On Gypsuin, 175 



know, that when the earth is deprived of these solvents, 

 subjects of affinity, or by whatever name they may be 

 called, he must supply them artificially. He will find, 

 as I believe, this conclusion agriculturally right, what- 

 ever may be its chymical theory. The opinions of chy- 

 mists I highly respect, on any chymical topic. Unum- 

 quisque in sua arte peri tus. They have in many impor- 

 tant instances, highly served the interests of agriculture ; 

 between which and chymistry, there is an intimate and 

 all important connection. It is to be wished, that more 

 chy mists were also farmers, and the soil their laborato- 

 ries. The whole earth, in connection with its atmos- 

 phere, is the grand laboratory of nature. All that it 

 contains, produces and supports, acting and acted upon, 

 distinctly or in combination, bring forth effects by chy- 

 mical processes, essential to their mutual existence. 

 But the matter and the manner, are to us more subjects 

 for conjecture, than of accurate knowledge. We must 

 therefore depend the most, on practical facts. 



Lord Dufulonald in his " Treatise on the connection of 

 agriculture with chymistry'''' (Lond. Ed. 55-6-7-8) has 

 given an account of the vitriolic acid^ and its operation 

 and effects, as they relate to agriculture. Some per- 

 sons of chymical information, are not satisfied with all 

 his theory. But I believe his book is generally allow- 

 ed to have great merit. One part of his account of this 

 acid, he applies to the use of plaister in ylmerica. In it 

 he observes what we know by experience in its result. 

 " Still the gypsum remaining in the soil would, on a re- 

 newed application of dung^ animal or vegetable matter, 

 be brought from the state oi gypsum, which is insolu- 

 ble, to a state approaching to that of hepar of lime, 



