HINDRANCES AND HELPS. 231 



direction its stimulating qualities are supposed to 

 work, he does not inform us. 



About the year 1840, I think, Dr. Dana, of Low- 

 ell, published a bouncing little book called a Muck 

 Manual, in which he affirmed very stoutly that gyp- 

 sum was quietly decomposed by the roots of the 

 plants, when its sulphuric acid flew off at the silicates, 

 and worried them into soluble shape ; and its lime, 

 on the other side, flew off at the geine, pounding 

 that into a good relish ; in short, he made out so charm- 

 ing a little theory, so vivacious in its action, so 

 appetizing to turnips, and so authoritatively stated, 

 that we farmers must needs accept it at a glance, and 

 take off our hats, with" That's it,"" I thought so," 

 " The very thing." 



But straight upon this, like a thunder-clap, conies 

 Liebig,* who declares, in his authoritative way, that 

 the value of gypsum " is due to its faculty of fixing 

 the small quantity of carbonate of ammonia, brought 

 down by the rain and the dew ; " at this, we farmers 

 put on our hats again, and waited for the rain. 



Some two or three years after, M. Boussingault, 

 who had gone through the South-American wars 

 under Bolivar, and studied agriculture at Quito, as 

 well as on his own country-estate of Bechelbron, 



* His first book appeared in America, if I am not mistaken, 

 iii 1841. 



