[ 567 ] 
XV. On the Clark Cell as a Standard of Electromotive Force. 
By R. T. Glazebrook, M.A., F.R.S., Fellow of Trinity College ; and S. Skinner, M.A., 
Christ's College, Demonstrator in the Cavendish Laboratory, Cambridge. 
Received February 17,—Read March 17, 1892. 
[Plate 16.] 
Summary of Contents. 
Part I.—The Absolute Electromotive Force of a Clark Cell. 
page 
§ 1.—Introduction. Enquiry and Report of the Committee of the Board of Trade . . 568 
§ 2.—General Theory of the Method.570 
§ 3.—The Standard Cell.570 
§ 4.—The Voltameters.570 
§ 5.--The Standard of Resistance.571 
§ 6.—The Balance and Weights.572 
§ 7.—The Chronometer.573 
§ 8.—The Resistance Boxes and Potentiometer.573 
§ 9.—Practical details of the Method.574 
§ 10.—Method of making an Experiment.576 
§ 11.-—Details of individual Experiments with Table of Results.577 
§ 12.—Discussion of Results.582 
Part II. —Comparison of Various Forms of Cells and of the Materials used. 
§ 13.—Introduction. General Remarks. The Method of Testing.583 
§ 14.—Tests on Various Cells used as Standards. Cells set up by Lord Rayleigh. 
Dr. Schuster, Mr. Elder, and Mr. Callendar, Nos. 1, 2, 90, 97; 3 a-10 . . 586 
§ 15.—Tests on Old Cells in the Laboratory, Nos. 11-24. 592 
§ 16.—Treatment of the Mercurous Sulphate.593 
§ 17.—Cells of Rayleigh Pattern set up by Mr. L. R. Wilbekforce, March, 1891, 
Nos. 25-35 . 593 
§ 18.—Cells set up by S. S., March, 1890, Nos. 48-53, 56-60 . 597 
§ 19.—Cells of modified form set up by L. R. W. and S. S., March and April, 1891, 
Nos. 36-41, 61-64 .o99 
§ 20.— Cells set up by S. S. in accordance with the first form of the Board of Trade 
Memorandum, May, 1891, Nos. 65-70 . 601 
§ 21.—Cells set up by S. S. in accordance with Second Form of Board of Trade Specifica¬ 
tion, Nos. 71-79, 86, 87 . 603 
7 12.92 
