32 REPORT — 1901. 



Mr. Matthey, however, is retaining for the present, for the use of the 

 Committee, some more of the wire, and it is, in their opinion, desirable 

 that they should purchase it also. It is essential for the success of the 

 scheme approved by the Committee at their last meeting that they should 

 have a sufficient stock of the wire for a very long period, and they are 

 anxious not to lose the present opportunity of acquiring such a stock. 



Expense will also be incurred in the preparation of the mercury 

 standards. 



The illness and death dux-ing the year of Professor Viriamu Jones 

 have prevented any great progress being made with the ampere balance. 

 Some part of the apparatus, however, has been constructed, and is in 

 Professor Ayrton's hands, and the Committee have good hopes that 

 further progress may be reported shortly. 



The Committee desire to put on record their sense of the loss which 

 Physical Science has suffered by the deaths of Professors J. V. Jones and 

 G. F. FitzGerald, who for many years had been members of the Committee, 

 and had contributed in a marked degree to its work ; and by that of 

 Professor Rowland, whose redetermination of the absolute value of the 

 B.A. unit was practically the starting-point of the work of the present 

 Committee. Professor Rowland had on more than one occasion been a 

 valued visitor at meetings of the Committee. 



A paper by Mr. Skinner on a pyridine voltameter is printed as an 

 appendix. Professor Callendar's paper on the variation of the specific 

 heat of water is closely coiinected with the work of the Committee. 



In conclusion, the Committee recommend that they be reappointed, 

 with a grant of 501. ; that Lord Rayleigh be Chairman, and Mr. R. T. Glaze- 

 brook Secretary. 



APPENDIX. 



I^ote on a Comparison of the Silver deposited in Voltameters containing 

 different Solvents. By S. Skinner, M.A., D>^.monstrator of Experi- 

 mental Physics, Cambridge. 



In 1892 Schuster and Crossley ' showed that when the same current 

 is passed through two silver voltameters containing silver nitrate in 

 aqueous solution, one voltameter in a vacuum and the other in air, about 

 0*1 per cent, more silver was deposited in the vacuum than in air. 

 This result was confirmed by Myers.^ These results clearly prove that 

 there is an uncertainty in the action of the silver voltameter depending 

 on the presence of air or oxygen, and consequently on the freshness of 

 the solution. Werner ^ found that a silver nitrate solution in pyridine 

 gives by the rise in the boiling-point of the solvent a nearly normal mole- 

 cular weight for the salt ; and Kahlenberg"* found that the solution was 

 an electrolyte, and could be used in the silver voltameter ; but that, 

 contrary to what follows, more silver was deposited from aqueous solution 

 than from pyridine solution by the same current. In the following 

 experiments a comparison has been made of the deposits produced by the 



> Prno. R.S., 50, p. 344. = Annalen, 55, p. 288. 



» Zeits. Anorg. Chevi., 1897, 15, p. 23. ■• Jo%irn. Phyaioal Chem., 1900, p. 349. 



