V. On the heat disengaged during metallic substitutions
In the present communication I propose to give an account of some new investigations on the heat disengaged in chemical actions, which may be considered a continuation of my former inquiries on the same subject. The greater number of the experiments to be detailed in this paper were made some years ago, and the conclusion at which I arrived was briefly announced in the Philosophical Magazine for August 1844. More recently, I have taken an opportunity to repeat many of my former experiments and to add new ones on the same subject, all of which confirm the general results formerly obtained. Having originally observed that although a very limited number of bases (potash, soda, barytes and strontia) develope nearly the same quantity of heat, when a chemical equivalent of each enters into combination with an acid, yet that the greater number of bases differ most widely from one another, when so treated, while on the other hand, that different acids (taken in the state of dilute solution) produce with the same base nearly the same amount of heat, I ventured to draw the general inference that the thermal effects produced are more intimately connected with the basic, or electro-positive, than with the acid, or electro-negative element. In conformity with this view, it appeared probable that in the decomposition of solutions of neutral salts by the addition of bases or metallic bodies, the nature of the acid or electro-negative element of the compound would exercise no special influence on the result. I have already endeavoured to establish by experiment the truth of this principle in the case of basic substitutions, and, in the present memoir, I propose to extend the same general law to the other case, in which one metallic element replaces, or is substituted for another.