J5 8 A TREATISE ON THE CONNECTION OF 



<ed, and the vitriolic acid of the gypsum will join with the 

 mineral alkali, forming Glauber salt, which is very soluble. 

 The quantity of gypsum previously existing in the soil is 

 to be ascertained by weighing, when properly dried, the 

 calcareous matter which had been precipitated by the al- 

 kali ; and by adding thereto, in calculation, the propor- 

 tion of vitriolic acid necessary to constitute it gypsvim ; 

 having previously deducted therefrom the proportion of 

 fixable air which the precipitated chalk contains. The 

 proportion of fixable air and vitriolic acid contained in 

 chalk and in . gypsum are in the proportions as here 

 stated : 



Fixahk Air Calcareous Matter 

 In chalk, 43 53 



Vitriolic Acid Calcareous Matter 

 In gypsum; 48 34 



The following is given as an example of the method 

 of making this calculation : 



Residuum 



