*=/w 



325 



TABLE 4. 



Fe2Co (saturated) 



Weiss- 



FeiTonichel (Fe^Ni, Weiss and von Freudenreich ^)). The dispersion 

 curve belongs to the general type showing a niunerical maximum 

 in the yellow and a minimum in the red. (Tab. 5). The rotation is, 

 however, greater and the form of the curve different than for the 

 nickel iron alloys (25.4, 27 and 36 percent nickel) investigated by 

 LoRiA^). As regards the effect of temperature, the rotation increases 

 on heating from — 78° at first slowly and then more rapidly (Tab. 6). 

 Owing to the ''tarnish colours" it was impossible to make measurements 

 above 250° at which point the rotation had decreased to about one 

 half its initial value. 



Metaferrite series. 



In these compounds, whose composition has been determined by 

 Hilpert') and which are related structurally to ferroferrite, the iron 

 oxyde acts as the acid radical and as the seat of the ferromagnetic 

 properties. Available were calcium-, ferro-, ferri-, cobalto-, cupii-, 

 and ziucferi-ite, all of which are more or less nuigneto-optically active. 

 They are arranged in the following in the order of the atomic 

 weight of the basic component. 



1) Cf. F. Hegg, Diss. Techn. Hochschule Züricli 1910. 



2) St. Loria, 1. c. As a matter of fact tlie compound, Fe^Ni, behaves differently 

 and forms an exception to the general nickel steel series ; cf. S. Hilpert and 

 E. Colver-Glaukrt, Zeitschr. f. Electrochemic 17, p. 7üO, 1911. 



3) S. Hilpert Verb. D. Phys. Ges. 11, p. 293, 1909. Ber. D. Chem. Ges. 42, 

 p. 2248, 1909. 



