^ Anal<jfts efthe Sydiuy Marth, 



tvtxh, for examplct was fometimes greater, and the alumine and iron proportlonably left. 

 Some fpeciniens were alfo nearly or totally deftitute of the dark grey fliining particles : in 

 fliort, <:yery circumftance wa» fuch as might be expected from a mixed fubftance, which, 

 from the nature of its formation, cannot have the ingredients in any fixed proportion *. 



As this fubftance agreed in its general chara£lers, for the greater part, with tlwt <k- 

 fcribed by Mr. Wedgwood, and as it was indifputably brought from the fame place, there 

 appeared every reafon to believe that the nature of both was the fame ; but, to obviate as 

 much as poffible any doubt or objection, I determined to repeat the experiments, and the 

 analyfis, on that portion which remained of the identical fubftance examined by Mr. 

 Wedgwood, and which from that period had been referved by Sir Jofeph Banks, who 

 kindly favoured me with it for this purpofe. 



SECT. III. 



Jnalyfis of the Sydiieia, No. 2. 



TPIIS fubftance, as has already been mentioned, confifts of a white tranfparent quartzofe 

 fand, a foft opaque white earth, fome particles of white mica, and a quantity of dark lead- 

 grey particles, which have a metallic luftrc. 



The Sydneia, No. 2, appears chiefly to differ from No. i, by being more arenaceous, 

 and by a larger proportion of the dark grey particles. Many experiments, fimilar to thofe 

 made on No. I, already defcribcd, were made on this fubftance, with pure concentrated 

 muriatic acid ; but, as none of thefe afforded any appearance of a precipitate by the means 

 of water, I do not think it neceffary to enter into a circumftantial account of them, and 

 ihall proceed therefore to the analyfis. 



A. 100 grains were expofed to a red heat, in a glafs retort, and, after half an hour, were 

 found to have loft in weight 2.20 grains. 



B. The 97.80 grains which remained were mixed with 300 grains of dry carbonate of 

 potafh, and the mixture was expofed to a ftrong red heat, in a crucible of filver, during 

 three hours. 



When cold, the mafs was foftened with water, and was put into a glafs matrafs. I 

 then added three ounces of pure concentrated muriatic acid, and digefted it for two 

 hours in a ftrong fand heat. BoiHng water was then added ; and the whole being poured 

 on a filter, the refiduum was edulcorated, dried, and made red-hot : it then weighed 85.50 

 grains. 



C. The filtrated folution was evaporated to one fourth ; and pure ammoniac being added, 

 a precipitate was formed, which, after a red heat, weighed 10.70 grains. 



D. One ounce of muriatic acid was poured on the to. 70 grains, in a matrafs, which was 

 then heated. The whole erf' the 10.70 grains was diflblved, excepting a fmall portion of 

 Cliceous earth, which weighed 0.30 grain. 



• The defcription given by Mr.KIapreth convinces me that his experiments were made on a portion of this 

 fubftance. • Moreover, wlien my late friend Mr. Haidingcr was in London, I gave him fome of this earth fop 

 bis colle£lion ; fo that, whether Mr. Kl'aproth made his experiments on that which had be«n received by 

 Mr. Haidinger from Sir Jofeph Siknks, or from mjfcff, it i* not lesfb certain that he operattd en tkat which 

 Mig^ be regarded a« (Iw geiMune $<«)iW«. 



E, The 



