Effect of withdrawing spark from central position between the poles.
8. As the spark was withdrawn from its central position between the poles of the magnet, the convex edge of the aura became gradually less perfect, and assumed a ragged and broken-up appearance, the inequality at times amounting almost to jets or flickering sprays of light. The spark was also slightly curved away from the electrodes (see Plate XVII. fig. 7).
Magnet had no effect upon condensed spark.
9. A condenser of four coated plates was introduced into the circuit, causing a sharp brilliant blue-white spark, apparently divided into streams and with no aura. The magnet had no effect whatever upon this form of spark.
CHAPTER XIX.
THE DISCHARGE IN VACUO IN LARGER VESSELS, AND MAGNETIC EFFECTS THEREON.
A Tate’s air-pump was used, and the spark from the larger coil. The exhaustion could not be carried very far.
Globular receiver described. Discharge described.
(1) A globular receiver was used, having brass caps for exhaustion, and platinum wires passing through the opposite sides for electrodes (see Plate XVIII. fig. 6). With partial exhaustion, from the positive electrode proceeded long, sharp, bright, rosy sparks, striking in zigzags across the receiver. From the negative terminal sprang a larger number of bluer and more diffuse streams of light, like spiders’ webs; and these were enveloped, for a short distance from the terminal, in a slight misty aura. Both sets played round the sides of the glass as well as across.