no An ANALYSIS of 



water through it feveral times. Being then dried on the fil- 

 trating paper, it contracted greatly, and was divided by fifTures 

 into a great number of fmall parts, as would have happened to 

 fine clay, had the fame quantity of it been dried on paper in a 

 limilar manner ;' and when it was feparated from the paper, and 

 further examined, it (hewed the qualities of an argillaceous 

 earth, combined with a fmall quantity of colouring matter. 

 This appeared by the following experiments : 



i. I put fome of it, which I had procured in different expe- 

 riments, into a, platina fpoon, and made it red hot. While 

 heating, it firft became black, then underwent a flight inflam- 

 mation, and afterwards became white, without changing its ex- 

 ternal form, being only a little contracted in its fize, and dimi- 

 nifhed in its weight. 



2. To another fmall mafs of it, laid on a plate of glafs, I 

 added a drop of aquafortis, which neither effervefced with it, 

 nor diffolved it, but only changed the colour to a paler red. 



3. Another fmall portion, which had been gently calcined, 

 was well mixed with an equal weight of the aerated. foffil alkali, 

 and then expofed to a ftrong heat in the platina fpoon. The 

 alkali was quickly melted and became cauftic ; but 1 could not 

 by its means bring the earth into fufion or if any was diilolved 

 by the melted alkali, it was only a very fmall portion, not per- 

 ceptible by the appearances. 



4. Nor did I fucceed much better, when I tried to melt ordif- 

 folve it by means of borax, heated on charcoal with the blowpipe. 

 A little mafs of this earth continued undiffolved in the melted 

 borax, and without any appearance of effervefcing with it, until 

 I was tired of the experiment. 



This earth therefore cannot be any other than the argilla- 

 ceous. Had it been the filiceous, it would have been melted with 

 the alkali into a tranfparent glafs, which happened eafily with 

 different fpecimens of pure filiceous earth, fubjecled to the fame 

 trial ; and had it been any of the alkaline earths, the borax 



would 



