314 On Gypsum. 



It appears in professor Barton'' s Medical and Physi- 



to that imported here, will annually amount to 20000 tons. 

 With this quantity 250000 acres may at this time be manur- 

 ed. The immense advantages derived in a long course of 

 years, by the progressive use of the plaister, may be conceiv- 

 ed, to be of great magnitude, but cannot be accurately cal- 

 culated. To say that by a process begun on txvo acres, txvo 

 millions of acres have been ameliorated from the beginning 

 of its application, would no.t perhaps be extravagant. 



These circumstances are mentioned to encourage experi- 

 ments, and persistance in applications of substances likely to 

 become useful in husbandry ; without regard to prejudices or 

 partial disappointments. Who can now tell, whether we may 

 not have among ourselves, some substances, perhaps passed 

 over every day without notice, which may turn out as won- 

 derfully productive and useful, as the plaister is now indis- 

 putably proved to be ? And these may be as little believed in, 

 or supposed as little likely to succeed, as the gypsum origi- 

 nally appeared. R. P. 



Since this communication was put to press, I am inform- 

 ed by a friend who lately conversed with professor Bart07i ; — 



That the Doctor " had lately received a letter from his bro- 

 ther in Virginia^ stating that genuine gypsum has recently 

 been found in three different parts of that state. In two of 

 these places, however, the Doctor has already hinted that he 

 believed it probably existed." 



In his oration (page 56) delivered before the Linnean So- 

 ciet)^ on the 10th of June, 1807, he says, " That important 

 substance, gypsum^ or plaister of Paris, is now kno^\'n to exist 

 in various paits of the United States. I have found it in 

 great abundance at the Falls of Niagara. It is likewise found 

 upon the same slope, at the Falls of the Jemsseia river ; and 



