Structural and Magneto-optic Rotation. 423 



practically identical with those obtained without the use of any 

 magnet. 



However, there seemed to be a tendency to group over the 

 poles. Though nothing very definite could be said about the 

 observed arrangement of these clusters, it may be positively 

 asserted that the distribution of the crystals under these cir- 

 cumstances was different from that ordinarily obtained, that is 

 without the use of a magnet. 



In order to get a still more intense field the Jamin magnet 

 was supported horizontally with its poles in a vertical line and 

 the crystallization was effected in a small vessel made of tin- 

 foil of just the proper size to tit between the poles, so as to be 

 in the strongest part of the field. Measurements proved the 

 field at this point to be about 800 C. G. S. units. Some diffi- 

 culty was experienced in getting the crystals to grow in this 

 vessel, but by cutting a plate of thin glass to fit the bottom 

 this difficulty was overcome, doubtless because the glass afforded 

 more nuclei about which the crystals form. A number of 

 crops thus collected failed to reveal any effect of this magnetic 

 field upon the optical property of the crystals. 



Crystallization of Sodium Chlorate in Electrostatic Field. 



Incidentally the effect of an electrostatic field was also inves- 

 tigated. For this purpose a Leyden jar was charged from an 

 electric machine. The poles from the two surfaces, after being 

 capped by fairly thick glass tubes in order to prevent dis- 

 charge, were brought as close together as was permitted by the 

 solution contained in a shallow, thin-glass, flat-bottom beaker 

 placed between them. Several preliminary experiments were 

 made, but no particular effect was noted upon the formation or 

 arrangement of the crystals in this field, nor upon the resultant 

 optical "activity of the crop of crystals. 



Experiments on Ferrous Sulphate. 



The tendency of the crystals of sodium chlorate to group 

 over the poles of the magnet, led also to some experiments 

 upon the crystallization of an iron salt in a magnetic field. It 

 was thought that because of its magnetic property the iron 

 would show a more decided effect. A number of experiments 

 fully confirmed this expectation. In each case the grouping 

 over the poles was very conspicuous and unmistakable. There 

 was, however, nothing definite in the arrangement of these 

 crystals or of their axes beyond the marked tendency to form 

 in the strongest part of the magnetic field. 



