The San Francisco call., 1896-04-26

lead. material that favors the oxidation
of aluminium, were worn away at uni
form rate.
When NJ. Guillemoux examined it the
condition of the boat presented nothing
alarming, but repairs should have been
made at once, as aluminium when once
attacked deterlorates, even out OF water.
All the alumina used should have been
removed, the paint scraped of and new
coat put on, and as the whole hull is made
of the metal it would have been necessary,
in order to clean the vessel thoroughly, to
take it completely to pieces. The work
was not done, and the hull seems to be ir-
reparably destroyed.
The Vendenesse has made two trips to
sea and was besides kept for several
mercial basin at Havre. The water OF the
basin began to attack the parts from
which the paint had been removed, and
the action of the water was intensified by
the neighborhood of the copper bottoms
of a number of yachts. The hull was
scraped and repainted, and ever since the
parts attacked have behaved like the rest
OF the hull.
Later, the linoleum which covers the
deck having become loose, the deck began
to oxidiZe, wearing out irregularly and
forming holes in many places, so that
several plates had to be changed, The
seams presented a curious phenomenon.
4Ac UocQ CA pdllQcQ SItdb1y
drove apart the plates covering the joints,
lengthening out the rivets and forcing
their heads into the countersinks, without
letting in water, however, for the alumina
was compressed enough to make a perfect
joint. OF two plates riveted together only
one is attacked, showing that some gal
vanic action has taken place among
the various aluminium materials. This
arises from the lack of homogeneity
IN the plates, taken from different
ingots, fact proved by plunging various
samples into solution of sodium chloride.
The electromotive force of the pile thus
formed was measured and brought to light
two important facts: l. That the more
electropositive aluminium is the better it
resists salt water. 2. When aluminium
materials, of the same chemical compost
ton commercially, are brought together
there is risk Of producing voltaic piles.
M. Gujllemoux is of the opinion that in
the Nendenesse the sea water has not
modified the texture of the portions of the
metal that remained sound or affected its
powers of resistance.
There is no exact information to be had
as to the behavior of the aluminium boats
and canoes used by the Colonial Depart
ment. nor could it throw much light on
the subject as the water in which they are
used is usually not salt.
M. Guillemoux concludes that alumni
nun is suitable material for seagoing ves-
sells, and that the failures made in the
past are due to our lack of knowledge of
its nature and proper use and the irregu-
larity in its production.
The metal selected should be as free
from impurity as possible; it should be
tested by the galvanometer, and only
ingots surprising in electropositiveness
a standard well tested by experiment in
sea water accepted; the ingots should be
mixed together as much as possible in
fusion, so as TO secure homogeneity. In
construction the precautions to be taken
are very simple; they are merely to avoid
absolutely contact with copper and to
naint ell surfaces