420 Wright and Kreider — Relation between 



One convincing proof of the optical indifference of the 

 ultimate molecule of sodium chlorate is found in the fact 

 observed in one of our experiments, that from a filtered solution 

 of pure dextro-rotatory crystals, upon spontaneous evaporation, 

 a very decided excess of laevo crystals was obtained. 



In the light of these facts as to the optically indifferent 

 nature of the molecule of sodium chlorate and the ease with 

 which its optically active molecular aggregation in the crystal- 

 line unit is influenced, it certainly is not unreasonable to suppose 

 that, since this particular molecular aggregation results in the 

 rotation of the plane of polarization in a certain direction, 

 if by means of the magnetic field we introduce forces tending 

 to produce rotation, it should result in a directive action upon 

 the molecules in this field, thus producing a preponderance of 

 those crystals whose optical activity corresponds to the field 

 in which they were formed. 



In the theoretical consideration of the possible influence of 

 magnetism upon the formation of optically active structure, it 

 should be recalled that a very characteristic difference exists 

 between natural and magneto-optic rotation, namely, that if a 

 ray of polarized light is caused to retrace its path through an 

 optically active natural substance, the plane is rotated in the 

 opposite direction so that the resultant rotation is zero, while 

 in the magneto-optic phenomenon the rotation is independent 

 of the direction in which the ray travels, the rotation being 

 increased as many times as the ray has passed through the 

 medium. Moreover, structural rotation is active and specifi- 

 cally equal in every direction, while the magnetic rotation 

 varies from a maximum in the direction of the lines of mag- 

 netic force, to zero at right angles thereto ; in other words, 

 varies as the cosine of the angle which the ray makes with the 

 lines of force. However, the magnetic whirl by itself appears 

 to be incapable of rotating the plane of polarization, at least 

 to any perceptible extent. The molecules of the medium 

 placed in the magnetic field seem to be essential to the phe- 

 nomenon, from which fact it is evident that the action in the 

 ether which takes place about the lines of magnetic force, 

 causes a change in the orbit or nature of the vibration of the 

 molecule, which consideration would still leave probable, dur- 

 ing the period of formation at least, some influence of the 

 magnetic field upon the molecular aggregation in the crystal- 

 line unit of a substance such as sodium chlorate, in which there 

 is nothing inherent in the molecule which determines the 

 optical nature of its aggregation. 



Nor can this fact, that the natural and magneto-optic rota- 

 tions are superposable without permanently affecting the struc- 

 ture, be considered conclusive against the supposition, the 



