68 BIOLOGICAL PROBLEMS 



which was sold as malt, brewers' grains, and dry 

 yeast. A good deal of discussion has been carried 

 on in the Press as regards the amount of fodder 

 obtained from the brewers; the discrepancies arise 

 from some of the writers taking the weight of the 

 brewers' grains in the wet state. This, of course, is 

 quite wrong, as the value of the fodder depends only 

 on the amount of solid matter, and not on the water it 

 contains. It is clear at once that the amount of cattle 

 food obtained from the brewer is considerably less 

 than would have been produced if the materials had 

 been sent to the miller. But this may be compen- 

 sated by an increased value of the beer as food for 

 man. In order to determine this, it is necessary to 

 consider how far beer compares with bread as a food 

 or energy-producer. When an engineer has to com- 

 pare the value of two fuels, such as coal and oil, he 

 determines how much heat a definite amount of each 

 is capable of producing. This may also be done for 

 the foods or fuels employed by the human machine, 

 and all experience indicates that the results obtained 

 by this method coincide with those obtained when 

 the foods are actually consumed by man. In this 

 way the beer and the original materials may each 

 be assigned a definite numerical value in calories as 

 producers of energy, and we may be confident that 

 these represent their relative worth as sources of 

 energy to man. 



In Table II, the value of the quantities given in 

 Table I is given in units of food (calories), and the 

 same alternative routes are given : A represents the 

 value of the food used directly for man and animals; 

 B, that where it is formed into beer. 



