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XYI. On the Sensitive State of Vacuum Discharges .—Part II. 
By William Spottiswoode, D.C.L., LL.D., Pres. R.S., and J. Fletcher Moulton, 
late Felloiv of Christ’s College, Cambridge. 
Received March 11—Read Apiil 8, 1880. 
[Plates 25-29.] 
Contents. 
Page. 
Introduction .... 564 
Section XIV .—On the effect of intermittent inductive action of an impulsive type upon continuous 
vacuum discharges. 
Effect of intermittent discharge from one Holtz machine on a continuous discharge from 
another through a tube. 566 
Effects as to sensitiveness of the same arrangement on two auxiliary tubes in circuit, one on 
either side of the main tube. 560 
Precautions as to length of air-spark. 570 
Successive extinction of striae by a gradual increase of air-spark in the interfering circuit .... 571 
Formation of striae by means of the interfering discharge. 572 
Section XV .—On the standard-tube method of examining intermittent vacuum discharges. 
Description of standard-tube method. 573 
Precautions to be observed ...- . 576 
Section XVI .—On the Leyden-jar effect of vacuum tubes. 
Description of the Leyden-jar effect . . 577 
Position of air-spark for these effects. k . 577 
Explanation of these effects.. 578 
Condition of the tube in advance of the discharge ascertained by two pieces of tinfoil con¬ 
nected by a fine wire. 578 
Experiment with negative air-spark and a relieving system held at sparking distance from the 
tube. 579 
Section XVII .—On the phenomenon of phosphorescence in vacuum tubes. 
Description of phosphorescence in tubes.,. 580 
Comparison of phenomenon with the “ electric wind ” . 581 
Comparison of phenomena with the deposit on the glass near a negative terminal. 581 
Comparison of phenomena with the projection of platinum black, &c., from a negative terminal . 582 
Phosphorescence produced in tubes of moderate exhaustion by means of a long air-spark .... 582 
Relief phosphorescence similarly produced... . 583 
Phosphorescence produced by method described in Part I., p. 170. 584 
Experiments with tubes at various pressures......... 584 
