OP ARTS AND SCIENCES. 



61 



angles I have compared those given by P. Friedlander, Zeitsch. f. 

 Krjst. u. Miu., iii. 21-1. 



calculated). 



Faces of the form {100} were very frequently striated, but still not 

 enough to materially vitiate the angles obtained from them, as shown 

 by the table. 



Twins are very common, the twinning plane parallel to the basal 

 section. 



I have in progress a comparison of the three iodides of antimony, 

 arsenic, and bismuth, and the results will be published as soon as crystals 

 of iodide of bismuth can be prepared large enough to measure. 



