S6 AMOUNT OF OXYGEN 



where labour 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 ap- 

 proximation, that the quantities of oxygen consumed 

 in these different cases are in the ratio of these 

 numbers ; 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 oxidised, 

 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 been equally unsatisfactory. Animals 

 have been allowed to respire in close chambers sur- 

 rounded with cold water ; the increase of tempera- 

 ture in the water has been measured by the ther- 

 mometer, and the quantity of oxygen consumed has 

 been calculated from the analysis of the air before 



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

 brown bread, 70 lbs. white bread, 132 lbs. meat, 19 lbs. sugar, 

 15*9 lbs. butter, 57 maass (about 24 gallons) of milk ; the carbon of 

 the potatoes and other vegetables, of the poultry, game, and wine 

 consumed, having been reckoned as equal to that contained in 

 the excrementitious matters, the carbon of the above articles was 

 considered as beinor converted into carbonic acid. 



