TRANSACTIONS OF THE SECTIONS. 
35 
from the iron-work at the bottom of each buoy, and of driving two 
or three short large-headed iron nails through the remaining lead 
into the wood, in order to protect both the lead and copper covering 
of the buoys from corrosion. These suggestions being promptly car¬ 
ried into effect, the author has during the last twelve months had 
frequent opportunities of examining the state of the iron-work at¬ 
tached to, and in the immediate vicinity of, the buoys, and he states 
that the removal of the lead has put a stop to the very rapid corro¬ 
sion of the iron-work. 
The action of sea-water on iron, under ordinary circumstances, 
is, as is well known, by no means inconsiderable. The author 
found that a piece of iron chain weighing 14 pounds 5 ounces, whea 
exposed for 24 hours in quarts of sea-water, lost 70 grains, and 
in a few days upwards of a quarter of an ounce : these facts led him 
to think it both desirable and practicable to coat the iron-work of 
the buoys, &c. with a varnish or japan which should be impervious 
to sea-water: and at the request of the Commissioners he made 
many experiments, using different varnishes and japans; but the 
results obtained were for the most part of a negative kind, owing not 
only to the action of sea-water on iron, but also to the constant fric¬ 
tion to which the metal must be exposed, from the unceasing influ¬ 
ences of tides, winds, and the strains from ships. He has hitherto 
found no varnish or japan that he can recommend as a means of pre¬ 
venting, for any length of time, the ordinary corrosion or oxidation 
of iron in sea water. 
The author made a number of experiments with a view to apply 
metallic protectors to the iron-work connected with the buoys, on 
the principle developed by the late Sir H. Davy. He found that 
when small ingots of zinc were attached to pieces of chain cable in 
sea-water, during several weeks, these lost no weight, and the cor¬ 
rosion of the zinc was inconsiderable. Hence it seemed obvious, 
that zinc will protect iron from corrosion in sea-water. These re¬ 
sults were so satisfactory that the author recommended the expe¬ 
riments to be tried on the buoys, and the Commissioners immedi¬ 
ately requested him to carry the same into effect. He has had 
under a course of trial for several months, in contact with the iron¬ 
work at the bottom of each buoy, two zinc protectors, each of which 
is about 6 inches long and 4 inch wide, and weighs about 8 ounces; 
and on a recent examination, the iron-work near the zinc exhibited 
a clean appearance. There is another and a still more recent ap¬ 
plication of the zinc, which the author thinks will be very beneficial 
in protecting a most important part of the iron-work already alluded 
to, namely, th e forelock. Several of the forelocks have stout zinc 
rings cast into holes made in their heads, and on lately examining a 
forelock so protected for several weeks, it was found quite free from 
corrosion. 
The late Sir H. Davy referred the corrosion of copper in sea¬ 
water to the agency of the oxygen of the air. The author from his 
experiments has obtained results which lead to the same conclusion 
d 2 
