552 LIME. 



Lime). This substance is considered to act in two ways : — 

 directly, as food for plants, to which, being soluble in water, it 

 supplies sulphur and lime ; and, indirectly, by its action on the 

 volatile carbonate of ammonia, which, wherever they meet, it 

 "fixes." In this latter respect it acts in the soil on the 

 ammonia of rain-water, as it does when applied to our dung- 

 hills. Between sulphate of lime and carbonate of ammonia, 

 when they meet in solution, a double action ensues ; each of 

 these salts is decomposed, and their elements unite in the forms 

 of carbonate of lime and sulphate of ammonia : the advantage 

 of the change arising from this latter salt of ammonia not being 

 volatile as the carbonate is. The ammonia, the most important 

 ingredient in manures, and the most fertilising element of rain- 

 water, is thus retained for the benefit of the soil — safe from 

 risk of loss by evaporation to the air again. Gypsum has been 

 found to benefit green crops, as the Turnip, Cabbage, Potato, 

 &c., and leguminous crops, as the Clovers, &c., more than 

 grain crops. The results of numerous experiments have been 

 published : much greater importance was at one time attached 

 to the manure, especially on the Continent, than subsequent 

 experience has justified, and accordingly its influence on a 

 variety of plants has been tested in every possible way. Those 

 who are curious on the subject wiQ find a long and interesting 

 chapter upon it in Boussingault's Rural Economy. Johnston's 

 Agricultural Chemistry, too, is as instructive upon the theory 

 and use of gypsum as it is upon all the other points regarding 

 manures, soils, and plants which come within its province. 



As to the rate at which this manure should be used, that of 

 course is dependent upon the composition of the soil and of 

 the plants for whose benefit it is to be applied : points so 

 difficult and expensive to ascertain, that the common practice 

 of sowing 4 or 5 cwt. per acre broadcast over the young plant 

 in spring must in general be adopted. And when applied 

 along with farm-yard manure, for the purpose of retaining the 

 ammonia evolved during the fermentation of the mass, it must 

 be used in the same rough way. It is cheap, and of itself 

 useful as a fertiliser, independently of its indirect value as a 

 fixer of ammonia. The theory of its action in this latter 



