66 The Principles of Part IL 



I TOOK, four ounces of it, and warned off 

 the light earthy parts by mixing water 

 often with it ; in this way I got ten drachms 

 of a whitifh powder, which appeared to be 

 clay. The remainder was compofed of 

 two parts, a fine grey powder, which ap- 

 peared to be fand; and fome large parti- 

 cles, white and green. Thefe did not ef- - 

 fervefce with acids, nor yielded a tindure 

 of fpirit of wine ; but felt foft and undtuous 

 in the mouth, and when boiled with fbap- 

 afhes, and fpirit of nitre added to the lixive, 

 afforded a heavy oil. This mews them to 

 be of an oily nature. 



SOAP-ROCK appears from thefe experi- 

 ments to contain near a third of clay, a 

 much greater proportion of fand, and a 

 body of an oily heavy nature. 



THAT I might go a little further, and 

 difcover its effects in vegetation, and with 

 what foils it would agree beft, the follow- 

 ing 



