Magnetism, Cohesion, Adhesion and Viscosity. 451 



I have already spoken of the manner of raising the ma<T- 

 netic uitensity of various substances, by keeping them in close 

 contact with a bar-magnet for a short time. The following 

 metals had then- magnetic intensities slightly raised bv this 

 means: — •' 



Platinum, from 65° to 90°; 

 Antimony, from 66° to 90°; 

 Bismuth, from 45° to 80°. 



It is very remarkable that it is not of the least consequence 

 whether the substance is kept in juxtaposition with the N. or 

 b. end of the magnet, for the result will be just the same in 

 either case, and the N. or S. end of the needle may be made 

 to attach Itself with equal indifference to the part of the sub- 

 stance that has been so excited. Whether this proceeds from 

 a want of polarity in ferruginous magnetism, or from the 

 molecules of the substances having been rendered more 

 obedient to the coercive energy of the needle, it is difficult to 

 say. As the magnetism still remains, after such influence, of 

 the insensible kind, it is clear that they cannot penetrate to 

 any depth and this may be the reason why no polarity can 

 be formally proved. The possible existence of polarity is 

 countenanced by the fact that the magnetism is capable of 

 being heightened, and by the analogy of the connexion that 

 takes place between two similar poles of magnets when 

 brought forcibly into contact, as well as by what takes place 

 with arsenic. The magnetism which is found to exist in all 

 matter, and that to a degree which has never been anticipated, 

 would be of tremendous operation in nature if it were not like 

 or identical with cohesive affinity, and consequently acting 

 only at distances that may be considered as insensible. In 

 this respect it contrasts strongly with the power of gravitation, 

 and with that even of the magnetism of steel. 



The effects that take place by keeping substances in con- 

 tact with a magnet cannot be attributed to induction, as they 

 continue for a longer or shorter space of time after separation. 

 I he measurements of the first class of substances speak so 

 clearly for themselves, that there would be but little occasion 

 for any remarks upon the greatest portion of them, if it were 

 not for the contrast in which some of them stand to the im- 

 portant results obtained by Dr. Faraday, when he operated 

 with a very powerful electro-magnet. From the effects he 

 observed he divides all metals into two classes, namely, ma^. 

 nclic-M\(\ diamagnclic, according as they showed attraction or 

 repulsion; the first of these states being indicated by the 

 cylinder placing itself in the line of the axis of the magnet, and 

 2 II 2 



