394 Scientific Intelligence. 



7. Action of Alcohol on Metals with which it'comesin Contact. 

 — After allowing pure 95 per cent alcohol to act upon several 

 metals for a period of six months in corked flasks, Dr. Malmejac 

 has found that a considerable amount of action took place in 

 several cases. With copper, there was no turbidity, and no resi- 

 due was left upon evaporating some of the alcohol. With tin 

 there was a decided turbidity, but the filtered alcohol gave a 

 hardly observable residue. In the cases of zinc, lead, iron, and 

 galvanized iron, there were considerable amounts of turbidity, 

 and the filtered alcohol in each case left a decided residue, which 

 was rather large in the case of lead. These experiments have an 

 important bearing upon the choice of vessels used for the storage 

 of alcohol. — Chem. News, lxxxiii, 115. h. l. w. 



8. On the Excitation and Measure of Sine Currents. — One of 

 the greatest needs in the subject of electrical measurements is an 

 apparatus which will produce sine currents. The theory of 

 periodic currents presupposes an accurate sinusoidal variation ; 

 but the instruments which are used to test the theory give in 

 no case hitherto true sine waves. Max Wien describes in a 

 leading article a method which seems to be a valuable one. The 

 sine waves are produced by the revolution of a brass wheel 

 in the periphery of which are numerous insertions of pieces 

 of soft iron. This wheel is the analogue of the perforated disc 

 of the syren in the subject of acoustics. The wheel revolves 

 between stationary poles of an electromagnet, upon which are 

 induction coils, in which the sinusoidal variations are produced. 

 By means of a condenser the circuit is tuned to resonance, and 

 accurate sine waves are produced, since by the tuning the har- 

 monics are rendered weak, and only the fundamental tone of the 

 circuit is preserved. — Ann. der Physik., No. 3, 1901, pp. 427- 

 458. j. t. . 



9. Metallic Reflection of Electrical Waves. — Righi has described 

 an experiment in which he claimed to have observed elliptical 

 polarization of electrical waves at metallic surfaces. Karl F. 

 Lindman quotes the theoretical conclusion of Poincare and of 

 Drude, to prove the impossibility of this for waves certainly 10 cm 

 in length. He concludes that this elliptical polarization does not 

 exist, and he finds that the electrical waves are linear polarized. 

 The results of Righi are attributed to some unexplained disturb- 

 ance. — Ann. der Physih., No. 3, 1901, pp. 617-637. j. t. 



1 0. The Light Transparency of Hydrogen. — V. Schumann, the 

 author of the remarkable paper on very short wave-lengths of 

 light in a vacuum, has shown that a layer of hydrogen gas is 

 very transparent to light and allows the shortest waves to pass 

 through it unabsorbed. He found, however, strange inconsist- 

 encies in his work, and in the present paper explains their cause. 

 In the earlier experiments the gas was led into the apparatus 

 through a rubber tube, and the use of this tube was found to 

 lessen the transparency of the hydrogen. When it was dispensed 

 with and great care was taken in preserving the hydrogen from 



