Page:Text-book of Electrochemistry.djvu/190

 XI.

��MOLECULAR MAGNETISM.

��the angle of rotation for the water contained in the solution, and obtained the following values for the ions : —

��CI.

��Br.

��I. 4'Gl

��NOs.

��*so.

��iCOa.

� �h

�1-7G

�9-36 ;

�^^^^

� �—

�—

�9-OH

� �—

�^_

� ��If we take the differences between two vertical rows, we find that these are nearly constant, e.g. for Br — CI —

��Na

�K

�iCa

�iSr

�J^Ba

�iCd

�3-96.

��The simplest relationships are found when the particular property is due exclusively, or, at any rate, for the greater part, to one of the two ions.

In such cases all salts, which in dilute solution contain the same quantity of the particular ion, have the same value for the property in question whatever be the nature of the other ion present. As examples of this, we may cite the molecular magnetism of the magnetic salts (particularly iron salts), the natural power of rotating plane polarised light, the colour and the light absorption.

Molecular Mag^netism. — Experiments on magnetic salt solutions were made by G. Wiedemann (7). The liquid to be investigated was placed in a small flask, which was suspended at one end of the horizontal rod of a Coulomb torsion balance, and this was equipoised by means of a weight. A strong electromagnet was placed near the flask, and when the current was started, the flask was attracted on account of the induced magnetism in the solution. This attraction was measured for several solutions, and was found to vary. By

�� �