fame Mineral Sub/lances. 3 3 
a feienite, which, when wafhed and dried with a ftrong 
heat, weighed 3 iij. and gr. xxxvi. 
Three drams of dried whiting, diflolvedin the fame 
acid, and treated in the like manner, afforded 5 iv. and 
gr. xviii. of feienite. The whiting was all diflolved, ex- 
cept three grains. The calcareous earth contained in the 
fpar muft, by its formation into feienite, be increafed in 
weight in the fame proportion as the whiting; and hence 
it: is evident, that three drams of this fpar contains ^ j if. 
and.gr. xix, of calcareous earth. The remaining part 
muft be the earth above-mentioned, with fame iron. 
E XPIRI1ENT I V. 
In order to judge of the quantity of ironthat this fpar 
contained (not having any more of it left) I took the fait 
of the firft experiment, and diflolved it with water, to 
which I added fome acid of fait. I then precipitated the 
iron in form of Prulftan blue with the common alkaline 
lixivium ufed for that purpofe, and thereby obtained fix- 
teen grains of a fine deep-Goloured blue. Acid of fait 
was added in the ufual manner, to heighten the colour, 
by which means nothing but iron was precipitated. 
Two drams of common green copperas, treated in the 
fame manner, produced ^ j. lefs than two grains of the 
Vol. LXIX. F fame 
