288 THE POTATO 



chemical point of view, is a compound of the hy- 

 pothetical substance ethyl with water, or with that 

 part of water remaining after the separation of one 

 of the atoms of hydrogen. This is a rather tech- 

 nical expression, but it is very difficult, without 

 using technical language, to give a definition of 

 alcohol from the chemical point of view. There 

 are three elementary substances represented in 

 alcohol: Carbon, the chemical symbol of which is 

 C; hydrogen, symbol H; and oxygen, symbol O. 

 These atoms are put together to form common 

 alcohol, or, as it is called, ethyl alcohol, in which 

 preparation two atoms of carbon and five atoms of 

 hydrogen form the hypothetical substance ethyl 

 and one atom of oxygen and one atom of hydrogen 

 form the hydroxl derived from water. The chemical 

 symbol of alcohol therefore is C^ H^ OH. Ab- 

 solutely pure ethyl alcohol is made only with^ 

 great difficulty, and the purest commercial forms 

 still have associated with them traces of other 

 volatile products formed at the time of the dis- 

 tillation, chief among which is that group of al- 

 cohols to which the name fusel oil is applied. 



"Starch is a compound which, from the chemical 

 point of view, belongs to the class known as car- 

 bohydrates — ^that is, compounds in which the ele- 

 ment carbon is associated by a chemical union 

 with water. Starch is therefore a compound made 

 of carbon, hydrogen, and oxygen, existing in the 

 proportion of two atoms of hydrogen to one atom 

 of oxygen. Each molecule of starch contains at 

 least six atoms of carbon, ten atoms of hydrogen, 

 and five atoms of oxygen. The simplest expres- 

 sion for starch is therefore C^ H5 O5. 



'*The principal starch producing plants are the 

 cereals, the potato^ and cassava. With the po- 



