MECHANICS AND USEFUL ARTS. 75 



NEW ALLOY FOR SHEATHING SHIPS. 



A patent has recently been taken out in England by Mr. Arthur "Wall, of 

 London, for a combination of metals possessing different electric characters 

 for the sheathing- of ships. The alloy is made by melting two and a half 

 parts of copper in one crucible ; in another nine parts of zinc, eighty-seven 

 of lead, one part of mercury, and a half a part of bismuth; then mixing the 

 contents of both crucibles, covering the surface with charcoal dust, and stir- 

 ring well until all are incorpoi-ated. It is stated that the mercury in this alloy 

 protects both the zinc and copper from the action of sea-water. The con- 

 tents of the crucible are run into ingots, and rolled into sheets. 



The same inventor luis also obtained a patent for protecting the bottoms 

 of iron ships from the action of sea-water, by the use of a composition of 

 litharge, made into a smooth, thin paste with turpentine, to which is added an 

 equal weight of resin. The whole is then put into a close iron vessel, placed 

 over a fire, naphtha added through an aperture in the lid from time to time, 

 and the boiling kept up slowly for about two days, until the whole has as- 

 sumed a tenacious, adhesive character, and a creamy consistency. It is then 

 fit to be applied to the iron of the vessel as a primary coating. A second 

 coating is given to the iron with a composition of resin, combined with one- 

 fifth of its weight of an oxyd of mercury and powdered charcoal mixed in 

 turpentine. This outer coating fills up all cracks or gaps left in the first 

 application, and the nature of the composition is stated to be such that it 

 prevents barnacles adhering to the iron, and resists the corroding action of 

 salt water. 



ON THE STRENGTH OF S03IE ALLOYS OF NICKEL AND IRON. 



At a recent meeting of the Manchester (Eng.) Society of Engineers, Mr. 

 Fairbairn, presented the result of some experiments made to ascertain 

 whether an infusion of nickel, in a given proportion, would increase the 

 tenacity of cast-iron, as originally imagined from the analysis of meteoric 

 iron, which generally contains 2 1-2 per cent, of nickel. Contrary to ex- 

 pectation, however, the cast-iron, when mixed with the precise quantity of 

 nickel indicated by the analysis of meteoric iron, lost considerably in point 

 of strength, instead of gaining by it. Mr. Fairbairn also stated in the course 

 of his paper, that during the last ten years, innumerable tests and experi- 

 ments had been made for the purpose of obtaining a metal of extraordinary 

 tenacity for the casting of mortars and heavy ordnance; but the ultimate 

 result appeared to be, in the opinion of the author and others, that for the 

 casting, or rather the construction, of heavy artillery, there is no metal so 

 well calculated to resist the action of gunpowder as a perfectly homogeneous 

 mass of the best and purest cast-iron when freed from sulphur and phosphorus 



In the discussion which followed the reading of the paper, Mr. Calvert said 

 that it was highly probable that nickel caused the increased brittleness of 

 cast-iron, just as carbon, phosphorus, and sulphur, but that the result with 

 malleable iron might probably be very different; and, as meteoric iron is 

 malleable, the trial could only be complete when soft iron and nickel were 

 united; nevertheless, these experiments, as far as cast-iron is concerned, were 

 decidedly new and of great value. 



