458 THE EXPENDITURE OF ENERGY. [BOOK ir. 



our guide we may easily calculate the total energy of any diet. The 

 following determinations, expressed both in gramme-degree (centri- 

 grade) units of heat, and kilogramme-metre units of work, may 

 serve as data. 



The direct oxidation of the gives lisa to 



following, dried at 100 C. gram.-deg. kilo.-met. 



1 grm. Beef-fat 9069 3841 



1 grm. Butter 7264 3077 



1 grm. Arrowroot 3912 1657 



1 grm. Beef-muscle purified with ether 5103 2161 



1 grm. Urea 2206 934 



Supposing that all the nitrogen of proteid food goes out as 

 urea, 1 grm. of dry proteid, such as dried beef-muscle, would give 

 rise to about J grm. of urea ; hence 



gram.-deg. kilo.-met. 

 1 grm. Proteid 5103 2161 



less 

 j grm. Urea 735 311 



would give as 

 Available energy of Proteid "4368 1850 



In a normal diet, such as Ranke's, p. 446, would be found : 



gram.-deg. kilo.-met. 



100 grm. Proteid 436800 185000 



100 grm. Fat 906900 384100 



240 grm. Starch 938880 397680 



Total Income 2281580 966780 



or, in round numbers, one million kilogramme-metres, 



The Expenditure. 



There are only two ways in which energy is set free from the 

 body: mechanical labour and heat. The body loses energy in 

 producing muscular work, as in locomotion, in all kinds of labour, 

 in the movements of the air, in respiration and speech, and, though 

 to a hardly recognizable extent, in the movements of the air or 

 contiguous bodies by the pulsations of the vascular system. The 

 body loses energy in the form of heat by conduction and radiation, 

 by respiration and perspiration, and by the warming of the urine 

 and faeces. All the internal work of the body, all the mechanical 

 labour of the internal muscular mechanisms with their accompany- 

 ing friction, all the molecular labour of the nervous and other 

 tissues, is converted into heat before it leaves the body. The 



