166 New Magnetic Electrical Machine. 
apart. A few turns of the wheel furnish mixed gases enough 
to make a smart explosion. A solution of sulphate of soda in cab- 
bage water, contained in separated glass cells, submitted to the 
action of the machine, gives immediately the characteristic chan- 
ges of color by decomposition ; reversing the motion of the wheel, 
the reverse change takes place. The light from charcoal points 
’ is insupportable. Plumbago gives an intense light. The metal- 
lic leaves burn with splendor. When a wire is suddenly with- 
drawn from one of the poles or brass straps, a bright spark is ob- 
po half an inch in length. When the circuit is broken from 
and clean metallic surface, an entirely new and beauti- 
fal appearance presents itself. A diffuse, irregular, nebulous 
spark, darts along the surface, (as 
seen in fig. 2,) sometimes in sev- ee 
eral directions at once, to the dis- 
tance of half or three quarters of 
an inch. It succeeds with all 
the metals yet tried, but best 
with a piece of iron finely stri- 
ated with a smooth file. When 
the lever trip is worked, the sec- 
ondary current frequently plays 
with an intense green light, 
across the separations between the pole changers. The shock 
from the direct current is uncomfortable with dry hands; but 
‘when the secondary current is used, it is painful to touch the 
poles, even with the fingers. It causes the gold leaves of the elec- 
troscope to diverge strongly, without the aid of a leyden jar, or ex- 
tended, insulated metallic surfaces. It charges a leyden jar at ev- 
ery touch. A charcoal point on the knob of the jar, affords a bright 
light at every touch. I have some time since shown, that the 
shocks and decompositions produced by the secondary current of 
flat spirals and helices in connexion with a single pair of plates, 
were greatly increased, if the surface of the mercury, (or solid 
conductor,) from which the cirtuit is broken, be covered with 
pure water or naphtha. I have since found that oil gives a far 
greater increase than either. The rationale is now obvious. 
When the battery circuit is completed, (as shown by Faraday’s 
‘discoveries of vol volta-electric induction,) a feeble secondary current 
flows in a direction opposite to that of the battery. When the 
