and the Weston Normal Cell. 255 



used to prepare others having from 14 to l(H per cent, of 

 cadmium, and from the 10 per cent, amalgam the 9 to 1 per 

 cent, amalgams were made. The amalgams were introduced 

 into the limbs of the vessels and melted either in a water 

 bath or over a bunsen flame ; the cells and amalgams were 

 allowed to cool in a normal manner. Afterwards, the other 

 constituents of the cells were introduced and the vessels were 

 hermetically sealed ; they were subsequently immersed in 

 paraffin oil and kept at a constant temperature of 20° C. 

 for 48 hours, after which they were placed in crushed ice 

 for 8 days. 



Ten Weston normal cells of the usual H form were con- 

 tinually maintained at a constant temperature of 20° C. and 

 the E.M.F.'s of the various combinations of the elements in 

 the 4 limb vessels were compared with these 10 cells from 

 time to time. 



When the experimental cells were at 0° C. the E.M.F.'s 

 were compared every day for 8 days; afterwards further 

 observations at 5°, 10°, and 15° (J. Mere made, but the first 

 two of these temperatures were not maintained constant 

 within less than 0°*1 C, and this for 3 hours only. The 

 temperature of 15° C. was maintained constant for 24 hours 

 before the first comparison of E.M.F.'s was made, and the 

 whole lot of cells did not deviate from 15° C. by more than 

 0°*5 during the following 3 months. From time to time 

 the temperature was adjusted to 15° C. and the cells com- 

 pared. After the 3 months had elapsed other comparisons 

 were made at intervals of 5° from 20° to 45°, these higher 

 temperatures being maintained constant for at least 4 hours 

 before making the observations. The oil baths were heated 

 electrically, and a toluene thermostat sensitive to 0°*01 was 

 used. For temperatures above 80° the cells were immersed 

 in crude olive oil. 



Results. 



The results of the E.M.F. comparisons are given in 

 Tables I, and TI. Table I. gives the E.M.F.'s of amalgams 

 containing from 1 to 13*5 per cent, of cadmium. When 

 maintained at a constant temperature the E.M.F/s of these 

 amalgams (with the exception of that containing (J per cent, 

 of cadmium) were found to be constant also within 1 or 2 

 parts in 100,000. It is not necessary, therefore, to give 

 more than one value at any one temperature. 



