Convert magnetism into electricity. Do pith balls diverge by disturbance of electricities in consequence of induction or not? General effects of compression, either in condensing gases, or producing solutions, or even giving combinations at low temperatures. Light through gold leaf on to zine or most oxidable metals, these being poles--or on magnetic bars. Transparency of metals. Sun’s light through gold leaf. Two gold leaves made poles--light passed through one to the other. Whenever any query found an answer, he drew his pen through it and added the date. In front of the book--probably at some later time--he wrote these words:-- I already owe much to these notes, and think such a collection worth the making by every scientific man. I am sure none would think the trouble lost after a year’s experience. A striking example had already occurred of similar suggestive notes in the optical queries of Sir Isaac Newton. In another manuscript notebook occur the following entries under date of September 10, 1821:-- 2 similar poles though they repell at most distances attract at very small distances and adhere. Query why.... Could not magnetise a plate of steel so as to resemble flat spiral. Either the magnetism would be very weak and irregular or there would be none at all. These are interesting as showing how Faraday was educating himself by continual experiment. The explanation of each of these paradoxes has long passed into the commonplace of physics; but they would still puzzle many who have learned their science bookishly at second-hand. It will be noted that amongst the entries cited above there are two of absolutely capital importance, one foreshadowing the great discovery of magneto-electric induction, the other indicating how the existence of electro-optical relations was shaping itself as a possibility in Faraday’s mind. An entry in his laboratory book of September 10 is of great interest:-- Polarised a ray of lamp-light by reflection, and endeavoured to ascertain whether any depolarising action [is] exerted on it by water placed between the poles of a voltaic battery in a glass cistern; one Wollaston’s trough used; the fluids decomposed were pure water, weak solution of sulphate of soda, and strong sulphuric acid: none of them had any effect on the polarised light, either when out of or in the voltaic circuit, so that no particular arrangement of particles could be ascertained in this way. [Sidenote: AN UNSUCCESSFUL EXPERIMENT.] It may be added that no such optical effect of electrolytic conduction as that here looked for has yet been discovered. The experiment, unsuccessful at that day, remains still an unsuccessful one. A singular interest attaches to it, however, and it was repeated several times by Faraday in subsequent years, in hope of some results.