Modern practice of the electric telegraph. A handbook for electricians and operators (1872)
Pope, Frank L. (Franklin Leonard), 1840-1895 · New York : D. Van Nostrand · leaf 27
of the projecting arm,as these are frequently eaten off while the rest of thezinc remains in good condition. * This solution is made as follows : Mix one gallon of sulphuric acid and threegallons of water. Then, in a separate vessel, dissolve five Ibs. bi-chromate of pot-ash in two gallons of… … . 29. INSULATION OF BATTERIES.—The cells of a bat-tery should always be thoroughly insulated from eachother. This is especially important in the case of theGrove battery. A convenient andeffective mode of insulation is shownin fig. 7, in which the battery tum-blers, AA, are set upon hollow…
Telegraph
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