230 MY FARM. 



lights in it, and again it is an alluvial meadow. 

 Hence it offers peculiarly one of those cases, where 

 an observant and earnest farmer would be desirous 

 of calling in the aid of scientific opinion. 



And what will he find ? 



Sir Humphry Davy, that devout old gentleman, 

 who was as good an angler as he was chemist, ex- 

 ploded the idea prevalent in his day that gypsum 

 was beneficial by promoting putrefaction of manurial 

 substances and expressed the opinion that it was 

 absorbed by the plants bodily; at least by those 

 plants whose ash showed large percentage of sul- 

 phate of lime. Sir Humphry was honest ; the 

 theory was not too absurd ; the farmers were doubt- 

 less glad to get a handle to their talk about plaster ; 

 and so for a dozen years or more, the lucerne and 

 clover went on absorbing the gypsum. At last 

 some inquisitive party ascertained, by careful experi- 

 ment, that a field of clover not treated with gypsum, 

 contained as large a percentage of sulphate of lime in 

 its ash, as another field which had been treated to 

 the salt. The inference was plain, that the superior 

 vigor of the last was not attributable to simple 

 absorption of the sulphate, and the theory of Davy 

 quietly lapsed. 



Chaptal, the French chemist, speaks of gypsum in 

 a loose way as a stimulator ; but in what particular 



