SMITH ON DAILY CONSUMPTION OF CARBON. 501 



may readily arise as to the accuracy of these modes of estimat- 

 ing the total work done in the animal frame, under the con- 

 version of heat into mechanical force, when it is remembered 

 that till lately it was the universal belief that the production 

 of carbonic acid in the animal body had no other effect than 

 to create a temperature sufficient to maintain that of the sys- 

 tem at the standard height above the surrounding medium. 

 For, according to the views which have been engaging our 

 attention, not even a third part of the total heat generated 

 by the daily combustion of carbon is devoted to that purpose, 

 two-thirds being converted into the forces expended in par- 

 ticular by the heart and the muscular system. 



The points that require revision to satisfy such doubts as 

 may arise on this subject are first, the amount of carbon 

 thrown forth daily by the lungs under the variation of circum- 

 stances involved in the case ; second, the precise amount of 

 heat generated during the combustion of given quantities of 

 carbon and oxygen ; and, third, the quantity of heat required 

 under the ordinary range of atmospheric temperature to keep 

 up the standard animal heat in the case of man and the ani- 

 mals included in our inquiry. 



As to the amount of carbon thrown out daily, the latest 

 observations, for example those of Dr Edward Smith, entirely 

 confirm the high estimate above stated. Dr Smith* says, 

 " My own experiments on the amount of carbon which is 

 thrown out of the body are by far the most extended on record, 

 and I have used them in the various Government reports on 

 the foods of the labouring classes ; " and he thus concludes the 

 passage : "It may be stated that the adult body requires an 

 average minimum daily amount of carbon of 9J to 10J oz. 

 in the middle and light-labouring classes, and of 12 J to 14- 

 oz. in the ordinary hard-labouring classes." His further 



* 'Practical Dietary,' p. 20. 18G4. 



