Chemistry and Physics. 77 



5. Refrigeration by Mixtures of Liquids. — The mixture of 

 two liquids is often accompanied by a lowering of temperature. 

 For instance, with carbon bisulphide and methyl formate the 

 variation of temperature is 16° C. For practical refrigeration 

 such mixtures have never been used on account of their cost and 

 low effect in comparison with the solution of a salt, such as 

 ammonium nitrate, in water. J. Ditclaux has devised an inge- 

 nious application of the two liquids method for the production 

 of very low and nearly constant temperatures. He allows the 

 liquids to flow through two long tubes, and after mixing they 

 flow back around the exterior of the tubes. In this way the 

 cooling effect is accumulated. The tubes used were very small, 

 about l nim in diameter, delivering one or two drops of liquid per 

 second. The most satisfactory liquids employed, on account of 

 economy and ease of recovery, are carbon bisulphide and acetone, 

 which produce quickly a temperature of —48° C. by this method, 

 When the apparatus is protected by a double-walled, silvered tube 

 it is easy to produce a practically constant low temperature for 

 a long time. It is a simple matter to recover the liquids nearly 

 pure by shaking the mixture three times with half its volume of 

 water and distilling the products. — Gomptes Rendus, cli, 715. 



H. L. W. 



6. The Relations between Chemical Constitution and Some 

 Physical Properties ; by Samuel Smiles, D.Sc. 12mo, pp. 583. 

 London, 1910 (Longmans, Green & Co.). — This is one of the 

 text books of physical chemistry edited by Sir William Ramsay. 

 As the title indicates, the aim has been to show the relations that 

 exist between certain physical properties and the chemical con- 

 stitution of compounds, particularly of organic compounds. The 

 various properties are dealt with under the general headings of 

 mechanical, thermal, optical and electrical properties and these 

 are further subdivided. Under mechanical properties, for in- 

 stance, are included capillarity, viscosity and volume relations. 

 There is a short historical introduction to each property, followed 

 by the common methods of determination and ending with a dis- 

 cussion of the results obtained. References to the literature ap- 

 pear to be excellent and the book will be found useful as a work 

 of reference. h. w. f. 



7. Positive Rays. — W. Wient contributes a very full paper on 

 this subject accompanied by many diagrams. His previous inves- 

 tigations had shown that the manifestations of canal rays are 

 dependent not only upon conditions of immediate excitation 

 but also upon length of path pursued and upon the conditions of 

 voltage and other circumstances in the escape of the positive ions 

 from one receptacle to another. The author does not agree with 

 Sir J. J. Thomson in regard to the non-dependence of the devia- 

 tion of the rays under magnetic and electric fields, upon voltage, 

 nor with the latter's assumption that the velocity of the rays 

 depends on the atomic energy or upon cathode rays instead of 

 upon the voltage. — Ann. der Physik, No. 15, 1910, pp. 871-927. 



J. T. 



