1835.] Chemical Analysis of Thulite. 93 



which the Thulite is disseminated. I am ignorant of the 

 name of the individual who discovered and named it. 



The colour is a fine rose-red, streak greyish, while my 

 specimen exhibits the thulite only in grains of a greater or 

 smaller size. But Mr. Brooke informs us that he found it 

 to yield to mechanical division an oblique prism, with angles 

 of 87° 30' and 92° 30'. But he could perceive no distinct 

 cleavage transverse to the axis of this prism. 



Lustre vitreous ; hardness about 6 ; but the grains 

 separate from each other so easily that it is not easy to 

 determine the hardness, translucent on the edges. 



Specific gravity of my specimens 3*1055. Breithaupt 

 states it at 3*124. This is a sufficient proof that thulite 

 differs entirely from bisilicate of manganese, for the specific 

 gravity of that mineral is 3*538. 



Before the blow-pipe it fuses with carbonate of soda into 

 a greenish white opaque globule. With borax it fuses into 

 a colourless transparent bead, with a quantity of uncombined 

 silica in the centre. If to this bead we add a little nitre, 

 and fuse rapidly, the bead assumes a violet colour, shewing 

 the presence of manganese. 



The analysis of this mineral was conducted in the follow- 

 ing manner: — 



1 . 20 grains, when ignited in a platinum crucible, lost 0*31 

 grains of its weight. This loss was considered as moisture. 



2. I found it partially, but not completely, decomposed 

 by muriatic acid ; 20 grains of it were treated with muriatic 

 acid till every thing soluble was taken up. The portion 

 unacted on had still a red colour. It was fused with twice 

 its weight of anhydrous carbonate of soda; most of the iron 

 and a portion of the cerium were dissolved by the muriatic 

 acid. But the silica and lime remained undissolved. As 

 from a previous analysis I had ascertained the nature of the 

 constituents, the two solutions were mixed together, and 

 the ingredients were separated in the following way : — 



3. The whole being evaporated to dryness, and the dry 

 matter digested in water, acidulated with muriatic acid, 

 the liquid was thrown on a weighed filter to collect the 

 silica. After washing, drying, and igniting the silica, its 

 weight was found to amount to 9*22 grains. 



4. The liquid thus freed from silica was rendered as 



