4 ESSAYS AND OBSERVATIONS 



Amon^g the fubjedls of the mineral 

 kingdom, fome are foluble in water, fome 

 not. Of the firft, one only, the toffil al- 

 kali, is pofTeffed of properties fi'nilar in 

 any' degree to thofe of marie. For this 

 fair, which is collected principally along 

 the coafts of the Mediterranean fea, eJEFer- 

 vefces violently with acids, and has been, 

 time Immemorial, in the highell efteem 

 as a manure. From thefe circumftances 

 it might be fufpedled, that a very inti- 

 mate affinity fubfills betwixt this alkali 

 and marie, and that the fimilar effects of 

 both thefe fubRances proceed from the 

 fame caufe. To fatisfy myfelf vvith re- 

 gard to this particular, I made the two 

 following experiments. 



EXPERIMENT I. 



Two drachmsofclay-marle, newly dug 

 from the pit, were put into an ounce of 

 water, and for twelve hoars digelted with 

 a confiderable heat. I he marie, when 

 feparated by filtration and dried, retain- 

 ed preciiely its original weight. The di- 

 gefted water was devoid of tafte and 



fmell, 



