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XLV. Defcrlpt'mt of the Schieferfpath. By Arthur, 

 AiKix, Efq. Member of the Britijh JMincralogical Sochlj. 



OCHIEFKRSPATH : Calcaiciis fpathum fcbiilofum : Wer- 

 ner. Argentine: Klrzcan. Spalh fchilieux : Brochant. 



Colour : very dilute yellowilli white ; by being kept for a 

 few minutes in a red heat, it becomes flighlly reddifli white. 



Lullre, internal ; ftiining peiiily. 



Frafture : wavcd-Ianiellar. 



Fragments : for the moft part blunt- edged, wedge-fliaped : 

 it is tranlhicid even when in mafs, and at the edges is occa- 

 fionally tranfparent. It is brittle; may be fcratched by the 

 nail, and has a (lightly unftuous feel : fpecific gravity 2740. 



This mineral differs from common calcareous fpar in its 

 fuperior brilliancy ; and efpecially in the total abfence of the 

 rhomboidal figure in its fragments. The fpecimen analyfed*, 

 and from which the above defcription was taken, differs from 

 the gfneral account of this mineral by Widcnman, Elmmer- 

 ling, Brochant, Sec. In being more tranfparent : it is probably 

 from Folgorth tin-mine, and is covered in various parts with 

 cryftallized oxide of tin and chlorite: on breaking the fpe- 

 cimen, a fmall quantity of fluor fpar was found It may be 

 well to remark, that Cornwall, and probably tlie fame mine, 

 has produced a calcareous fpar of the ufual rhomboidal frac- 

 ture and of a brilliant pearly luftre : it contains no (ilioa, 

 and appears to be lime combined with the ufual quantity of 

 carbonic acid and a little oxide of iron : fpecific gravity 3723. 



XLVI. A Jhort Jecoujit 0/" Mr. Smith's Air-pipuf Vapour- 

 bath. jB)- ilir. Henry Jamks. 



To Mr. TiUoch. 



A KRMIT me, Sir, to lay before the readers of your Maga- 

 zine fuch an account of a Phllofophicol Apparatus (not lefs 

 ufeful than ingenious) as may in fome meafurc corrclpund 

 with the general intention (jf fo valuable a publication. 



The Air-pump rupour-bath, after fifteen years alnioftcon- 

 fiant attention, and at a very confidcrable expcnfe, has at 

 length been brought to fuch a degree of perfection as to be 

 ap|)licable, with cood cfleds, in fome of the mnii dillreiling 

 complaints to wTiich fuffering humanity is liable. 'J he aji- 

 plication of this apparatus is now at length con)niittcd to the 

 direction of medical men, fo that, I trult, its good properties 

 will uot, as heretofore, be overlooked ; or, what antaunts to 

 "* Sec tlir mtcciling article. 



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