182 FOREST UTILIZATION WOOD USES AND ECONOMICS 



portant products. The principal hardwoods distilled for these 

 products are beech, birch, maple, and hickory. Hard, heavy woods are 

 preferred. Steam distillation and solvent extraction methods are also 

 used with southern pine chiefly for the recovery of rosin, pine oils, and 

 turpentine. 



The larger volume of wood is utilized by the hardwood distillation 

 process, by which cordwood in 4- or 5-foot lengths is thoroughly sea- 

 soned for one year or more, then placed on buggies and moved into 

 ovens 52 feet or more in length, about 8 feet in height, and 6 feet wide. 

 After closing the doors, the ovens are heated underneath to tempera- 

 tures of 450 to 600 F. for about 24 hours. The gases from this 

 heating process are condensed and form pyroligneous acid, the residue 

 remaining as charcoal. 



This industry has been able to survive after keen competition from 

 synthetic alcohol and acetate products only through research and the 

 application of new practices. Waste gases from the distillation are 

 now used to furnish heat by which the wood is rapidly seasoned, thus 

 making a long air-seasoning period unnecessary. Wood is cut into 

 small pieces, making mechanical handling possible, and in the Staf- 

 ford process the ovens are insulated so that heat lost during the 

 exothermic reaction may be used to bring the temperature of new 

 wood up to the carbonization point. This is therefore a continuous 

 process using finely divided wood, and it promises to offer a method 

 whereby large quantities of sawmill waste in form of dust and slabs 

 may be utilized. 



10. Maple Syrup and Sugar. Throughout the Northeast and the 

 Lake States the sap is collected from the sugar maple during the early 

 spring season. The industry is centered in Vermont, New York, Ohio, 

 Pennsylvania, and Michigan. From one to four or more buckets are 

 attached to spouts inserted in auger holes 7/16 inch in diameter. 

 About 45 million pounds of maple sugar have been made annually 

 in this country. Individual trees may yield from 1 to 7 pounds of 

 sugar. From a standard sugar bush of 500 buckets there is an average 

 yield of about 6400 gallons of sap. This is equivalent to about 200 

 gallons of maple syrup or 1500 pounds of sugar. Ordinarily it re- 

 quires 32 gallons of sap to make a gallon of syrup, and 4^ gallons of 

 sap are required for a pound of sugar. An average of about 12.8 

 gallons of sap is secured from each bucket in the average sugar bush. 

 A gallon of good syrup will yield about 7% pounds of sugar. Many 

 forests are managed in the northern New England States as well as 

 in New York and Ohio for the production of maple syrup and sugar 

 and at the same time cattle are permitted to graze in them. The graz- 



