300 ; MORRIS LOEB 



sometimes was enabled to use double that number, and in 

 several instances obtained the current directly from the dy- 

 namo, employing as full a current as the apparatus would 

 safely bear. Because the results were always virtually identi- 

 cal, no pains were taken to determine the exact strength of 

 the magnetic field, but 18,000 c. g. s. is a low estimate of the 

 maximum reached. 



The axes of the cores being horizontal, a prismatic battery 

 cell, 2jx6X6 inches, was placed between the poles to serve as 

 a bath of constant temperature. It was therefore protected 

 from direct contact with the poles by thin layers of cotton 

 batting, and was traversed by a rapid current of water from 

 a reservoir whose contents were kept within 0.1 C. of the 

 desired temperature. 



The solutions were contained in a sort of pocket-flask of 

 100 cc. capacity, an inch thick, and having two flat sides of 

 circular outline three inches in diameter. This flask was sus- 

 pended in the bath in such a manner as to be just between 

 the poles of the magnet. The solutions which were not to be 

 subjected to the influence of the magnet were contained in a 

 precisely similar flask, and the water-bath in which this was 

 placed was fed by the overflow from the first mentioned one. 

 Where it was not feasible to observe the two reactions at the 

 same time, especial care was taken to keep the temperature 

 constant. 



The following solutions were employed : a one-third molec- 

 ular solution of potassium chlorate, a one-half molecular 

 solution of sulphuric acid, a one-half molecular solution of 

 ferrous sulphate, a solution of potassium permanganate of 

 which 12.5 cc. corresponded to 1 cc. of the iron solution. The 

 latter was made from crystallized ferrous sulphate, with a 

 little sulphuric acid and an excess of metallic iron, so that 

 it was very nearly neutral. 



