374 Dr. Thomas Thomson on some new [May 



This is obviously 



1 atom carbonate of barytes. 



2 atoms carbonate of lime. 



Thus, it contains exactly twice as much carbonate of lime 

 as the baryto-calcite of Brooke, though the constituents of 

 the two minerals are the same. It was the necessity of 

 having names by which these two minerals could be dis- 

 tinguished from each other that obliged me to alter the 

 name imposed by Brooke, and to adopt the terms calcareo- 

 carbonate, and bicalcareo- carbonate of barytes. 



Sp. 6. Bary to- Sulphate of Strontian. — This species is 

 found in Drummond Island, in Lake Erie, and also at 

 Kingston, in Upper Canada. I got specimens from the 

 former locality from Major Menzies, and from the latter 

 locality from Dr. Holmes of Montreal. 



The colour is white, with a very slight shade of blue. 



The texture is laminated, and the laminae, which are 

 obviously imperfect crystals, diverge so as to form a kind 

 of pencil. 



Brittle; very friable; hardness 2*75. Specific gravity 

 3-921. 



Before the blowpipe in the platinum forceps, becomes of a 

 dazzling white, but does not easily fuse. Melts readily with 

 carbonate of soda into a transparent colourless bead, which 

 becomes white and opaque on cooling. With borax it fuses 

 easily into a white opaque globule. 



Its constituents are atoms. 



Sulphuric acid . . . 40-202 - 8-04 - 10* 



Barytes 23*059 - 2'43 - 3-02 



Strontian 35*724 - 5-49 - 6-82 



Protoxide of iron . . 0*588 - 0*13 - 0*16 

 Water 0-720 - 



100-360 

 This is obviously equivalent to 



3*02 atoms sulphate of barytes. 

 6*82 ,, sulphate of strontian. 

 0.16 ,, sulphate of iron. 

 Including the sulphate of iron with the sulphate of 

 strontian, we have for the constitution of this mineral 

 3 atoms sulphate of barytes. 

 7 ,, sulphate of strontian. 



