?i4 ESSAYS AND OBSERVATIONS 



appears until the fubjedt be converted into 

 afhes, and is fuppofed to be formed by the 

 fire, and to be the refult of a particular com- 

 bination of fome of the principles of the ve- 

 getable ; one of which principles is air, which 

 is contained in large quantity in all vege-r 

 table matters whatever. But as foon as the 

 fmalleft part of a vegetable is converted intd 

 afhes, and an alkali is thus formed, this fait 

 necelTarily fufFers a calcination, during which 

 it is kept in a fpongy form by the aflies, and 

 fhcws a very confiderable degree of acrimony 

 if immediately applied to the body of an 

 animal j but if the afhes are for any time 

 expofed to the air, or if we feparate the alkali 

 from them by the addition of a large quantity 

 of water and fubfequent evaporation, the 

 fait imbibes fixed air from the atmofphere, 

 and becomes nearly faturated with it : tho* 

 even in this condition it is generally more 

 acrid than fait of tartar, when this is pre- 

 pared with a gentle heat. 



Borax has fometimes been referred to the 

 clafs of alkalis, on account of fome refem- 

 blance it bears to thofe falts : but it has been 

 demonftrated by accurate experiments, that 

 we fhould rather confider it as a neutral fait s 



that 



