1895.] 



on the Rarer Met ah and their Alloys. 



517 



Sup230sing, therefore, that a ship-of-war was built in our climate 

 of ordinary steel, and clad with some 3000 tons of such nickel-steel 

 armour, we are confronted with the extraordinary fact that if such a 

 ship visited the Arctic regions, it would actually become some 2 feet 

 longer, and the shearing which would result from the expansion of 

 the armour by exposure to cold would destroy the ship. Before I 

 leave the question of the nickel-iron alloys, let me direct your 

 attention to this triple alloy of iron, nickel and cobalt in simple 

 atomic proportions. Dr. Oliver Lodge believes that this alloy will 

 be found to possess very remarkable properties ; in fact, as he told 

 me, if nature had properly understood Mendeleef, this alloy would 

 really have been an element. As 

 regards the electrical properties of 

 alloys, it is impossible to say what 

 services the rarer metals may not 

 render ; and I would remind you 

 that " platinoid," mainly a nickel- 

 copper alloy, owes to the presence 

 of a little tungsten its peculiar 

 property of having a high electrical 

 resistance which does not change 

 with temperature. 



One other instance of the kind 

 of influence the rarer metals may 

 be expected to exert is all that time 

 will permit me to give you. It 

 relates to their influence on alumi- 

 nium itself. You have heard much 

 of the adoption of aluminium in 

 such branches of naval construction 

 as demand lightness and portability. 

 During last autumn Messrs. Yarrow 

 completed a torpedo-boat which 

 was built of aluminium alloyed 

 with 6 per cent, of copper. Her 

 hull is 50 per cent, lighter, and she 

 is 3^ knots faster than a similar 

 boat of steel would have been, and, notwithstanding her increased 

 speed, is singularly free from vibration. 



Her plates are ^ inch thick, and ^ inch where greater strength 

 is needed. It remains to be seen whether copper is the best metal to 

 alloy with aluminium. Several of the rarer metals have already been 

 tried, and among them titanium. Two per cent, of this rare metal 

 seems to confer remarkable properties on aluminium, and it should do 

 so according to the views I. have expressed, for the cooling curve of 

 the titanium-aluminium alloy would certainly show a high subordinate 

 freezing point. 



Vol. XIV. (No. 89.) 2 n 



Fig. 9. — Half-section Midship of 

 Aluminium Torpedo-boat. 



