Faraday had done no special electric work during the first nine months of 1835. He had worked at a chemical investigation of fluorine through the spring, and in July took a hurried tour in Switzerland, and returned to work at fluorine. Not till November 3rd does he turn to the subject over which he had been brooding. On that date, intercalated between notes of his chemical studies, filling a dozen pages of the laboratory book, are a magnificent series of speculations as to the nature of charges, and on the part played by the electric--or, as we should now say, the dielectric--medium. They begin thus:-- “Have been thinking much lately of the relation of common and voltaic electricity, of induction by the former and decomposition by the latter, and am quite convinced that there must be the closest connection. Will be first needful to make out the true character”--note the phrase--“of ordinary electrical phenomena.” The following notes are for experiment and observation. “Does common electricity reside upon the surface of a conductor or upon the surface of the [di-]electric in contact with it?” He goes on to consider the state of a dielectric substance, such as glass, when situated between a positively charged and a negatively charged surface, as in a charged Leyden jar, and argues from analogy thus:-- “Hence the state of the plate [of glass] under induction is the same as the state of a magnet, and if split or broken would present new P[ositive] and N[egative] surfaces before not at all evident.” This speculation was later verified by Matteucci. “Probable that phenomena of induction prove more decidedly than anything else that the electricity is in the [di-]electric not in the conductor.” He still worked for a week or two on fluorine, interposing some experiments on the temperature-limit of magnetisation, but on December 4th decides not to go on with fluorine at present. Then, beginning on December 5th, there follow twenty-nine pages of the laboratory diary, illustrated with sketches. He had borrowed from a Mr. Kipp a large deep copper pan thirty-five inches in diameter, and he set to work electrifying it and exploring the distribution of the charges, inside and out, and the inductive effect on objects placed within. Everywhere he is mentally comparing the distribution of the effects with that of the flow of currents in an electrolyte. Before many days he writes:-- [Sidenote: PREGNANT SUGGESTIONS.] “It appears to me at present that _ordinary_ and _electrolytic_ induction are identical in their first nature, but that the latter is followed by an effect which cannot but from the nature and state of the substances take place with the former.” Then comes this pregnant suggestion:-- “Try induction through a solid crystalline body as to the consequent action on polarized light.”