The sun. [volume] (New York [N.Y.]) 1833-1916, 1896-04-12
ALUMINruM noArs ~ SEA WATER.
How the Two French wrr Vessels stood the
D-nriv HouEht E<pcricnce show
ING NXhnt IL to &c Avoidrh In Emimrc.

How the Two French wr- Vessels stood the
Test D-nriv HouEht Experience show
Ing What IL to Be Avoided In Future.
An nvcstlrntlon into tho condition Of the
two aluminium vessels OF the French navy, tho
Vcndencssc. n yacht. and tho Snrrow torpedo
boat La Foudrc. made by ". GuiilcmouX. and
reported IN Lc Gfpic Ciri. throws much light on
the conditions under which aluminium may he
used in naval construction. 10th vessels have
now been two yenrs In use.
Tho hull Of the Yarrow torpedo boat has only
suffered where tho metal has como into direct
contact with salt water. either through the peel
ing Off of tho paint or its lacking tho requisite
imperviousncsa. IA for instance in the portions
above the water line. The deck, covered by
rubber cloth glued to tho metal. Is intact. The
interior portions. painted over with rcd lead. n
material that fnvors the oxidation Of aluminium,
were worn away Uniform rate. When NJ.
Guillemoux exam I the condition of the
boat presented moth alarming. but repairs
should have been mad, t once, as aluminium
when once attacked deh ~iorates. even ont NJ
water. All the alumina used should have
been removed, the paint scraped of. and a new
coat put on. and "a tho whole hull Is made of
the metal II would havo been necessary, In order
~ clean the vessel thoroughly, to take IL com
pletely to pieces. The work was not done. and
the hull seems to he irrcparably destroyed.
The Vendenesse has made two trips to sea,
and was. besides. kept for several months when
FIRST launched in the commercial basin at
Havre. The water OF the basin began to attack
the parts from which the paint had been re-
moved. and the action Of the water was inten-
sifed bv the neiRhborhood of the copper bot
toms Of n number OF yachts. Tho 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 ont irregularly and forming holes In
many places. so that several plates had to be
changed. The seams presented a curious pho
nomenon. Tho alumina used expanded great
ly and drove apart tho plates covering the
joints. lengthening out tho rivets, and forcing
their heads into the counter sinks, without let
ting IN water, however. for the alumina was
compressed enough to make n perfect joint.
OF two plates rivctea together only one Is at
tackled, showing that some galvanic action has
taken place among the various aluminium ma
terials. This arises from tho lack OF homo
geneity in the plates. taken from different
ingots. a fact proved by p~lunging various sam
pies into n solution of sodium chloride. The
electromotive force OF the pile thus formed was
measured ana brought to light two important
facts: /. That the more electropositive alumni
ium IL. the better 1t rcsists salt watct. 9. When
composition commercially. are brought together
there Is n risk Of producing voltaic piles. NJ.
GuillemouX Is OF the opinion that in the Ven
denesse the sea water has not modified the tex
ture of the portions Of the metal that remained
sound or affected its powers of resistance.
There Ia no exact Information to be had as to
the behavior OF the aluminium boats and canoes
used by the Colonial Department, nor could 1t
throw much light on the subject. as the water
in which they are used is usually not salt.
NJ. Guillemoux concludes that aluminium Is q
suitable material for seagoing vessels, and that
the failures made in the past are due to our
lack OF knowledge of its nature and proper use
and the irregularity in its production.
The metal selected should be rs free from i'm
purity as possible: 1t should be tested by tho
g~alvanometer, and only ingots surprising in
electro positiveness n standard well tested by
experiment in sea water. accepted: the ingots
should he mixed together as much as possible
in fusion, so as 10 secure homOgeneity. In con-
struction, the precautions to be taken arc very
they are merely to avoid absolutely
contact with copper and to paint all surfaces.