ON A MINERAL FROM DEVONSHIRfi, 155 



leaving any notable rcfiduum ; but a fmall part remains un- 

 dilfolved, when coloured or opaque (peciiiiens are expoled to 

 the alkaline lixivia. 



A fmall remi-lranfparent piece, aded on by the higheft Forge hea^t^gave 

 heat of an excellent forge, had its cryftalline texture deftroy- °^J'/^}^' luUti 

 cd, and was rendered opaque; but it did not enter into fufion. oncfourth. 

 After the experiment it adhered ftrongly to the tongue, and 

 was found to have loft more than a fourth of its weight. Water 

 and alcohol, whether hot or cold, had no efFed on the foflil. 

 When it was aded on by a heat of from 212® to 600^ Fahren- It emitted water, 

 heit in a glafs tube, it gave out an elaftic vapour, which when 

 condenfed appeared as a clear fluid pofleffing a flight em- 

 pyreumatic fmell, but no tafte different from that of pure 

 water. 



The folution of the foflil in fulphurlc acid, when evaporated Sulphuric folu- 

 fufficiently, depofited cryftals which appeatS in thin plates, phateSifnt 

 and had all the properties of fulphate of^lumine; and the 

 foiid matter, when rediffolved and mixed with a little carbo- |^ ^ 



nate of potafli, flowly depofited Of^ahedral cryflals of alum. 

 The folid matter precipitated from the folution of the white Muriatic folu- 

 and femi-tranfparent foflil in muriatic acid, was in no manner ai°'^|^°"^^;"^** 

 aded upon by folution of carbonate of ammonia, and therefore 

 it could not contain any glucine or ittria ; and its perfect 

 folubility wltho^Jt refiduum in alkaline lixivia Ihewed that it 

 was.alumlne. . |^^ 



When the opaque varieties of the foffil were fully ex- The white va- 

 pofed to the agency of alkaline lixivia, the refiduum never ^'^^'<^s 5ontainc4 

 amounted to more than one-twentieth part ot the weight ot 

 the whole. In the \vhite Qpaque variet^ijt was mereTy calca- JK^ 



reous earth, for when diflblved In muriatic acid, not in excefs, 

 it gave a while precipitate when mixed with folution of oxalate 

 pf ammonia, and did not affect folution of prufliate of potafli 

 and iron. 



In the green opaque variety, calcareous earth was indicated and the green, 

 by folution of oxalate of ammonia : and it contained oxide of *"aDganefe : 

 manganefe; for it was not precipitated'by folution of ammo- 

 nia; but was rendered turbid," and of a gray colour, by folution 

 of pruffiate of potafli and iron. ' , ,, 



The refiduum of the alkaline folution of the yellow variety, the yellov.-, a 

 when difll)lved in muriatic acid, produced a fmall quantity of ^'^^^ °^ '*°"' 

 white folid matter when mixed with the/oluUoji pf the oxalate 



of 



;^Kt. 



