306 On Sodalile. 
Specific gravity, at the temperature of 60°, 2°378. The 
Specimen was not absolutely free from sahlite. 
When heated to redness, does not decrepitate, nor fall 
to powder, but becomes dark-gray, and assumes very nearly 
the appearance of the Swedish natrolite of Mr. Allan, which 
J consider as fettstein. If any particles of sahlite be mixed 
with it, they become very conspicuous, by acquiring a 
white colour, and the opacity and appearance of chalk. 
The loss of weight was 2°1 per cent. I was not able to 
melt it before the blow-pipe. 
II. Chemical Analysis. 
_1. A hundred grains of the mineral, reduced to a fine 
powder, were mixed with 200 grains of pure soda, and ex- 
posed for an hour to a strong red heat, in a platinum cru- 
cible. The mixture melted, and assumed, when cold, a 
beautiful grass-oreen colour. When softened with water, 
the portion adhering to the sides of the crucible acquired a 
tine brownish-yellow. Nitric acid being poured upon it,, 
a complete solution was obtained. 
2. Suspecting, from the appearance which the fused mass 
assumed, that it might contain chromium, I neutralized 
the solution, as nearly as possible, with ammonia, and then 
poured into it a recently prepared nitrate of mercury. A 
white precipitate fell, which being dried, and exposed to’a 
heat rather under redness, was al] dissipated, except a small , 
‘portion of gray "matter, not weighing quite O°1 grain, This 
matter was insoluble in acids, but became white. With 
potash it fused into a colourless glass. Hence I consider 
‘it as silica. This experiment shows that'no chromium was 
present. I was at a loss to account for the precipitate | 
thrown down by the nitrate of mercury. But Mr. Allan 
having shown me a letter from Ekeberg, in which he men- 
tions that he had detected muriatic acid in sodalite, it was 
easy to see that the whole precipitate was calomel. The 
white powder weighed 26 grains, indicating, according to 
the analysis of Chenevix, about 3 grains of muriatic acid. 
3. The solution, thus freed from muriatic acid, being 
concentrated by evaporation, gelatinised. It was evaporated 
nearly to dryness; the dry mass digested in hot water 
acidulated with nitric acid, and poured upon the filter. The 
powder retained upon the filter was washed, dried, and 
heated to redness. It weighed 37-2 grains, and was silica. 
4, The liquor which had passed through the filter was 
supersaturated with carbonate of potash, and the sepiaye 
white 
