= 2276-0 



3 



2259-5 



1 



2208-3 



4 



2200-5 



1 



2197-6 



3 



2170-0 



1 



2152-3 



1 



150 Scientific Intelligence. 



The Volatility of Metals. — One of the most interesting facts 

 ascertained by this investigation is the volatility of all the metals 

 examined, except platinum, and particularly the extraordinary 

 volatility of manganese, and, to some extent, of the infusible 

 metal iridium. Metal believed to be pure iridium is seen to have 

 diminished after the flame has played upon it for about two hours. 



2. New Calcium Lines. — J. M. Eder and E. Valenta state 

 that they have discovered a new group of calcium lines in the 

 ultra violet. These lines appear by the use of strong induction 

 sparks and have the following wave lengths {i denotes relative 

 brightness, for the strongest calcium line £=10, and for the weak- 

 est i = 1) : 



i i 



A = 2140-3 3 



2133-0 1 



2131-2 1 



2123-0 1 



2112-9 3 



2103-2 2 



* 



— Wien. Anz., 1892, p. 252-253. j. t. 



3. The Hall Effect in Iron, Cobalt and Nickel. — Kundt has 

 examined this effect in thin layers of theme.tals deposited by elec- 

 trolysis on platinized glass, and states that in the three metals 

 examined the Hall effect is proportional to the rotation of the 

 plane of polarization of light in these metals in a magnetic field, 

 and since the rotation of the plane of polarization in these metals is 

 proportional to the magnetizing force, therefore the Hall effect is 

 proportional to the magnetizing force. He states as a curious fact 

 that electrolytically deposited bismuth shows a very weak Hall 

 effect whereas cast bismuth shows the effect to a great degree. — 

 Ann. der Physik und Chemie, no. 6, 1893, pp. 257-271. j. t. 



4. Measurement of Electrical Resistance by means of alternat- 

 ing Currents. — F. Kohlrausch in an important paper discusses 

 the limits of the method which owes its elaboration to him. 

 Other observers have criticized the method and the author takes 

 up their criticism and discusses the results which have been ob- 

 tained. He states that fluid resistances as high as 100,000 ohms 

 can be measured with precision by his method. He shows how 

 the introduction of condensers can in certain cases increase the 

 accuracy of the measurements. The want of symmetry of the 

 telephone which is employed on the Wheatstone Bridge is also 

 discussed. — Ann. der Physik und Chemie, no. 6, 1893, pp. 225- 

 256. J. t. 



5. A New Form of Induction Balance. — The Hughes induc- 

 tion balance is an instrument of great sensitiveness, but it has not 

 come into use in the measurement of specific resistance, for abso- 

 lute measurements cannot be made with accuracy by means of it. 

 It is true that Overbeck and Bergman have reached a fair degree of 

 accuracy in the use of the balance, but the metals measured had 



