12 



COMPOSITION OF THE ASH. 



The ash of the peeled root and the bark of the root was subjected to 

 analysis, with the following results : 



Analysis of the ash of cassava root. 



From the above numbers it is seen that the ash of the peeled root is 

 especially rich in potash, almost one-half of the total weight being com- 

 posed of this substance. The potash is combined chiefly with carbonic 

 and phosphoric acids. In the ash of the bark, as might be expected, 

 silica is the predominant element, more than half the total weight con- 

 sisting of this substance. 



Assuming a yield of 5 tons of roots per acre, the weights of the 

 important fertilizing materials removed by such a crop can be readily 

 calculated from the data given. 



Since the bark forms approximately 2.2 per cent of the entire root, 

 the total crop would be made up of the following amounts of bark and 

 peeled root which would contain the amounts of mineral matter given 

 belo.w : 



The more important mineral matters contained therein are : 



