294 THE WORLD'S LUMBER ROOM. 



brilliant colours extensively used for dyeing silk, woollens, 

 and other goods, and for printing calicoes. 



Not long ago the Corporation of Antwerp used to spend 

 ;i,ooo a year in getting rid of the refuse of the town, 

 whereas now they sell their street-sweepings and sewage for 

 ^"40,000. 



Some years ago, when English miners from Cornwall 

 arrived in Chile, they were astonished to find the natives 

 throwing away as useless the copper pyrites which they 

 knew to be so valuable ; this being the common form in 

 which copper ore is found in Cornwall. But the Chileans 

 were so certain that it contained no copper at all, that they 

 not only laughed at the ignorance of the English, but sold 

 them their richest veins for a few dollars. Then, again, the 

 cinders from the old furnaces were thrown away as utterly 

 useless, and it was actually found worth while to transport 

 them to England, where, by stamping and washing, particles 

 of copper were recovered in such abundance as to amply 

 repay the purchasers. 



Soda-ash, or sodium carbonate, is a substance manu- 

 factured in England on an enormous scale and used for 

 glass-making, soap-making, bleaching, and various other 

 purposes. Formerly it was prepared from barilla i.e., the 

 ashes of sea-plants but now it is obtained from sea-salt or 

 sodium chloride, which is a compound of the metal sodium 

 with chlorine gas. 



In making soda-ash, sulphuric acid is poured upon the 

 salt, and the sulphur combining with the sodium forms 

 sodium sulphate, or " salt cake," which is the first step in 

 the manufacture. But what becomes of the chlorine ? It 



