xiv Preface. 



I had intended to form, from my own expe- 

 rience, assisted by the materials I could obtain 

 from others, an essay, in which all the knowledge 

 we have of the agricultural uses of the gypsum 

 might be concisely promulgated. But, on a subject 

 in which practice is the surest guide, /fl!c/5, vouch- 

 ed by men of practical knowledge exhibited in 

 their own words, seemed to me best calculated to 

 promote truth, remove prejudice, and to excite 

 and encourage inquiry and exertion. 



I had answered the queries on this subject 

 for private information, chiefly from the know- 

 ledge I had gained, in a long course of practical 

 attention to the uses and effects of the gyps; and 

 I find, since receiving the communications from 

 my friends, that their experience and mine, in 

 general, agrees. 



As to opinions and conjectures though they 

 may not at first be solid, they may possibly lead to 

 farther discoveries. In statements of agricultural 

 facts, made to those who are to judge of the merit 

 of experiments or practice, it is perhaps right to 

 avoid opinions and speculations. But in the pre- 

 sent publication, 1 have thought it proper to throw 

 out opinions, and even slight conjectures. My 

 view is to draw forth better opinions, and to set 

 scientific men to thinking on the subject. 



