_Charging, Work, and Duration of the Pile._--The inventor has made a large number of experiments with solutions of bichromate of potash of various degrees of saturation, and has found the following to give the best results:
Bichromate of potash. 1 kilogramme. Sulphuric acid 2 liters. Water 8 "
When a larger quantity of the salt is used, crystallization occurs in the pile.
Constants and work Constants and work of an element of a round Bunsen having a zinc of element, 20×30 cm. 16×20 cm.
Volts. 1.9 1.8 Resistance. 0.05 0.24 Work disposable in the external circuit. 1.839 k. 0.344 k.
The work disposable in the external circuit is deduced from the formula:
It will be seen that an element thus charged gives as much energy as 5.3 large Bunsen elements.
The battery is charged with 10 liters of solution, and is capable of furnishing for 5 hours a current of 7 amperes with a difference of potential of 9 volts at the pile terminals. The work, according to the formula (EI)/g, equals 6.422 kilogram-meters; with a feebler resistance in the external circuit it is capable of producing a current of 19 amperes for an hour and an half. In this case the resistance of the external circuit equals the interior resistance of the pile. Upon immersing the electrodes in new liquid, and with no resistance in the external circuit, the current may reach 100 amperes. On renewing the liquids during the operation of the pile, a current of 7 amperes is kept up if about a liter of saturation per hour be allowed to pass into the battery. For five hours, then, only 5 liters are used instead of the 10 that are necessary when the liquid is not renewed while the pile is in action.--_La Nature._
The energy produced by the phenomena of diffusion is exhibited in lecture courses by placing a bell glass filled with hydrogen over a porous vessel at whose base is fixed a glass tube that dips into water. The hydrogen, in diffusing, enters the porous vessel, increases the internal pressure, and a number of bubbles escapes from the tube. On withdrawing the bell glass of hydrogen, the latter becomes diffused externally, a lower pressure occurs in the porous vessel, and the level of the water rises.
The arrangement devised by Mr. C.J. Woodward, and recently presented to the Physical Society of London, is an adaptation of this experiment to the production of an oscillating motion by alternations in the internal and external diffusion of the hydrogen.