33 4 
Dr. withering on the 
B. The undififolved part was rubbed with twice its weight 
of mild fofiil alkaly, and then expofed to a red’ heat in a black 
lead crucible for one hour. 
C. This mixed mafs was reduced to powder, and repeatedly 
boiled, firfl in marine, afterwards in ftrong vitriolic acid : the 
rcfiduum now weighed 56, and was perfectly white. 
D. i lie liquors of exp. A. and C. being put all together, 
piiiOgiicicateci fixed aikaly was added until no further precipi- 
tation eniued. This precipitate was a Prufiian blue, which, 
when wafhed and dried, weighed 36 t s 0 . 
Atici expolure to a led-heat in a crucible for fortv minutes, 
it weighed only 29, and was wholly attracted by the magnet. 
i\o\v the 2 oz. 5 dr. and 32 gr. of phlogifticated fixed 
alkaly ufied in this experiment contain 13 gr. of calciform iron, 
as afeertained by a leparate trial ; therefore, deducing 13 from 
29, we have 16 for the quantity of calciform iron obtained 
from the itone. 
E. The earthy parts were next precipitated from the liquors 
by the addition of mild fofiil alkaly. The precipitate, when 
perfectly edulcorated and dried, weighed 29 r i. 
F. Difiilled vinegar was added to this powder, and fuffered 
to ftand in a cool place for four hours; the vinegar was poured 
ori, and the refiduum repeatedly wafhed with pure water. To 
theie liquors mild fixed alkaly was added, and a white precipi- 
tate fubfided, which, when wafhed and dried, weighed 7 s _. 
G. To the refiduum (F) dilute vitriolic acid was added : a 
folution took place, which folution, by evaporation and cry- 
firallization, yielded allum. 
H. The part of the refiduum (F) undiflblved by the vitriolic 
acid was boiled in nitrous acid, in marine acid, and in aqua 
iregia, without being diminifhed ; the weight of it when dried 
was 
