[Sidenote: Tube No. 1 between the poles of the magnet. Change of colour in capillary stream. “Tailing-over” of capillary stream.] (3) The capillary part of tube No. 1 was arranged between the poles of Ladd’s electro-magnet, the conical ends of the armatures almost touching the tube (Plate XVII. fig. 1). With the magnet not excited, the capillary stream was bright and of a slightly rosy-yellow tinge. It varied a little in apparent diameter with the current. As soon as the magnet was excited the capillary stream, as also (in a less degree) that in the bulbs, were seen to contract, and to change from a _rosy_ tint to a distinctly _blue-violet_. The polished armatures, acting as reflectors, showed this change of tint in a most marked manner each time the magnet was excited. At the same time the capillary stream was seen to run into the negative bulb, as if overflowing, and with an effect resembling the “tailing-over” of a gas-flame. This effect took place each time the magnet was excited, and was not found at the positive-bulb end. [Sidenote: Spectrum examined.] Occasionally, when the magnet was excited, flashes of light were discharged in the negative bulb from the capillary towards the violet-pole. The spectrum was then carefully examined. No change was seen in the actual position of any of the lines or bands when the tube was influenced by the magnet, but those towards the violet end of the spectrum were conspicuously brightened. [Sidenote: Negative bulb between poles of the magnet. Positive bulb within action of the magnet.] (4) The extremity of the negative bulb was now placed between the poles of the magnet. A bright violet-coloured arc, following the magnetic curve, was at once formed, as in the case of the large Plücker tubes; and at the same time a straight stream of not very bright light ran along the bulb. The positive bulb was next placed within the action of the magnet; and immediately a brilliant spiral of flickering light appeared in the bulb, lighting it up, and reminding one in shape of the spiral which water forms on being poured from a lipped jug (see Plate XVII. fig. 9). [Sidenote: Spiral formed.] This was repeated each time the magnet was excited. The spiral, though flickering in character, was permanent in form, and inclined to the side of the tube which was in contact with the N pole of the magnet. _Oxygen-tubes._ [Sidenote: O tube No. 1; spectrum described.] A tube (No. 1) was lighted up and examined with the spectroscope, and found to give the spectrum shown on Plate XIV. spectrum 3, but with a strong set of H lines in addition. [Sidenote: O tube No. 2; spectrum described.] A second tube (No. 2) was then lighted up. The spectrum was a bright one, similar to the foregoing, the principal H lines being present, but not strong. [Sidenote: Tube-glow described. Effect upon glow when magnet excited. Bulbs between poles of the magnet. Effect of magnet on spectrum.]