166 PROCEEDINGS OP THE AMERICAN ACADEMY 



chloride used was the same in every case, the values in either column 

 may be directly compared with each other. 



The first noticeable fact observed in the above table is, that the 

 difference between the heats of formation of chloride and sulphate is 

 not the same for all metals, as it was found to be in the case of the 

 chlorides and nitrates. It will be noticed, however, that with sulphates 

 of allied bases the agreement is as close as before, but the sesquioxide 

 salts give a larger amount of heat than the protoxide, and the double 

 salts a still larger quantity, and sulphuric acid much the largest of all. 

 It is a singular fact, that in the case of common alum the heat evolved 

 is greater than it is with either of its constituent salts. 



