MINERALOGY. 
SECT. CXXIV, 
B. The acid of vitriol mixed or faturated with 
■earths, Acidum vitrioli terris mixtim feu fa- 
turatum. 
1. With a calcareous earth. Gypfum. See 
Sed. xiii. 
2. With an argillaceous earth. The Alum 
kind. Alumina, 
a. With a fmali quantity of clay, Acidum 
vitrioli argilld faturatum. Native or 
plumofe alum, Alumen nativum five flu- 
mofum. 
Is found on decayed alum ores in very 
fmall quantities ; and therefore through 
ignorance the alabaftrites and felenites, 
both of which are found among moft of 
the alum flates, are often fubftituted in 
its dead ♦, as is alfo fometimes the af- 
beftus, notwithftanding the great dif- 
ference there is between the alum and 
thefe, both in regard to their ufes and 
effeds 
h. With a greater quantity of pure clay, 
• Argilla pura acido vitrioli imhuta. White 
alum ore. Miner a aluminis alba* 
♦ The gypfa and afbefti, but more efpecially the latter, 
have been ufed through ignorance, in moft countries, for 
plumofe native alum ; and the fort fold formerly in the Ihops 
•for it v/as a greenifti white kind, from Germany, very rigid, 
but extremely 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 ftmiiarity of ftrudure, not, as our author fays, 
oil account of their being found together. See my Ledures. 
p. a 
K3 
I. Indu- 
