WORK OF VEAZEY. 



EXPERIMENTAL. 



APPARATUS. 

 CONDUCTIVITY. 



The conductivity measurements were made by the Kohlrausch method, 

 using a Wheatstone bridge, induction coil, and telephone receiver. 



The bridge-wire, which was of "magnanin," was carefully calibrated by 

 the method of Strouhal and Barus, 1 and was found to have practically uniform 

 resistance throughout its entire length. 



All readings were taken within 100 mm. of either side of the center of the 

 wire. 



The resistance coils were made by Leeds & Co. and were accurate to within 

 0.04 per cent. 



The conductivity cells were those used by Jones and Bingham 2 and by 

 Jones and McMaster. 3 These cells were found to be very satisfactory. The 

 cell constants in no case varied more than one unit in twelve months' con- 

 tinual use. 



The zero-bath was prepared in the following manner: A porcelain en- 

 ameled bucket, of about 1^ gallons capacity, was filled with finely crushed ice 

 moistened with pure water. This vessel was placed in a fibroid bucket of 

 3 gallons capacity, the intervening space between the two being filled with 

 ice and water as above described. 



The bath thus prepared was found, when tested with a standard ther- 

 mometer, to vary from the desired temperature not more than 0.05, and to 

 remain practically constant for at least 5 hours. 



The 25 bath consisted of a round galvanized-iron vessel, of about 20 liters 

 capacity, filled with water. The bath was stirred by means of a small pro- 

 peller, driven by a Heinrich hot-air motor. 



The thermometers used were graduated to 0.2, and were carefully stand- 

 ardized by comparison with a thermometer which was tested at the "Reichs- 

 anstalt." 



All burettes and flasks used in the preparation of solutions were carefully 

 calibrated at 20. 



Wied. Ann., 10, 326 (1880). a Ibid., 36, 331 (1906). 



'Amer. Chem. Journ., 34, 493 (1905). 



170 



