1 82 On plaster of Pans. 



If I wanted a strong proof of its failure after the vege- 

 table matter was exhausted, or its efficacy when that 

 matter uas in plenty ; I could not be furnished with 

 one more in proof, than that of the farmer you mention. 

 In his orchard, the magazine for setting the plaster at 

 work, were found in profusion ; as is always the case m 

 old, and even weedy fields. In the other parts of his farm, 

 it wanted the indispensable pabulum ; and had also to 

 encounter the decadency of the clover, which, sooner 

 or later, on the best cultivated fields, will occur. The 

 observation that the contrast in highly improved land, is 

 certainly less discernible, than it can be in soil of the 

 the contrary description, is reasonable. The first re- 

 quires less plaster ; but a bushel to the acre, will always 

 do good. I say always ; but I am still consistent in my 

 ori^'inal assertions, — that its non-appearance in some sea- 

 sons, is not to be taken as a ^e'W(?rcf/ objection ; fori 

 x^^vA\(^K\ facts to shew, that it has laid torpid, for one, 

 two, and three years ; and has afterwards operated vigor- 

 ou.^ly. Perseverando \ya% been my motto ; and, with 

 the auxiliaries 1 have mehtioned, I can truly say, Ihave 

 never found reason to alter my first opinions. I have 

 known it fail on Indian corn plants ; and have seen the 

 spots v^here the corn had been, several years thereafter, 

 throw up spontaneous growths of luxuriant clover. If 

 in repeatedly plastered fields its efficacy is lost, on limed 

 lands its inefficacy is as often perceivable. Nothing is 

 more mischievous than a too frequent or profuse appli- 

 cation of lirne. We cannot account for every thing we 

 see ; although, in the pride of human reason, we aim at 

 impracticable flights, whilst we endeavour to explain 

 inexplicable things. 



Accept my respects, 

 R. Petees, 

 Dr, JVilliam Darlmgfon. 



