245 



in by far the most cases, directly isomorphous with the rhodiiim- 

 salts of corresponding constitution, suspicion arises that llie contefnt 

 of crystallisation-water is really the same in the two series of com- 

 plex salts. The divergence mentioned would then be explained by a 

 systematical error in the rather difiicult determinations of the element 

 rhodium in these cases. 



^ 2. In the following pages the result of the direct measurements 

 of the racemic salts and of the optically active components are in 

 the first place dealt with, and the data concerning the rotation- 

 dispersion of these perfectly colourless sails are subsequently 

 commujiicated. Some considerations of a more general character, 

 regarding the stereometrical configuration of these complex substances 

 will then be inserted. 



The results of the study of some other compounds of this series 

 will be published later-on. 



SODIUM-RHODIUM-CHLORIDF,. 



\RhoCl,\Na,-]- i2H,0. 



This salt may be prepared by dissolving the calculated quantity 

 of rhodium-trichloride in a concentrated solution of sodium-chloride, 

 evaporating the solution on the water-bath, and by crystallisation 

 at room-temperature. The solution of the black-red, often voluminous 



and apparently octahedral crys- 

 tals, has a beautiful crimson 

 colour. The crystals are hygros- 

 copical, and they soon become 

 dull, when softly heated. 

 Monoclinic-prismatic. 

 a: 6: c = 1,2034: 1:1,4576; 



^=57°9r 

 Forms observed: c = |001|, 

 small but lustrous; ordinarily 

 the facet (001) appears much 

 broader than (001); r, = jlOlj, 

 Fig. . 1 r, = \I01\, and q = \0U\, com- 



Sodium-Rhodium-Ghloride. monly equally well developed, 



and giving good images; ^=: |010|, narrow, mostly absent ; .9 = |021|, 

 very narrow, often absent, but sharply reflecting; m = \^30\, small, 

 dull, and often absent. The external shape is apparently octahedral, 

 and isometrically developed. 



