6q8 Mr. woulfe’s Experiments to ascertain 
I N order to afcertain how far the method, I propofed 
to p.urfue in the following experiments., was calculated 
for the purpole of making a proper analyfis of the mi- 
nerals I here treat of; and particularly to difcover the 
exiftence of the acids of fait and vitriol in them; 1 
thought it expedient to make fome artificial preparations, 
which I judged to he fimilar to the natural fuhftaftces, 
and I fubmitted them to the* fame trials, and in fimilar 
quantities; for as many of the minerals, which are the 
fubject of the prefent paper, are exceeding fcarce, I was 
under the ireceffity of ufing in thefe experiments fmal- 
ler quantities of them, than I fhould otherwife have em- 
ployed. 
[a] With that intent, I diftblved half an ounce of re- 
fined filver in pure aqua fort is, and made a tuna cornea, 
by adding to it a folution of fea-lalt in water; this w T as 
well edulcorated, dried firft in the air, and afterwards 
with a firong heat, but not fo great as to melt it; the 
luna cornea, thus obtained, weigh five drams and one 
fcruple, which is one-third more than the original 
weight. I muft here obferve, that 1 have ufed Troy- 
weights in all thefe experiments. 
The like quantity of the fame filver, difiolved in 
the fame acid, and precipitated with a folution of tartar 
of vitriol, and treated as at [a], weighed five drams and 
twenty-two grains. It is worthy of obfervation, that if 
fal polycbrejl be made ule of in the place of tartar of vi- 
triol, its precipitate will not exceed three drams and fifty- 
6 four 
