On Plaister of Paris. 95 
It is customary, with some farmers, to sow plaister 
every year, onthe same ground,in smaller quantities, 
7. e. about a bushel to the acre; and some sow less, for 
several successive seasons. Some sowit 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 winter grain, which I have seldom sowed 
on my worn lands, unless they are previously limed, or 
than some others, which, not being susceptible butiof a very 
slow decomposition, such as chalk, lime, burnt and pounded 
bones, gyps, 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 Iam 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. 
NN 
* Whether the decomposition of the gyfs is slow or quick, is a mere conjecture. I find myself 
safest when I adhere to facts. From the invigorated appearance of vegetation, if 2 rain immedi- 
ately succeeds the sowing the plaister, I have thought the gyps was quickly decomposed ; though 
not so rapidly, as not gradually to yield its acid. Ido not contend for theories, if results are suffici- 
ent without them. — 
R. P. 
September; 1810. 
in 
