English Mechanic and World of Science Volume 39 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1884 edition. Excerpt: ...batteries, which contains a quantity of pure copper in the metallic state; but from nearly 70,000 cells the sum realised last year by the sale of the " black mud" was 167 14s., or a fraction more than a halfpenny per cell As Mr. Preece pointedout, however, the Daniella re resent only a third of the battery ' power employed by the Post Ofiice, and the waste really does not pay for collecting, as the actual supply of current required for telegraphic work is so small compared to that needed for lighting. Several of the more promising new batteries were shown at the meeting, and were described in the inventors' words by Mr. Probert. Thus the Holmes and Burke battery, which we believe is employed by some of the railway companies, is noticeable for the facility with which it can be charged and discharged, the cells being connected by siphons; for the means adopted to seize the fumes and utilise them; and for its cheapness, the cost of the solution being about Gd. a gallon, which is said to furnish T50 to S00 ampere hours, at an E.M.F. of 1'9 volt. The solution is prepared by dissolving nitrate of soda in sulphuric acid, and nitric acid is produced as required by the decomposition of the solu, tion. R0ss's battery has carbon plates dip.ping into dilute hydrochloric acid and " Eureka," the zinc being in common salt. The cell of Oliphant, Burr, and Gowan is a two-fluid bichromate, having zinos coated with a thin film of gold before amalgamation. The chairman, Mr. Preece, stated that no fewer than 150 patents for primary batteries had been taken out within the last three years, and specially mentioned that of Mr. Skrivanofi' (see p. 82, Vol. XXXVI.) as remarkable for compactness and power. Mr. Holmes...