GOVERNMENTAL REGULATION OF FOODS 345 



main purposes in the animal economy: (1) They supply building and 

 repair materials, and (2) they furnish energy for all the physiological 

 activities. Let us consider the latter purpose first. Physiologists have 

 demonstrated by numerous experiments that all the energies manifested 

 in the body finally leave the body as heat which can be measured by an 

 instrument known as the calorimeter. The heat unit employed in these 

 calculations is known as a calorie, which is the amount of heat neces- 

 sary to raise one kilogram of water 1° Centigrade. The quantity of heat 

 measured agrees exactly with the quantity which may be calculated from 

 the known amount of oxidation of foodstuffs which has taken place in 

 the body. When muscular work is done in a calorimeter and the work is 

 all made to take the form of heat, the increased heat production is again 

 what it should be as judged by the increased oxidation. Similarly, the 

 energy value of foods is determined either by analysis and computation 

 or by burning it in oxygen. Given then foods capable of producing a 

 certain quantity of heat, it is a fairly easy task to compute the amount 

 of each which would be necessary to furnish the energy requirements 

 of the body under any given set of conditions. 



An engineer who wishes to supply a certain amount of power must 

 know the heat value of certain kinds of fuel and the waste from each. 

 From these he reckons the net cost of his power. Any one who cares 

 to do so can make the same sort of a computation for his body. If the 

 engineer pays $7 for a ton of coal, he sees to it that he gets $7 worth of 

 heat. Why is it not just as reasonable when a person pays a certain 

 price for food to expect a certain amount of food value? To demand 

 the worth of one's money in heat units when the fuel in the house is 

 under consideration is a plain proposition, and when housewives gener- 

 ally understand food values it will be a plain proposition in respect to 

 fuel for the body. A properly educated public opinion will demand 

 from manufacturers such information in regard to the food on which 

 its energies depend. 



Let us see if this is not a practical suggestion, and whether, after all, 

 it may not prove a simple solution to a supposedly difficult problem. If 

 our foods were all simple substances like sugar or olive oil, and if the 

 energy content of the food were the only one of which we need take any 

 account, the problem would be just as easy as calculating the yield of 

 energy in horse-power from a ton of coal. It is because our foods are 

 mixtures of various foodstuffs, each having a different fuel value and a 

 different functional value, that the matter requires some study. 



The simplest method yet devised for keeping account of the energy 

 supply in one's diet is that devised by Professor Irving Fisher, of Yale 

 University. The idea underlying this method is to do away with intri- 

 cate calculation by familiarizing one's self with the amount of each 



VOL. LXXXIII. — 24. 



