III. Account of a Mineral from Orkney. 5?/ Thomas Stew- 

 art Tkaill, M. D. F. R. S. Edin. 



(Read April 21. 1817.; 



W HiLE examining an abandoned lead-mine in the vicinity 

 of Stromness, in the year 1803, I found a mineral which, from 

 its weight and appearance, I supposed to be carbonate of ba- 

 rytes. A few hasty experiments soon convinced me that it 

 was a different substance ; but circumstances occurring which 

 prevented a more accurate investigation, the mineral lay ne- 

 glected among the duplicates of my collection till last autumn, 

 when having mentioned my doubts and conjectures respecting 

 it to my friend Dr Murray of Edinburgh, I was strongly 

 urged by that gentleman to undertake its analysis. During 

 his short visit to Liverpool, a few preliminary experiments 

 were begun, from which it appeared, that the mineral contain- 

 ed carbonate of strontia, and I have since completed its che- 

 mical examination. 



I may here observe, that a specimen having previously been 

 submitted to several very able mineralogists, they were un- 

 able, from its external characters, to ascertain its nature ; a 

 circumstance which affords a fresh proof of the necessity of 

 uniting chemical investigations to a knowledge of the external 

 appearance of mineral bodies. 



VOL. IX. p. I. L External 



