In 1823 Faraday published his work on the liquefaction of gases, from which he concluded that there was no difference in kind between gases and vapours. In the course of this work he met with more than one serious explosion. On January 8, 1824, he was elected a Fellow of the Royal Society, and in 1825, on the recommendation of Sir Humphry Davy, he was appointed Director of the Laboratory of the Royal Institution, and in this capacity he instituted the laboratory conferences, which developed into the Friday evening lectures. For five years after this, the greater part of Faraday's spare time was occupied in some investigations in connection with optical glass, made at the request of the Royal Society, and at the expense of the Government. Mr. Dollond and Sir John Herschel were associated with him on this committee, but the results obtained were not of much value to opticians. The silico-borate of lead which Faraday prepared in the course of these experiments was, however, the substance with which he first demonstrated the effect of a magnetic field on the plane of polarization of light, and with which he discovered diamagnetic action. Faraday's experimental researches were generally guided by theoretical considerations. Frequently these theories were based on very slender premises, and sometimes were little else than flights of a scientific imagination, but they served to guide him into fruitful fields of discovery, and he seldom placed much confidence in his conclusions till he had succeeded in verifying them experimentally. For many years he had held the opinion that electric currents should exhibit phenomena analogous to those of electro-static induction. Again and again he returned to the investigation, and attempted to obtain an induced current in one wire through the passage of a powerful current through a neighbouring conductor; but he looked for a permanent induced current to be maintained during the whole time that the primary current was flowing. At length, employing two wires wound together as a helix on a wooden rod, the first capable of transmitting a powerful current from a battery, while the second was connected with a galvanometer, he observed that, when the current started in the primary, there was a movement of the galvanometer, and when it ceased there was a movement in the opposite direction, though the galvanometer remained at zero while the current continued steady. Hence it was apparent that it is by changes in the primary current that induced currents may be generated, and not by their steady continuance; and it was demonstrated that, when a current is started in a conductor, a temporary current is induced in a neighbouring conductor in the opposite direction, while a current is induced in the same direction as the primary when the latter ceases to flow. Before obtaining this result with the wires on a wooden bobbin, he had experimented with a wrought-iron ring about six inches in diameter,