2 74 TEE POPULAR SCIENCE MONTHLY 



of no practicable use, even if they liad desirable properties, have only 

 to be searched for, to be found in sufficient quantity for our needs. 



Eeturning to the eleven well-known true metals, viz., aluminum, 

 copper, gold, iron, lead, mercury, nickel, platinum, silver, tin and zinc, 

 wonderful progress has been made during recent years in the matter 

 of their production. Few of us appreciate the extent to which we are 

 absolutely dependent on some of these substances which, a generation 

 ago, were so rare. It is quite impossible now to conceive of a metal- 

 less civilization, or one in which they were so costly as to be practically 

 unavailable for the ordinary affairs and circumstances of life. In the 

 home, the office, the factory and the club they confront us everywhere. 

 Upon the person of a day laborer ordinarily clothed, half of the list 

 will usually be found, while in the home of the average well-to-do 

 citizen every one, except perhaps platinum, will exist in more or less 

 abundance. It will be both interesting and instructive to note just 

 what amounts of these metals have been taken from the crust of the 

 globe during recent years, for the benefit of our modern civilization. 



Aluminum 

 This metal began to appear on the market as a costly curiosity, 

 in 1888, just twenty years ago, commanding a price of $5 per pound, 

 and the total world's output for that year did not exceed 50 tons. By 

 the end of the century, however, the annual production had increased 

 to nearly 5,000 tons, while the price had fallen to $1.50 per pound. 

 Since then there has been a steady increase of output until during 

 1906 it amounted to about 20,000 tons, while the price had fallen to 

 35 cents, causing the metal to be available in so many waj's and forms 

 that the civilized world would now find very great difficulty in getting 

 along without it. But, remarkable as has been this growth, it is 

 as nothing to what may be expected in the near future. For alum- 

 inum is the most abundant of all the metals, existing in such enor- 

 mous quantity in the crust of the earth, and in deposits so accessible 

 and so easily mined, that it is certain to become, before another 

 century has passed, and as soon as its metallurgy has been perfected, 

 the rival and supplanter of iron. Every clay bank and slate quarry 

 is a high-grade mine of the metal, only we have not yet learned how 

 to extract it cheaply from these ores. Innumerable other rocks and 

 formations contain it in various quantities. A well-known geologist 

 has recently calculated that 8.13 per cent, of the earth's crust is 

 aluminum, against 4.71 per cent, for iron, and less than one tenth of 

 one per cent, for copper. Bulk for bulk, aluminum has one third the 

 weight of iron. In tensile strength it is almost the equivalent of 

 cast iron, though far inferior in that respect to steel. Yet the metal- 

 lurgists are rapidly learning how to increase its strength by alloying 



