14 



thus making the cost of operating high. To obviate this objection, 

 what is known as the oven retort (fig. 6) was devised and in recent 



FIG. 5. Round retort with condenser: 1, retort; 2, fire walls; 3, grate; 4, neck; 5, pipe to condenser; 

 6, condenser; 7, trapped delivery pipe; 8, gas pipe; 9, gas main. 



years has been largely used in equipping new plants for hardwood 

 distillation. These retorts are rectangular iron chambers, a common 

 size being 6 feet wide, 7 feet high, and from 27 to 50 feet long, accord- 



FIG. 6. A modern o?en retort. 



ing as they are intended to hold two or more cars loaded with wood. 

 The ovens are set in brickwork, or are made with double iron walls 



[Cir. 36] 



