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portion of alumlne. In thofe of the fecond, 

 the quantity of lime was great, and that of 

 the filex moderate. In the third, the por- 

 tion of the Ume was moderate, and that of 

 the filex large. In the laft, the quantity of 

 filex was very great, and that of the lime 

 fmall. 



From thefe fa6ls it appeared to me evi- 

 dent, that it was not neceffary to have re- 

 courfe to an imaginary tranfmutation, fince 

 the gradations in the fame ftone above de- 

 fcribed might be explained without it, 

 Thofe flints which make a part of the fame 

 ftratum with the calcareous carbonates, fhew 

 that tiiey were fonned at the fame time with 

 them ; that is, when they were produced by 

 the numerous fediments of the fea-water 

 loaded with calcareous mixed with filiceous 

 particles. When the latter were abundant 

 in the fame place, they united by the force 

 of affinity ; forming, by their precipitation, 

 filiceous ftrata continued with calcareous; 

 and when the filiceous particles were few 

 in proportion to the calcareous, they united 



witl^ 



