In 1848 Faraday gave five Friday night discourses, three of them on the “Diamagnetic Condition of Flame and Gases.” In 1849 he gave two, one of them on Plücker’s researches. In 1850 he gave two, one of them being on the electricity of the air, the other on certain conditions of freezing water. He had meanwhile continued to work at magnetism. The twenty-third series dealt with the supposed diamagnetic polarity. It incidentally discussed the distortion produced in a magnetic field by a mass of copper in motion across it. The twenty-fourth series was on the possible relation of gravity to electricity. The paper concludes with the words: “Here end my trials for the present. The results are negative. They do not shake my strong feeling of the existence of a relation between gravity and electricity, though they give no proof that such a relation exists.” The next series (the twenty-fifth) was on the “Non-expansion of Gases by Magnetic Force” and on the “Magnetic Characters of Oxygen [which he had found to be highly magnetic], Nitrogen, and Space.” He had found that magnetically substances must be classed either along with iron and the materials that point axially, or else with bismuth and those that point equatorially, in the magnetic field. The best vacuum he could procure he regarded as the zero of these tests; but before adopting it as such, he verified by experiment that even in a vacuum a magnetic body still tends from weaker to stronger places in the magnetic field; while diamagnetic bodies tend from stronger to weaker. He then says we must consider the magnetic character and relation of _space_ free from any material substance. “Mere space cannot act as matter acts, even though the utmost latitude be allowed to the hypothesis of an ether.” He then proceeds as follows:-- [Sidenote: MORE NEW WORDS.] Now that the true zero is obtained, and the great variety of material substances satisfactorily divided into two general classes, it appears to me that we want another name for the magnetic class, that we may avoid confusion. The word _magnetic_ ought to be general, and include _all_ the phenomena and effects produced by that power. But then a word for the subdivision opposed to the diamagnetic class is necessary. As the language of this branch of science may soon require general and careful changes, I, assisted by a kind friend, have thought that a word--not selected with particular care--might be provisionally useful; and as the magnetism of iron, nickel, and cobalt when in the magnetic field is like that of the earth as a whole, so that when rendered active they place themselves parallel to its axes or lines of magnetic force, I have supposed that they and their similars (including oxygen now) might be called paramagnetic bodies, giving the following division:--