ON THE SENSITIVE STATE OF VACUUM DISCHARGES. 
563 
Page. 
Section XXIII .—On the relief-effect in tubes of high exhaustion with a positive air-spark. — III. The 
'positive luminosity and its attendant phosphorescence. 
Sensitive thread-like luminosity. 616 
Its attendant phosphorescence. 616 
Best produced by means of positive unipolar discharge . 616 
Due to local action from the sides of the tube . 617 
Distinct from relief phosphorescence. 618 
Experiments on attendant phosphorescence with thin films of glass inside the tube. 619 
Effect of a magnet on its shape . 619 
Separation of attendant phosphorescence from positive luminosity . 621 
Special phosphorescence at angles of positive luminosity when the latter is zigzag. 621 
Bulging of the shadow of a conductor in the attendant phosphorescence.. 621 
Splitting of the attendant phosphorescence . 622 
Section XXIV .—On the special effect in tubes of high exhaustion with a positive air-sparlc. 
Effects on luminosity of an external wire connected with the positive terminal; attraction when 
it is near, repulsion when it is close to the tube . 622 
Explanation of these effects... .... 622 
Long strip of tinfoil connected with positive terminal; used also with unipolar discharge .... 624 
Other modes of phosphorescence with positive unipolar connexions... 624 
Section XXV .—On the relief and special effects in tubes of high exhaustion with a negative air-spark. 
Virtual shadows produced by negative special connexions. 625 
Correspondence between positive special and negative relief; also between positive relief and 
negative special. 626 
Section XXVI .—General conclusions as to the electric discharge. — I. The comparative magnitudes of 
the small time-quantities of the discharge. 
Enumeration of small time-quantities. 628 
Interval between successive discharges a measurable quantity . 628 
Duration of intermittent discharges immeasurably short.... 628 
The time occupied by the passage of either electricity along the tube is of a greater order of 
magnitude than the time required for it to pass along an equal length of wire . 629 
Law proved by experiments of Section XIII... 629 
Positive and negative discharges appear to pass along the tube with the same velocity .... 630 
The negative discharge occupies a period greater than that required by the particles composing 
the molecular streams to go the length of the tube, but comparable with it.... 631 
Proved by virtual shadows ... 631 
Also by bulging of shadows... 632 
Also by experiment with screen having a small hole .. . . 633 
Also by virtual shadows with negative special arrangement .... . 633 
The time occupied by the passage of either kind of electricity along the tube is incomparably 
shorter than that occupied by the emission of these molecular streams, or (what is 
the same thing) by the negative discharge, proved by revocation experiment . 633 
Velocity of negative electricity ... 636 
Phosphorescence due to the time-element of the negative discharge. 637 
Positive luminosity and the blank space.. 639 
Time of emission of the positive discharge. 641 
Order of small time-quantities... . 641 
