HELMHOLTZ ON THE CONSERVATION OP FORCE. 161 



force. As the latter compared with the quantity of heat repre- 

 sents but a small quantity of work, the question of the conserva- 

 tion of force is reduced to this, whether the combustion and meta- 

 morphosis of the substances which serve as nutriment generate a 

 quantity of heat equal to that given out by animals. According 

 to the experiments of Dulong and Despretz, this question can be 

 approximately answered in the affirmative. 



In conclusion I must refer to some remarks of Matteucci^s 

 which have been directed against the views advocated in this 

 memoir, and which appear in the Bib, Univ. de Geneve, No. 16, 

 1847j 15 May, p. 375. He proceeds from the proposition, that 

 according to the above views a chemical process could not 

 generate so much heat w^here it at the same time developes elec- 

 tricity, magnetism, or light, as when this is not the case. He 

 takes pains to show by a series of measurements which he 

 adduces, that zinc, during its solution in sulphuric acid, generates 

 just as much heat where the solution is effected directly by 

 chemical affinity as when it forms a circuit with platinum ; and 

 that an electric current produces just as much chemical and 

 thermic action while it deflects a magnet as when no such 

 deflection is produced. That Matteucci regards these facts as 

 objections, is due to his total miscomprehension of the views 

 which he undertakes to refute, w^hich will be at once evident 

 from a consideration of our statement of the subject. He then 

 brings forward two calorimetric experiments on the heat which 

 is developed by the combination of caustic baryta with concen- 

 trated or dilute sulphuric acid, and on that generated by the same 

 electric current in a wire immersed in gases of different cooling 

 capacities, whereby the above mass and the wire were sometimes 

 glowing and sometimes not. He finds the quantity of heat in 

 the former cases not less than in the latter. When we, how- 

 ever, reflect upon the incompleteness of our calorimetric arrange- 

 ments, it will not appear extraordinary that differences of cooling 

 through radiation, which are due to the fact that this radiation, 

 according to its luminous or non-luminous nature, passes with 

 less or more difficulty through the surrounding diathermanous 

 bodies, escape observation. In the first experiment of Matteucci 

 the union of the baryta with sulphuric acid was effected in a 

 non-diathermanous leaden vessel, where the luminous rays were 



