On the protection of iron from oxidation and from becoming foul when it is exposed to the action of sea and other waters

For attaining the objects mentioned in the title of this paper, the author was led by a process of experimental research, founded on chemical principle, to the discovery of the superior efficacy of a varnish consisting of one part of pitch and two parts of naphtha, together with ten pounds of the sub- and per-oxides of copper to each quart of the varnish. This varnish is made to adhere by applying it to the iron previously rendered hot by placing underneath it braziers of ignited charcoal. He found that this coating of varnish not only protected the iron from oxidation, but formed a perfect barrier to electro-chemical action between the copper oxide and the iron. Two or three of these coats are applied in succession, each being laid on after the preceding one has become hardened. The trials made of this method on various ships, the results of which are detailed in an appendix to the paper, have proved perfectly satisfactory.