VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 299 



mixed with the other substances at the time when they were transported, and de- 

 posited, 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 granitic sand which covers the 

 borders of the Mer de Glace, at Chamouni, in Savoy, also much resembles the 

 terra australis, excepting 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 decomposition of granite, or gneiss. 



My. 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 exa- 

 mine, by analysis, a portion of the same earth on which Mr. Wedgwood made his 

 experiments, and as I received it from Sir Jos. Banks, the same gentleman who 

 had furnished Mr. Wedgwood with it, no suspicion can be entertained about. its 

 identity. 



Some of the experiments which I have related, and which prove that some of the 

 finer earthy particles remained suspended in the concentrated muriatic acid, and 

 were precipitated when the acid was diluted with water, appear in some measure to 

 account for the mistake which has been made, in supposing that a primitive earth, 

 before unknown, was present ; but this alone will not account for many of the other 

 properties mentioned by Mr. Wedgwood, such as, 1st. The repeated and exclusive 

 solubility in the muriatic acid, and subsequent precipitation by water. 2d. The 

 butyraceous mass which was formed by evaporation. And, 3dly. The degree of 

 fusibility of the precipitated earth. These indeed I can by no means explain, but 

 by supposing that the acids used by Mr. Wedgwood were impure. This supposi- 

 tion appears to be corroborated by a passage in Mr. Wedgwood's paper, where he 

 says, " here the Prussian lixivium, in whatever quantity it was added, occasioned 

 no precipitation at all, only the usual bluishness arising from the iron always found 

 in the common acids." Now if, as it seems from this expression, Mr. Wedgwood 

 employed the common acids of the shops, without having previously examined and 

 purified them, all certainty of analysis must fall, as the impurity of such acids is 

 well known to every practical chemist : but, whether this was the cause of the 

 effects described by Mr. Wedgwood, I do not hesitate to assert, that the mineral 

 which has been examined does not contain any primitive earth, or substance pos- 

 sessing the properties ascribed to it, and consequently, that the Sydneian genus, in 

 future, must be omitted in the mineral system. 



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