Salts of the Magnetic Metals. 367 



to which the German-silver wire was attached, a definite direc- 

 tion could be assigned to the glass flask, which was read off by- 

 means of the mirror fixed to the brass rod. The current was 

 then opened, and the position of the mirror again observed. 

 The rotation of the mirror measures the magnitude of the tor- 

 sion in the German-silver wire which supports the apparatus, 

 and thus the force of magnetic attraction. 



By numerous experiments it was shown that, within the limits 

 of observation, this attraction is proportional to the square of 

 the magnetic momentum of the attracting electromagnet — that 

 thus, 



1. The temporary magnetic momentum of the vessel filled with 

 various saline solutions is directly proportional to the magnetising 

 power. 



An approximation to the maximum of magnetizing could not 

 be observed with the magnetizing forces used. 



If the glass vessel was filled with solutions of the same salt of 

 different degrees of concentration, and with solutions in differ- 

 ent solvents (perch loride of iron in alcohol, ether, water), and, 

 from the temporary momentum imparted to the solution by the 

 magnetizing power, unit of the momentum subtracted which was 

 produced by the same force when the vessel was filled with the 

 solvent alone, values were obtained which are proportional to the 

 weights of the salt contained in the unit of volume. 



2. The magnetic momentum of the salts dissolved in different 

 solvents is directly proportional to the weights contained in the unit 

 of volume, and independent of the solvent. 



If in the same way the temporary momentum of the glass 

 vessel when filled with various aqueous saline solutions (proto- 

 sulphate of iron, protochloride of iron, perchloride of iron, sul- 

 phate of nickel, sulphate of cobalt, ferricyanide of potassium) 

 was investigated at different temperatures, and in each case the 

 magnetism was subtracted of the vessel filled with water for the 

 same temperature and the same magnetizing force, it was found 

 that, 



3. The temporary magnetic momentum of salts decreases with 

 increasing temperature, and in the same ratio in all salts inves- 

 tigated. Ift is the temperature in degrees Centigrade, m the tem- 

 porary momentum at 0°, m, at t°, then approximately 



m t = m {l-0'00325t). 

 Afact interesting in relation to the theory of magnetism is, that 

 this decrease of magnetic momentum, whose magnitude corre- 

 sponds to the intensity of the Amperian molecular currents circu- 

 lating round the magnetic molecules, is not very different from 

 the decrease of the conductibility of the metals for the voltaic 

 current for the same changes of temperature. 



