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Art. XV . — Results of some Experiments made at Liverpool , 
on Sir H. Davy's Method of protecting the Copper-Sheath - 
ing of Ships. Communicated by T. S. Traill, M. D. &c. &c. 
[The importance of Sir Humphry Davy’s method of protecting 
the copper-sheathing of ships, and the rather hasty statements 
made, by some who have engaged in the controversy on this 
disputed subject, induce us to lay before our readers the follow- 
ing communications from Dr Traill, although portions of them 
have appeared in another Journal.] 
The 
Dear Sir, Liverpool , March 17. 1825. 
following communication made to me, by my friend 
Charles Horsfall, Esq. of this place, contains two facts so inte- 
resting to science, that I feel no hesitation in requesting you to 
give them a place in your J ournal. 
1. We have here a striking instance of the curious fact, first 
observed, I believe, by some Highlanders, many years ago, 
when employed in attempts to weigh the wreck of a vessel be- 
longing to the celebrated Spanish Armada, which sunk off To- 
bermory, in the Isle of Mull, and considered as fabulous, un- 
til a similar occurrence directed Dr MacCulloch to the subject ; 
I mean the conversion of cast-iron by long immersion in water, 
impregnated with saline matter, into a sectile substance, resem- 
bling plumbago in colour and consistence, and which, when 
first exposed to the air, extricates a very considerable portion of 
heat, probably by the rapid absorption of oxygen from the at- 
mosphere. 
2. It proves that Sir H. Davy’s method of protecting the 
copper-sheathing of ships, by means of slips of a more oxidable 
metal attached to the bottom, although it protects the surface of 
the copper from corrosions, yet does not prevent the adhesion of 
Barnacles to the sheathing, in such an high degree as to form 
a serious impediment to the sailing of the ship ; and thus mate- 
rially to detract from the practical utility of the method. How 
far the substitution of zinc, or tin may obviate this inconvenience, 
or what might be the effect of applying the protecting metals to 
