ECONOMY OF MUSCLE COMBUSTION. 105 



intimate constitution of muscle is, however, too imperfect to allow 

 of our estimating the amount of motion producible by its oxida- 

 tion with any degree of exactitude ; but, as the result of a rough 

 calculation, it may be taken that the combustion of the unburnt 

 carbo-hydrogen of one gramme of dry muscle, free from fat, is 

 capable of furnishing 1923 kilogrammetres of motion, or will 

 suffice to lift 1923 kilogrammes to the height of I metre.* 



(112.) Now, although the ratio of the [amount of motion 

 actually produced to that theoretically producible by the com- 

 bustion of a given weight of muscle, has not. I believe, been 

 satisfactorily ascertained, this much is. certain, that muscular 

 tissue is, without exception, by far the most perfect of machines 

 for manifesting the force liberated by chemical action in the form 

 of motion. No artificial contrivance with which we are ac- 

 quainted is at all comparable to it in economy that is to say, in 

 the proportion of mechanical work performed to the total force 

 liberated. The steam-engine, for instance, is an artificial ma- 

 chine, expressly intended for the conversion of chemical force 

 into motion. Heat is generated in the boiler-furnace by a com- 

 bination of the carbo-hydrogen of the coal with the oxygen of 

 the air, but only a certain amount of this heat is absorbed in the 

 evaporated water, and then only a certain amount of the heat so 

 absorbed is translated into motion. According to Sir W. Arm- 



* Assuming for muscle the formula C Ia H I9 N 3 4 x 6, and subtracting all 

 the oxygen and nitrogen, with the necessary hydrogen, in the forms of water 

 and ammonia, so as to leave a residue of C^H., x 6, then 269 grammes of 

 muscle would leave 144 grammes of carbon and 2 grammes of hydrogen for 

 oxidation, which should furnish 517,280 kilogrammetres of motion, thus: 



Grammes Kilogrammetres Kilogrammetres 



CABBON 144 x 3,39^ = 488,448 



HYDROGEN 2 x 14,416 = 28,832 



517,280 



Hence one gramme of muscle should furnish 517,280-4-269 = 1923 kilogram- 

 metres of motion ; but from the imperfection of the data on which the * 

 calculation is based, particularly as regards the heat absorbed in the sepa- 

 ration and volatilisation of carbon, this result can only be regarded as ap- 

 proximative. 



