Through the kindness of the United States Navy Department your committee
is enabled to give the results of a series of experiments (Nos. 26 to 41
inclusive) which have been carried on at the Norfolk, Va., Navy Yard,
for a series of years, by Mr. P.C. Asserson, Civil Engineer, U.S.N., to
test the effect of various substances as a protection against the
_Teredo navalis_. It will be noticed that the application of two coats
of white zinc paint, of two coats of red lead, of coal tar and plaster
of Paris mixed, of kerosene oil, of rosin and tallow mixed, of fish oil
and tallow mixed and put on hot, of verdigris, of carbolic acid, of coal
tar and hydraulic cement, of Davis' patent insulating compound, of
compressed carbolized paper, of anti-fouling paint, of the Thilmany
process, and of "vulcanized fiber," have proved failures.
The only favorable results have been that oak piles cut in the month of
January and driven with the bark on have resisted four or five years, or
till the bark chafed or rubbed off, and that cypress piles, well
charred, have resisted for nine years.
This merely confirms the general conclusion which has been stated under
the head of creosoting, that nothing but the impregnation with creosote,
and plenty of it, is an effectual protection against the _teredo_.
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