PAPERS OX BIOLOGY AND AGRICULTURE 235 



cost to the operator is not far from 5 cents per ton. Take 

 one-fourth of our coal production, then, and you get al- 

 most 20,000,000 cubic feet of wood required yearly for 

 coal mining, costing delivered at the mine almost $4,000,- 

 000. Furthermore, the ordinary mine prop has an aver- 

 age length of life of about two years. Only a few com- 

 panies in Illinois have begun to apply preservative treat- 

 ment to mine timbers or to think seriously of perpetuat- 

 ing the supply of mine timbers. Both of these lines of 

 work present worth-while problems in practical forestry 

 for mining companies. 



This shortage of timber for mining purposes seems to 

 be rather general. The U. S. Bureau of Mines (Hornor 

 and Hunt '22) z under date of February, 1923, says 

 that in the East and Middle West, the Lake Superior re- 

 gion and the metal mining regions of the West, the 

 sources of mine timber are becoming more remote from 

 points of consumption, the timbers are getting more diffi- 

 cult to obtain and, naturally, more costly. Moreover, the 

 better and more durable varieties are being exhausted 

 rapidly; consequently the less durable varieties must be 

 used in their place. • 



CHARCOAL 



It takes almost 2,000,000 kegs of powder for blasting 

 purposes in Illinois in connection with mining operations. 

 Leaving out smokeless powder, which is made from gun 

 cotton, charcoal is a very important constituent of 

 powder used for blasting and sporting purposes. Some 

 of the facts which we have learned about this industry 

 of charcoal making in Illinois may be of interest. 



We have found that in a limited region of southern Illi- 

 nois near to a supply of second growth bottomland 

 hardwoods over 15,500 cords of wood are reduced annual- 

 ly in brick kilns in the making of charcoal, most of which 

 finds a market in Illinois. Some of the powder companies 

 have their own kilns, one large company getting over 

 6.000 cords of charcoal wood annually from islands of the 

 Illinois and Mississippi rivers. 



-Hornor and Hunt. 1922. "Mine timber preservation". Reports of 

 Investigations. Bureau of Mines. Serial No. 2321. February, 1922. Re- 

 printed in Coal Trades Bulletin, April 17, 1922. 



