74 PROCEEDINGS OF THE AMERICAN ACADEMY 



conclusive evidence in itself, confirms the conclusion in regard to the 

 crystalline system, which was based on the symmetry of the external 

 form. 



Crystalline Form of Antimonious Chloride. 



Orthorhombic System. 



Forms {110} and {011} 



Figs. 1 and 2, Plate I. 



a =1.263 5=1 c= 1.109 



Angles between normals. 



110 on ITO = lOS'^ 16' 



Oil „ OTl = 115^ 57' 



In order to obtain the specific gravity of antimonious chloride in 

 the solid state, we filled a specific-gravity bottle nearly full of the 

 melted substance ; and, after the mass had " set," we added (so as to 

 completely fill the bottle) some rock oil, which had been rectified over 

 sodium. We then kept the bottle in the exhausted receiver of an air- 

 pump, long enough to remove any entangled air ; and, finally, after in- 

 serting the ground stopper and wiping away the excess of oil, we took 

 the weight at a carefully regulated temperature. We could find no 

 liquid on which antimonious chloride does not act, to a greater or less 

 extent. It acted slightly even on this rectified rock oil, although only 

 very slowly ; so that, by working as quickly as possible, we must have 

 obtained a result which was at least nearly accurate. We used the 

 same preparation of antimonious chloride, of which a complete analysis 

 is given on page 70 of the previous paper. The weight taken was 

 19.9575 grammes, which displaced 5.0212 grammes of oil. The 

 specific gravity of the rock oil at 26°, referred to water at the same 

 temperature, was 0.7693 ; and we found — 



Specific gravity of Antimonious Chloride at 26°,) « qy/. 



referred to rock oil at same temperature . . ' 

 Specific gi-avity of Antimonious Chloride at 26°, \ „ ^^ . 



referred to water at same tempei'ature . . . ^ 



The melting point of antimonious chloride was determined by ob- 

 serving the constant temperature during the slow crystallizing of a 

 considerable mass of the melted substance, the liquid being stirred 



