Anal^isofthe Sydney Earth. figi 



pltate of a pale yellowlfli colour was produced ; which, colle£led, edulcorated, and made 

 red-hot, weighed 103.70 grains. ' '/■' .■<.r.>1 



E. The filtrated liquor of D was again evaporated ; and carbonate of potafli -being' 

 added, a flight precipitation of earthy matter took place ; which, by the teft of fulphuric 

 acid, proved to be fome alumine which had not been precipitated in the former experi- 

 ment : this weighed 1.20 grain. 



F. The 103.70 grains of D were completely diflblved when digefted with nitric acid, 

 excepting a fmall refiduum of filiceous earth, which weighed 0.90 grain. 



G. The nitric folution was evaporated to drynefs, and a fecond portion of the fame acid 

 was added, and. in like manner evaporated. The refiduum was then made red-hot, and 

 digefted with diluted nitric acid, which left a confiderable portion of red oxyde of iron. 

 The folution was again evaporated, and the refiduum, being treated as before, again de- 

 pofited fome oxyde of iron, much lefs in quantity than the former. 



The whole of the oxyde was then heated with wax in a porcelain crucible, was taken up 

 by a magnet, and weighed 26.50 grains. 



H. The nitric folution of G was faturated with ammoniac, and a loofe white preci- 

 pitate was formed ; which, edulcorated and made red-hot, weighed 76 grains. 



I. Thefe 76 grains were diflblved when digefted with diluted fulphuric aid; and, when 

 the excefs of acid had been expelled by heat, the faline mafs was diflblved in boiling water. 

 To this folution I added fome lixivium of potafh, and, by gradual and repeated evapora-. 

 tions, obtained the whole in regular odtoedral cryftals of alum. 



K. The 274.75 grains of C now alone remained to be examined. They appeared to 

 confift of filiceous earth, mixed with the dark grey (hining particles already mentioned ; 

 but, as I Ihall defcribe, in the following experiments, the procefs by which thefe were fe- 

 narated, I fliall now only fay 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 foda. 

 It formed a colourlefs glafs ; and with four parts of the fame it diflblved in water, and 

 formed a liquor filicum : it was therefore pure filiceous earth or filica. 



The fubftance here examined was compofed therefore of the following ingredients : 



Grains. 



Pure filiceous earth or filica 

 Alumine - _ , 



0.90 

 267.25 

 1.20 

 76 



Oxide of iron - . . . G. 26.50 



Dark grey particles - - K. 7.50 



Water and vegetable matter - A. 19.20 



{h: 



398-55 



. The foregoing analyfis was repeated feveral times, and always with fimilar refults ; ex- 

 cepting that, as I had taken the fpecimenr from different parts of a large quantity, I found 

 that the proportioKS of the ingredients were not conftanUy the fame ;_ that of the filiceous 



L 2 earth. 



