CARBOHYDRATES. 123 



But, while infection is not destroyed by freezing, it is by boil- 

 ing, and there is no surer way of destroying the germs which 

 water may contain than by boiling it for half an hour. Boiled 

 water is not as unpalatable as is generally supposed. Even if it 

 was, unpalatability is less objectionable than infection, and in all 

 doubtful cases water should be boiled. 



Another lesson to be learned from this epidemic and from the 

 laboratory experiments referred to is that ice may be a source 

 of infection as well as water, and even though the water i boiled 

 this will be of no avail if infected ice is used to cool it. In ice 

 which was suspected of having caused typhoid fever at the St. Law- 

 rence State Hospital, on the St. Lawrence River, Hutchings and 

 Wheeler found typhoid bacilli. 



The writer investigated an epidemic of dysentery in which the 

 disease was traced to ice used in drinking-water. The ice had 

 been cut from a pond in which during the summer hogs wallowed, 

 and in which they deposited their excreta.. When melted this ice 

 had a most offensive odor. Other instances might be given show- 

 ing the danger from the use of impure ice, but the one cited will 

 suffice. Fortunately, there is now furnished for use in many of 

 our cities artificial ice, which, if properly prepared, is free from 

 all contamination. In this process of manufacturing ice the water 

 is not only boiled, but is distilled, and when ready for freezing is 

 absolutely pure. But even this ice is not always what it claims to 

 be. Unscrupulous dealers will often supply river ice when they 

 are supposed to deliver the artificial product, and manufacturers 

 of the latter are sometimes careless. With boiled water and prop- 

 erly manufactured artificial ice, all danger of infection through 

 these channels will surely be prevented. 



Salts. The list of salts taken in with the food has already 

 been given, the most important being sodium chlorid, calcium 

 phosphate, and the alkaline carbonates and phosphates. The 

 offices which these salts perform in the economy of the body vary. 

 By some of them the solubility of certain ingredients is made 

 possible, such as the globulin of the blood by virtue of the presence 

 of sodium chlorid. From the chlorids the hydrochloric acid of 

 the gastric juice is produced. Salts are stimulants also to the 

 glands, causing the latter to secrete more actively ; thus the diges- 

 tive fluids are more abundantly poured out when the food is prop- 

 erly salted, and the kidneys more completely perform their .func- 

 tions under the stimulation of the salts. If salts are removed 

 from the food of a pigeon, it will die in three weeks ; the same 

 deprivation of salts in the case of a dog will cause its death in 

 six weeks. 



Carbohydrates. These food-stuffs, in the form of starch and 

 sugar, are especially abundant in vegetable foods. They are present 

 also in milk, but less so in other animal foods. 



Cane-sugar is an article of diet which is used to an enormous 



