THE STORY OF OUR FOODS 19 



revealed by the fact that on water alone (and of 

 course on air, which is really part of our food 

 supply) a man may exist for periods varying from 

 twenty to thirty days or more, whereas, if deprived 

 of water and solid food as well, his existence would 

 probably end in from six to seven days. Water is 

 thus the only food which will maintain existence for 

 a considerable period, having also regard to the air 

 breathed. The quantity of water contained in the 

 various organs and tissues of the body is very great. 

 In the blood 90 per cent of water exists, and even in 

 the brain-substance a very large amount of water is 

 contained. 



MINERALS. Our mineral food-supply amounts 

 on an average to about one ounce per day. The 

 minerals demanded for nutritive purposes are repre- 

 sented by phosphate of lime, which is of extreme 

 importance in early life, seeing that it forms the 

 material from which bone derives its hardness. 

 Common salt, or chloride of sodium, is a necessity of 

 life, and appears to be required not merely for the 

 purpose of digestion in the stomach, but also seems 

 to be in other ways a necessity for the body, the blood 

 itself containing a fair amount of this mineral which 

 is given off or excreted in almost every fluid of the 

 body, ranging from the perspiration to the tears. 

 Other minerals required for the support of the body 

 include potash this mineral being apparently of 

 much importance seeing that a lack of it gives rise 

 to the serious trouble known as scurvy, which is 

 inevitably associated with errors in diet. This 

 disease of old was well known in connection with 

 ships making long voyages, the sailors being fed on 

 salt meat in the absence of fresh meat or vegetables. 

 The salt meat alone could not be regarded as the 



