1868. | Physics. 117 
depended to prove that the polarization proceeded from the gases 
adherent to the electrodes. In fact, polarized metals should be con- 
sidered as fugitive combinations formed by the metals and gases, and 
the author is of opinion that in polarization couples as well as in 
Grove’s gas pile the electro-motive force is the affinity exerted on 
one of the elements of the water by a gas associated in a particular 
manner with a metal. 
Dr. Henry Morton, of the University of Penna, Philadelphia, 
has lately described an important adjunct to the induction coil. He 
prepares the arrangement in the following manner :—Take eight 
plates of glass, about 11 inches by 14 inches, and attach to both 
sides of each plate, sheets of tinfoil, 7 inches by 10 inches in size, 
with rounded corners. Set these plates upright in a box (provided 
with grooves for the purpose) about 14 inches apart; then rolling 
up some balls of paper large enough to fit between the plates, and 
wrapping a strip of tinfoil around each ball, thrust them between 
the plates, and, lastly, make an outside pole to the terminal sheets 
of foil, by means of wires enclosed in glass tubes passed through 
the side or top of the box. It is evident that we have here a com- 
pact form of Leyden battery, arranged for “cascade.” With the 
ordinary electrical machine such an arrangement would be worthless, 
from its want of insulation. With the induction coil, however, 
which developes an entire charge in an instant, it becomes of great 
value in a certain class of experiments, because it gives us at once 
the concentrated charge peculiar to the Leyden battery, combined 
with a spark length, which it would otherwise have lost. (This 
property of long spark in the “cascade” arrangement of jars is well 
known.) If such an apparatus as here described be connected with 
the secondary poles of an induction coil, and other wires are then 
led off (with a break in the circuit, however, of + to ? inches) to 
some piece of apparatus for the illustration of electric discharge in 
vacuo, such as Gassiot’s cascade (especially with a canary goblet), 
the aurora tube, an electric egg of canary glass, &. (but not a 
Giessler tube), the brightness of the illumination and volume of the 
discharge will be immensely increased. Thus a goblet invisible at 
30 feet, when the unaided coil is used, becomes brilliant at 50 feet 
with this attachment. The author has used two coils with the 
above apparatus, both made by Mr. E. 8. Ritchie, of Boston, one 
yielding a spark of 8 inches, the other, which gives, in its present 
mounting, sparks of 16 inches, to provide against accident ; such a 
length being abundantly sufficient for use. Geissler tubes, unless 
of very large area, are not benefited in appearance by this arrange- 
ment, because the unaided coil can supply all the electricity they 
are capable of transmitting, and this excessive charge only tends to 
develop inductive resistances in the glass tubes themselves, which 
resistances this momentary current is the least fitted to overcome. 
