VOL. LXXXVIII.J PHILOSOPHICAL TRANSACTIONS. 1Q3 



expressing a desire to examine this substance with more accuracy, Sir Jos. Banks, 

 not only permitted me to take specimens from different parts of the box which 

 contained the earth already mentioned, but that every doubt might be obviated, 

 gave me about 300 grs. which remained of the identical substance examined by Mr. 

 Wedgwood. On these the following experiments were made ; and, to distinguish 

 them, I shall call the first, N° 1, and that examined by Mr. Wedgwood, N° 2. 



§ 2. Analysis of the Sydneia, N° 1. — The Sydneia, N° I, is in masses and 

 lumps, of a pale greyish white, intermixed with a few particles of white mica, and 

 also occasionally with some which are of a dark grey, resembling graphite or 

 plumbago. Jt easily crumbles between the fingers, to a powder nearly impalpable, 

 which has rather an unctuous feel. Small fragments of vegetable matter are also 

 commonly found intermixed with it; and the general aspect is that of an earthy 

 substance which has been deposited by water. 



Exper. 1 . 400 grs. were put into a glass matrass, and 1 quart of distilled water 

 being added, the whole was boiled to 4-th. The liquor was then filtrated, and a 

 portion being examined by the re-agents commonly used, afforded no trace of 

 matter in solution. The remainder was then evaporated, without leaving any re- 

 siduum. 



Eocper. 2. About 200 grs. of the earth, rubbed to a fine powder, were put into 

 a glass retort, into which I poured 3 oz. of concentrated pure muriatic acid. The 

 retort was placed in sand, and the acid was distilled, till the matter in the retort 

 remained dry. 2 oz. of muriatic acid were again poured on it, and distilled as 

 before, till -f remained. The whole was then put into a matrass, which was 

 placed in an inclined position, so that when the earth had subsided, the liquor 

 might be decanted, without disturbing the sediment. When it had remained thus 

 for 12 hours, the acid was carefully poured into a glass vessel; but, as I observed 

 that it was not so perfectly transparent as before it had been thus employed, I suf- 

 fered it to remain 24 hours, but did not perceive any sediment. Half of this 

 liquor was diluted with about 12 parts of distilled water, and after a few hours a 

 very small quantity of a white earth subsided. This however did not appear to be 

 a precipitate caused by a change in the chemical affinities, but rather an earthy 

 matter which had been suspended in the concentrated acid, and afterwards de- 

 posited, when the liquor was rendered less dense by the addition of water. To 

 ascertain this, I poured the remaining portion of the concentrated liquor on a 

 filter of 4 folds: it passed perfectly transparent, and, though diluted with 24 parts 

 of water, it remained unchanged, and as pellucid as before. I now filtrated the 

 former portion, and added it to that already mentioned, 



It was then evaporated to dryness, and left a pale brownish mass, which was dis- 

 solved again, by digestion, in the smallest possible quantity of muriacic acid. 

 Water was added, in a very large proportion, to this solution, without producing 

 any effect; I then, by prussiate of pot-ash, precipitated a quantity of iron, which 

 was separated by a filter. The clear solution was then saturated with lixivium of 



