THE CHEMISTRY OF FOOD. 53 



CHAPTER IV. 

 THE CHEMISTRY OF FOOD. 



The Source of Food Inorganic Substances Water Salt Lime Iron 

 Organic Substances Albumen, Fibrin, and Casein The Fats or 

 Oils The Sugars, Starch, and Gum Stimulating Substances 

 Necessity of a Regulated Diet. 



1. The Source of Food. The term, food includes all 

 those substances, whether liquid or solid, which are neces- 

 ~ary for the nourishment of the body. The original source 

 of all food is the earth, which the poet has fitly styled the 

 " Mother of all living." In her bosom, and in the atmos- 

 phere about her, are contained all the elements on which 

 life depends. But man is unable to obtain nourishment 

 directly from such crude chemical forms as he finds in the 

 inorganic world. They must, with a few exceptions, be 

 prepared for his use, by being transformed into new and 

 higher combinations, more closely resembling the tissues 

 of his own body. 



2. This transformation is effected, first, by the vegetable 

 world. But all plants are not alike useful to man ; while 

 some are absolutely hurtful. Accordingly, he must learn 

 to discriminate between that which is poisonous and that 

 which is life-supporting. Again, all parts of the same 

 plant or tree are not alike beneficial: in some, the fruit, 

 in others, the leaves, and in others, the seeds only are 

 'sufficiently refined for his use. These he must learn 

 to select ; he must also learn the proper modes of prepar' 

 ing each kind for his table, whether by cooking or othe 

 processes. 



1 . The term food ? Source of food ? Need of preparing: food ? 



2. Usefulness and hurtfulness of plants ? What then must man do ? Parti? of 

 the same plant or tree ? 



