SOILS, MANURES, &c. 233 
In the above arrangement, the mod 
powerful attra&ors are placed firft, and 
the reft in their proper order : if any of 
the acids be mixed in due proportion 
with any of the alkali’s, and diffolved in 
water, they will combine and reciprocally 
naturalize each other; again, if cauftic 
volatile alkali be united with any acid,, 
fixed vegetable alkali, on being added to 
the folution, will take poffefiion of the 
acid, and drive off the volatile alkali; 
or if calcareous earth be united with an 
acid, on the application of fixed vegeta¬ 
ble alkali to the folution, the acid and 
alkali will unite, and the earth will be 
feparated, and precipitate or fall to the 
bottom. 
Alkaline falts appear to contain the 
bafis, or matrix, of the nutritive matter 
proper for plants ; they attrafl the nitrous 
acid of the air, which is fuppofed to be 
H h the 
