scholarly journals The Electromotive Force of Standard Cells

Nature ◽  
1911 ◽  
Vol 85 (2155) ◽  
pp. 508-508
Author(s):  
R. T. GLAZEBROOK
Keyword(s):  
Electromotive Force ◽  
Standard Cells

THE MAINTENANCE OF A STANDARD OF ELECTROMOTIVE FORCE: NOTES ON STANDARD WESTON CELLS

1930 ◽  
Vol 3 (5) ◽  
pp. 473-489
Author(s):  
A. Norman Shaw ◽  
H. E. Reilley
Keyword(s):  
Electromotive Force ◽  
Essential Feature ◽  
Mean Deviation ◽  
Entire Group ◽  
Standard Cells ◽  
Characteristics Analysis ◽  
A Cell ◽  
The Mean ◽  
The Difference

A detailed procedure for the maintenance of a standard of voltage to within one or two parts in a million is described.In so far as these investigations have proceeded, neutral saturated cells have been found to be superior to acid cells as independent standards for a period of many years, though the latter are preferable for purposes of ordinary precision or shorter periods. The recommended code of procedure is briefly as follows: a number of cells should be constructed according to standard specifications with the new requirements of uniformity of container and speed of preparation, and observations made upon them every few days for a period of three months. The differences in electromotive force (at constant temperature) should be determined between each cell in the group and any one of them chosen arbitrarily as reference cell, and certain new selection and rejection rules applied. In accordance with these rules a cell should be rejected: (a) if its deviation from the mean electromotive force of the group has increased or decreased by 10 microvolts or more during the preceding two weeks; or (b) if it differs in electromotive force from the mean of the group by more than 10 +d microvolts where d is the mean deviation of the cells of the group. If d exceeds 20 microvolts the entire group should be considered untrustworthy. The selected cells should be observed for three additional months, the rejection rules again applied and if a specified proportion survive elimination, the initial reference mean of the laboratory may be established.At intervals of several months additional groups of cells, neutral and acid, should be constructed and exchanges made with laboratories possessing cells of known characteristics. Analysis of the resulting observations determines: (a) the constants in the aging* equation for the reference batch, and (b) the difference between the initial reference mean of the laboratory and the estimated value of the international reference mean.Examples of the analysis of cell observations are given, illustrating the establishment of the initial reference mean, the recapture of this value when the aging coefficients are known, and the preliminary determination of the aging equation for a given group of cells. The use of the aging equation is found to be the essential feature in the attainment of increased precision.A summary of data on standard cells is included.

On the variation of the electromotive force of different forms of the Clark standard cell with temperature and with strength of solution

1898 ◽  
Vol 62 (379-387) ◽  
pp. 117-152 ◽  
Keyword(s):  
Electromotive Force ◽  
Accurate Determination ◽  
Scientific Paper ◽  
Standard Cells ◽  
Temperature Coefficients ◽  
Primary Object ◽  
Mcgill University ◽  
Series Of Experiments ◽  
The Subject

The primary object of the present series of experiments was that of equipping the McDonald Physics Building of McGill University with a reliable and accurate set of standard cells, and not that of forming the subject of a communication to any scientific paper. In the course of the work, however, several points have come under our notice, which we venture to think may be of interest to others engaged in any investigation requiring the employment or construction of such standards. Among other points, we have devoted special attention to the accurate determination of the temperature-coefficients of various forms of Clark cell; to the construction of cells free from “diffusion-lag” consequent upon change of temperature; and to the investigation of the limits of accuracy attainable with Clark cells under both constant and varying temperature conditions.

scholarly journals The ageing of standard cells; increased accuracy in their use; and international comparisons

1930 ◽  
Vol 229 (670-680) ◽  
pp. 125-162 ◽  
Keyword(s):  
Electromotive Force ◽  
International Comparisons ◽  
Absolute Measurement ◽  
Considerable Importance ◽  
Standard Cell ◽  
Descriptive Data ◽  
Present Contribution ◽  
Independent Investigation ◽  
Standard Cells ◽  
The Absolute

The results of this investigation have arisen as a further outcome of the long series of McGill researches on standard cells, originally started by H. L. CALLENDAR, F.R.S., in 1896, and continued for several years by H. T. BARNES, F.R.S.; they may be regarded as a new by-product of the investigation on the absolute measurement of the electromotive force of the normal Weston Standard Cell, conducted by A. N . Shaw from 1909- 1911, and described in the ‘ Philosophical Transactions ’ in 1913 (loc, cit,) . It is, however, considered that the present contribution brings forward entirely new points of considerable importance, and it is in no sense whatever a recapitulation or further treatment of results discussed in earlier articles. Apart from the descriptive data about apparatus and old cells, contained in former papers,* the results recorded now, and the treatment developed, constitute an independent investigation.

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