PHYSICAL A^jD LITERARY. 217 



contiguous particles as are deftitute of it, and 

 no effervefcence appears until that part of the 

 alkali, which was in a cauftic fotm or defti- 

 tute of air, be nearly faturated with the 

 fedative fait. But if, on the other hand, a 

 large proportion of the fedative fait be per- 

 fedlly and fuddenly mixed with the alkali, 

 the whole, or a large part, of the air is as 

 fuddenly expelled. 



In the fame manner may we alfo ex- 

 plain a fimilar phanomenon^ which often 

 prefents itfelf in faturating an alkali with 

 the different acids : the effervefcence is 

 lefs confiderable in the firft additions of 

 acid, and becomes more violent as the 

 mixture approaches the point of faturation. 

 This appears moft evidently in making the 

 Jal diureticus or regenerated tartar : The 

 particles of the vegetable acid here employed 

 being always diffufed thro' a large quantity 

 of watsr, are more gradually applied to thofe 

 of the alkali, and during the firfl additions 

 are chiefly united to thofe that are freeft of 

 air *. , 



Vol. IL E e That 



* Boerh. Operat. Chem. procefs. LX XVI. 



