40 Journal of the Asiatic Society of Bengal. [February, 1910. 



Object of Present Experiments. 



The main object of this paper is to show that the matter is 

 not by any means so complicated as it at first appears, and that 

 it is possible to prescribe simple conditions under which a single 

 experiment lasting for a quarter of an hour will give a value of 

 the e.c.e., not differing from the mean of a large number of 

 similar experiments by more than four parts in a thousand, the 

 mean also agreeing very closely with the value of the e.c.e., 

 which is usually adopted. It also appears probable that if 

 special attention be paid to the chemical purity of the materials 

 used, it will be possible to give a value of the atomic weight 

 of nickel with considerably greater accuracy than one which 

 can be expected from the purely chemical processes of investi- 

 gation which have hitherto been used. 1 



The work recorded below may be conveniently divided into 



two parts. Part I is an investigation into the nature and 



causes of the variations in the experimental value of the 



e.c.e. of nickel. Part II gives a gradual development of 



the method of successfully arresting these variations and of 



securing a steady value for the e.c.e. of nickel, agreeing 



within a very close limit with the value deduced from 

 Faraday's law. 



Part I. 

 Preliminary Experiments. 

 The voltameter used in these experiments consisted of a 



with a pair of nickel 



means 



Kelvin 



Ampere balance, previously standardized with a silver 



was used with 



eas 



current. The current values 

 a thousand. Both the cathode and anode were polished rect- 

 angular plates of nickel (10 c. m. x 4 c. m.), the area immersed 

 being about 35 sq. c. m. Borda's method of double weighing 

 was used in weighing these plates. 2 The temperature of the 

 room was about 25°C on the average. 



The double sulphate of nickel and ammonium was the first 

 salt tried. Observations were made with different strengths of 

 aqueous solutions and for various values of current between 

 •2 to 1-2 amperes. The deposit was generally good, but a rapid 



I Russell in Journ. Chera. Soc, 2. i., 1863, p. 58:— 58. 59m. Rus- 

 sell in ibid 2. vii.. 1869, p. 292:— 5856. Schneider in Pogg. Ann., ci.. 

 1857, p. 387:— 57-90. Dumas in Ann. Chim. Phys., ser. 3. lv., 1859- 

 p. 129:— 5887. Winkler in Zeit. Ann. Chem., vi., 1867, p. 22 :-- -58*83. 

 Winkler in Zeit. Anorg. Chem., iv., 1893, p. 462, also viii., 1894. p. 281 : 

 5860 or 58 -42. Richards and Chusman in Zeit. Anorg. Chem., x 



\ TJ 16 »a«bility of the balance was 11 divisions per milligram) 

 tor a load of 70 emus, on the scale pans. 



