828 



GYPSUM. 



that it cannot be reasonably ascribed to the mineral manure : in fact, 

 the quantity obtained from the gypsed surface does not exceed that 

 which we constantly take from fields in the ordinary course of cul- 

 tivation, and which have received no gypsum. 



The action of gypsum, limited as it is to certain crops, will not 

 allow us to admit that it produces its effect by fixing in the ground 

 the carbonate of ammonia contained in rain-water ; were it connect- 

 ed with any fixation of ammonia, it would be manifested generally, 

 and not in particular instances only. Davy's theory therefore ap- 

 pears the more plausible, and requires discussion. Did the ashes of 

 the clover grown in gypsed soils actually contain a large proportion 

 of sulphate of lime, as affirmed by the illustrious English chemist, 

 the action of gypsunff would be readily understood. The whole 

 question, therefore, seems to turn upon the composition of the ashes. 



I have analyzed the ashes of clover grown at Bechelbronn, with- 

 out and with the concurrence of gypsum. I shall here give the 

 conclusions come to in 1841, a year remarkable for the heavy crops 

 of clover, and those also for the year 1842, when the clover crop 

 was but indifferent. The first table contains the results in the order 

 in which they were registered ; the second contains those obtained 

 after the deduction of the carbonic acid and carbon which had re- 

 mained in the ashes examined : 



