USE OF GYPSUM ON LIMED LAND. 129 



to soils in which the proportion of lime has been determined by 

 analysis, might help us towards clearer views as to the agency 

 of the lime contained in gypsum. 



Again, is its effect less upon land which has been regularly 

 limed? I have elsewhere shown that all our limes contain 

 gypsum, and that the natural presence of gypsum upon limed 

 land may modify the action of this substance when afterwards 

 directly applied to it.* I need only indicate the companion 

 series of experiments upon soils more or less rich in sulphuric 

 acid, in any of its states of combination. 



g Peas and beans are known to be sometimes what are 

 called good, sometimes bad, boilers to boil sometimes hard, 

 and sometimes soft and mealy. Gypsum is accused, while it 

 promotes their growth, of imparting this quality to tares, peas, 

 common beans, and haricots. Is the accusation just? has it 

 such an effect upon any of these crops ? Have waters which 

 contain gypsum the property of hindering the boiling of 

 legumes?f and will a little soda prevent this effect? Expe- 

 riments on these subjects are easy to make. They require only 

 a testing of the quality of such crops as have been doctored 

 with gypsum, applied in weighed proportions, at different 

 seasons and on different soils. 



h Experiments with gypsum as a fixer of ammonia. I have 

 already explained, in the previous section, that gypsum, when 

 moist, has the property of decomposing carbonate of ammonia, 

 and forming a sulphate of ammonia which is fixed not volatile, 

 that is, or likely to fly off into the air as the carbonate does. 

 In consequence of this property of gypsum, it has been much 

 recommended as a means of removing the smell of stables, and 

 preventing the escape of ammonia from dung-heaps. The 

 practical man may try experiments of this kind, and possibly 



* See The Use of Lime in Agriculture, pp. 212, 248. 



f This is a very old opinion. Thus Palladius alludes to it in his section on 

 The proving of water : " You will prove new water thus you sprinkle it over 

 a clean brazen vessel, and if it makes no blur it may be discovered to be proof. 

 Being boiled, also, in a brazen vessel, if it leaves no sand or mud at the bottom, 

 it will be good for use; if it also boils pulse soon, or if it is pellucid, free from 

 moss and from every mark of pollution." (Agriculture of Palladius, translated 

 by OWEN, book ix., 10.) 



I 



