A laboratory manual of electrotherapeutics / by William James Herdman and Frank W. Nagler.

  • Herdman, William James.
Date:
[1898], ©1898
Catalogue details

Licence: Public Domain Mark

Credit: A laboratory manual of electrotherapeutics / by William James Herdman and Frank W. Nagler. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    or SO part of the acid, is displaced in the other direction. All metals and hydrogen are electro positive, and travel in an electrolyte with the positive current. Zinc sulphate is formed at the expense of zinc and sulphuric acid, and hydrogen is set free at the copper plate. The simple chemical action taking place is the displacement of the hydrogen of the acid by zinc, forming zinc sulphate instead of hydrogen sulphate. The electro-motive force (E.M.F.) of this cell is about i volt and this is reduced to ]/i volt upon polarization. The Daniell Cell.—This cell most commonly con- sists of a glass vessel containing a clear solution of cop- per sulphate, in which is placed a cylinder of sheet copper which serves as the negative plate. Within the copper cylinder is placed a porous cup of unglazed earthen ware, which contains the zinc rod immersed in dilute sul- phuric acid or preferably a dilute solution (5%) of zinc sulphate. The Gravity Cell.—Is a modified form of the Daniell, in which the two liquids are separ- ated only by their difference in density. If we represent the arrange- ment of metal plates as follows: illy,,. A ibiiiHii i Fig. 5. Gravity Cell. Znx | H2 So4 I H2 S04 || Cu So4 | Cu S04 | Cuy then after the first interchange it becomes Znx_j | Zn S04 | H2 S04 || H2 S04 | Cu S04 | Cuy+I