Star.
London, England, 1824-12-24 00:00:00

ON DRY ROT iN TIMBER.

berore.a Committee of Chemi,ts, held at the
Adel phi Roval Instittoinn for the ercoaragement of
Arts, on 'the es-citing cif 11. e 21st instant—a Revolt of
Experiments f. .r Naupegi in Purposes, conducted by
Lieutenant John Couch,- of the Royal Navy, for pre-
venting the 1):y Rot in Timber, adding to its durabi-
lity, by strengthrnirg it, in causing it to imbibe lime
ater of 10.162 specific gra7ity, by which the putres-
ro•A effects of vegetable glltin or gelatin is overcome,
a-d afterwards hardened with oak tanner] :of the ut-
most importance to this maritime empire, in rendering
oak of young wow th equal in strength to o.tk of ma-
ture and verfective growth ; and at the same time les-
sening the effects of corrosion in copper and ir-ln fas-
tenings, and td e decay of the wood, from the effects of
corrosion, as the butt ends :n merchant vessels fre-
(woody, start, when lab.nting at sea in gales, and they
founder in consequence of the wood decaying, and
(Ming its tenacity; while at the same time the corrosion
of the iron lestens also the size of the fastenings.
The dry rot exfetienced by the naupegi (or ship-
wrights) pat ticulat ly in his Majesty's ship Queen Char-
lotte, was occasioned by a want of a proportional quan-
tity of tannen to harden, and thereby check the
putrescent effects of the vegetable glutin or gelatin :
vegetable glutin or gelatin, dissolved in rain water, will
in a few days become fetid, in this state in timber it
will feed insects.
In order to strengthen that part of timber which the,
naupegi call sap, it is only necessary to overcome the
putrescent effects in the gelatin, by causing the timber
to imbibe a sofficient quantity of lime water, of 10.162
speCific gravity ; after which, when thoroughly dry, to
cause it to imbibe a quantity of infusion of nutgalls in
water, which will tender the oak of 9.260 specific gra-
vity; when the timber, being thns treated, will be free
from dry rot, and more durable than any other ; but if
the oak tannen alone be extracted (with spirit of 8.660
specific gravity) from the nutgalls, and applied, the de-
fective parts will be rendered still more durable, and
acquire an additional degree of hardness.
The annexed table exhibits the result of Lieutenant
Couch's expetiments on the corrosion of copper and
iron fastenings in salt water, of 10.30() specific gravity.

Weight of I Weight off Quantity
Weight of the the copper in. the iron in- Time lost by cor-
Fir in Georgian serted in the serted in the inn- rosion in
pains. fir, in Geor- fir, in Geor- men- Georgian
ian grains. ian grains. ed. grains.
•••••MMIr
Unprepared
with lime 7 522 7-10 I. days. lital
Prepared with
lime water 7,0001 544 2.3 IS days. 22 4-10
Unprepared i
with lime 1,000 i" 635 I days. 90 5-7
Prepared with I I
lime water llBO a days. 1136

Thus, the above results are highly in favour of lime
seasoning.

Lieutenant Couch has given the term Georgian cubic
to his grains, because he -has . formed and contrived a
set purposely to conduct his philosophical experiments,
agreeing better with the cubic foot of water than either
the avoirdupois or troy weights; in the formation of
which he considers the cubic foot of water to weigh
one million of grains; and one ounce avoirdupois, to
weigh one thousand grains, which weights he recom•
mends to the MC of all philosopher s.

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