MINERALOGY. 133 



SECT. CXXIV. 



B. The acid of vitriol mixed or faturated with 

 earths, Actdum vitrioli terris mixtum feu fa- 



1. With a calcareous earth. Gypfum. See 

 Seel. xiii. 



2. With an argillaceous earth. The Alum 

 kind, Alumina. 



a* With a {mail quantity of clay, Actdum 

 vitrioli argilla faturatum. Native or 

 plumole alum, Alumen nativum five plu- 

 mofiim. 



Is found on decayed alum ores in very 

 fmall quantities •, and therefore through 

 ignorance the alabaftrites and felenites, 

 both of which are found among moil of 

 the alum dates, are often fubftituted in 

 its Head •, as is alfo fometimes the af- 

 foeftus, notwithftanding the great dif- 

 ference there is between the alum and 

 rhefe, both in regard to their ufes and 

 effects *. 



b. With a greater quantity of pure clay, 

 Argilla pura acido vitrioli imbuta. White 

 alum ore, Minera aluminis alba. 



* The gvpfa and afbefti, but more efpecially the latter, 

 have been ufed through ignorance, in moft countries, for 

 pjumofe native alum ; and the fort fold formerly in the ihops 

 for it was a greeniih white kind, from Germany, very rigid, 

 but ext-emely brittle, and breaking into fpicula or prickles. 

 Selenites was never fubftituted for alum ; and the reafon the 

 afbefti and fibrofe gypfa were fubftituted for it, was only on 

 account of the fimiiarity of ftru&ure, not, as our author fays, 

 on account of their being found together. See my Lectures. 

 D C. 



K 3 1. Indu- 



