GYPSUM, AND HOW IT WORKS. 245 



vitoe, the great specific, which is to retrieve all lands from 

 barrenness. % 



No fact is more apparent than that no such specific exists. 

 The rccoirimendations of salt, lime, iron, nitre, ammoniacal salts, 

 and a dozen other specifics, in our numerous excellent and useful 

 agricultural papers, cannot be regarded as beneficial to agricul- 

 ture. It is quite natural for a soil cultivator, when, in the 

 course of a series of experiments, he hits upon an article pecu- 

 liarly adapted to the condition of his soil, to desire to communi- 

 cate to others a knowledge of what has been so beneficial to 

 him. The motives are honorable and praiseworthy, but he may 

 thereby lead a neighbor into trying an experiment which ends 

 in utter failure ; and not only this, may do harm, by creating 

 prejudice against that which, under a change of circumstances, 

 might prove exceedingly useful. It will be understood that 

 these remarks are made against the empyrical use of single 

 fertilizing substances. If any one has time, and inclines to 

 experiment for his amusement, no harm can result, provided it 

 be understood that the field of knowledge cannot be greatly 

 extended by such labors, and that no observed beneficial results 

 are of much use, except to the experimenter. 



Perhaps gypsum may form an exception to these remarks. 

 Because of its peculiarly isolated character, and of the uncer- 

 tainty of its mode of fertilization, it must continue to be 

 employed empyrically until it is better understood. Gypsum 

 has been the great stumbling-block in the way of chemists, and 

 the question of its method of imparting fructifying influences 

 to plants is still an unsettled one. The facetious author of a 

 popular book upon husbandry remarks : " There has as yet been 

 found no law by which to govern its application. On one field 

 it succeeds ; on another, to all appearances precisely the same, 

 it fails. At one time it would seem as if its efficacy depended 

 upon showers following closely upon its application ; in other 

 seasons showers lose their effect. In one locality a few bushels 

 to the acre work strange improvements, and in another fifty 

 bushels work no change whatever. Now it is a hill pasture that 

 delights in it, and again it is an alluvial meadow." 



Liebig, after having advanced a very decided hypothesis 

 regarding its mode of action, has in his more recent work, " The 



