TEE WORLDS ANNUAL METAL CROP 273 



The most of these are as yet merely names to the general public, 

 and some are certain to remain no more than chemical curiosities for 

 years to come. There are good reasons to believe, moreover, that the 

 list is still incomplete. But of the fifty-nine now known, eleven, 

 aluminum, copper, gold, iron, lead, nickel, mercury, platinum, silver, 

 tin and zinc, are, as metals, among the staple articles of commerce, 

 which are being produced in large and ever increasing quantities, as 

 the demand grows; while another list of six (manganese, tungsten, 

 molybdenum, titanium, chromium and vanadium) are market staples 

 in the form of alloys with iron, being largely used in the production 

 of certain brands of steel. These are known in the trade as the ferro- 

 metals. Again, there are six more (bismuth, arsenic, cobalt, uranium, 

 thorium and cadmium) that are regularly produced, but not in the 

 metallic state, for use mainly in the ceramic and electrical arts. 

 Finally are iridium, osmium and palladium which find emplo3anent to 

 a small but steadily increasing extent among makers of delicate instru- 

 ments and tools of precision; tantalum, of which the electricians are 

 now making incandescent light filaments, and magnesium, which for 

 a number of years has been used by the photographers in the produc- 

 tion of flash light. Thus nearly half of the total list may be said to 

 be already among the indispensables of civilization, and already several 

 of the remainder are under consideration by scientists, engineers and 

 inventors — notably potassium, sodium and calcium — on account of the 

 qualities they possess. Lithium, the featherweight of the metallic 

 family, which will float in water, and has only one fifth the weight of 

 aluminum, may before long be commandeered by the aeronauts, if a way 

 can be found to protect it from the corroding action of air and water, 

 while rubidium, that is as soft as fresh putty or wax at ordinary tem- 

 peratures, zirconium, that possesses many of the qualities of thorium, 

 and ruthenium, that is extremely infusible, are all certain to fill a want 

 in the arts before long. In fact, each of the remaining known metals 

 appears to possess some inherent and exclusive quality that will sooner 

 or later be needed in our complex civilization. The most of those 

 that are not yet exploited occur apparently in very small quantities 

 in the crust of the earth, as, for instance, the last discovered, radium, 

 which is so rare that but a few grains can be obtained from many 

 tons of its ore. Yet it is one of the surprising facts of recent years 

 that as soon as one of these rare metals is proved to be of real use 

 to humanity, new sources of supply have quickly been found. We 

 know little as yet as to the capacity of the wonderful storehouse we 

 live upon. Nature seems to have provided a substance for every con- 

 ceivable want of mankind, and beyond question, some of these sub- 

 stances that appear now to be useless are merely in reserve for wants 

 not yet developed, while others that apparently are so scarce as to be 



VOL. LXXIV. — 19. 



