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OAO 0B0 OcO See also:ODO pep OFO
a b
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a WI
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and when made as directed below it has at t° C. an electromotive force E, volts, such that
E =1.0184 -0.0000406 (t -20) -0.00000095 0—20)2 +
0.00000001 (t-20)3.
After the See also:platinum wires have been sealed through the See also:glass, a
little aqua regia is placed in the See also:cell legs until bubbles pi See also:gas arise
from the platinum, when it is thrown out and replaced by a See also:solution of mercurous nitrate. Then, by the use of another piece of platinum as anode, See also:mercury is electrolytically deposited upon the platinum, which may also be amalgamated by making it See also:- WHITE
- WHITE, ANDREW DICKSON (1832– )
- WHITE, GILBERT (1720–1793)
- WHITE, HENRY KIRKE (1785-1806)
- WHITE, HUGH LAWSON (1773-1840)
- WHITE, JOSEPH BLANCO (1775-1841)
- WHITE, RICHARD GRANT (1822-1885)
- WHITE, ROBERT (1645-1704)
- WHITE, SIR GEORGE STUART (1835– )
- WHITE, SIR THOMAS (1492-1567)
- WHITE, SIR WILLIAM ARTHUR (1824--1891)
- WHITE, SIR WILLIAM HENRY (1845– )
- WHITE, THOMAS (1628-1698)
- WHITE, THOMAS (c. 1550-1624)
white hot in a See also:Bunsen See also:flame and plunging it in mercury. To prepare the See also:cadmium See also:amalgam, one See also:part of pure cadmium is dissolved in six parts of pure mercury, and the product while warm and fluid is placed in one See also:limb of the cell and warmed, to ensure perfect contact with the platinum See also:wire. The cadmium sulphate solution is
prepared by digesting a saturated solution of cadmium sulphate with cadmium hydroxide to remove See also:free See also:acid, care being taken not to raise the temperature above 7o° C., and then by digesting it still further with mercurous sulphate until no more precipitation occurs. The cadmium sulphate solution must be saturated and have free crystals of the See also:salt in it. The mercurous sulphate must be free from acid, and made neutral by trituration with finely divided mercury. In making the See also:paste, so much cadmium sulphate must be added that a saturated solution of that salt is formed and is See also:present in the cell. The cell has the electromotive force above stated if the amalgam of cadmium has from 6 to 13 parts of mercury to 1 of cadmium. The See also:German investigators seem to have a See also:great preference for the H See also:form of cell, but it is clear that a narrow tubular cell of the See also:British See also:board of See also:trade form not only comes more quickly to the temperature of the See also:water See also:bath in which it is placed, but is more certain to be wholly at one temperature. In a modification of the H form devised by F. E. See also:- SMITH
- SMITH, ADAM (1723–1790)
- SMITH, ALEXANDER (183o-1867)
- SMITH, ANDREW JACKSON (1815-1897)
- SMITH, CHARLES EMORY (1842–1908)
- SMITH, CHARLES FERGUSON (1807–1862)
- SMITH, CHARLOTTE (1749-1806)
- SMITH, COLVIN (1795—1875)
- SMITH, EDMUND KIRBY (1824-1893)
- SMITH, G
- SMITH, GEORGE (1789-1846)
- SMITH, GEORGE (184o-1876)
- SMITH, GEORGE ADAM (1856- )
- SMITH, GERRIT (1797–1874)
- SMITH, GOLDWIN (1823-191o)
- SMITH, HENRY BOYNTON (1815-1877)
- SMITH, HENRY JOHN STEPHEN (1826-1883)
- SMITH, HENRY PRESERVED (1847– )
- SMITH, JAMES (1775–1839)
- SMITH, JOHN (1579-1631)
- SMITH, JOHN RAPHAEL (1752–1812)
- SMITH, JOSEPH, JR
- SMITH, MORGAN LEWIS (1822–1874)
- SMITH, RICHARD BAIRD (1818-1861)
- SMITH, ROBERT (1689-1768)
- SMITH, SIR HENRY GEORGE WAKELYN
- SMITH, SIR THOMAS (1513-1577)
- SMITH, SIR WILLIAM (1813-1893)
- SMITH, SIR WILLIAM SIDNEY (1764-1840)
- SMITH, SYDNEY (1771-1845)
- SMITH, THOMAS SOUTHWOOD (1788-1861)
- SMITH, WILLIAM (1769-1839)
- SMITH, WILLIAM (c. 1730-1819)
- SMITH, WILLIAM (fl. 1596)
- SMITH, WILLIAM FARRAR (1824—1903)
- SMITH, WILLIAM HENRY (1808—1872)
- SMITH, WILLIAM HENRY (1825—1891)
- SMITH, WILLIAM ROBERTSON (1846-'894)
Smith, of the See also:National See also:Physical Laboratory (Phil. Trans., A, 207, pp. 393-420), a contraction formed in the See also:side of the See also:vertical See also:tube tends to hold the contents in See also:place. Fig. 4 shows this cell, hermetically sealed, mounted in a See also:brass See also:case.
In cases when great accuracy is not required, a See also:Daniell cell can be used as a See also:standard of electromotive force. The form designed by J. A. See also:Fleming (Phil. Mag., 20, p. 126) consists of a U tube, one See also:leg of which contains a See also:rod of pure amalgamated See also:zinc, and the other a rod of freshly electrotyped See also:copper. The legs are filled with solutions of zinc sulphate and copper sulphate, the zinc rod being in the zinc sulphate and the copper rod in the copper sulphate. When so made, the cell has an electromotive force of 1.072 volts and no sensible temperature variation. The solutions are made by dissolving the purest recrystallized sulphate of copper and sulphate of zinc in distilled water. For the zinc solution, take 55.5 parts by See also:weight of crystals of zinc sulphate (ZnSOa7OH2) and dissolve in 44.5 parts by weight of distilled water; the resulting solution should have a specific gravity of 1.200 at about 2o° C. For the sulphate of copper solution, take 16.5 parts by weight of pure crystals of copper sulphate (CuSO4,5OH2) and dissolve in 83.5 parts by weight of water; the resulting solution should have a specific gravity of 1.100 at 20° C. The solutions should be adjusted exactly to these densities and kept in stock bottles, from which the reservoirs of the cell should be filled up as required.
A form of See also:potentiometer employing a vibration See also:galvanometer and suitable for alternating current measurement by null methods has been devised by Dr Drysdale (see Proc. Phys. See also:Soc. Lond. 1909, 21, 561.)
See J. A. Fleming, Handbook for the See also:Electrical Laboratory and Testing See also:Room, vol. i. (See also:London, 1903)-vol. i contains on pp. 108-110 an extensive See also:list of various See also:original See also:memoirs published on the See also:Clark and See also:Weston cells; G. D. Aspinall See also:Parr, Electrical See also:Engineering Measuring See also:Instruments (London, 1903) ; W. C. See also:Fisher, The Potentiometer and its Adjuncts (London, 1906).
End of Article: OAO 0B0
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