PHYSICAL AND LITERARY. 49 



the operation of marie in agriculture ; 

 for the marles here employed had cer- 

 tainly been expofed as long as might 

 have been fuflicient for the attracflion of 

 a confiderable portion of the aerial acid, 

 and the confeqaent formation of a fenii- 

 ble quantity of a neutral fait. But thefe 

 marles evidently contained nothing of 

 a faline nature. For, by digeflion in 

 water, the proper menjlnium of every 

 fait, they fufFered in weight no diminu- 

 tion of any confequence. The grain 

 wanting in Experiment 30. and the half 

 grain in Experiment 31. may be fafely 

 allov9-ed as the confequence of lofs of fub- 

 ftance, which no atuention can prevent 

 in the procefs of fuch experiments. But, 

 fuppofing this diminution of weight really 

 to proceed from the folution of fome fa- 

 line iubiUnce, luch an inconfiderable 

 quantity ot fik will by no means account 

 for the effects produced by marie; there- 

 fore thele eff^cls mult proceed from 

 fome other caule. 



The filtered waters left, upon their e- 



Taporation, a fubitance which did not in 



Vol. III. G the 



