34 AMOUNT OF OXYGEN 



origin of animal heat, are destitute of practical value in 

 regard to this question, since we have seen, that the 

 quantity of oxygen consumed varies according to the 

 temperature and density of the air, according to the 

 degree of motion, labor, or exercise, to the amount and 

 quality of the food, to the comparative warmth of the 

 clothing, and also according to the time within which 

 the food is taken. Prisoners in the Bridewell at Ma- 

 rienschloss (a prison where labor is enforced), do not 

 consume more than 10-5 oz. of carbon daily ; those in 

 the House of Arrest at Giessen, who are deprived of 

 all exercise, consume only 8-5 oz. ; (6) and in a family 

 well known to me, consisting of nine individuals, five 

 adults, and four children of different ages, the average 

 daily consumption of carbon for each, is not more than 

 9' 5 oz. of carbon.* We may safely assume, as an 

 approximation, that the quantities of oxygen consumed 

 in these different cases are in the ratio of these num- 

 bers ; but where the food contains meat, fat, and wine, 

 the proportions are altered by reason of the hydrogen 

 in these kinds of food which is oxidized, and which, in 

 being converted into water, evolves much more heat 

 for equal weights. 



The attempts to ascertain the amount of heat evolved 

 in an animal for a given consumption of oxygen have 



* In this family, the monthly consumption was 151 Ibs. of brown 

 bread, 70 Ibs. white bread, 132 Ibs. meat, 19 Ibs. sugar, 159 Ibs. but- 

 ter, 57 maass (about 24 gallons) of milk ; the carbon of the potatoes 

 and other vegetables, of the poultry, game, and wine consumed, hav- 

 ing been reckoned as equal to that contained in the excrementitious 

 matters, the carbon of the above articles was considered as being 

 converted into carbonic acid. L. 



