254 



Physics. — "^fa(J1ieto-chl'nü■cal researches ou/errous salts in sulntioii" . 

 By P. Wmss and Miss C. A. Frank amp. fConiimuiicated by 

 I'rof. H. A. LoRENTZ). 



The investigation included ferrous sulfate 7 aq. and the animoiiiacal 

 double-salt thereof, fen-ous-aminoniiini sulfate 6 aq. 



According to the method of Quinckr, as it has been (inally iinproved 

 by PiccARD '), the ascension is measured of the solution, placed 

 between the pole-pieces of a WEiss-magnet. Standard-liquid is distilled 

 water, which is also used in preparing the solutions. 



According to the equation : 



/l-„, /( / . k, 



Psui, «V Q 



we are able to deduce the coefficient of magnetisation from the 

 ascension; x being this coefficient, -/' the one, belonging to water, 

 ko^ and ko^ the susceptibilities of air at the average temperatures of 

 the experiment, finally /« and h.' the ascensions of the solution and 

 of water respectively. 



The meaning of the ^'s is evident. 



By means of the theorem of Wiedemann 



""^ ^ V^ "" ÏÖÖ J ^ ^ Too ^''' 



X being the percentage in weight of the salt without aq, •/« has been 

 calculated, which, multiplied by the molecular weight of the salt, 

 gives the molecular coefficient of magnetisation. 



After correction as to the diamagnetism of the other elements, 

 the atomic coefficient of magnetisation of iron -/„ i*? obtained, from 

 which, by means of the well-known formulae: 



and 



''"■ 1123.5 

 the number of magnetons may be derived; r,,„^ being liie maximum 

 value of the molecular magnetisation at the absolute zero, whereas 

 1 J 23.5 indicates the average value of the so-called grammagnefon ^). 

 Since ferrous-sails, and ferrous sulfate in jiarlicular, are easily 

 oxydated wlicn exposed to the air and even in solutions, we soon 

 carried out our measurements in a magnetical-indifrerent atmosphere 



1) A. PicüAKu. Diss. 1913 Zurich. 



2j P. Weiss. I'liysik. Zeilschrift IflU S- 935. 



