290 Intelligence and Miscellaneous Articles. 



the existence of simultaneous, but different wave-lengths proceeding 

 from the same primary conductor may be established ; only in air 

 are the limits much closer than in wires. In order to obtain clear 

 results the dimensions of the primary conductors must here bear 

 a given ratio to that of the resonator, which does not differ greatly 

 from unity. 



For circles of the diameter 2R, the distance of the node in air L, 

 and in the wires D, there was obtained : — 



2R .. 



. . 0-26 m. 



0-36 



0-75 



L .. 



.. 1-12-1-25 m. 



1-40-1-80 



3-00-3-3 



D .. 



.. 1-12 



1-47 



2-96 



The waves in air are thus not at all, or but little, longer than in 

 wires. — ArcJiiv. de Geneve, [3] xxii. p. 557 (1890); BeibVdtter der 

 PJnjsiJc, vol. xiv. p. 1200 (1890). 



ON THE CONDUCTION OF ELECTRICITY BY THE VAPOURS OF 

 HEATED SALTS. BY SVANTE ARRHENIUS. 



The author gives a long and important paper on this subject ; 

 the method of experimenting was to produce the vapour in the 

 flame of a Bunsen-burner, and to measure the conductivity between 

 two platinum wires placed at a given distance from each other. 

 The various experimental precautions are fully described and dis- 

 cussed ; the experiments extended to various classes of salts, and 

 the author sums up his conclusions as follows. 



The extremely fruitful hypothesis of van't Hoff, that matter in 

 the form of gas and in that of dilute solution has perfectly ana- 

 logous properties, has so far been established in the most brilliant 

 manner ; and with the aid of the laws of gases a light has been 

 thrown on the nature of solutions, hitherto undreamed of. In 

 the present paper I have followed the reverse way, and with a 

 knowledge of the electrolytic properties of dilute solutions the same 

 properties which have hitherto been unknown have been demon- 

 strated in gases. Hence there is a complete analogy in this respect 

 between the two conditions of matter. — Wiedemann's Anndlen, 

 vol.xlii.p. 18 (1891). 



ELECTRICAL WAVES. BY ERNST LECHER. 



The author describes a new method of studying Hertz's phe- 

 nomena. Instead of a resonator of the type employed by the 

 latter, a Geissler tube is used. Two parallel wires of known 

 self-induction terminate at one end in condenser-plates, which are 

 charged in an oscillatory manner by a large Euhmkorf coil excited 

 by storage-cells. Upon the other ends of the parallel wires rests 



