called Sydneia or Terra Australis. 119 
second portion of the same acid was added, and in like man- 
ner evaporated. The residuum was then made red-hot, and 
digested with diluted nitric acid, which left a considerable por- 
tion of red oxide of iron. The solution was again evaporated, 
and the residuum, being treated as before, again deposited some 
oxide of iron, much less in quantity than the former. 
The whole of the oxide was then heated with wax in a por- 
celain crucible, was taken up by a magnet, and weighed 26.50 
grains. 
H. The nitric solution of G was saturated with ammoniac, 
and a loose white precipitate was formed ; which, edulcorated 
and made red-hot, weighed 76 grains. 
I. These 76 grains were dissolved when digested with di- 
luted sulphuric acid ; and, when the excess of acid had been ex- 
pelled by heat, the saline mass was dissolved in boiling water. 
To this solution I added some lixivium of potash, and, by gra- 
dual and repeated evaporations, obtained the whole in regular 
octoedral crystals of alum. 
K. The 274.75 grains of C now alone remained to be exa- 
mined. They appeared to consist of siliceous earth, mixed with 
the dark grey shining particles already mentioned ; but, as I 
shall describe, in the following experiments, the process by 
which these were separated, I shall now only say that they 
amounted to 7.50 grains. 
L. The earth with which the abovementioned particles were 
mixed weighed 267.25 grains. This earth was white, and arid 
to the touch : when melted with two parts of soda, it formed a 
colourless glass ; and, with four parts of the same it dissolved 
in water, and formed a liquor silicum : it was therefore pure 
siliceous earth or silica. 
'0h0£ ) 
' ✓ 
•/ 73// 3 
v/37/ 3 
