Chemistry and Physies. 7 
tricity. A zine and a copper plate in contact give a difference of 
potential ; by their mutual attraction they can give out a certain 
amount of work. Their action can be represented by a piece of 
aving criticized Exner’s results, Braun shows how important 
the study of electromotive force is to the subject of thermal 
chemistry. A part of the matter in the series of difference of 
ment due to a process is zero, still exchanges can take place in 
Pe ' 
