52 CYANAMID MANUFACTURE, CHEMISTRY AND USES 



Kappen shows the relative decomposing ability of some well- 

 known constituents of ordinary soils. These materials were 

 selected so as to diifer as widely as possible from one an- 

 other, so that the effect of individual constituents might stand 

 out. Each substance was used in its natural condition, with- 

 out being sterilized, but ground to a fine powder. They are 

 all in the class of compounds that form gels in the soil. 



1. Meadow iron ore from Guben, Niederlausitz ; contain- 



ing considerable manganese. 



2. Meadow iron ore from Otrotschin, Bohemia; contains 



no manganese. 



3. Earth of Siena, yellow natural product containing iron 



oxide. 



4. Umber, brown natural product containing iron and man- 



ganese oxides. 



5. Laterite earth from Kamerun. 



6. Manganese ore, principally manganese hydroxide. 



7. Manganese dioxide. 



8. Red Bauxite, aluminum hydroxide gel containing iron 



oxide. 



9. White Bauxite, without iron oxide. 



10. Kaolin from Meissen. 



11. Sandy Kaolin from Tiirkismuhl. 



12. Glass sand. 



Of the above minerals No's i, 2, 3, 4, 6, 7, 8, 9 and 12 

 were used alone, while No.'s 5, 10 and 11 were mixed with an 

 equal quantity of glass-sand. One hundred grams of each was 

 placed in an Erlenmeyer flask and treated with 10 cc. of a 

 0.5 per cent, cyanamide solution, containing 33 mg. cyanamide- 

 nitrogen. Immediately after the addition of cyanamide, and 

 at the end of various periods of time the content of cyanamide- 

 nitrogen was determined, with the following results: 



