in exceptional seasons I have known an extra crop of clover hay to be
harvested in the late fall on the land where the oats were grown.

"In regard to the lime question," Percy continued, "I wonder if you know
of the work the Pennsylvania Experiment Station has been doing with the
use of ground limestone in comparison with burned lime."

"No, I never heard of ground limestone being used. I supposed it had to
be burned. I should think it would be very expensive to grind
limestone."

"No, it costs much less to grind it than to burn it," Percy replied.
"Mills are used for grinding rock in cement manufacture, and the rock
phosphate and bone meal must all be ground before using them either for
direct application or for the manufacture of acidulated fertilizers; and
limestone is not so hard to grind as some other rocks. Furthermore it
does not need to be so very finely ground. If fine enough so that it
will pass through a sieve with ten meshes to the inch it does very well.
That you see would be a hundred meshes to the square inch; and, of
course, a great deal of it will be much finer than that. In fact the
ground limestone used in the Pennsylvania experiments was only fine
enough so that about ninety per cent. of it would pass a sieve with ten
meshes to the inch, and yet the limestone gave decidedly better results
than the burned lime, and it is not nearly so disagreeable to handle.
Besides this, the ground limestone is much less expensive. It can be
obtained at most points in Illinois for about a dollar and fifty cents a
ton."

"A dollar and fifty cents a ton!" exclaimed Mr. Thornton. "Well, that is
cheap, but how about the freight and the barrels and bags? Freight is a