Loss of Energy due to Chemical Union Sfc, 51 



where chemical change by heating occurred. The gains are 

 largest and most frequent in those mixtures in which no 

 recognized chemical change took place, and in which an acid 

 or halogen existed in a free state to act strongly upon the 

 positive metal, as in Sections H, I, and J. 4th. In cases 

 of chemical union, increase of mean specific gravity of the 

 uniting substances was usually attended by decrease of mean 

 electromotive force, and in those of mere dilution it was 

 accompanied by increase of mean electromotive force of the 

 ingredients. 5th. In certain cases heating the liquid 

 permanently altered the amount of change of energy, and 

 converted a gain into a loss, evidently because it produced 

 chemical change. These instances may be viewed as ones of 

 unstable mixture, the chemical equilibria of which are per- 

 manently upset by elevation of temperature, and the molecular 

 changes of which are not reversible. 6th. As action and 

 reaction are always equal and contrary, we may conclude that 

 the losses of energy suffered by the two mutually reacting 

 substances are always equal in amount ; this remark would 

 apply equally to the two soluble substances during the act of 

 mixing, and to the positive metal and the substance which 

 acts upon it. And 7th. As the whole of the cases of 

 change of mean amount of electromotive force in this research 

 may be arranged in an unbroken series, beginning with those 

 of strongest chemical action and ending with those of simple 

 physical mixture and dilution, and as the relative amount of 

 change of mean electromotive force in this series varies by 

 insensible degrees from a large percentage of loss to a con- 

 siderable one of gain, we may conclude that essentially the 

 same fundamental kind of energy operates in all the cases ; 

 and the entire order and its energy may be compared with 

 those of a volta-tension series of metals. 



The results in general indicate the existence of an extensive 

 system of quantitative relations between voltaic electromotive 

 force and the atomic weights of the positive metals and of the 

 negative and positive constituents of the compounds acting 

 upon them ; and largely also between the losses of electro- 

 motive force and the amount of chemical heat ; the latter is 

 already known to a considerable extent. With the zinc series 

 of positive metals the electromotive force was usually greater 

 the smaller the atomic weight of the positive metal and of that 

 of the halogen, of the acid or salt, and the larger that of the 

 metallic base of the salt. With the halogens and their acids 

 it was greater the smaller the atomic weight of the halogen. 

 With the alkali salts of the halogens it was larger the smaller 

 the atomic weight of the halogen and the greater that of the 



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