ON THE BALANCE OF THE VITAL ECONOMY. 



435 



or neat. JNoweacn unit nt neat can De converted into raecnauicai iorce, t 

 pressed in kilogrammetres, by multiplying it by the number 423; that is 

 say, the heat required to raise one kilogramme of water 1 C. if convert 

 into mechanical force would raise 423 kilogrammes one metre in height, 



bining with oxygen, or rather with ozone, the force may either become 

 direct! v apparent as heat or electricity, or may, through the agency of muscle 

 gland or nerve-tissue, produce movement, secretion, or thought. We 

 have only indirect means of estimating this last; but the quantity of food 

 required for the mechanical and calorific force developed by the body has 

 been rendered capable of being estimated by the experiments of Frankland, 

 Haughton, and others. 



347. According to the observations of Prof. Frankland, one gramme 

 (15.44 grains) of purified albumen, when burnt in oxygen, yields 4.998 units 

 of heat. Now each unit of heat can be converted into mechanical force, ex- 



to 

 rted 



kilogrammes one metre in height, or 

 an amount of heat equivalent to 1 C. would be produced by the expendi- 

 ture of an amount of force equal to the raising of 423 kilogrammes to the 

 height of one metre; hence one gramme of albumen in burning in oxygen 

 yields 4.998X423, or 2117 kilogrammetres that is, a force sufficient to raise 

 2117 kilogrammes to the height of one metre. But it is to be remembered 

 that albumen, in passing through the body, is not so completely oxidized as 

 when burnt in oxygen. It is only reduced to the condition of urea; and 

 Professor Frauklaud has shown that urea can itself be burnt in oxygen, 

 yielding 2.206 units of heat, which is equal to 934 kilogrammetres of force ; 

 and as it is found that one gramme of pure albumen in passing through the 

 body, furnishes almost exactly one-third of its weight of urea, the effective 

 force developed in the body by its consumption is obviously less than when 

 it is burnt in oxygen to the extent of the amount of force still produced 

 when one-third of a gramme of urea is burnt in oxygen. Hence the effective 

 force of one gramme of albumen is equivalent to 1803 kilogrammetres. 1 Fat, 

 on the other hand, is as completely burnt in the body as outside of it, and 

 yields weight for weight a much larger amount of effective force than albu- 

 men. The following table contains some of the more important determina- 

 tions made by Professor Franklaud : 



1 It must be acknowledged that the estimates of different experimenters in regard 

 to the calorific value of different substances vary considerably. Thus, Franke esti- 

 mates that the combustion of one gramme of starch produces 5232 units of boat, 

 Ludwig 4568, Dulong 3232, Bischoff and Voit 5100, and Frankland 3941. The warm- 

 ing of one pound of water 1 C. is equivalent to a mechanical force of 1390 foot- 

 pounds. 



