22 Elements of Mineralogy. 



CHAP. IV. 



Calcareous Genus. 



SPECIES 1. 



Calcareous Earth^ uncombined 'with any 

 Acid. 



This ftone is of a grey colour, moderately 

 hard, or rather foft, found near Bath ; it is 

 mixed with calcareous Earth combined with 

 fixed air; and hence it effervefces with acids, 

 but at the fame time it is foluble in water, to 

 which it communicates the tafte of lime \ and 

 if this folution be mixed with fulphur, it 

 diffolves it, and forms a calcareous liver of 

 fulphur, with the affiftance of heat ; whence 

 It is plain that part of the calcareous earth is 

 in an uncombined ftate. See Falconer on 

 JBath Waters, vol. i. p. 156 and 257. When 

 expofed to the air for foine time, it hardens, 

 by attracting a fufficiency of the aerial acid, 

 I have obferved feyeral linie-ftones to have 

 the fame property of hardening fome time 

 affer they have been dug. Mr. Monnet alfo 

 found this Earth in a Joofe, dry, powdery 

 form, of' a yellowifh colour, in the moun- 

 tains of Auvergne, and fufpe&ed it to be of 

 yojcanic origin. Miner ahgie^ p. 515. 



SPECIES 



