CHEMISTRY OF THE POTATO. 135 



Starch, 18.8 per cent. 

 Suojar, 3.2 '' 

 Fat, 0.2 '* 



Ash, 0.7 '* 



But in a substance which varies so widel}' in composition, such an 

 average is of little value when applied to a particular case. 



L. Raab examined twent3'-two different varieties of potatoes and 

 found a variation in starch contents from 9.54 per cent, with a total 

 dr}' matter of 16.96 per cent, in the ''Zebra," to 26.74 per cent 

 starch, with a total dry matter of 34.96 per cent in the "Carmoisinrothe 

 Larnet." 



The variation in the composition of potatoes is not confined to 

 different varieties. The composition of the same variety varies with 

 soil, climate, season and manuring. 



Raab in investigating the composition of potatoes in different sea- 

 sons found the foliowinof variation in starch contents : 



The lesson to be drawn from the analyses given above is that some 

 lots of potatoes are worth treble what other lots are worth, whether 

 they be used as an article of diet or for making starch. 



I know, also, of a case in which a man selling directly to consumers 

 gets ten to fift?een cents more per bushel for his potatoes than the 

 market price, on account of superior quality. 



An analysis of the ash of the potato, bj' E. Hj'den, shows : 



Oxide of iron, 1.92 per cent. 



Lime, 2.03 " 



Magnesia, 4.26 '^ 



Potash, 64.80 " 



Soda, 1.44 



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