 and Mr. W. L. Calderwood and Mr. Jamieson, Members of the Staff 

 of the Fishery Board for Scotland. 



XXVI. " Electrochemical Effects on Magnetising Iron." By 

 Thomas Andkews, F.R.S.E., F.C.S. Communicated by Pro- 

 fessor Gr. G. Stokes, P.R.S. Received June 2, 1887. 



Having for many years past been engaged in researches relating 

 to the various aspects of the corrosion and oxidation of metals, 

 nearly two years ago it occurred to me to investigate the probable 

 effect of magnetisation on the relative electrochemical position of a 

 pair of bright iron bars, one magnetised by a coil, the other un- 

 magnetised, when thus simultaneously exposed in circuit, in a suit- 

 able apparatus, to the action of various powerful oxidising agents 

 and saline solutions. I accordingly specially prepared numerous 

 long polished rods of soft wrought scrap iron 0*261 inch diameter, 

 for use in the investigation. I was not able to commence the pre- 

 liminary observations until towards the end of 1885, and, after much 

 consideration and various trials then made, decided to adopt the 

 following method of experimentation as perhaps calculated to yield 

 the most delicate and accurate results ; pressure of other work has, 

 however, delayed the earlier completion of the work. The general 



