76 OUR PHYSICAL WORLD 



is so deep down or in such narrow seams it can scarcely be mined 

 with profit. Then other forms of energy production may take 

 the place of production by coal. We are already using water- 

 power very extensively. 



Out of every 1,000 tons of coal, industry uses 350 tons; rail- 

 roads, 250 tons; domestic heating and cooking, 165 tons; coke, 

 130 tons; fuel at the mines, 35 tons; gas works, 10 tons; and we 

 export 60 tons. Our methods are still so wasteful that less than 

 half of the energy in the coal actually dug out of the earth gets 

 to the consumer in available form. 



Oil and gas are also derived from the coal measures. Since 

 oil was struck in 1859 we have used 5,467,000,000 barrels, nearly 

 50 per cent of the estimated supply, and we are using it at the 

 rate of over 500,000,000 barrels annually, so that the available 

 supply of oil that can be pumped out of the earth in the United 

 States will necessarily soon be exhausted. Fortunately, there 

 are almost limitless supplies available in the oil shales from which 

 it can be distilled. This is a more costly process and oil prices 

 probably must rise, but still there is no danger of an oil famine 

 for generations. Indiana alone has oil shales estimated to yield 

 100,000,000,000 gallons. 



We are burning about 800,000,000,000 cubic feet of natural 

 gas annually purposely, and there are many millions of cubic 

 feet going to waste as it escapes into the air or burns at wells 

 where it is not being utilized. 



