150 Coke Iron Iron Furnaces. 



1 8. Coke bears the same relation to coal that 

 charcoal does to wood. The coal is heated in 

 air-tight iron vessels, from which tubes run into 

 water, so that all the gas may bubble through 

 into another vessel and be drawn thence to 

 light our houses. Thus we contrive to make 

 coke and gas at the same time. 



1 9. The coke we burn in our grates to warm us ; 

 and the gas, in our gas-burners to give us light. 



20. The annual coal production of the world is about 

 300,000,000 tons ; one-half of which is obtained in Great 

 Britain, one-sixth in the United States, one-sixth in Ger- 

 many, and nearly all the rest in France, Belgium, and 

 Austria. The deepest mines in the world are in England. 

 They are more than 2,000 feet beneath the surface of 

 the earth. One is over 2,400 feet in depth. 



21. There are many things represented in the 

 chart that are made of iron. Mention some of 

 them. 



22. Iron is the most useful metal in the world ; 

 it is far more useful to us than gold and sil- 

 ver. Iron is very seldom found pure. , It is 

 almost always mixed with other substances, and 

 this mixture is called iron ore. To get the iron 

 from this, men build large furnaces of fire-proof 

 brick, and after they have built a very hot fire 

 in the bottom of one of these they put in a 

 quantity of iron ore, then about as much lime- 

 stone broken up into a convenient size, and then 

 on top of the limestone about as much coal. 



