294 



GENERAL SCIENCE 



Ammonium sulphate, a by-product of the manufacture 

 of coke, contains about 20 per cent of nitrogen. 



Dried blood, tankage, and bone meal are all good ferti- 

 lizers and contain considerable nitrogen which is rendered 

 available by the action of soil bacteria. This fact makes 

 it slower in its action and more desirable for many crops 

 than sodium nitrate, which is very soluble and therefore 

 likely to leach out of the soil. 



Potassium as a Fertilizer. Wood ashes contain much 

 potash and would make an excellent fertilizer if the 



FIG. 253. Results Obtained from Using Different Fertilizers. 



Unfertilized Nitrogen 



Phosphorus 

 Potassium 



supply were not so limited. The common commercial 

 forms of potash are muriate of potash and sulphate of 

 potash (Figure 253). 



Nearly all of the potash used in America was formerly 

 manufactured from Kainit from the mines of Germany in 

 the form of muriate or sulphate of potash. 



