622 Mr. woulfe’s Experiments to afcertain 
effervefcence of the mixture, to make ufe of a larger 
retort, and to let it ftand for twelve hours before any 
fire was made under it, in which time the fpiculine cry- 
ftals appeared. 
EXPERIMENT XIII. 
Somerfetfhire white-lead ore, treated in like manner, 
fhewed the like appearances; but here there was only a 
very flight effervefcence. 
EXPERIMENT XIV. 
Cornifh tin-grains, treated in this manner, caufed no 
change in the oil of tartar; nor was there the leaf! ap- 
pearance of cryftallization in the receiver. 
EXPERIMENT XV. 
White fpatliofe iron ore, diftilled per fe with a ftrong 
fire, fhewed the fame appearance of cryflallizations in 
the oil of tartar and in the upper part of the receiver, as 
when diftilled with oil of vitriol ; fee the eleventh expe- 
riment. 
I now faturated each of the cryftallized alkalies of the 
eleventh, twelfth, thirteenth, and fifteenth experiments, 
with diftilled vinegar, and having filtered them, they 
were flowly evaporated to drynefs, and dilfolved with 
rectified fpirit of v r ine, as in the firft experiment, but no 
neutral fait was left ; from hence we may certainly con- 
clude, that thefe minerals contained neither acid of fait, 
nor acid of vitrioL The caufe of the cryftallization of 
S- the 
