[ 41 ] 



Answers to Queries on Plaister of Paris^ by Mr John 

 Curwen, of Upper Merton^ Montgomery County. 



W, Hill, August lOth, 1796, 

 Dear Sir, 



Inclosed are my answers to your queries, agreeably 

 to your request. 



If the plaister is compounded of a mineral acid and 

 calcareous earth, it may be suspected that both have a 

 share in its effects ; for it can hardly be supposed that 

 such can be produced from it less than a bushel of cal- 

 careous earth to an acre ; and may it not be presumed 

 that some active substances, which in large quantities 

 are poison to vegetation, may, in very small ones be 

 friendly to it ; or may not the compound have quali- 

 ties, not found in any of its parts ? 



If in England it has no effect on grounds which have 

 been long under cultivation, and especially those which 

 have been limed, America may boast of superior ad- 

 vantages. My answer to the 10th Query shews the re* 

 suit of my experience on that point. 



Query 1. How long have you used the plaister? 



Ansxver. Ten or eleven years ; at first in small quan- 

 tities, but finding it beneficial, have used a good deal 

 for several years past. 



Query 2. What state was the land in when you be- 

 gan to use it ? 



Answer. Generally on limed and dunged land which 

 had been much exhausted previous to this by bad tillage 

 without manure. 



Query 3. What quantity per acre have you generally 

 used? F 



