INDUSTRIAL MODEL OF THE REYNIER ZINC ACCUMULATOR. The three models of a secondary battery that I recently made known to the readers of this journal have been the object of continuous experiment. Conformably to the provisions of theory, the zinc accumulator has shown itself practically superior to the two others, and I have therefore chosen this type for getting up an industrial model, which is shown in the annexed cut. The accumulator contains four Planté positives, having a wide surface, and three negatives constructed of smooth sheets of lead covered with zinc by the electrolysis of the acidulated solution of zinc sulphate in which the couple is immersed. Accidental contact with the interior of the pile is prevented by glass tubes fixed to the negatives by means of leaden bands. The seven electrodes are carried by as many distinct crosspieces of paraffined wood, which rest upon the edges of the trough and hold the plates at a certain distance from the bottom. These various crosspieces, which touch one another, take the place of a cover. Each plate is provided with a terminal. The four positive terminals are all on the same side, and the three negatives are on the opposite side. Two brass rods ending in a wire-clamp connect the respective terminals of the same name. The trough consists of two oblong wooden receptacles, one within the other, and having a play of several millimeters. This space is lined with a tight, elastic, insulating cement having tar for a base. [Illustration: REYNIER'S ZINC ACCUMULATOR. (One-fifth actual size.)] The careful insulation of the trough and all parts of the apparatus, and the purity of the metal and its amalgamation, reduce the local attack of the zinc to almost nothing. So the coefficient of restitution is now comparable with that of accumulators of the Planté type. The following are the principal numerical data of the new zinc accumulator. PHYSICAL DATA. E. Electromotive force. 2.36 volts. R. Mean resistance. 0.02 ohm. I. Normal intensity of the discharge current. 25 amperes. i. Intensity of the charge current. 5 to 10 amperes. Q. Capacity of accumulation after 200 hours' formation. 550,000 couples. DATA CONCERNING CONSTRUCTION. Efficient surface of the 4 positive electrodes. 200 square dec. Efficient surface of the 3 negative electrodes. 15 square dec. Weight of the positive electrodes. 8.2 kilogrammes. Weight of the negative electrodes. 1.4 kilogrammes. Weight of the trough. 2.7 kilogrammes. Weight of the liquid. 4.4 kilogrammes. Weight of the attachments. 0.46 kilogrammes. Weight, total. 17.16 kilogrammes.