995 



mation of two gravitating bodies towards each other, and their separa- 

 tion, were the onl}^ points which offered this kind of coincidence ; 

 and therefore, using the earth as one gravitating body, he employed 

 a cylinder of metal, glass, resins, or other substances, as the other, and 

 endeavoured to ascertain when the latter was allowed to fall, being 

 surrounded by a helix of wire, whether any electric current was 

 generated. Sometimes the cylinder was allowed to fall through the 

 helix ; at other times with the helix ; and occasionally the helix was 

 made the falling body. But when the various sources of error which 

 sprung up were gradually removed, no traces of electric action re- 

 mained which coidd be referred to the power of gravity. 



In order to obtain a greater effect, an aparatus was employed (being 

 nearly that used in the 23rd Series of these Researches) by which 

 the effect of raising a body from the earth could be combined with 

 that of a falling body by the fit use of commutators (if any action at 

 all were produced). The apparatus was very good, and gave ex- 

 ceedingly delicate results, as was shown by other consequences of 

 its action ; but in respect of gravity it produced no effect whatever. 

 Notwithstanding his failure in obtaining any experimental relation 

 between gravity and magnetic or electric force, the author still ex- 

 presses his conviction that there is a relation, and his hopes that it 

 may be hereafter practically demonstrated. 



2. " Experimental Researches in Electricity." Twenty-fifth Series. 

 On the Magnetic and Diamagnetic Condition of Bodies. By Michael 

 Faraday, Esq., D.C.L., F.R.S. <^^c. Received September 9, 1850. 



As the author could find no polarity in diamagnetic bodies when 

 under magnetic influence (a result described in the 23rd Series of 

 these Researches), he endeavoured to discover some other physical 

 condition of them, and of magnetic bodies, by which he might obtain 

 an insight into their respective natures, and establish the true place of 

 the magnetic zero ; and considering the power with which a magnetic 

 body moves, or tends to move, from weaker to stronger places of action, 

 and that of a diamagnetic body to pass from stronger to weaker places 

 of action, he hoped to obtain some results of condensation with the 

 first class, and of expansion with the second, when they were subjected 

 to very strong magnetic action ; the respective bodies being selected 

 from the class of gaseous substances, in which change of volume 

 can be easily produced and measured. In the first place, therefore, 

 a ray of light vras passed over the surface of powerful magnetic poles 

 surrounded by different gases, and the place of its source carefully 

 examined by telescopes, micrometers, and other means, to ascertain 

 * whether the layer of air in contact with the poles was affected in its 

 refracting force ; but though the experiment was made in oxygen, 

 nitrogen, and other gases, not the slightest effect was visible. 



Resigning this process, therefore, two air-tight chambers were 

 made, in which the magnetic poles formed the chief part of the 

 internal surface of the chamber. The one was formed by bringing 

 the flat ends of the two poles to within -g-Vth of an inch of each 

 other, with a frame all round to form the sides ; and the other by 



