256 THE POPULAR SCIENCE MONTHLY. 



Bridge or of the Eiffel Tower. If the engineers of those stupen- 

 dous structures had had at their disposal a metal of forty tons 

 strength and twenty-eight tons elastic limit, instead of thirty 

 tons strength and seventeen tons elastic limit in the one case 

 and, say, twenty-two tons strength and fourteen to sixteen tons 

 elastic limit in the other, how many difficulties would have been 

 reduced in magnitude as the weight of materials was reduced ! 

 The Forth Bridge would have become even more light and airy, 

 and the Tower more netlike and graceful, than they are at pres- 

 ent." And Sir Frederick Abel, in his presidential address at the 

 Leeds meeting of the British Association, remarked, " It has been 

 shown by Riley that a particular variety of nickel steel presents 

 to the engineer the means of nearly doubling boiler pressures 

 without increasing weight or dimensions." 



On the other hand, it must be admitted that there are those who 

 maintain that the future of nickel steel has been painted in too 

 rosy colors. For example, in Stahl und Eisen for October, 1889, 

 Prof. A. Ledebeer criticises the claims made for nickel steel, and 

 predicts that the alloys of nickel and steel " belong to that class 

 of inventions which crop up at intervals, finally to be buried in 

 oblivion because of their impracticability." The criticisms of this 

 German writer were practically answered by a report in some of 

 the trade journals immediately after the appearance of his criti- 

 cism, to the effect that there existed among steel-makers a demand 

 for several thousand tons of ferro-nickel for use in the prepara- 

 tion of nickel steel ; and trials of armor plate made by a board of 

 United States naval experts at Annapolis, Md., have shown that 

 nickel steel is superior to ordinary steel for armor plate. As a 

 result of these tests the House of Representatives at Washington 

 made an appropriation of one million dollars for the purchase of 

 nickel for use in the manufacture of armor for the new armored 

 war-ships. 



Coming now to consider the source of t?he nickel of commerce, 

 we find it is derived principally from two classes of ores — viz., a 

 nickelif erous pyrrhotite and a silicate of nickel. A very remark- 

 able deposit of the latter occurs in New Caledonia, one of the New 

 Hebrides and a penal colony of France, and since the period when 

 productive work was begun on these deposits it may be said that 

 the New Caledonia mines have entirely controlled the market. 

 The ore known as garnierite is a hydrosilicate of nickel and mag- 

 nesia, and is found in beds of serpentine mixed with oxide of iron, 

 chrome iron ore, and a little cobalt. It is especially valuable on 

 account of its entire freedom from arsenides and sulphides. Simi- 

 lar ores occur on this continent — for instance, in North Carolina 

 and Oregon — but these deposits have not been developed to any ex- 

 tent. The discovery of the New Caledonia deposits aroused great 



