76 Scientific Intelligence 



the test with sulphurous acid is only about one-tenth as delicate. 

 The sensitiveness of the reaction is increased, as far as the rapid- 

 ity of the coloration is concerned, if the acetylene contains hydro- 

 chloric acid fumes. — Chem. JSTews, lxxxiii, 243. h. l. w. 



V. Qualitative Chemical Analysis, Organic and Inorganic; 

 by F. Mollwo Perkin. 8vo, pp. viii, 266. London, 1901 

 (Longmans, Green & Co.). — This is an elementary text-book that 

 is unusually full in respect to the explanations and chemical equa- 

 tions that are given, and good judgment has been used in the 

 selection of the analytical methods that are employed. The book 

 presents a novel feature in including a treatment not only of the 

 more common organic acids, but also a variety of other organic 

 substances, such as aldehydes, alcohols, acetone, glycerol, several 

 sugars, starch, a few bases and glucosides, and about a dozen of 

 the more important alkaloids. h. l. w. 



8. Viscosity *of Argon. — Lord Rayleigh obtained the value 

 1*21 for the irictional coefficient of argon at ordinary tempera- 

 ture. Hugo Schultze, thinking that the apparatus employed by 

 Lord Rayleigh was not suitable for obtaining extreme accuracy, 

 has made new determinations. Extraordinary care was taken in 

 cleaning the glass of the apparatus and in purifying the argon. 

 It was possible to force the argon back and forth through the 

 glass tubes, and to measure the time of flow with accuracy. The 

 gas was also heated in a well devised calorimeter and a much 

 improved manometer of water in combination with mercury was 

 employed. The relative value obtained by the author is a little 

 larger than that obtained by Rayleigh. Tables are given of the 

 relative values of the coefficient with reference to air. The tem- 

 peratures varied from 15° C. to 183° C. — Ann. der Physik y No. 5, 

 pp. 140-165. j. t. 



9. Conductivity produced in Hydrogen and Carbonic Acid 

 Gas by the Motion of Negatively Charged Ions. — This subject 

 has been studied by Professor Townsend and Mr. P. J. Kirkby 

 by the aid of the Rontgen rays, which were allowed to fall on 

 the gases contained between two parallel plates — maintained at 

 various differences of potential. The authors conclude that a 

 negative ion makes 11 '5 collisions per centimeter in hydrogen at 

 jmm p ressurej an d 29 collisions per centimeter in carbonic acid gas 

 at the same pressure. It was found that the mean free path of 

 an ion is longer than the mean free path of a molecule in the 

 following ratios : 



4 8:1 in hydrogen. 



46 : ] in carbonic acid gas. 



4*3 : 1 in air. 



—Phil. Mag., June, 1901, pp. 630-642. j. t. 



10. Electromotive Force of the Clark- and the Weston -Cell. — 

 An exhaustive examination of the constancy of the electromo- 

 tive force of these elements has been made at the Reichsanstalt, 

 by W. Jaeger and S. R. Lindeck. This result of their work 

 shows that the criticisms of Cohen, in regard to an instability of 



