. [ 213 ] 



tartarin which decompofed loo parts of vitriolated ftronthian, con- 

 fequently the earthy part amounts to 58 grs. 2 Klap. 96, 97. 

 Then 100 of this earth take up 72,41 of real vitriolic acid ; and 

 loo grs. real vitriolic acid would take up 138 of ftronthian earth. 



SeSiion c^tb. 



Aerated Lime and Selenite. 



In artificial aerated lime formed by precipitation, by foda or even 

 by common tartarin, if added to excefs, the proportion of lime to 

 fixed air is conftant, being as 55 of the lime to 45 of the air, that 

 is, as I r to 9, fo that the quantity of air being given that of the lime 

 in the compound may be known ; and if the compound be free 

 from any other ingredient, and heated to rednefs to free it from 

 water, then its weight being given the quantity of lime it contains 

 is found by multiplying it into 0,55, and the quantity of air by 

 multiplying it into 0,45, ; but whether dry or not, the weight of th& 

 air being found, the weight of lime is found by the i ft analogy. 



Mr. Bergman repeatedly afferts, that 100 grs. of calcareous 

 fpar contain 55 of mere lime, 11 of water, and only 34 of fixed 

 air. It always gives me concern to find my refults different from 

 thofe of this great man, but on this occafion I am happily able to 

 detedt the caufes of this difference. 



I ft.. 



