CONTENTS. 



Page. 



Introduction 7 



Experimental methods 9 



Results with pure solutions 9 



Results with maize (Zea mays) 9 



Eesults with cotton ( Gossypium) 9 



Results with sorghum ( Andropogon sorghum ) 10 



Results with oats ( Avena sativa ) 11 



Results with sugar beets (Beta vulgaris) 11 



Comparison of results with eight species in pure solutions 12 



Results with mixed solutions 14 



Neutralizing effect of an excess of calcium sulphate 15 



Neutralizing effect of smaller amounts of calcium sulphate 16 



Results with Lupinus albus 16 



Results with Andropogon sorghum 17 



Summary 19 



Index 21 



113 5 



