Manchester Memoirs, Vol. li. (1907), No. 15. 19 



causes fatigue, which leaves the edge of the razor after 

 stropping in a comparatively soft and non-elastic con- 

 dition. In the language of the theory I am putting 

 forward to-day, it leaves the edge of the razor composed 

 very largely of dissenting communities. These dissenting 

 communities tend to resolve themselves with mere lapse 

 of time into conformity. I do not know why it should 

 be so. Possibly the disturbance caused by heat, even at 

 the ordinary temperature of the air, produces enough 

 movement of the molecules to tend at least to break 

 up those feebly stable groups and restore them to the 

 original tactical formation. Anyhow the fact remains 

 that fatigue is recovered from slowly in this way, and 

 you can enormously accelerate the recovery by dipping 

 the razor into hot water. Thus the theory explains a 

 piece of domestic practice which for a long time was so 

 unintelligible that I for one was not inclined to believe 

 that the hot water had any value at all. Experiments 

 made on bars of steel in the testing machine in my 

 laboratory by Mr. James Muir demonstrate this recovery 

 very clearly* It occurs slowly at ordinary temperatures, 

 but a quick restoration can be effected by the application 

 of sufficient warmth. 



Just one other point before I close. A good many 

 years ago I showed that the facts of magnetic quality 

 could be explained by supposing that iron and other 

 magnetic metals had molecules which were capable of 

 being rotated, these molecules being possessed of per- 

 manent magnetic polarity, and being free of all constraint 

 except that which is due to their natural magnetic forces. 

 The process of magnetisation consists in turning these 

 molecules round so that they tend to face more or less 

 one way, and the iron becomes saturated when they all 



*Muir, Phil. Trans., ser. A, vol. 193, p. r, 1899. 



