^8 Br. Wall on the Ortg'm of the 



me the honour to affociate me with them, to thefe? 

 fubjedts, fo far as to lead to any new experiments, 

 by which-the qualities and preparation of arti- 

 cles fo important may be more perfcftly in- 

 veftigated and explained, and the great expenc'e 

 attending the prefent mode of preparing or im- 

 porting them diminiflaed. 



The very curious procefs, difcovered by Mr. 

 Birch, and related by you. Sir, wich fo much 

 perfpicuity in the Philofophical Tranfaftions, 

 for procuring the vegetable alkali from the 

 water of dunghills, may be adduced as a proof, 

 that very confiderable improvements have been 

 lately made in the preparation of this fait. And 

 as the fum paid by the nation to RufTia, and other 

 foreign dates, is no lefs than one hundred and fifty 

 thoufand pounds per annum, for pot-afh, * every 

 hint towards an improvement that can be fug- 

 gefted in its preparation, is valuable, efpecially 

 as it is not impoffible, that we may now alfo lofe, 

 in a confiderable degree, the advantage of that, 

 which has been hitherto prepared for the ufe of 

 thefe iflands in North America. 



This alkali, having been long obtained folely 

 by the combuftion of vegetable fubfl-ances, was 

 by moft chemifts confidered, as a produflion of 

 the fire, formed by fome fecret combination of 

 the earthy, and perhaps fome portion of the in- 



* Watfonh Efiays, Vol. I. p. 135. 



flammable 



