The Washington times. [volume] (Washington [D.C.]) 1902-1939, 1917-01-04
BOOKWORMS BUSY
ON LIBRARY ROOF?
Something Has Been Burrowlng
Little Holes and Grooves
in the Copper.

Have the book worms grown tired
OF the rows and rows OF volumes up
at the Library OF Congress and climb
ed opt to burrow little holes and
grooves in the roofing?
A scientist, not a layman. suggest
ed that theory, in fun, when he went
up to inspect a phenomenon which
is the subject OF a forthcoming tech
nical paper of the Bureau of stand
ards.
Around the famous gold-lsafed
dome of the best known library
building in the world, lie long
stretches OF timed sheet copper roof
ing. 1t was constructed back In 1893
End 1894, when the price of copper
was about IL cents a pound, instead
OF 30 cents. and before galvanized
iron, and tin-iron. and lead roofings
we're so generally used.
Reof Trouble Il Aeademie.
The postoffice in Pittsburgh, Pa.
has the same kind of a roof, and the
same thing has been happening there
grooves and perforations appeared
Ia It.
The custodian of that buildiog
adopted a novel expedient. He COW
cred the roof with q coat of wool,
then poured q tar preparation on
that, thus achieving q roof which IL n
cross between that OF the Library Of
Congress and an up-to-date hen roost.
The idea Of putting the Library here
into its winter underwear in this
fashion is not contemplated.
The whole trouble about the roof.
as becomes the covering for a library,
is highly academic, so far as any
danger to the books 10 concerned. The
timed sheet copper lies on cement
or terra Gotta Not for many years
yet will the roofing wear away, and
IL II did the base would be protec-
ton from the elements for some time
longer.
OF Interest to Experts.
But the study OF the corrosion If
this roof Is OF great interest to the
experts out at the Bureau Of stand
ards, who have ben trying to find
out the longevity of different kinds
of roofs.
The case Of the library roof is ex-
planned at length in q printed paper
by DR.. Paul d. Mercis, read at a
recent annual meeting of the Amer
lean Institute Of Metals.
The corroslon Is possible, this paper
says, in any sort of timed copper,
since the present process Away pro-
duces an intermediate layer Of alloy,
which acts as an acceleratSr OF cor
rosion.
MT. MereIa's Cohclusion.
The Forthcoming publication of the
Bureau OF Standards will deal with
samples OF other timed sheet copper
roofngs affected similarly to that at
the Library of Congress.
DR.. Mercia's conclusions are
summed up at the end OF his paper
as follows:
1.-THE explanation OF the LEGAL char
acter of the corrosion of the timed
sheet copper roofing material seems
fairly elearN Along the line Of
scratches, tool marks, etc, the thin
coating OF tin thickness, about 0.012
nm. in averagel was penetrated and
the copper underneath exposed. This
copper Is in contact with an alloy
layer, which is proved to be electro
negative, and less readily corrodible,
than the copper; at these points the
copper and the alloy layer form a gal
vanic couple, the copper being at
tackled more readily than il the alloy
were not there.
at, therefore, appears that this type
OF corrosion is possible, inherently.
in any sample OF timed copper, since
the present process OF timing always
produces this intermediate layer Of
alloy, which acts as an accelerator
OF corrosion, once the underlying cop
per Is exposed"