158 0?i Gypsum. 



rotted dung, compost, or ashes, to which it gives re- 

 markable activity. I do not profess so accurately to 

 know causes ; but only, with confidence, relate effects 

 on vegetable products. The first must remain con- 

 jectural ; the latter are too visible and sti'iking to con- 

 tinue disputable. It still evinces the like effects ; with 

 similar materials to work on. What in my compen- 

 dious compilation, I threw out as a conjecture ; is fiDund 

 on experience, with the strongest appearance of proba- 

 bility, to be the chymical principle or agent of its ope- 

 ration. When I first mentioned this to the late Dr. 

 Priestley; he received it \vith hesitation. But some 

 years thereafter, he told me he was convinced of its cor- 

 rectness. He had received information from Europe 

 (I think from France) confiniiative of the opinion, that 

 whatever substance contained sulphuric acid foii of vi- 

 triolj would produce similar effects in agriculture. He 

 told me, that our then minister, Mr. Livingston^ had 

 observed the Flemish farmers applying burnt pyrites^^ 

 in the same manner, and for the same purposes, we use 

 the gypsum. 



The first time I saw the agricultural effects of the 

 gypsum^ was several years before the commencement of 

 our revolutionar}^ war; on a city lot belonging to, or 

 occupied by, Mr. Jacob Barge, on the commons of 

 Philadelphia. He was the first person who applied the 

 gypsum in America to agricultural purposes ; but on a 

 small scale. This worthy citizen still lives, at a very 



* Mr. Livingston's account of the mode of preparing this 

 substance and the particulars respecting its use, are annexed 

 to the present volume. 



