Structural and Magneto-optic Rotation. 



419 



pretty well established. Its solution possesses no activity,"* 

 and Landoltf has further proved that even the supersaturated 

 solution fails to exhibit the slightest optical activity. More- 

 over, the form which the crystals assume can be influenced and 

 determined by external causes. Thus it has been pointed out 

 by GernezJ and by Landolt,§ in a slightly different way, that 

 if into a supersaturated solution of sodium chlorate some 

 fragments of dextro or laevo crystals are placed, only crystals 

 of a like nature result. These experiments we have repeated 

 but not with the extreme results noted above. While invaria- 

 bly there is a very marked preponderance of the same kind of 

 crystals as those introduced, we have never failed of finding a 

 very considerable quantity of the opposite kind. In order to 

 put on record something more definite in regard to the rela- 

 tive quantities of the two forms deposited under these circum- 

 stances, we give in Table I the results of three experiments 

 chosen at random from a considerable number. The rotation 

 was determined by suspending 0*2 grm. of the finely powdered 

 product in a liquid of the same refractive index, according to 

 the method given at the end of this paper. 



Table I. 

 Crystals deposited from a saturated solution of NaC10 3 , to which had been added : 



3. 



A sprinkling of 



Resultant rotation 





powdered dextro 



in divisions of scale. 





crystals 



+ 436 



Large crop ; all 





(i. e., 74^) 



small crystals, but 

 *" distinctly crystal- 



A sprinkling of 





powdered laevo 





line. 



crystals 



— 4-2 



(i. e., 73'/) 





One large and 





The six original 



five small dextro 





crystals, which had 



crystals _. 



+ 1-86 



doubled in size, were 

 removed before test- 

 ing the rotation. 



Rotation of an equal wt. of pure dextro or laevo forms, ± 8 - 96 division. 



It has even been claimed || that the influence of a small per- 

 centage of some other optically active body in solution with 

 the sodium chlorate influences the formation of the crystals, a 

 conclusion which, however, our results as recorded in Table IV, 

 with comment, do not sustain. 



* Marbach, Pogg\ Ann., xci, 487. 



fBer., xxix, 2. 2410. 



tCompt. Rend., lxvi, 855. 



§ Loc. cit. 



| Pope and Kipping, Chem. News, lxxv, 45. 



