274 



racemic oxalate, is obtained by means of potassium-iodide. First the 

 less soluble racemic salt crystallizes in the form of fig. 2, sub- 

 sequently tlie laevogyrate antipode in splendid, garnet-red, flattened 

 crystals. 



Commonly tiie external aspect is that of fig. 4a, with a flattening 

 parallel two opposite faces of the rhombohedron, of which one is 

 often excavated and uneven. Occasionally also crystals of the aspect 



m 



mi. 



m' 



m 



a Fig. 4. h 



Laevogyrate Potassium-Rhodium-Oxalate (+ 1 HoO). 



of tig. 46 were obtained. Both combinations are also met with in 

 the case of the dexti-ogyrate salt, but the antipodes differ in the 

 occurring of a /e/>-handed trigonal bipyramid //^|4221| [751] in 

 the /a^wgyrate forms, where the dextrogyrate manifested the riyht- 

 handed trigonal bipyramid . I' = |2241} [715J. For the rest the angular 

 values are the same as found in the case of the dextrogyrate salt. 

 A review of some values may convince the reader of this: 



Angles : Observed: 



/?:/? = (FlOl ) : (lOH) =* 77° 0' 



£•:/? = (0001) :(10ri) = 46 1 



c:r =(0001): (01 H) = 45 52 



r:s =(0iri):(0221) = 18 3 



s:m = (0221) :(0ir0) = 26 



m: / =(0lT0):(022l) = 26 1 



y:m = (4221) : (10ÏÖ) = 40 58 



y.r =(4221) :(1 101) 



28 



y: 7? = (4221): (1101) = 78 8 



Calculated : 



45°54' 

 45 54 

 18 15 

 25 51 

 25 51 

 40 54 

 28 2 

 78 17 



