CJiemistry and Physics. 56 



nearly twice the weight of the oxalate. After standing several 

 days, the temperature being allowed slowly to reach that of the 

 atmosphere, the liquid was distilled, whereby some rnosityl oxide 

 passed over. The residue, freed from an oily layer by a sej)ara- 

 tin^ funnel, was neutralized with potassium carbonate and agjita- 



CgHi202. Its vapor density was 

 hoi, and it has the rational foVmula 

 CH3 

 CH, . CO. CH,— C-— OIL— iie%'5 Annalen, clxxviii, 342, Oct., 

 CH3 



8, A new relation between JElectricity and Light — Mr, John 

 Kerr has succeeded in showing that dielectiitied media are bire- 

 fringent. Two holes were drilled in a block of plati' ghiss so us 

 to leave a space of only about a tenth of an inch between their 

 ends. Copper wires covered with rubber and shellac were inserted 



► these holes, and the current from an induction coil capable 

 of giving a spark of 20 to 25 cms. passed through them. A sec- 

 ond passage is opened to the current of variable length through 



that when the spark passes the glass is subjected 

 an electric strain. The light of a lamp is passed through a \icol 

 prism, then through the glass, and finally through a second Nicol 

 at right angles to the first. Since every plate of glass exerts a 

 depolarizing action a certain amount of light is transmitted. 

 This is cut off by interposing a second piece of the same plate of 

 glass and slightly turning one of the Nicols. If the plane of 

 polarization is inclined 45° to the line along which the electric 

 action is exerted through the glass on closing the primary circuit, 

 light will be visible in about two seconds. It brightens continu- 

 ously for nearly half a minute, and if the current is broken, will 

 gradually fade away. The light thus restored cannot be extin- 

 guished by any rotation of the analyzer. If the plane of polariza- 

 tion is parallel or perpendicular to the lines of electric force no 

 action is obtained. There is as great an effect with a rapi<l suc- 

 cession of contrary electrizations as with a continued electrization 

 in one direction. 



A small square of glass held edgewise in a vice was then intro- 

 duced in the path of the beam and compressed feebly horizontally. 

 A second plate like a microscope slide was also inserted and bent 

 by the hands until the light introduced by the depolarization of 

 the first plate was extinguished. From this arrangement of the 

 apparatus, it appears that the dielectrization of the i)late glass is 

 equivalent optically to a compression of the glass along the lines 

 of elect ric force. Dielectrified glass acts upon transmitted light as a 

 luuative uniaxial crystal with its axis parallel to the lines of force. 



quartz, gave results worth mentioning. ' The great difficulty was 

 to get a sufficiently strong superficial insulation, the masses being 



