ti:owi;ridge. 
UK. II ELECTROMOTIVE FORCE. 193 
other, the singing of the non-luminous discharge is very distinct. Then a bright white, 
threadlike discharge occurs, which is immediately followed by a flaring yellow dis 
charge, which, as I have said, can be drawn out 50 to GO cm. with a difference of 
potential of 40,000 volts. These experiments illustrate forcibly the modern Idea ot 
ionization. The glow at the negative terminal shows that tin- entire air of the room 
between this terminal and the positive terminal of the battery parli< |>a1es in this 
ionization. It would probably be impossible by any method of insulation of th< 
accumulator cells to insulate the positive pole of the battery so that this silent 
discharge would not manifest itself by this negative -low; for a large surface of any 
perfect, in a limited form, becomes a coml 
extended surface. 
CHARGING CONDENSERS. 
The form of condensers I have adopted is that of the so-called Franklin 
These plates are 30 x 40 cm. The glass is 3 mm. thick lor an accumulator of 10,000 
d 5 mm. for 20,000 cells. It is evident fi 
B 
lator that the strength of current which the aceumulator can deliver on a short 
circuit influences to a marked degree the insulating strength of the condenser which 
the 
D 
The plates of the condensers are arranged in wooden tray, w.th wutaWc switches, 
which enabled me to vary the nnmber of plates. They w,re also arranged so that 
they could be charged in multiple and then discharged in scries (Proceed,,, s of the 
American Academy of Arts and Sciences, Vol. XXX 1 1 1 
This form of condenser, namely the Franklin plate form, do, I not withstand the 
potential of the battery so well as the jar for,,, of Ley.len jar : a thick,,, of glass „, 
jar form which will perfectly insulate the terminals of the 20,000 cell, when charged 
to a 
difference of potential of 40,000 volts would break down when F 
d of the same thickness. I found that such plat l could not bo .ess tnan < 
f an inch, approximately 3 mm., in thicknc I to withstand constant use of 
battery of 40,000 volts. The large storage battery illustrated 
ssaryto charge condenser- to a definite poten' 
\Y 
ing 
of a Leyden jar of about 10,000 electrostatic units is connected with one pole of 
the other terminal rest- upon a wooden table upon which the jar is 
battery, and 
placed, this jar will discharge through a small spark gap 
about ten seconds. 
When 
connected directly with the outer coating of 
pidity of discharge increases to at least one hundred a ^econd an 
13 
