Michael Faraday, his Life and Works. 419 



by the globules of water or other substances carried up by va- 

 pour — experiments undertaken iu Consequence of the invention 

 of Armstrong's machine. Lastly, there are others which only 

 contain the more or less indirect Consequences of the funda- 

 mental discoveries, which will be explained in one of the three 

 subdivisions under which we have grouped them. We shall not 

 Swell upon any of these, thinking that we may give a more 

 exact and complete idea of all the progress which Faraday caused 

 the science of electricity and magnetism to make by confining 

 ourselves to pointing out in some detail the most prominent parts 

 of his researches upon these subjects. 



Faraday commenced with chemistry in his scientific career ; 

 it is therefore not surprising that he approached electricity by 

 the study of electrochemistry. It was, moreover, towards elec- 

 trochemistry that his attention must have been first directed in 

 that laboratory of the Royal Institution which had witnessed 

 the magnificent discoveries of Davy in chemical decompositions 

 effected by the pile, and especially in the production of the alka- 

 line metals. In taking up this subject, Faraday only followed 

 the traditions left to him by his predecessor. 



His researches upon the electrical conductibility of bodies con- 

 stitute a first step in this path. The business was to ascertain 

 whether, as was previously supposed, the presence of water is ne- 

 cessary to render solid bodies conductors, and whether solid non- 

 metallic (and consequently compound) bodies can conduct elec- 

 tricity without being decomposed. Commencing with water, 

 which is an insulator when solid and a good conductor in the 

 liquid state, Faraday shows that a great number of compound 

 substances are in the same case. Such are many oxides, some 

 chlorides and iodides, and a multitude of salts, which do not 

 conduct electricity in the solid state, but, without any intermix- 

 ture of water, become excellent conductors when liquefied by heat, 

 and are not decomposed by electricity with separation of their 

 elements in the same way as aqueous solutions. To the list of 

 these compounds Faraday adds that of those substances, either 

 simple, like sulphur and phosphorus, or compound, such as the 

 periodides and perchlorides of tin, and many others, which con- 

 tinue isolators when fused as well as in the solid state. In this 

 first investigation, notwithstanding a great number of experi- 

 ments in which he employed the influence of heat and of elec- 

 tricity of high tension in the study of the conductive power of 

 solid bodies, he did not succeed in determining very accurately 

 the conditions of electrical conductibility ; he only ascertained 

 that, with one exception, which he justly regards as only apparent, 

 there is not a solid body which, on becoming conductive by its 

 passage to a liquid state, is not decomposed by the electrical cur- 



