Static electricity, on account of its high tension, passes through water and other liquids as soon as it is formed, whatever the length of its course may be. Voltaic electricity, on the contrary, is weakened by the distance it has to traverse. Pure water is a very bad conductor; but ice absolutely stops a current of Voltaic electricity altogether, whatever be the power of the battery, although static or common electricity has sufficient power to overcome its resistance. Dr. Faraday has discovered that this property is not peculiar to ice; that, with a few exceptions, bodies which do not conduct electricity when solid acquire that property, and are immediately decomposed, when they become fluid, and, in general, that decomposition takes place as soon as the solution acquires the capacity of conduction, which has led him to suspect that the power of conduction may be only a consequence of decomposition. Heat increases the conducting power of some substances for Voltaic electricity, and of the gases for both kinds. Dr. Faraday has given a new proof of the connexion between heat and electricity, by showing that, in general, when a solid, which is not a metal, becomes fluid, it almost entirely loses its power of conducting heat, while it acquires a capacity for conducting electricity in a high degree. M. Becquerel regards the production of heat and that of electricity to be concomitant; their dependence being such, that when one is increased the other diminishes, and _vice versâ_, so that one may altogether disappear with the increase of the other. For instance, when electricity circulates in a metallic wire, the greater the heat produced, the less the quantity of electricity which passes, and the contrary, so that the affair proceeds as if electricity were converted into heat, and heat into electricity. Again, in a closed galvanic circuit the sum of the heat produced in the chemical action of the acidulated water upon the zinc and in the conducting wire is constant, so that the quantity of heat disengaged in the reaction is greater in proportion as less electricity passes through the wire. These, and other circumstances, prove such an intimate connexion between the production of heat and electricity, that in the change of condition of substances the electrical effects might disappear or be annulled by the calorific effects.