The Saint Paul globe., 1899-03-05

case with aluminium, which ie destroyed by
eleotro1yas action az rapidly with an alternat-
nE f as sesTa r1a dss9s aesS c, mad. that IN.
Sy sieetrolysls. I may say that IN s the s,ss one
nc reported S%tst me- where pipes have
" caused by the expansion caused by freez-
ing, and was not discovered until the Ice
had been melted by the current and the now
started.
1t has been suggested by some that SUM-
caent heat might be generated at some -point
Where there was q bad contact to get uD q
This could only occur under very exceptional
conoacons, II at all, since the water main ID
In a way an open system. and the pressure
could not rise above the normal water pres
sure unless the pipe were completely ologged
with ice or some other obstruction on each
side OF the heated spot. Even then 1t Is
unthinkable that steam at high enough
pressure could exist in the pipe to rupture
1t. as condensation would be exceedingly
rapid. r.. ". Wood
Madison, Wis. Feb. 2S
FROZEN SOIL A ANON-CoNDUCToR
Addressing the same paper Prof Jack
son says:
The following reasons seem to preclude in
Jury from electrolysis on the outside or in
side Of water mains under the usual condi-
tion In which the electric thaw Is used
F1rst-Damage to the outside OF buried
water pipe can occur by electrolysis only
WAeu al eieCtTlc current causes the metal
OF the pipe to enter moist soil around It,
Frozen soil Is not concuctor of electricity
so that the electric current cannot leave the
pipe buried in it and in almost all cases
the ground around frozen pipe is itself
frozen solidly.
Second-In most cases the thawing is ac-
complished by means Of alternating electric
currents currents that have very rapid
reversal of direction) and these are quite un-
likely to cause injury on the inside of
the pipe even If the current continues to
now after the Ice within the pipe is thawed.
Injury may be caused to the inside of the
pipe at Joints If currents of continuous d.
rection are used in the process and these
are therefore to be avoided.
Sometimes thawed pipe is found to be
leaky, but this Is not a result OF the eec-
trical process. 1t is well known that pipes
may be and often are split by the expansion
OF freezing water, and split. pipe will in
sist on leaking whether it is thawed by
sunshine by electricity or by the plumber
The cure in such a case can be made by
the plumber. After a small pipe has been
thawed it Is desirable to keep the water
running through it to avoid the possibility
of the cold earth around it causing it to
freeze up again. -Dugald c. Jackson,
Professor Of Electrical Engineering, Univer-
sity of Wisconsin.
Madison, Wis, Feb. 2S.
1t will be seen that both Prof
Wood and Prof. Jackson suggest
again that the only danger from cleo
trolysis lies in the suddenly interrupt
ed circuit. It Is safe to say that sci
ence could hardly produce SO useful an
application as electricity without be
Ing able to discover also a remedy for
all attendant evils. This has been
demonstrated by demonstration of cleo
trical experts, and they have proved,
1t might be thought conclusively, that
the return current system, properly ap-
piled. will remove all anticipated dan
ger of electrolySis