A HARD-WORKING DIET. 347 



It is one of the important discoveries of recent years Combinations 



that take 

 that THESE COMBINATIONS, WHICH TAKE PLACE IN place in the 



world around 

 THE WORLD AROUND US, ALSO TAKE PLACE IN OUR us a i so take 



OWN BODIES. T! 



We take in compounds of C, H, and N in our 

 foods, we take in O from the air we breathe. 



The H combining with the O forms water, which 

 leaves us as perspiration (more as invisible perspiration 

 than in visible " sweat "), as moisture in our breath 

 (visible on a frosty day), and through the bladder. 



The C combining with O forms carbonic acid, which 

 leaves the body mostly through the lungs. 



The N combining with H forms ammonia, which 

 leaves the body through the kidneys. 



The solid excreta which leave the body consist for 

 the most part of actual waste that is, material which 

 has not been made use of at all. 



It is the knowledge of these forms of outgoings 

 of oxidized C and H that is, C and H, which 

 have within our bodies combined with the O we 

 have taken in in our breath and of ammonia that 



forms THE FOUNDATION OF OUR PRESENT WAYS OF The founda- 



T tion of our 

 STUDYING FOOD VALUES. The quantity Of C, H, pre sent ways 



and N taken in as food is weighed, and the out- f 00 Vvaluel 

 goings in perspiration, breath, urine, and excreta are 

 weighed. They have been ascertained for different 

 conditions of exercise and different conditions of 

 health, and to some extent for different conditions of 

 surrounding weather, so that the intakings and the 

 various outgoings of the body can be balanced up, 

 like the introduction of raw material and the turning 

 out manufactured stuff in a mill can be. 



That was a great advance when the genius and 



