The first named, Father Beccaria, was a celebrated Italian physicist who did most valuable work in connection with atmospheric electricity, and who published several classical works on that and allied subjects. Among these may be mentioned his _Lettre del Elettricità_, 1758, and _Experimenta_, 1772. He ascertained that water is not by any means a good conductor, as it had previously been supposed to be, and, by using pure water, he caused the electric spark to become visible in it, a phenomenon capable of occurring only through media almost nonconducting. In these experiments he used thick glass tubes with wires led through the opposite ends, the latter being sealed, and the tubes filled with water. These were invariably shattered by the passage of the spark on account of the accompanying elevation of temperature, which caused expansion. He also established the facts that the atmosphere adjacent to an electrified body acquires electrification of the same sign by abstracting electricity from the body, and that the air then parts with its electricity very slowly. He advanced the theory that there is a mutual repulsion between the particles of the electric fluid and those of air, and that a temporary vacuum is formed at the moment of the passage of a disruptive discharge or spark. Robert Symmer, in 1759, described some most entertaining experiments, making use of the opposite electrifications of superposed stockings of different materials or merely of different colors (the dye matters in the latter case causing differentiation). If, in a dry atmosphere, a silk stocking be drawn over the leg and a woolen one pulled over it, the two will be found, upon being removed, to be very powerfully electrified in opposite senses. If the four stockings of two such pairs be used and then suspended together, they will indulge in remarkable antics due to each of the silk stockings trying to attract both of the woolen ones, and _vice versa_, and, on the other hand, each of each kind repelling the other. The amount of electrical attraction and repulsion produced in this simple way in a dry atmosphere is remarkable. The experiment may also be performed with all silk stockings, one pair white and the other black.