Spottiswoode on Stratification in Electrical Discharges. 241 



side, each being 174 yards (159 metres) long, another with two 

 wires each 350 yards (320 metres) long ; of the latter we have two 

 coils. 



Kg. 1. 



A- -A' 



In addition to these accumulators we have several others formed 

 of alternate plates of tinfoil and insulating material, such as paper 

 saturated with paraffine, and also sheets of vulcanite. These are 

 of various capacities and contain from 5 to several hundred square 

 feet. The largest has a capacity of 47*5 microfarads ; when it is 

 discharged it gives a very bright short spark, accompanied by a 

 loud snap ; the charge deflagrates 8 inches (20*32 centims.) of 

 platinum wire, -005 inch (0*127 niillim.) in diameter, when it is 

 caused to passed through it. Each accumulator gives different 

 results ; but for the present we shall confine ourselves to a descrip- 

 tion of the experiments made with the coil-accumulators. 



When the terminals of the battery are connected with the wires 

 of a vacuum-tube which permits of the passage of the current, 

 the wires (especially that connected with the zinc end) become sur- 

 rounded with a soft nebulous light, in which several concentric 

 layers of different degrees of brilliancy are seen ; in most cases there 

 is either no indication of stratification, or only a feeble ill-defined 

 tendency to stratification : the tubes selected for these experiments 

 were those in which the stratification did not appear at all. 



"When the battery, already in connexion with the vacuum-tube, 

 was also joined, as in fig. 2, on to one or more coil-condensers 

 (coupled to introduce a greater length of wire) in the following 

 manner, then immediately well-defined stratifications appeared in 

 the vacuum-tube. 



Fig. 2. 



^~1S 



PUl. Mag. S. 5. Vol. 1. No. 3. March 1876 



