different conditions of Age and Employment. 265 



dietaries. Taking the soldier and sailor as illustrating 

 healthy adult men, they consumed weekly about 35 ounces 

 of flesh-formers, 70 to 74 ounces of carbon ; the relation of 

 the carbon in the flesh-formers to that of the heat-givers 

 being 1:3. If the dietaries of the aged were contrasted 

 with this, it would be found that they consumed less flesh- 

 formers (25 — 30 ounces), but rather more heat-givers (72 — 78 

 ounces) ; the relation of the carbon in the former to that of 

 the latter being about 1 : 5. The young boy, about ten or 

 twelve years of age, consumed about 17 ounces weekly, or 

 about half the flesh-formers of the adult man ; the carbon 

 being about 58 ounces weekly, and the relations of the two 

 carbons being nearly 1 : 5J. The circumstances under which 

 persons are placed influence these proportions considerably. 

 In workhouses and prisons the warmth renders less neces- 

 sary a large amount of food-fuel to the body ; while the re- 

 lative amount of labour determines the greater or less 

 amount of flesh-formers. Accordingly, it is observed that 

 the latter are increased to the prisoners exposed to hard 

 labour. From the quantity of flesh-formers in food, we may 

 estimate approximatively the rate of change in the body. 

 Now, a man weighing 140 lb. has about 4 lb. of flesh in 

 blood, 27 J lb. in his muscular substance, &c, and about 

 5 lb. of nitrogenous matter in the bones. These 37 lb. 

 would be received in food in about eighteen weeks ; or, in 

 other words, that period might represent the time required 

 for the change of the tissues, if all changed with equal rapidity, 

 which is, however, not at all probable, 



All the carbon taken as food is not burned in the body, 

 part of it being excreted with the waste matter. Supposing 

 the respirations to be 18 per minute, a man expires about 

 8*59 oz. of carbon daily, the remainder of the carbon appear- 

 ing in the excreted matter. 



In conclusion, Dr Playfair explained how the dietary-tables 

 elucidated the various admixtures of food common to cookery, 

 and how they might even be made to bear on certain national 

 characteristics, which were in no small degree influenced by 

 the aliments of different nations. 



