3 i2 SCIENCE PROGRESS. 



and another of the same salt in methyl alcohol, ethyl 

 alcohol, or acetone, has been determined by H. C. Jones 

 (178). The aqueous solution was always positive. The 

 results indicate that the solution pressure of a metal varies 

 with the solvent. 



A paper by Nourisson, in which the E.M.F. was cal- 

 culated from thermal data, has given rise to a discussion 

 (179) involving a question of priority between Berthelot 

 and Le Blanc. The main point to notice is that both 

 Berthelot and Nourisson employ the old idea that the 

 E.M.F. of a cell can be calculated from Thomson's rule on 

 the supposition of the perfect transformation of chemical 

 into electrical energy. Le Blanc points out that this view 

 is now untenable. 



In an extremely suggestive paper (180), entitled the 

 " Chemometer," Ostwald deals with the question of 

 chemical intensity. A thermometer measures the intensity 

 of heat energy, an electrometer measures the intensity of 

 electrical energy ; a similar instrument in the case of 

 chemical energy would be a chemometer. Ostwald points 

 out that if we perform a chemical process in a voltaic cell, 

 there is attendant upon it a movement of electricity, and 

 work derived from the chemical process may be manifested 

 as electrical energy. Now the electrical energy is equiva- 

 lent to the chemical energy, and since the capacity factor 

 of the electrical energy, that is, the quantity of electricity, 

 is according to Faraday's law proportional to the capacity 

 factor of the chemical energy, that is, the quantity of matter 

 decomposed, it follows that the intensity factors must be 

 proportional, and hence the electromotive force is propor- 

 tional to the chemical intensity. In this way is the problem 

 of the chemometer solved in the case of electrolytes. How 

 it is to be done in the case of non-electrolytes, or by means 

 of the other forms of energy into which chemical energy 

 can be transformed, has yet to be. seen. 



Drude and Nernst (181) draw attention to a conse- 

 quence of the electrostatic charges of the ions. If the 

 dielectric constant of a medium increases on compression it 

 will contract in an electrostatic field, consequently if free 



