THE 

 LOXDOX, EDIN"BURaH, and DUBLIN 



PHILOSOPHICAL lAIAGAZINE 



AND 



JOUHNAL OF SCIENCE. 



[FIFTH SERIES.] 



SEPTEMBER 1877. 



XXI. On the Magnetic Behaviour of Chemical Compounds. 

 ^y Professor G.Wiedemann*. 



SCARCELY twenty-five years have elapsed since, in che- 

 mistry, the so-called theory of types united in its artifi- 

 cial scheme the special theories of radicals and of substitution 

 (in which the earlier experiments found a first hypothetical 

 expression), and thereby rendered possible the discovery of a 

 great number of new compounds, the composition of which 

 fitted perfectly into the once-given formulary. These scienti- 

 fically valuable results misled not a few chemists to regard, 

 with a certain fanaticism, the new doctrine as an almost irre- 

 fragable gospel of chemistry, even though on the part of 

 others the arbitrary equalization of elements which in the 

 compounds stand in the most decided electrolytic opposition, 

 the parallelism of utterly heterogeneous compounds, &c. was 

 at the same time looked upon as in the highest degree pro- 

 blematical. 



Again after barely ten years, in a perfectly natural process 

 of evolution, especially in consequence of greater attention to 

 the regularities expressed in the notion of valency introduced 

 into the law of multiple proportions, that theory was replaced 

 by the structure theory. Its solid classification, apparently 

 resting on such simple principles, its far more important con- 

 sequences in the production of an extraordinarily great quan- 

 tity of substances ranging themselves under it and especially 

 more valuable for the arts, gained for it the adhesion of the 



* Translated from the Decanal Dissertation prefixed to the List of Doc- 

 tors of Philosophy and Masters of Arts created by the Leipzig University 

 in the Academical year 1875-1876, communicated by the Author. 



PML Mag. S. 5. Vol. 4. No. 24. Sept. 1877. M 



