On a subsequent examination the tube and spectrum both brightened up under the influence of the magnet. The N lines, which were faint without the magnet, shone out under its influence distinctly—the red and yellow parts of the spectrum specially showing this effect. The H lines also brightened up, but hardly so much in proportion as the N. _Carbonic-Acid tube._ [Sidenote: Tube marked C A; lighting-up described.] A Geissler tube marked C A was examined. Capillary stream a brilliant bluish white; bulbs grey-blue, with a slight tint of green; slight stratification in positive bulb; stream diffuse, not quite filling the bulbs, and changing in volume as the coil-break was touched; glow round the violet-pole considerable, but markedly white in tint, rather than violet; stratification strong in capillary. With magnet excited, the capillary stream diminished in volume, but greatly increased in brightness. It “tailed over” into the negative bulb, and the stream through both bulbs curved towards the sides. A slight pattering noise was heard in the tube. In the positive bulb bright, imperfectly formed, saddle-shaped rings of light, with a tendency to spiral formation, were seen, somewhat similar to the effects in the Plücker tube after described (see Plate XVII. fig. 11). [Sidenote: Effects when magnet was excited.] The whole spectrum, under influence of the magnet, became much brightened up. Faint bands in the red came out bright, as also did some in the violet. The violet-glow was examined (without the magnet), and the light was found condensed into four prominent shaded bands, one red, one yellow-green, one green, and one blue, with fainter bands seen between. _Chlorine-tubes._ [Sidenote: Chlorine-tube No. 1 lighted-up. Action of magnet upon the tube and spectrum.] A chlorine-tube (No. 1) was lighted-up with the small-coil. Capillary stream of a pale green tint. Bulbs with very little glow in them; spectrum pale, and not very distinct. Under action of the magnet this tube brightened up throughout, and the glow became more condensed, and ran to the sides of the tube. The spectrum also brightened, the faint lines becoming stronger, but the general character was preserved. [Sidenote: Chlorine-tube No. 2 lighted-up. Effect on glow when magnet was put on.] A second chlorine-tube (No. 2) was then tried. Both bulbs were completely filled with a dense white (very slightly rosy-tinted) opaque light, and capillary the same, but brighter. A very slight violet tinge was seen at the negative pole. When the magnet was put on, both bulbs were at once filled with flickering bright streams of light, running towards the side of the tube, according to the direction of the current. The capillary stream at the same time changed from white to an intense bright green. The spectrum without the magnet consisted of sets of lines, with two well-marked absorption-spaces between, all seen somewhat faintly, as if through a mist.