228 



of the liquid; in tlie case of the laevogyrate antipode the six different 

 solutions employed conlained 1,3512 grams {E), half ov e^ quarter oï 

 this [F, G) in 100 grams of the liquid, and 0,0927 grams (//), 

 0,0464 grams (/), and 0,0232 grams (/v) respectively of the 

 anhydrous salt in 100 grams of the liquid. 



Tiie dispersion-curve for the molecular rotation, shewn by mea- 

 surements is plotted in the diagram (fig. 1). It has much analogy 

 with that of the corresponding cohalti-ssihs, but only a slight analogy 

 with that of the triethylenediami7ie-rhodium-compounés. 



Probably the magnitude of the rotation for corresponding wave- 

 lengths in the case of these analogously built complex ions greatly 

 depends on the magnitude of thé atomic volume of the central 

 metallic atom, in such a way that the rotation appears higher, if 

 the atomic volume of the metal is smaller. As for instance: 



The values for A = 6600 A. Ü., are mentioned at the same time 

 for the purpose of demonstrating that this antiparallelism of 

 rotations and atomic volume is surely not true for «7// wave-lengths: 

 for rays of great wave-length, as e. g. in the visible red part of the 

 spectrum, — the rotation of the /^Ao-salt suipasses even that of 

 both the other salts; only in the domain of appreciable dispersion, 

 is the said regularity met with. 



As regards the absorption, we were able to state the following. 

 In a layer of the solution of 20 cm., a liquid containing. 



1,12 12% of the salt, allows the passage of all red and yellow rays up to those of5380A.U. 



0,5606 0/0 „ „ „ „ „ „ „ , , . „ „ ,, 5220 A.U. 



0,2X030:0 „ M » » ., ., .. » .. .. » .. " .. » 5030 A.U. 



0,1402% „ „ „ „ „ „ „ „ „ „ „ „ „ „ „4850 A.U. 



0,0701 '•'„ „ „ „ „ „ „ . „ „ „ „ „ „ „ „3940 A.U. 



§ 3. Numerous attempts were made to win these chromi-88i\ts in 

 well measurable crystals, and to investigate the validity of Pastkur's law 

 also in this case. But a heavy impediment in reaching this aim was 

 created not only by the facility with which those salts decompose 

 in solution, especially under the influence of the light, — but also 



