365 



SECTION XX. 



The Nature of Plaster of Pam, and proper 

 Directions given for itsing it. Several Ex- 

 periments tried, and a Proof oj' its valuable 

 Qualities. 



The French plaster of Paris and that from 

 Nova Scotia are both of the same nature : no 

 difference is to be discerned in using them : 

 and I am of opinion that the EngUsh 

 plaster, ground in the same manner, would 

 have a similar effect, as the principal use of 

 it is, that it attracts moisture, hinders the 

 heat of the sun from penetrating so deep 

 into the soil, and prevents exhalation : 

 so much so, that the earth where the turnips 

 growed would look much blacker intheparts 

 to which the plaster was applied : the sun 

 causes so great exhalation in America, that, 

 in the evening of a hot day, the vapours 

 rise from the swamps like the steams of hot 



