CONDUCTIVITY OF SODIUM HYDKOXIDK IN AQUEOUS SOLUTION. 



2fil 



by placing an indiarubtmr band between the platinum flanges of the lid and the pot ; 

 these flanges were strengthened by means of heavy silver rings and were held 

 together by means of three clamps. The silver cradle used to contain the sodium 

 had the form shown in fig. 2 and occupied the whole of the upper half of the pot. 

 It consisted essentially of a cylindrical box, 2^ inches in diameter and 3^ inches high ; 

 one-third of the cylinder was cut away to allow of filling and emptying (this aperture 

 was covered with silver foil whilst the sodium was weighed) ; the upper surface was 

 pierced by a circular hole for the admission of steam, and the projecting part of the 

 lower surface was provided with a series of small holes for the escape of the caustic 



Fig. 3. 



soda. A stout silver wire held the cradle in position in the pot, and when the 

 conversion was complete the cradle was lifted out, inverted and used for mixing the 

 solution after the soda adhering to the silver wire had been washed down by means 

 of water. 



The arrangement used in effecting the conversion is shown in fig. 3. The pot was 

 heated to about 45 C. and water was distilled into it under reduced pressure from a 

 pear-shaped flask heated to about 60 C. in a second water-bath. A manometer was 

 provided to indicate the pressure, and a mercury trap to prevent water from being 

 sucked back into the pot if the pump should cease to act. The completion of the 

 action was marked by the distillation of water, which was condensed in a vertical 



