16 FIELD AND LABORATORY STUDIES OF SOILS 



ganic matter which they contain. Muck soils are composed 

 almost entirely of organic matter, while some sandy 

 soils contain comparatively little dead plant and animal 

 remains. Whenever the supply of organic matter in a 

 soil is low the crop yields are small. Applying manure 

 and plowing under clover are good ways of increasing the 

 amount of organic matter in the soil. 



Note. — A very good balance can be purchased for about $12.00. 

 Small dishes should be about two or three inches in diameter. If 

 tin, they must be without soldered seams. 



Gas or alcohol stoves may be purchased at a small cost, or a very 

 good alcohol lamp may be constructed in the laboratory without 

 cost, by following the diagram shown on page 14. 



