Mr Connell oji the Chemical Constitution of Brewsterite. 357 



gave well characterized crystals of muriate of baryta and mu- 

 riate of strontia, the former being the more abundant of the 

 two. The former tinged the flame of a candle slightly green 

 or greenish-yellow, and the latter gave the well known fine red 

 of salts of strontia. Both, when dissolved, gave white precipi- 

 tates, with sulphuric acid. 



On decomposing a quantity of the first mentioned specimen, 

 by carbonate of baryta, I got no trace of alkali. 



It is thus plain, that lime and soda do not enter into the con- 

 stitution of the specimens examined by me in the quantity 

 given by the formula of Berzelius. I have also reason to believe 

 that silica and water are not so abundant as shown by that for- 

 mula. The precipitate by ammonia, I have little doubt, was 

 principally alumina. 



It is not impossible that, as in Harmatome, baryta may be re- 

 placed by other substances, a similar replacement may occur 

 with respect to this mineral. 



I am unwilling to offer any opinion at present as to the quan- 

 tity in which baryta and strontia exist in this mineral. It ap- 

 peared to me, however, in my examination of the first specimen 

 I have mentioned, that the baryta and strontia together, and 

 including the insoluble residue remaining after ignition of the 

 muriates, amounted to somewhere about 15 per cent, of the 

 mineral. But I wish to be understood as giving no definite 

 opinion at present on this point, or on the relative proportions 

 of the two earths. 



Supposing the earths to exist in the mineral in the state of 

 silicates, which appears to follow from the preceding researches, 

 this mineral will afford the second instance only, so far as I 

 know, of baryta occurring in nature in any other state of com- 

 bination than with sulphuric or carbonic acids, Harmatome being 

 the first instance ; and should the strontia be found to be in 

 sufficient quantity to form an essential constituent, as my re- 

 searches, so far as they go, seem to show, it will be the first in- 

 stance of this earth occurring in nature, unless as a sulphate or 

 carbonate. 



I shall proceed in completing a regular analysis of this mine- 

 ral as soon as possible. 



