90 THE PHYSICAL PROPERTIES OF SOILS 



the results. Discuss the value of mechanical analysis 

 as an indicator of the adaptability of soils to crops. 



DETERMINATION OF THE LOSS ON IGNITION 



Heat the dishes containing the oven-dry samples to 

 dull redness, over a bunsen burner, until all of the 

 organic matter is burned away. Allow to cool, and 

 then moisten the mass with a few drops of ammonium 

 carbonate. Heat slowly to about 150° C, to drive off 

 the excess of ammonia, cool in a desiccator and weigh. 



The loss in weight of the sample represents the or- 

 ganic matter, volatile salts, and water of combination. 



References : 



Burkett, "Soils," pp. 30-33. 

 Bureau of Soils, Bulletin No. 5. 

 Bureau of Soils, Bulletin No. 24. 



