456 Prof. Gr. Quincke on the Measurement of Magnetic 



III. 



These magnetic pressures may also be employed for the 

 calculation of the quantity which Herr G. Wiedemann * has 

 called the atomic magnetism of the metals, in a series of salts 

 of similar chemical composition. 



The increase of pressure Ap produced in a saline solution by 

 magnetic forces consists of two portions, Api and Ap 2 . The 

 first portion, Ap l7 depends upon the water (or other solvent) 

 contained in the unit volume of the fluid ; the second portion, 

 Ap 2i upon the anhydrous salt in the same unit volume. 



If we denote by 

 Gr the percentage of anhydrous salt in the solution ; 

 A the chemical equivalent of the salt ; 

 Hi the magnetic force of the magnetic field ; 

 a the specific gravity ; 



h the magnetic increase in height of the fluid ; 

 cr w the specific gravity of the water ; 

 A w the magnetic increase in height of water for the same 



magnetic force H x ; 



then Ap = h<r = Ap 1 + Ap 2) (4) 



a 7 100-G /K , 



&Pi = K<r„ 1Q0 , (5) 



A^Sl^.H^; (6) 



and therefore 



9Lm(h'-k 2? 10 °-^ A 1 (7) 



51 is the magnetic pressure in grammes per square centi- 

 metre by which the pressure upon the anhydrous salt would 

 exceed the atmospheric pressure in a magnetic field of unit 

 intensity, if A grin, of anhydrous salt were diffused through 

 the unit volume, or so many grammes of the salt as is ex- 

 pressed by the chemical equivalent of the salt. 



The quantity termed by Herr Gr. Wiedemann the atomic 

 magnetism must be proportional to the constant 21 of equa- 

 tion 7. 



* Pogpr. Ann. cxxvi. p. 23 (18G5) ; G. Wiedemann, l Die Lehre von der 

 Elektricitat; 3rd ed. p. 852 (1883). 





