Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III. TWO-FLUID CELLS. BATTERY FORMATION. Construction of Two-Fluid Cells.—In the two-fluid cell polarization is either wholly prevented, or so reduced that the cell may be used for work requiring greater constancy than can be obtained from a one-fluid cell. The construction requires that the conducting electrode shall be surrounded with a fluid capable of suppressing the hydrogen, while the soluble electrode is surrounded with a fluid capable of chemical combination with the material of which the electrode is composed; and that the means of separation between the fluids shall not be such as to prevent electric or chemical action. For this purpose a porous cup, like that in the Leclanch6 cell, made of unglazed porcelain, is placed inside the larger vessel, and contains one of the electrodes with its fluid, while the other electrode with its fluid is placed in the outer vessel, and electric and chemical action takes place through the pores of this cup, where the fluids come into contact. Various other means of separating the fluids are used, as vessels or partitions of wood, paper, or animal membrane. Gravitation is also employed; a heavy fluid being used in connection with a light fluid, the former settling to the bottom of the vessel, while the latter rises above it. The Daniell Cell.—This is one of the oldest and best two-fluid cells in use. In was invented by Daniell, an English electrician, in 1836, and has undergone various modifications. Fig. 8 represents one of the best known styles. The outer vessel is a glass jar containing water or dilute sulphuric acid, in which is placed a hollow cylinder of zinc, having a slit in one side for the free circulation of the fluid. Inside this cylinder is placed a porous cup containing a solution of copper sulphate in w...