!'IIY>I< >. PROGRESS < 





rH ..biaine.l b\ I'- mm and . 

 are not onlin.in dilTnietion ima-. -. b;r 



..\\n with 

 ordinary light, ami tin* fact, the author I* 



i pro\ing the X ra\- to U- undula- 



U -Jlide-4 i meihiNl of delermin- 



Mgth of K S, the result of 



n*ll, founded on 



the fact that a |"-rfe-tiy idcnsic.il deflection it 

 i, pr ngihs. 



. diffi 



:imte manner. I'. 



iHin de - knOaiSS de Ph\ -iqiie." 



that for unlinary n\- the sin-citi 

 lined as the ai 



: unit surface density) increases with 

 the density*, but that re-nils vary with the quality 

 ..flh r.t\-. He a ume- that at the limit, a 



and higher frequency are produced, t he 



n of all -ub-' 



equal. Swintoii (Londoi , i ha- in- 



ited Home proper!: ,:_'. n ra\ - b\ 



- of the luminescence they produce on | 

 bon surface. He has thu- demonstrated the \n>\- 



lowile-sof the convergent and divergent OODl 



iibe. has shown that the rays cross 

 at the focus with no rotation, and has proved that 

 the cathode ray-, to produce Koiitgen ray.-, must 



fall on solid matter. Hemptinne (Paris Academy 



iiiids that while electric vibra'- 



cause gases to become luminous at a low 



_ n ra\-. u-ed at thi- same time, 



which luminosity OG 

 I'errin (Paris Academy' of 

 1 1 finds that the effect produced on a ch.. 

 conductor by the Kontgcn rays eon-i-t< of two 

 . "lie depending "ii the nature of the gas ami 

 tl t her on the metal. Villari (" Atti dei Lincci." 



VI. page ll has investigated the relation between the 



11 produced in gases by Kontgen rays, in 

 virtue of which such gases discharge electrified 



i the molecular association in which 



- Iran-formed into o/one by the electric spark. 

 He finds that an o/..nator through which passes a 



:it of air first traversed by Kontgen rays de- 

 I that air of its power of discharging aii elec- 

 troscope. Hcmiitinnc r/citschrift fiir physika- 

 li-chc < hemie." December, i*'.<;i i, a s attempt'ed t<. 

 detect some action of Kontgen rays on chemical 

 -. II- lid d. -. : DO effect ai all on the 

 conductivity <f aqueous solutions Of electrolytes. 



the ! t ethereal -alt- by acids, and' the 



nation of chlorine with hydrogen and carlion 

 rnotinxide. and only minute traces of change on so- 

 lutions, such as that of silver nitrate in alcohol, that 

 -.posed bv light. iVrrin (Socielc Fran- 

 ie, f >cc. 4. 1806), in investigation- on 

 of neutral electricity in gases by 

 ';iys. finds that at OOQStanl pre un- the 

 f dissociated electricity per unit volume 

 portional to t|,,- pressure. 'ami hence to the 

 n-taiit pressure it i- independent of 

 nature. The quantity dissociated JHT 

 unit mn- rariei a- M..- ab-olute temperature. 

 Child (American Association) find- that electricity 

 can M continuously discharged by X 

 when the char. ;,d j n . 



sulntor. a* paraffin. Villari ("Nature." M ; . 

 finds that the ,| ,f conductor in air, pro- 



1 by Kontgen rays, seems to take place b\ 

 u. as if by an electric dance ,,f ti 

 in air, roused by radiation. Thi- di-charge lessens 

 when the exposed surface is diminished, as l>\ 

 ering it with paraffin. The paraffin, under the 

 action of the ray-, does not gain in conductivity. 

