called Sydneia or Terra Australis. 127 
decomposed; and Mr. Wedgwood probably did not succeed, 
because his process was in some respect different, or that the 
distillation was not sufficiently repeated. 
I have not thought it necessary to be more circumstantial in 
the account of this second analysis, as the operations were si- 
milar to those of the former. 
§• 4 - 
These experiments prove, that the earthy substance called 
Sydneia or terra australis, consists of siliceous earth, alumine, 
oxide of iron, and black lead or graphite. 
The presence of the latter appears to be accidental, and it 
probably was mixed with the other substances at the time when 
they were transported, and deposited, by means of water; for 
this appears evidently to have been the case, from the general 
characters of this mixed earthy substance. 
The quartz and mica, which are so visible, indicate a granitic 
origin ; and the soft white earth has probably been formed by 
a decomposition of feldt spar, such as is to be seen in many 
places, and particularly at St. Stephen’s, in Cornwall. The gra- 
nitic sand which covers the borders of the Mer de Glace, at Cha- 
mouni, in Savoy, also much resembles the terra australis, ex- 
cepting that the feldt spar is not in a state of decomposition : 
in short, the general aspect, and the analysis, concur to prove, 
that the Sydneia has been formed by the disintegration and de- 
composition of granite, or gneiss. 
Mr. Wedgwood’s experiments are so circumstantial, that 
had I only examined the earth last brought to England, I should 
have supposed, with Mr. Nicholson, that I had operated on a 
different substance ; but, as I had an opportunity to examine, 
