The accompanying cut represents a battery of 6 elements, with a reservoir, R, for the liquid, provided at its lower part with a cock for allowing the liquid to enter the pile. The vessels of the different elements are of rectangular form. At the upper part, and in the wider surfaces of each, there are two tubes. The first tube of the first vessel receives the extremity of a safety-tube, A, whose other extremity enters the upper part of the reservoir, R. This tube is designed for regulating the flow of the liquid into the pile. When the cock, r, is too widely open, the liquid might have a tendency to flow over the edges of the vessel; but this would close the orifice of the tube, A, and, as the air would then no longer enter the reservoir, R, the flow would be stopped automatically. The second tube of the first vessel is connected with a lead tube, 1, one of the extremities of which enters the second vessel. The other tubes are arranged in the same way in the other vessels. The renewal of the liquids is effected by displacement, in flowing upward from one element over into another; and the liquids make their exit from the pile at D, after having served six times. The electrodes of the two first elements are represented as renewed in the cut, in order to show the arrangement of the tubes. [Illustration: ESTEVE'S AUTOMATIC PILE.] _Dimensions._--The zinc, 2, has a superficies of 15x20 centimeters, and is cut out of the ordinary commercial sheet metal. It may be turned upside down when one end has become worn away, thus permitting of its being entirely utilized. The negative electrode is formed of four carbons, which have, each of them, a superficies of 8x21 centimeters. These four carbons are less fragile and are more easily handled than two having the same surface. Their arrangement is shown at the left of the figure. They are fixed to a strip of copper, a, to which is soldered another strip, L, bent at right angles. There are thus two pairs of carbon per element, and these are simply suspended from a piece of wood, as shown in the figure. Upon this wooden holder will be seen the two strips, LL, that are designed to be put in contact with the zinc of the succeeding element by means of pinchers that connect the electrodes with one another. This arrangement permits the pile to be taken apart very quickly. _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.