3^0 Mr. Knox’s experiments and observations 
expelled again with sulphuric acid. The inspissated mass 
he washed with hot water, filtered, and saturated the filtered 
liquor with excess of ammonia. The residuum being separated 
by the filter, the remaining fluid was evaporated to dryness ; 
the sulphate of ammonia having been driven off at a moderate 
heat, sulphate of soda was left behind. This being dissolved, 
was decomposed by acetate of barytes, and filtered ; the 
filtered solution evaporated to dryness, and the dry salt ex- 
posed to a red heat in a platina crucible. The saline residue 
was then re-dissolved and evaporated to dryness. It was car- 
bonate of soda. 
I have detailed this well known process, chiefly to remark 
an occurrence in one part of it, which continued to confirm 
me in the opinion that the stone contained an inflammable 
substance. 
When I was expelling the sulphate of ammonia, I was 
struck by the melted mass in the crucible, which had before 
been white, suddenly becoming black, and, as the sulphate 
of ammonia flew off', gathering into a black powder. This 
powder being insoluble in water, was easily collected ; and, 
like that which I had got before from the acid solution, re- 
sisted the acid, and was volatilised by a red heat. 
The alkali which I obtained was soda. By converting it 
into nitrate, sulphate, and muriate, and observing the crystal- 
lization of each, and by testing it with muriate of platina, I 
ascertained that it contained no potash. It had none of the 
characters of lithia, neither the crystals of the muriate nor of 
the nitrate were deliquescent, nor did they tinge the flame 
when burned with alcohol. When a small portion of the stone, 
enveloped in soda and placed on platina leaf, was treated by 
