I RAW MATERIALS AND PRIMITIVE MANUFACTURES 7 



from the juice of the grape and other fruits, whilst saltpetre 

 and sal-ammoniac have been referred to already as products 

 of the decay of animal matter. 



Substances prepared by the action of fire. Many other 

 substances were prepared from natural materials by the 

 action of fire. LIME, obtained in this manner from lime- 

 stone or chalk, has been mentioned previously, but greater 

 importance attaches to the use of fire as an agent for the 

 preparation of metals. Two metals, GOLD and SILVER, are 

 distributed somewhat widely in a native state, and were 

 known from the earliest times. Native COPPER was also 

 found and used. 1 MERCURY (Latin hydrargyrum, or liquid 

 silver), which occurs in minute droplets in certain rocks 5 

 was known to the Greeks. 



Other metals were obtained by smelting their ores, that 

 is, by heating them with charcoal. Amongst these was TIN, 

 obtained by smelting TINSTONE and valued highly as a 

 means of hardening copper. The hard alloy of copper and 

 tin is known as BRONZE. The stage of civilisation during 

 which this alloy came into common use has been called the 

 " Bronze Age," although the various European peoples 

 learnt to use it for the manufacture of weapons and imple- 

 ments at widely different times. The smelting of IRON was 

 a more difficult process, since a much higher temperature 

 was required than in the case of tin or copper. The use of 

 iron, therefore, follows that of bronze in the history of each 

 race. Thus, the Greeks, as described in the Homeric poems, 

 were accustomed to the use of bronze weapons and imple- 

 ments, but esteemed iron much more highly a lump of 

 iron being described as a valuable prize in a contest. The 

 Romans had reached the " Iron Age " by early classical 

 times. Four hundred years later, at the opening of the 

 Christian era, the Germanic races still employed the earlier 



1 "A land whose stones are iron, and out of whose hills thou 

 mayest dig brass " (Deut. viii. 9). 



