168 ON THE RATIONALE OF CERTAIN MANURES, ETC. 



begins by calculating- tliat the quantity of clover covering 

 an acre of land had gained by the application of gypsum as 

 much azote as it would have required 134 lb. of carbonate 

 of ammonia to produce. 



Now, the average quantity of rain which falls in Alsace 

 could in no case convey to the gypsum in a year anything 

 approaching to that quantity of carbonate of ammonia, so 

 that it is impossible that the application of gypsum to the 

 land could have generated the whole of that quantity. But 

 who does not see that the gypsum, according to Baron 

 Liebig's hypothesis, Vv'ould not only absorb ammonia from 

 the rain water, but also condense that which was exhaled 

 from the ground, in consequence of the decomposition of 

 animal matters; and it is the more surprising that this 

 should have been overlooked by Boussingault, as he states 

 just afterwards that gypsum exerts no truly beneficial in- 

 fluence upon artificial meadows, excepting when the soil to 

 which it is applied contains an adequate proportion of azo- 

 tised organic manure. 



The ])ractice, therefore, of sprinkling the clover leaves 

 with gypsum may have its use in arresting the ammonia 

 exhaled from the ground, as well as that which descends 

 with the rain from the heavens, and in bringing both the 

 one and the other into immediate contact with the absorbing 

 surfaces of the plant. 



According to this view of the subject, the uses of g3'psum 

 in agriculture will be partly general and partly special — 

 general, in fixing ammonia, which all plants more or less 

 require; special, in supplying sulphate of lime to those 

 species which contain it in their organization, and therefore 

 most serviceable to those, like the leguminse, which con- 

 tain the largest proportion of this ingredient. When the 

 substance alluded to is sprinkled over the leaves of the 

 young crop, as is the case in France, it would seem that the 

 first of these objects is the one principally attained ; where 

 it is mixed with the soil, the second. 



The former mode may prove serviceable, whatever may be 

 the com])osition of the soil itself; but the latter method of 

 administration appears to presuppose that the soil was de- 

 ficient in it, and, consequently, ought to be preceded by an 

 actual analysis of its ingredients. 



Farmer's Magazine, Nov. 1846, 



