112 PROCEEDINGS OP THE AMERICAN ACADEMY 



was more probability that a definite compound might be isolated be- 

 tween Sb^O-CI., and Sb^Oj ; and there is some evidence that such a 

 compound had been analyzed.* With the hope of obtaining an inter- 

 mediate product, we exposed to the direct sunlight during the sum- 

 mer months of 1876, a quantity of precipitated oxichloride of antimony, 

 under a very large volume of water, which contained, besides the 

 hydrochloric acid resulting from the decomposition of antimonious 

 chloride, also a small quantity of tartaric acid. During this time 

 there formed a considerable quantity of small acicular crystals, that 

 were easily washed clean from the light amorphous precipitate with 

 which they were mixed. The crystal appeared under the microscope 

 perfectly homogeneous, and their surfaces had a brilliant vitreous 

 lustre. They were rhombic prisms, having one of the two pairs of 

 prismatic edges truncated by pinacoid planes. They presented, how- 

 ever, no distinctive terminations, sometimes tapering on the four pris- 

 matic i:)lanes to a point, and at other times on the pinacoids to an edge. 

 They had the aspect of trimetric crystals, resembling some forms of 

 Arragouite ; and, as accurately as could be determined with the polariz- 

 ing apparatus of a microscope, the principal optical sections were 

 parallel to the prismatic edge, in whatever position the prisms might 

 lie on the stage of the instrument. Nevertheless, these characters are 

 not conclusive ; and a delicate oblique striation which we observed on 

 some of the prismatic planes led us to suspect that the crystals are 

 really monoclinic. An analysis of the above crystals, made by Mr. 

 Richardson, gave the following results : — 



Analysis of Antimonious Oxichloride (SbgOnClj ?). 



No. Weight taken. ^'oftline^^^^ % of Chlorine. 



1. 0.3605 0.0852 5.84 



2. 0.7353 0.1759 5.91 



Mean value 5.875 



Theory for Sb^O^CP 5.88 



It is therefore probable that we have here the intermediate com- 

 pound sought ; although it is important that these observations should 



* Gmelin's Hand-book of Chemistry, Cavendish edition, iv. 367. 



