274 H. L. Wells — Bismutosphcerite from Connecticut. 



c. 



ii. 

 Black residue insoluble in HC1, 0-49 per cent. 



Deduct insoluble silicates, - 08 



Bi 2 S 3 by difference, 0*41 



The result obtained from the analysis of the Willimantic min- 

 eral led me to examine a specimen of bismuth carbonate in 

 Professor Brush's collection from Pelton's quarry, Portland, 

 Conn. This specimen has a greenish-yellow color, and gives 

 reactions like the specimen from Willimantic, except that it 

 does not leave a black residue when dissolved in HC1. It 

 shows evidences of a bent columnar structure, but on a much 

 smaller scale than the other specimen. Under the microscope 

 it appears as a somewhat porous mass, made up almost wholly 

 of an apparently homogeneous material of a yellowish green 

 color with an oily luster, but with some streaks of different col- 

 ored material varying from white to dark gray. A specific 

 gravity determination gave the number 6*83, but this is of little 

 value on account of the porosity of the mineral. Chemical an- 

 alysis gave the following results : 



Ignited residue, 91*82 



C0 2 7-54 



HO 0-94 



100-30 

 A determination of Bi 2 3 in the "ignited residue" gave 89*03 

 per cent. The difference, amounting to 2*79 per cent, between 

 the Bi 2 O s determined and the "ignited residue " is probably to 

 be accounted for by the presence of - 49 per cent of insoluble 

 silicates, and also a little CuO and a considerable amount of 

 Fe 2 3 which were not determined. 



The anatyses given in this article were all made on the air- 

 dry material ; drying, even in the desiccator, having been avoided 

 from fear of removing water which belonged to the composition 

 of the mineral. From the small amount of water found, since 

 a part of it was probably hygroscopic moisture, and, since 

 weighing water in a calcium chloride tube is apt to give slightly 

 high results, these two specimens of bismuth carbonate must 

 be regarded as virtually anhydrous; and, since the analyses 

 agree quite closely with the composition corresponding to the 

 formula Bi 2 3 .C0 2 , the existence of bismutosphse-rite must be 

 considered as established, although the name is not appropriate 

 to the external form of the specimens under consideration, un- 

 less, indeed, the slight coating on that from Willimantic shows 

 on a small scale the form from which the mineral is named. 

 Sheffield Laboratory, May 18, 1887. 



