392 On SODALITE, a new 
matter, not weighing quite 0.1 grain. This matter was info- 
luble in acids; but became white. With potafh it fufed into a 
colourlefs glafs. Hence I confider it as filica. This experi- 
ment fhews that no chromium was prefent. I was at a lofs to 
account for the precipitate thrown down by the nitrate of mer- 
cury. But Mr Arian having fhown me a letter from Exr- 
BERG, in which he mentions, that he had detected muriatic 
acid in fodalite, it was eafy to fee that the whole precipitate 
was calomel. The white powder weighed 26 grains, indicating, 
according to the analyfis of CHENEVIXx, about 3 grains of mu- 
riatic acid. 
3. Tue folution, thus freed from muriatic acid, being con- 
centrated by evaporation, gelatinifed. It was evaporated near- 
ly to dryneis; the dry mafs, digefted in hot water acidulated 
with nitric acid, and poured upon the filter. The powder re- 
tained upon the filter was wafhed, dried, and heated to rednefs. 
It weighed 37.2 grains, and was filica. 
4. Tur liquor which had paffed through the filter, was fu- 
perfaturated with carbonate of potafh, and the copious white 
precipitate which fell, collected by the filter, and boiled while 
yet moift in potafh-ley. The bulk diminifhed greatly, and the 
undiflolved portion affumed a black colour, owing to fome 
oxide of mercury with which it was contaminated. 
5. Tue potafh-ley being paffed through the filter, to free it 
from the undiffolved matter, was mixed with a fufficient quan- 
tity of fal-ammoniac. A copious white precipitate fell, which 
being collected, wathed, dried, and heated to rednefs, weighed 
27.7 grains. This powder being digefted in fulphuric acid, 
diflolved, except 0.22 grain of filica. Sulphate of potafh being 
added, and the folution fet afide, it yielded alum cryftals to the 
very laft drop. Hence the 27.48 grains of diflolved powder 
were alumina. 
6. THE 
‘ aap 
eee 
