RECENT ADVANCES IN SCIENCE 629 



author recommends finally the use of cobalt borate as the 

 most suitable catalyst for technical purposes. 



Electrolytic Dissociation. — As is well known, the outstanding 

 difficulty in regard to equilibrium between ions is the so-called 

 " Anomaly of strong electrolytes." Strong electrolytes, e.g. 

 salts, when dissolved in water dissociate into ions in such a 

 manner, that, with increasing concentration the mass action 

 equilibrium constant, in place of remaining unchanged, rises 

 markedly and does not even exhibit the same order of magni- 

 tude. Since this anomaly occurs in those cases in which the 

 dissociation is very extensive the two effects have been more 

 or less associated. The work of Schlesinger and Coleman 

 (Journ. Amer. Chem. Soc. 38, 271, 191 6), however, has disproved 

 the conclusion that large dissociation per se is the cause of 

 the anomaly. These authors have investigated, by means of 

 electrical conductivity, the degree of dissociation of alkali 

 formates dissolved in anhydrous formic acid. This solvent 

 resembles water in being an excellent dissociating medium. 

 The dissolved formates are therefore highly ionised, e.g. a 

 decinormal solution of sodium formate is dissociated to the 

 extent of 88 per cent, at 18 C, and similar values are obtained 

 for the lithium, rubidium, and caesium salts. In spite of this 

 extensive ionisation, however, these electrolytes in formic 

 acid obey the Ostwald " Dilution Law " with a high degree of 

 accuracy. It looks, therefore, as if the " anomaly " of strong 

 electrolytes may be attributed eventually to the abnormality 

 of water as a solvent. 



Phase Equilibria and Change of State. — A useful contri- 

 bution to this field has been recently published by E. Janecke 

 (Z. Phys. Chem. 90, 265, 191 5) by the determination of fusion 

 points and transition points with the help of a special electrically 

 heated pressure apparatus. The method has been applied 

 with success to the accurate determination of the melting 

 points of a number of hydrated salts of sodium, calcium, 

 barium, and copper. In connection with the hydrates of copper 

 sulphate Janecke infers from his results that a subhydrate 

 (probably CuS0 4 |H 2 0) exists. The author has also redeter- 

 mined the transition points of the nitrates of silver, ammonium, 

 and potassium, and has discovered a new modification of 

 potassium nitrate. Finally, Janecke has verified Cohen's work 

 on the transition of the stable and unstable forms of metals 



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