On Plaister of Paris. 95 



It is customar}^, with some farmers, to sow plaister 

 every year, on the same ground, in smaller quantities, 

 L e, about a bushel to the acre ; and some sow less, for 

 several successive seasons. Some sow it every other year. 

 Those who practice these methods (by all of which I 

 have occasionally profited) consider them most bene- 

 ficial, for grass grounds particularly. I have generally 

 thought it best, to get abundant products in the shortest 

 time. I have therefore applied the gypsum in greater 

 quantities, to the clover husbandry ; and its operations 

 were in full vigour, as long as the clover continued on 

 the ground. When the clover fails, I plough and pro- 

 ceed with the usual course of crops, till it falls again 

 into its common rotation. This- generally happens in 

 the third year from my ploughing up the ley or sod, as 

 it succeeds w^inter grain, which I have seldom sowed 

 on my worn lands, unless they are previously limed, or 



than some others, which, not being susceptible biit of a very 

 slow decomposition, such as chalk, lime, burnt and pounded 

 bones, ^i//?^', impart, during several years, to the soil a pro- 

 lific quality."^ I had not seen this essay, when I gave an 

 account of my experience on the plaister. But I am much 

 confirmed in some of my conjectures, since reading this pro- 

 duction ; and particularly in my opinion, that the plaister ope- 

 rates most powerfully, when in connexion with animal or ve- 

 getable putrefied, or putrefying, substances. 



* Whether the decomposition of the gyps is slow or quick, is a mere conjecture. I find myself 

 safest wlieii I adhere to ikets. From the invigorated appearance of vegetation, if a rain immedi- 

 ately succeeds the sowing the plaister, I have thought the gjys was quiciily decomposed ; though 

 not so rapidly, as not gradually to yield its acid. I do not contend for tlieories, if results are suffici- 

 ent without them. 



R. P. 

 September^ 1810. 



