HARDWOOD DISTILLATION 201 



cylindrical vessels originally of cast iron and later steel cylinders 50 in. 

 in diameter by 9 ft. in length. They were placed horizontally in pairs, 

 and batteries of 10 to 15 pairs were common in long brick rows in the 

 earlier plants. Each retort was sufficiently large to hold about five- 

 eighths of a cord of wood. Heating was provided externally by a 

 fire box located underneath the retort. For fuel, coal, charcoal, wood gas, 

 wood oil, wood tar, and wood itself, have been used. The retorts are 

 built and discharged from the single door in front which can be fastened 

 tightly and sealed with clay to prevent the entrance of oxygen after the 

 heating process is started. Along the top of these rows of retorts the 

 surface is bricked over and serves as a drying floor for the acetate of lime. 

 A run, that is the period from the first charging of the retort to the removal 

 of the charcoal after the process, usually requires from twenty-two to 

 twenty-four hours. 



Oven Retorts. 



The small round retort is now being rapidly replaced in the larger and 

 more progressive plants by the large rectangular retort or oven retort. 

 This is also known as an oven. Until about 1900 a large number of 

 these round retort plants were in operation, but about 1895 the oven 

 retort came in, which provides for loading and unloading the retort by 

 the use of cars which are run directly into the chamber. This resulted 

 in a considerable saving of labor charges so that all of the new plants now 

 being constructed are introducing the ovens. In several of the states 

 there are not as many plants active now as there were twenty years ago, 

 but there is a vastly larger amount of wood being consumed per plant, 

 due to the fact' that the oven retorts can consume as high as 10 to 12 

 cords in a single oven, whereas the old round retort held only about | 

 to I cord of wood. 



The modern hardwood distillation plant, therefore, is usually the 

 oven retort plant. This was a decided advance in the manufacture of 

 wood distillation products. As noted above, it is largely a labor-saving 

 device and, although the initial cost is considerably greater the operating 

 charge per cord is so much smaller than with the round retort that it is 

 being universally introduced. The ovens are rectangular in cross- 

 section and may be anywhere from 25 to 56 ft. in length. The conmion 

 form is an oven 52 ft. in length, 8 ft. 4 in. in height and 6 ft. 3 in. in width. 

 These ovens are usually arranged in pairs similar to the process followed 

 with the round retort. The cars, each loaded with about 2 cords of wood, 

 are run in on standard or narrow gauge tracks directly into the ovens. 



