Chemistry and Physics. 399 



- = 1,878.10' Abraham 



ft 



" = 1,876.10' Bucherer 



" = 1,881.10' Lorentz 



—Ann. der Physik, No. 3, 1906, pp. 487-553. j. t. 



7. Retardation of the Velocity of the a Particles in passing 

 through Matter. — Professor Rutherford gives a preliminary 

 note on this subject. He has repeated his former results, and 

 concludes that further experiments confirm them. An active 

 wire was coated with radium C. The velocity of the a particles 

 was found to decrease in passing through aluminum. The low- 

 est value of the velocity observed was '64V , where V is the 

 initial velocity of projection of the a particles from the bare wire. 



The value of — for the a particle from radium C after passing 



through a screen equal in absorbing power to 5 5 cms of air, was 

 found to be the same as for the a particle of the bare wire. 

 This experiment shows that the a particle retains its charge and 

 mass unaltered over a great part of its range in air. — Phil. 3Iag., 

 April, 1906, pp. 553-554. j. T. 



8. Electrical Conductivity of Flames containing Salt Vapors 

 for alternating currents. — For rapidly alternating currents a 

 flame containing an alkali-salt vapor behaves like an insulating 

 medium having a high specific inductive capacity. The view is con- 

 firmed that the negative ions from all salts have the same velocity. 

 Not more than one molecule in 30 salt molecules is ionized at 

 any instant in the flame, but each molecule is probably ionized 

 and recombines several million times per second. The steady 

 currents observed through salt vapors in flames are very far from 

 the maximum possible currents corresponding to the number of 

 ions produced per second. The paper is a full one and is by 

 Prof. N. A. Wilson, and E. Gold.— Phil. Mag., April, 1906, pp. 

 484-505. j. T. 



9. Electrically prepared Colloidal Solutions. — The size of the 

 diameters of the particles of gold, silver and platinum in elec- 

 trically prepared colloidal solutions lies between the limits 

 (2 — 6)xl0 _5cms . The electro-negative, non-oxidizable metals, 

 gold, silver and platinum, give solutions in water and ethyl malo- 

 nate, in which the particles are negatively charged. The electro- 

 positive, oxidizable metals give solutions in water, methyl alcohol 

 and ethyl alcohol, in which the particles are always positively 

 charged. The velocity of the particles under a known electric 

 force have been determined and the potential differences between 

 the liquid and the particle have been deduced by using the formula 



47T LLV 



V = ==-.-~r . — E. F. Burton, Cavendish Laboratory, Phil. Mag., 

 lv 2L. 



April, 1906. j. T. 



10. Recombination of Ions in Air and other Gases. — Among 



the large number of important papers on ions in the April num.- 



