Whereon he told the neighbouring farmers that they had a mine of wealth opened to them, if they would but use them for manure.

And after a while he was listened to.

Then others began to find them in the Eastern counties; and then another man, as learned and wise as he was good and noble--John Paine of Farnham, also now with God--found them on his own estate, and made much use and much money of them: and now tens of thousands of pounds' worth of valuable manure are made out of them every year, in Cambridgeshire and Bedfordshire, by digging them out of land which was till lately only used for common farmers' crops.
But how do they turn Coprolites into manure?
I used to see them in the railway trucks at Cambridge, and they were all like what I have at home--hard pebbles.
They grind them first in a mill.

Then they mix them with sulphuric acid and water, and that melts them down, and parts them into two things.

One is sulphate of lime (gypsum, as it is commonly called), and which will not dissolve in water, and is of little use.