174 On Gypsum. 



which is soluble." The effects of this re-application of 

 dung^ &c. we have often experienced; and let chymists 

 judge of the modus operandi. This book should be read 

 by all farmers desirous of gaining valuable information. 

 That new applications of plaister, with animal and vege- 

 table substances, will again operate, has been frequent- 

 ly and universally proved. But I met with an instance 

 to shew that gypsum lying in the earth for years, will 

 again operate, with such re -applications of subjects. 

 It also confirms my assertion, in the outset, that if too 

 much is applied, only the necessary quantity is opera- 

 tive. Many years ago, I gave an account of my having 

 used plaister, after it had remained five or six years, on 

 old indian com hills, whereon too great a quantity had 

 been injudiciously and unnecessarily lavished by a c 

 nant. It operated again where dung was applied, 

 though I thought not so vigorously as that recently ob- 

 tained. The excess of that applied too profusely, be- 

 yond what was required by the substances in the earth, 

 remained in its original state of composition. 



The author of nature (as Lord D. observes) has thus 

 v/isely directed, that acids, salts, and such volatile, -fu- 

 gacious and soluble parts of the system, should have an 

 affinity for, or tendency to form a chymical union with 

 stationary and more solid substances; that they may be 

 detained in the earth for the purposes designed by their 

 creator, and be ready again to act, when their agencies 

 are again demanded. If this were not the case, they 

 would escape, or be washed away in the waters of the 

 earth or the ocean; and thus pollute and poison one 

 part of the creation, while they left the other barren, and 



