350 



General Botany 



U. S. Depl. of Agriculture 



Fig. 217. Map showing the acreage of sorghums, buckwheat, and velvet beans in the 



United States. 



best in the states from Wisconsin to Maryland and Maine. 

 The sap flows longest and the yield is greatest during a gradual 

 northern spring, when there is freezing at night, thawing in the 

 daytime, and a slow thawing of the ground. Such conditions 

 are most perfectly attained in Vermont, New York, and northern 

 Ohio, and the industry centers in these three states. 



The distillation of hardwoods for the production of wood al- 

 cohol, acetate of lime, and charcoal is another industry that 

 centers in Wisconsin, Michigan, New York, and Pennsylvania 

 because of the large available supply of beech, birch, and maple, 

 and the nearness to blast furnaces, which are the chief users of 

 the charcoal. Much charcoal has been made in the past by simply 

 driving out the volatile matter in the wood by slow combustion 

 in pits. But in this way all the volatile matter was lost. Now the 

 wood is heated in great retorts, and the by-products are far more 

 valuable than the charcoal. Ash, oak, and hickory are also being 

 used for distillation as the more desirable species become scarcer. 



