243 



inn. h more directly connected with their geometrical character, i. c. 

 with their atomic configuration in space, than is the case with tin n 

 solubility. If in the cldoro-d-tartrate of an optically-active tri-cthy- 

 lenediamine-cobalti -ion of definite configuration, the central Co-atom 

 under complete preservation of arrangement of the radicals, be replaced 

 1>\ a Rho-atom which, according to our investigations, will replace 

 it quite isomorphously, then it must be obvious that the resultant 

 rlioiiium~sa.lt will appear perfectly isomorphous with the original 

 chloro-d-tartrate. Experience however now proves beyond any doubt, 

 that both the less soluble chloro-d-tartrates of the Rho-, and Co-salt 

 possess quite different crystal-forms, the one being triclinicpedial, 

 the other monoclinic, while their parameters do not show the least 

 analogy. Moreover, direct analysis proves that the chloro-d-tartrate of 

 the Co-salt crystallises with five, that of the Rho-salt with four mole- 

 cules of water, a fact which is in full agreement with the absence 

 of direct isomorphism between both derivatives too. Both chloro-d- 

 tartrates therefore, cannot have an analogous configuration, but they 

 must necessarily possess antilogous configurations. This is the simple 

 and true explanation of the fact that the cobalti-, and rhodium-sa\ts, 

 set free from the less soluble chloro-d-tartrates, also show optical 

 rotations of opposite algebraic signs. In contradiction to Werner's, 

 our conclusion, therefore, is that the cobalti- and rhodium-salts with 

 the same direction of rotation possess also the same arrangement of 

 the constituent radicals in space. The influence of replacing a central 

 coofl//-atom by a rhodium-atom, is therefore manifested only by the 

 change in size of the specific rotation, but not by a change of its 

 direction. As long as no urgent experimental data are available to 

 compel us into another way, it is of importance to construct our 

 plan of the mutual dependence of natural phenomena as simply 

 and transparently as possible; and the conception of the relations 

 between optical activity and configuration of molecules, as explained 

 in the above, seems to us really a simpler and more perspicuous one 

 than that proposed by Werner. For this reason the algebraic signs 

 of the rotation of the rhodium-salts are here taken identical with 

 those of the corresponding cobalti-salts 1 ). 



20. From the foregoing it is evident that for the considerations 

 regarding the eventual possibility of the separation of a chemical 



i) F. M. Jaeger, Proceed. Kon. Akad. v. Wet. Amsterdam, Vol. 19. (June), 

 (1917); Chemisch Weekblad, 14. 728, (1917). 