 India rubber and insulating liquid- Ix-havc almost 



:iducli\e I ,M'- under 



the illtltiellce of t ll- ! ..- - with their dell-i- 



_: nheimer - aces, 



l-'i-li. 1"' -lio\\- thai ill,' l.".iil^en ra\- inlluence the 



: tin- elect ric spark, tin- in- 

 of this di-taiice depending "ii the iiiten-ity of the 



hat fall on the spark gap when the sparking 

 distance ami potential difference an- con-taut. If 



the potential and the intensity of ti kept 



.llll. the IIHTea-c of c \plo-i\e d i-t a lice depend - 



on the distance of the spark -rap ir,,m the cmi i\e 

 wall of the tube. 



'inifrii/i/ii/ hi/ Iin/Hii-f. 1 1. II .Met in 



of th< I a photo- 



graphic impression of Ixcopodium j.owder that i- 

 allowed to fall on a -en-ili\e plate. l.\ mean- of the 



electricity developed by tin- impact of the p. 

 with the plate. With an uncovered plate a : 

 but distinct impression wa- obtained after an Imnr 

 and a half, but with a covered plate (he impr< 

 wa- more powerful. Where the covering \\a- 

 broken. dark ramifications extend into ti 

 portion, apparently following the dirc.ii,.! 

 which electricity wa- propagated along the -urface 

 of the plate. An-oii ("Nature." .Ian. ',' I > I. 

 cured \ery perfect images of the invisible electric 



discharge. !! Bays: "This discharge, or possibly, 



more strictly speaking, the electrified stream- o| 

 air driven off by it . appears to act upon the plate 



fly a- light does, It i- thu- pos-ibie to seemv 

 Impressions <f such di-charge- by simple electri- 

 fication and subsequent development.' 1 



Itixclmnji- It'ni/x. llofTmann ( VN'iedeinann's " An- 

 nalen." Pebrnary) deSCZibea a kind of rays called by 

 him "di--harge ray-." which are contained in tin- 

 spark discharge in air. hydrogen, and nil rogen. at 

 ordinary or low pn un-. They have no photo- 

 graphic" action, but impart luminescence to -olid 

 solutions of magnc.-ium sulphate in gyp-urn when 

 In -a I I'd to a tempi-rat lire below incandescence. They 

 are intercepted by mica, quart/, fluorspar, and ot her 

 -..lids (unless produced at low pre--urcs). pi 

 in straight lines, are not deflected in a ma-neti.' 

 field, and are not reflected by solid-. They differ 

 from ultra-violet light in their power of pem-t rat- 

 ing air and not fluorspar. 



1,'ml Hint J'l n/,, , I/' .< ' . Md'el 



( Paris Academy of Science-. March 1 1. in re-i-arche- 

 on his "uranic ra\-" f Annual Cyclopa-dia," \^'.'>. 



Sage 641 1. finds that uranium ha- the pn-p. 

 ischarging elect rifled bodies at a ili-tane,-. the tim.- 



of discharge being the -ame for positive ami ; 

 live charges. !', ,r potentials below l."i volts tl 

 locity of di-charge is proportional to the potential. 

 Kor potential- between l.."i(Hland t2.(MM) thi- vdo.-ity 

 is constant. Lord Kelvin and other- (Edinburgh 

 Royal Society. March 1 and J) obtain similar re- 

 sults. They 'find that two poli-he.l metallic sur- 

 faces connected to the sheath and the insulated 

 electrode of an electrometer give a deflection from 

 the metallic xero of about the same amount when 

 the air between them i- influenced by the uranium 

 rays, as when the metals are connected by a drop 

 of water. Kelvin. IVatt ie. and l>e Smolaii dln<l., 

 April 4) find that the elect ric leakage induced by 

 metallic uranium is not proportional to thce]< 

 moti\ ! i- not perceptibly incn-a-ed when 



the uranium i- heated or when sunlight falls on it. 

 The rate of leakage is greater in oxygen than in 

 .. In carbonic acid it i- 



le for low ai lor higher pressure.-. In 



Millimetre- the leak- 



rly proportional to the atmospheric 



pressur.-. Lead 2 millimetres thick i- not tran-- 

 parent to the influence of the uranium, but g 

 millimetre- thick doe- not stop it entirely. Mica i- 

 quite transparent, and copper and zinc partially 



