On Plaister of Paris. | 45 
the desired effect, and I am inclined to think there is 
little or no difference. 
~ Query 12. Its duration ? 
Answer. With me it has not been uniform. Whether 
it depends on the quantity put on, the nature of the soil, 
the difference in seasons, or the goodness of the plaister, 
I cannot say; but it will sometimes fail the second 
year ; sometimes it will last four or five, and where it 
has been put on the hills of Indian corn, and afterwards 
mixed with the soil by ploughing, I have known its ef- 
fects visible for six years, and continue the same length 
of time on an exhausted soil never manured. 
It is no small addition to the value of plaister, that 
the grass lands on which it has been spread, are not 
near so much injured by drought as others, and that 
cattle love to pasture on them better. 
The expence of raising red clover with plaister and 
a small quantity of dung, and raising it with dung alone 
(if bought at the common prices) may I think be esti- 
mated as one to five. 
I am, Sir, your’s sincerely, 
Joun Curwen. 
