Electrical Beseatrches by De la Eire and, Gassiot. 31 



ELECTEICAL EESEAECHES BY DE LA EIVE 

 AXD GASSIOT. 



aT. de la Eive lias transmitted to the French. Academy an account 

 of his researches into the phenomena of the transmission of elec- 

 tricity — obtained from a Euhmkorff coil — through rarefied gases. 

 He states that the gas on which he operates is placed in tubes 4 

 or 5 centimeters in diameter, and 15 to 100 centimeters* long; or 

 in vessels 16 to 20 centimeters wide, and from 20 to 2-5 high. In 

 the longest tube, the platina balls, serving as electrodes, maybe 

 approached or brought into contact, as the wires carrying them 

 pass through leather collars. His experiments on the influence 

 of rarefaction on resistance to the discharge agree pretty well 

 with those of other observers, but he adds that when the 

 rarefaction approaches that degree which corresponds with 

 most perfect condensation, the gases on which he operated — 

 hydrogen, nitrogen, atmospheric air — follow precisely the law 

 ■ of conduction, being inverselv as length. 



Eemarking on the well-known appearance of stratification 

 in air sufficiently rarefied to permit of continuous discharge, a 

 phenomena that begins by slight striae on the side of the posi- 

 tive electrode, he details the following observations : — 



" It is with hydrogen that these striae appear most quietly 

 and sharply, when the discharge consists only of a rose-coloured 

 thread two or three centimeters in diameter. Gradually, as 

 the elastic force is diminished, the discharge enlarges as well 

 as the striae. Moreover, a black space, which is also seen : : 

 enlarge itself gradually, and which may reach five or six centi- 

 meters in length, seDarates the extremitv of the luminous column 

 from the negative electrode, which remains surrounded bv a 

 blueish atmosphere. The phenomena of stratification take 

 place in precisely the same way whether the gas be dry, or 

 more or less moist : it therefore does not depend on the ele- 

 mentary, or compound nature of the medium. At a very slight 

 pressure of one cr two millimeters, the annular divisions, alter- 

 nately dark and luminous, which form the stria?, become im- 

 moveable and very narrow (a quarter of a millimeter in breadth), 

 while under a stronger pressure they were animated with a 

 decided oscillatory movement, and had a breadth extendin. 

 five millimeters. "When the pressure is less than two milli- 

 meters, a gleam of pale rose appears in the black space, and 

 some luminous rings, which contrast, by their immobility and 

 sharply-defined contours, with the agitated striae in the rest 

 of the electric discharge ; and even at a pressure exceeding 



* It is time this -word was naturalized, so we spell if English fashion. I: is 

 to be hoped our own vexatious measures will not endure much lor 



