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.
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).
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.
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.