THE WORLDS ANNUAL METAL CROP 271 



THE WOELD'S ANNUAL METAL CROP 



By THEO. F. van WAGENEN, E.M. 



zacatecas, mexico 



SOME one has characterized the present as the " age of metals." 

 There are at least fifty-nine of these useful substances known to 

 the chemist of to-day, yet if the average well-educated man was asked 

 to name them, it is doubtful if he could enumerate more than a score. 

 In that far distant period called by the archeologists the " dawn of his- 

 tory " (say 8,000 to 10,000 years ago), only four appear to have been 

 recognized, viz., copper, tin, gold and silver. Sometime later, iron, 

 lead and mercury were added to the list. These seven constituted the 

 metallic stock in trade of the ancients, and of the moderns for the first 

 thousand years of the Chiistian era. In the opinion of most historians, 

 copper, as the metal that is found most abundantly in the native or 

 pure state, was the first to attract the attention of primitive man, and it 

 is likely that tin was recognized very soon thereafter, for the latter, 

 though far from abundant, and never existing naturally in the metallic 

 state, yet occurs under conditions where it would be easily noted by its 

 weight as a substance very different from ordinary stone, and in a 

 chemical combination from which it can be smelted by the simplest 

 of fire processes. Moreover, the greatest tin-producing district in the 

 world lies in a part of the globe that has been inhabited from most an- 

 cient times. Both copper and tin are alone too soft to be utilized as 

 weapons or tools, and humanity at a very early period in the progress 

 of civilization learned to produce, by combining the two, that most 

 serviceable alloy we know as " bronze," which can be forged and 

 tempered to a keen edge and point, and which is so resistant to the 

 attacks of air and water that great numbers of the implements made by 

 the ancient smiths are pi-eserved in the museums of the present day. 

 Gold and silver were doubtless recognized as separate entities at a very 

 early date, and their rarity and beauty set them apart at once as suit- 

 able measures of the value of other things. It is thought that iron, 

 though the most abundant of all the common metals, did not come into 

 general use until 1500 or 1000 B.C. Eor a long time lead was re- 

 garded as another form of tin. It does not occur in a metallic con- 

 dition in nature, only one of its ores (cerrusite) is easily smelted, and 

 most of them are associated with ores of antimony, arsenic and zinc, 

 from which it is separable only with considerable skill. Mercury, on 

 the other hand, comes from its ore with much ease, but it was a puzzle 



