Lessons in elementary physics / by Balfour Stewart.

  • Balfour Stewart
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: Lessons in elementary physics / by Balfour Stewart. Source: Wellcome Collection.

    427/502 page 407
    purpose, either directly or in the state of bichromate of potash or of soda. A solution of one of these substances is usually mixed with sulphuric acid to form the battery solution. When used without a porous pot, and with plates of carbon and zinc, a strong' electric current can be ob- tained, which however is wanting in constancy. Fig. 127^ shows the form often used for the purpose of exciting medical coils. It is known as the Poggendorff bottle form. It has two plates of carbon metallically connected to a binding screw let into the ebonite top cover. Sliding between the two Fio. ii-jc. carbons is a plate of zinc connected to a second binding screw. When the cell is not in use, the zinc sliould bo pulled up out of the liquid. 392. The Leclanchg Battery.—As in the three hast men- tioned batteries zinc and gas carbon form the positive and negative plates. The exciting liquid is ,a solution of ammoitiuin chloride (commonly called s.il ammoniac). This attacks the zinc, forming zinc chloride with the evolution of ammonia and hydrogen. To oxidise the latter maitifanese dioxide is used. The ordinary form of the cell is shown in
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