OF ARTS AND SCIENCES. 283 



remarks concerning the planes {430}, {034}, {304}, {740}, {470}, 

 (474), {047} ? : " These symbols were for the most part deduced from 

 the zone intersections, and the indices could only in a few cases be 

 verified by angular measurements. The faces of the vertical prism 

 especially were very irregular, in consequence of the alternations caused 

 by parallel grouping, so common with artificial crystals ; and although 

 the relative position of the fundamental planes could be accurately 

 fixed, the symbols of the intermediate planes must be regarded as 

 doubtful ; these planes were seldom seen, and only in the vertical zone. 

 The symbols given on the projection were obtained by finding the in- 

 tersection with the vertical zone of other zones never well defined on 

 the same crystal, and it can only be claimed that the approximate an- 

 gular measurements on the vertical zone were compatible with the 

 indices given above." 



The composition of the purified acid was shown by analysis : — 



I. 0.2254 grm. of the substance gave 0.4435 grm. AgCl + AgBr. 

 II. 0.2046 grm. of the substance gave 0.3980 grm, AgCl + AgBr. 

 III. 0.8187 grm. of the substance gave 0.3920 grm. COg and 

 0.0273 grm. Hfi. 



Found. 

 I. 11. III. 



74.03 73.19 



13.05 

 .37 



In determining the solubility of this acid in cold water according to 

 the method of V. Meyer, a saturated solution was neutralized with 

 baric carbonate, and the barium determined in the filtered solution by 

 precipitation with sulphuric acid. 



I. 11.0890 grm. of a solution saturated at 20° gave 0.2344 grm. 



BaSO,. 

 II. 1.6299 grm. of a solution saturated at 20° gave 0.0379 grm. 

 BaSO,. 



From these results the following percentages were calculated : — 



I. II. 



5.18 5.68 



The barium, calcium, potassium, and silver salts of this acid were pre- 

 pared and analyzed. 



Baric a - ChlordibromacryJate, Ba ( CgCl Br^^) 2 • ^ H^. — On satu- 

 rating an aqueous solution of the acid with baric carbonate a neutral 



