24 



Messrs. Stroud and Henderson on the 



-J molecular equivalent per litre. The arms rr of the bridge 

 were each 1000 ohms, 30 volts were used, and the balancing 

 resistance R was of the order of 20,000 ohms. Between each 

 two measurements of resistance the electrodes were washed, 

 heated to redness, replaced, and the current reversed. The 

 method of making an experiment was as follows : — The current 

 was made for about half a minute to polarize the plates, and 

 then broken ; two minutes were allowed to elapse to enable 

 the electrolyte to assume the temperature of the bath, which 

 was constantly stirred, and then the balance was obtained by 

 momentarily making the current and adjusting the resistance. 

 Solution I. — The solution was made from KC1 twice re- 

 crystallized from water and dried in the air between filter- 

 paper. With Kohlrausch's notation we found 



- =1005-5 xlO" 8 . 



We give no details of the experiment with this solution 

 because the atomic weights used in making up the solution 

 were only approximate, viz. : — K = 39 and Cl = 35*5. Cor- 

 recting for this error the result would come about 0*1 per 

 cent, higher. The salt, too, was dried in air, and it is pro- 

 bable that all the moisture was not removed, and any error 

 resulting from this would cause the value obtained to be too 

 low. 



Solution II. (prepared for us with great care by Dr. Ewan). 

 — The salt was prepared by fusing KC10 3 in a platinum crucible 

 until no more gas was evolved. It was then recrystallized 

 from dilute hydrochloric acid and dried by heating over a 

 bunsen. The molecular weights used were K = 39*13 and 

 01 = 35*45. The strength was as before £ molecular equi- 

 valent per litre. 



Table I. 



Direction of 

 current. 



Temp. 



Resistance. 



Resistance reduced 

 to 18° O. 



-f 



18-26 

 1819 

 1817 

 18-11 

 18-08 

 18-06 



21035 21149 





21045 

 21045 

 21065 

 21085 

 21095 



21129 

 21119 

 21113 

 21120 

 21121 



+ 



-4- 







