At first Faraday attributed the repulsion of diamagnetic substances to a polarity, separate and distinct from ordinary magnetic polarity, for which he proposed the name, diamagnetic polarity. He believed that when a diamagnetic substance is brought near to the north pole of a magnet, a north pole was developed in its approached end, and that therefore repulsion occurred. He afterwards rejected this view, though it has been subsequently adopted by Weber and Tyndall, the latter of whom conducted an extended series of experiments on the subject. The majority of physicists, however, at the present time, do not believe in the existence of a diamagnetic polarity. They point out that the apparent repulsion of diamagnetic substances is due to the fact that they are less paramagnetic than the oxygen of the air in which they are suspended. During this investigation Faraday observed some phenomena that led him to a belief in the existence of another form of force, distinct from either paramagnetic or diamagnetic force, which he called the magne-crystallic force. He had been experimenting with some slender needles of bismuth, suspending them horizontally between the poles of an electro-magnet. Taking a few of these cylinders at random from a greater number, he was much perplexed to find that they did not all come to rest equatorially, as well-behaved bars of diamagnetic bismuth should do, though, if subjected to the action of a single magnetic pole, they did show this diamagnetic character by their marked repulsion. After much experimentation, he ascribed this phenomenon to the crystalline condition of the cylinder. By experimenting with carefully selected groups of crystals of bismuth, he believed he could trace the cause of the phenomenon to the action of a force which he called the magne-crystallic force. Extended experiments carried on by Plücker on the influence of magnetism on crystalline substances led him to believe that a close relation exists between the ultimate forms of the particles of matter and their magnetic behavior. This subject is as yet far from being fully understood. There was another series of investigations made by Faraday between the years 1831 and 1840, that has been wonderfully utilized, and may properly be ranked among his great discoveries. We allude to his researches on the laws which govern the chemical decomposition of compound substances by electricity. The fact that the electric current possesses the power of decomposing compound substances was known as early as 1800, when Carlisle and Nicholson separated water into its constituent elements, by the passage of a voltaic current. Davy, too, in 1806, had delivered his celebrated discourse "On Some Chemical Agencies of Electricity," and in 1807, had announced his great discovery of the decomposition of the fixed alkalies.