66 Observations on Colonel Taylor’s Letter. 
existence. Theories sink under facts ; and I depend on 
the latter. Young grass does no harm. But I have lost 
crops by plaistering clover ; and throwing up luxuriant 
vegetation under wheat. 
You must get Dr. Seybert, or some other chemist, 
to inform how to discover the quantity of the sulphuric 
acid in plaister. It is good or bad, according to the 
proportion of this acid contained in it. My way has 
been to heat it ina dry pot ; and judge by the ebullition. 
But I now take it as I can get it. I find hard or soft 
stone very little different in effect; though it makes a 
great odds in pulverization. The colour is given by 
metals—most commonly—by iron. It is a sulphat ;— 
and its distinguishing characteristic is the sulphuric 
acid. If Mr. T. would keep this in view, and attend to 
the principles ] have mentioned often, both in the 
“ agricultural inquiries” and in our memoirs, he would, 
with his great industry, and agricultural, as well as 
other capacities, help us all in developing causes. The 
half bushel, doing as much as any quantity, is account- 
ed for on these principles. Our pupil will soon be our 
master. He wants no instruction. His facts agree with 
my experience, ever since gypsum was used here. With 
wheat or other culmiferous chaft-bearing crops, I never 
found it anywise efficient: except that rolling the seed 
in it gives an impetus to the first spring or shooting of 
the plant. I wish Mr. T. would gradually banish the 
heterodox custom of maize with wheat, in the same field. 
But the southern farmers will never listen to this Penn- 
sylvamanisme. We meet the fate of all preachers against 
inveterate habits. 
