On tlie nianurlal Kflfect of Calcium Cyaiiainide. 



95 



C 



D 



lo.o g. lime-nitrogen 



4.6 g. double superphosphate 



3.91 g. potassium sulphate 



8.44 g. sodium sulphite 



lo.o g. limt-nitrogen 



g.38 g. secondary sodium phosphate 



3.91 g. potassium sulphate 



Of these four mixtures, A was decidedly acid, D decidedly alkaline, 

 while B and C approached the neutral reaction. Further, in order to 

 provide the pots A and B with as much lime as was contained in the 

 lime-nitrogen, 17.27 g, gypsum were added to these pots on Sept. 7. 

 Gypsum was selected in order not to change chemically the ammonium 

 sulphate ; and in order to observe here at the same time the difference in 

 action between gypsum and limestone, two other pots A' and B' were 

 prepared in which the equivalent amount of powdered limestone was added 

 on Sept. 7. By this addition, perhaps a little of ammonium sulphate was 

 gradually transformed into ammonium carbonate, the same product which 

 also would be the active principle in the pots C and D. While ammonium 

 carbonate in high dilution is probably more favorable than ammonium 

 sulphate, some loss of this compound by volatilizition may take place from 

 soils of little absorptive power, so that the benefit produced in one respect 

 may be frustrated by a disadvantage in another. The following table shows 

 the manuring data, g : 



