Prof. Frankland on the Origin of Muscular Power. 183 



Owing to the want of these data, the numerical results of 

 the experiment of Fick and Wislicenus are rendered less con- 

 clusive against the hypothesis of muscle-oxidation than they 

 otherwise would have been ; whilst similar determinations which 

 have been made by Edward Smith, Haughton, Playfair, and 

 others are even liable to a total misinterpretation from the same 

 cause. 



I have endeavoured to supply this want by the calorimetrical 

 determination of the actual energy evolved by the combustion of 

 muscle and of urea in oxygen : but, inasmuch as uric and hip- 

 puric acids frequently appear in the urine as products of a less 

 perfect muscle-oxidation, I have also determined the calorific 

 value of these substances, and have added purified albumen and 

 beef fat to the list. Creatin would also have been included ; but, 

 although I was furnished with an ample supply of this substance 

 through the kindness of Dr. Dittmar, all attempts to burn it 

 in the calorimeter were fruitless. In numerous trials under 

 varied conditions it always exploded violently on ignition. 



The determination of the actual energy developed by the com- 

 bustion of the above-named substances is surrounded by formi- 

 dable difficulties, which have probably prevented their previous 

 execution. It is impossible to effect their complete combustion 

 in oxygen gas, under conditions which permit of the accurate 

 measurement of the heat evolved; but preliminary experiments 

 showed that complete oxidation could be secured by deflagration 

 with potassic chlorate; and, although this method is doubtless 

 inferior in accuracy to the calorimetrical methods usually em- 

 ployed, it is hoped that, with the corrections described below, 

 the results obtained merit sufficient confidence to render them 

 useful in subsequent discussions of this and allied subjects. The 

 determinations were made in a calorimeter devised some years 

 ago by Lewis Thompson, and which I have repeatedly used with 

 satisfaction in other determinations of a like kind. This in- 

 strument consists of a copper tube made to contain a mixture of 

 potassic chlorate with the combustible substance, and which can 

 be enclosed in a kind of diving-bell, also of copper, and so 

 lowered to the bottom of a suitable vessel containing a known 

 quantity (2 litres) of water. The experiments were conducted 

 in the following manner: — 19*5 grams* of chlorate of potash, 

 to which about one-eighth of manganic oxide was added, 

 were intimately mixed with a known weight (generally about 

 2 grams) of the substance whose thermal value was to be deter- 

 mined; and the mixture being then placed in the copper tube 

 above mentioned, a small piece of cotton thread, previously 



* I follow the example of the Registrar-General in abbreviating the 

 French word gramme to gram. 



