504 THE RARER METALS AND THEIR ALLOYS. 



If the "use of mechanical art" includes the study of chemistry on 

 the basis of the mechanics of the atoms, I may be permitted to offer 

 the modern school the following rendering of nature's plaint : 



How nature sighs without restraint, 

 And grieving makes her sad complaint 

 Against the subtle sophistry 

 Which trusts atomic theory. 



An explosion such as is produced when aluminum and oxide of lead 

 are heated in presence of each other, which suggested the reference to 

 the old French verse, does not often occur, as in most cases the reduc- 

 tion of the rarer metals by aluminum is effected quietly. 



Zirconium is a metal which may be so reduced. I have in this way 

 prepared small quantities of zirconium from its oxide, and have formed 

 a greenish alloy of extraordinary strength by the addition of 0.2 per 

 cent of it to gold, and there are many circumstances which lead to the 

 belief that the future of zirconium will be brilliant and useful. I have 

 reduced vanadium and uranium from its oxide by means of aluminum 

 as well as manganese, which is easy, and titanium, which is more diffi- 

 cult. Tungsten, in fine specimens, is also before you, and allusion will 

 be made subsequently to the uses of these metals. At present I would 

 draw your attention to some properties of titanium which are of special 

 interest. It burns with brilliant sparks in air; and, as few of us have 

 seen titanium burn, it may be well to burn a little in this flame. [Ex- 

 periment performed.] Titanium appears to be, from the recent experi- 

 ments of M. Moissan, the most difficultly fusible metal known; but it 

 has the singular property of burning in nitrogen — it presents, in fact, 

 the only known instance of vivid combustion in nitrogen. 1 



Titanium may be readily reduced from its oxide by the aid of alu- 

 minum. Here are considerable masses, sufficiently pure for many pur- 

 poses, which I have recently prepared in view of this lecture. 



The other method by which the rarer metals may be isolated is that 

 which involves the use of the electrical furnace. In this connection the 

 name of Sir W. Siemens should not be forgotten. He described the 

 use of the electric arc furnace in which the carbons were arranged 

 vertically, the lower carbon being replaced by a carbon crucible; and 

 in 18S2 he melted in such a furnace no less than 10 pounds of platinum 

 during an experiment at which I had the good fortune to assist. It 

 may fairly be claimed that the large furnaces with a vertical carbon in 

 which the bath is maintained fluid by means of the electric current, the 

 aluminum and other metals being reduced by electrolytic action, are 

 the direct outcome of the work of Siemens. 



In the development of the use of the electric arc for the isolation of 

 the rare, difficultly fusible metals Moissan stands in the front rank. 



1 Lord Rayleigh has since stated that titanium does not combine with argon, and 

 M. Guntz points out that lithium in combining with nitrogen produces incandesence. 

 M. Moissan has also shown that uranium does not absorb argon. 



