the 'Nature of fome Mineral Subfiances . 621 
Having now tried in my manner, without fuccefs a 
great number of the minerals which M. le sage affirms 
to contain the acid of fait, it became alfo neceffary to trv 
his method; and I chofe fuch fubftances as he fays are 
the moll replete with that article. 
experiment xi. 
White, fpathofe, iron ore from Bayreuth, tried in 
M. le sage’s manner. 
I put into a fmall glafs retort three ounces of this mi- 
neial powder, and poured on it an equal quantity of oil 
of vitriol. The ietort was placed in a proper reverbera- 
tory fui nace, and a quilled receiver luted to it; an ounce 
meafure of oil of tartar, per deliquiutn , was previoullv 
put into the receiver, and fhaken fo as to moiften all its 
internal parts : a very flow fire was made under the re- 
tort, fuch as caufed no moiflure to rife ; and this gentle 
degree of heat was continued for five hours. In a little 
time the upper part of the receiver was lined with long 
fpiculine cryftals; and, after the operation, the oil of 
tartar, which was at the bottom of the receiver, was, for 
the moft part, cryftallized. 
EXPERIMENT XIl, 
Somerfetfhire manganefe, treated in the like manner, 
produced the fame fpiculine cryftals in the upper part of 
the receiver; and the oil of tartar was, in like manner, 
cryflallized. It was here neceffary, on account of the 
' 4 M 2 effetvefcence 1 
