166 Prof. G. AViedemann on the Magnetic 



Therefore, so far as can be concluded from the preceding 

 observations, the magnetism of the dissolved salt diminishes 

 proportionately with the rise of temperature, and, for all the 

 salts hitherto investigated , notivithstanding their great cheinical 

 difference, according to the same laic. 



The number 0'325 coincides approximately with the coeffi- 

 cient of the diminution of electric conductivity of the metals 

 with rise of temperature. 



5. Magnetism of various Salts dissolved in Water. — If the 

 magnetism calculated for the unit of weio'ht of the salts dis- 

 solved in water is equal to on, and the molecular weight of the 

 salts A, the value /jb=Am is the magnetism of one molecule 

 of the salt in question, its molecidar magnetism. In like 

 manner the magnetism of each atom of the magnetic metal in 

 the salts, its atomic magnetism a, can be calculated. 



It has been found, as the result of numerous trials, that, 

 with the oxj^gen, as well as with the haloid salts, the m.olecular 

 magnetism of the dissolved salts of the same metal ivith cUfferent 

 acids is ajoproximately the same. Thus, for example, in an 

 arbitrary unit, for nickelous sulphate, nitrate, and chloride, 

 yL6 is = 1426, 1433, 1400 ; for ferrous sulphate, nitrate, and 

 chloride, 3900, 3861, 3858 ; for the relatively feebly mag- 

 netic cupric nitrate, acetate, and chloride, 480, 489, 477; &c. 



If the atomic magnetism of the iron in the ferric salts be 

 denoted by 100, that of the metals of the other salts will be: — 



ex. a. 



Cupric 10-8 



Cerious 10*3 



Ferric lOO'O 



Chromic 41*9 



Manganous 100*4 



Ferrous 83*1 



Cobaltous 67-2 



Nickelous 30-5 



Didymic 22-6 



According to this, the mean molecular magnetism of the fer- 

 rous salts stands appro.mmately midway between the inagnetisms 

 of the manganous and cobaltous salts, aiid the molecular mag- 

 netism of the cobaltous salts midway between those of the man- 

 ganous and nickelous. 



The molecular magnetisms of the four groups of salts men- 

 tioned (the nickelous, cobaltous, ferrous, and manganous) 

 are, therefore, to one another in the ratio a :a-\-b : a+\^b -.a 

 + 2^. One would suppose that this relation of the magnetic 

 properties of the four groups of salts would also find expres- 

 sion in the series of the atomic weights of their metals ; but 

 at least the values hitherto fixed for them do not accord 

 therewith. 



6. Magnetism of the Solid Salts. — The magnetism of the 

 solid salts combined with the water of crystallization is ap- 



