FIXED ALKALIES. Iu9 



not be advantageously made, I have been of opinion, that 

 a farmer might easily unite the manufacture of them to his 

 agricultural labors, and thus increase the income arising 

 from his lands: I shall therefore enter into some details 

 respecting it. 



All plants do not yield the same quantity of ashes, nor 

 do equal weights of the ashes of different plants afford the 

 same quantity of potash. Of the comparative value of cer- 

 tain vegetables, we may judge from the following Tables, 

 prepared from the experiments of Messrs. the Superin- 

 tendents-general of the powder and salt-petre works, for 

 the year 1779, and from those of Messrs. Kir wan, Pertuis, 

 and Vauquelin. 



15 



