46. THOMSON’S EXPERIMENT. VELOCITY OF STRIAE CHECKED AT THE CATHODE. _Nature_, Lon. Jan. 31, ’96, p. 330.—A tube 50 ft. long was exhausted, § 8_a_., as to striking distance. In this particular experiment, he caused a single interruption in the primary of the induction coil, and observed the motion of the striae from the anode to the cathode by means of a rotating mirror. § 43. The luminosity began at the anode and travelled toward the negative with a high velocity, but upon its arrival at the negative pole its velocity was checked. He said that the striae did not disappear at the cathode like a rabbit would in entering a hole, but they lingered around the electrode for some time. As a consequence of this delay, he found as expected, an accumulation of positive electricity, § 4, in the neighborhood of the cathode. It is a general principle, therefore, that when a discharge passes between a gas and metal, there is an accumulation, illustrating that the discharge experiences a difficulty or resistance. § 32 and 33. The experimenter, Prof. J. J. Thomson, acknowledged that Profs. Liveing and Davy had noticed similar effects. 47. THOMSON’S EXPERIMENT. DISRUPTIVE DISCHARGE AND ELECTROLYSIS. _Nature_, Lon. Jan. 31, ’95. _Lect. S. Inst. The Electr._, Lon. vol. 31, p. 291, 316, and vol. 35, p. 578. _Trans. R. So._, ’95.—The discharge of electricity through conducting liquids is, with scarcely an exception, (example, mercury) accompanied by a chemical action. Faraday and Davy both performed early experiments in this direction. Prof. J. J. Thomson has set forth some instructive facts and which act as evidence that there is a close relation between the disruptive discharge and chemical action between the dielectric and electrodes. § 6 and 7. He made this experiment in connection with his investigations relating to the difficulty the positive electricity experiences in passing from a gas to the negative electrode. § 46. He carried this experiment further, by testing gases of different chemical natures. The apparatus he employed consisted first of an alternating current generator, a high tension converter, a bulb for containing first one gas and then another, whose metal electrodes were connected with the secondary of the transformer, and an electrometer connected to a third electrode which could be moved about within the bulb. The operation was as follows: when the bulb contained oxygen which is an electro-negative gas, the third movable electrode received a positive charge in whatever part of the bulb it was moved to, but with hydrogen instead of oxygen at atmospheric pressure, the third electrode received a positive charge far away from the arc between the other electrodes, but very near the arc it received a negative charge. He then rarefied the atmosphere of hydrogen and he noticed that the space where the third electrode became negative, contracted, and at about 1/3 of an atmosphere became practically