344 FOODS AND DIETARIES 



legislation that will safeguard the water used by our towns and cities. 

 Boiling water for ten minutes or longer will render it safe from all 

 organic impurities. 



, Stimulants. — We have learned that food is anything that sup- 

 plies building material or releases energy in the body; but some 

 materials used by man, presumably as food, do not come under 

 this head. Such are tea and coffee. When taken in moderate 

 quantities, they produce a temporary increase in the vital activities 

 of the person taking them. This is said to be a stimulation ; 

 and material taken into the digestive tract, producing this, is called 

 a stimulant. In moderation, tea and coffee appear to be harmless. 

 Some people, however, cannot use either without ill effects, even in 

 small quantity. It is the habit formed of relying upon the stimulus 

 given by tea or coffee that makes them a danger to man. In large 

 amounts, they are undoubtedly injurious because of a stimulant 

 called caffeine contained in them. Cocoa and chocolate, although 

 both contain a stimulant like caffeine, are in addition good foods, 

 having from 12 per cent to 21 per cent of proteid, from 29 per cent 

 to 48 per cent fat, and over 30 per cent carbohydrate in their compo- 

 sition. 



■ Is Alcohol a Food? — The question of the use of alcohol has 

 been of late years a matter of absorbing interest and importance 

 among physiologists. A few years ago Dr. Atwater performed a 

 series of very careful experiments by means of the respiration 

 calorimeter, to ascertain whether alcohol is of use to the body as 

 food.^ In these experiments the subjects were given, instead of 

 their daily allotment of carbohydrates and fats, enough alcohol 

 to supply the same amount of energy that these foods would 

 have given. The amount was calculated to be about two and 

 one half ounces per day, about as much as would be contained in 

 a bottle of light wine.- This alcohol was administered in small 

 doses six times during the day. Professor Atwater's results may 

 be summed up briefly as follows : — 



' Alcohol is made up of carbon, oxygen, and hydrogen. It is very easily oxidized, 

 but it cannot, as is shown by the chemical formula, be of use to the body in tissue 

 building, because of its lack of nitrogen. 



2 Alcoholic beverages contain the foUomng proportions of alcohol : beer, from 

 2 to 5 per cent ; wine, from 10 to 20 per cent ; liquors, from 30 to 70 per cent. Pat- 

 ent medicines frequently contain as high as 60 per cent alcohol. (See page 350.) 



