158 REPORT— 1898. 



perfectly constructed, iind therefore of a much more expensive character, 

 to enable the error, if any, in this value to be ascertained with accuracy. 



We, therefore, started on the design of the instrument, of which we 

 now submit the working drawings, and for the future construction of 

 which we would ask for a grant of 300?. including the unexpended grant 

 of 751. voted last year. And we anticipate that this new piece of appa- 

 ratus may prove worthy of constituting a national Ampere Balance, the 

 counterpoise weight for which will be determined purely by calculation 

 based on the dimensions of the instrument, the number of convolutions 

 of wire in the three coils, and the value of the acceleration of gravity at 

 the place where the instrument may be permanently set up. In this par- 

 ticular it will differ entirely from the ' Board of Trade Ampere Standard 

 Verified 1894,' which has had its counterpoise weight adjusted so that the 

 beam is horizontal when a current passes through the instrument, which 

 will deposit exactly 1-118 milligramme of silver per second under specified 

 conditions. In fact, the proposed Ampere Balance and the existing 

 Ampere Standard will differ exactly in the same way as do a Lorenz 

 apparatus and the 'Board of Trade Ohm Standard Verified, 1894.' 



We have to express our thanks to Mr. Mather for taking charge of 

 the construction and use of the preliminary apparatus, for checking all 

 the calculations in connection with the determination of the electroche- 

 mical equivalent of silver that was made with it, as well as for superinten- 

 ding the making of the working drawings of the new Ampere Balance. 

 We have also to thank Messrs. W. H. Derriman and W. N. Wilson, two 

 of the students of the City and Guilds Central Technical College, for their 

 cordial assistance in carrying out the work. 



Mectrolysis and Medro-chemistry. — Interim Report of the Committee, 

 consisting of Mr. "W. N. Shaw (Chairman), Mr. E. H. Griffiths, 

 Eev. T. "O. FiTZPATRiCK, Mr. W. C. D. Whetham (Secretary), on the 

 present state of our Imowledge in Electrolysis and Electro-chemistry. 



The grant of 35?. made last year has been expended in improving the 

 apparatus for experiments on the electrical properties of solutions. 

 Measurements have been obtained by Mr. Whetham of the electrical 

 conductivity at 0° C. of dilute solutions of potassium chloride, barium 

 chloride, potassium ferricyanide, potassium bichromate, and sulphuric 

 acid. The freezing points of identical solutions have been observed by 

 Mr. E. H. Griffiths. The measurements are sufficient to indicate that 

 important and unexpected results will be obtained. The reduction of the 

 observations is not yet completed, and, in consequence, the account of the 

 experiments is not ready for publication. 



The apparatus is now in working order, and it is hoped that measure- 

 ments may be obtained for other salts. Unfortunately the room in Mr. 

 Griffiths's laboratory where the experiments have been carried out is no 

 longer available, and some considerable expense must be incurred in 

 reconstituting the arrangement in a different situation. To meet this 

 and the additional expenses incidental to the continuance of the observa- 

 tions it is estimated that at least 25/. will be required. 



The Committee accordingly ask for reappointment, with the addition 

 of the name of Mr. S. Skinner, one of the Demonstrators at the Cavendish 

 Laboratory, and with a grant of 251. 



