U. S. NATIONAL MUSEUM 
BULLETIN 102, PART I PL. 8 
Gas Retort Bench. 
A complete bench of six retorts and adjoining one sectioned showing operative features. Coal is charged 
into the retorts, about 200 pounds to each retort, and the doors closed tightly. When heated from the 
coke fire below, the volatile ingredients break away, and are carried off for further dissociation into gas, 
tar, and ammonia. The residual coke is then withdrawn for use primarily in maintaining the temper- 
ature of the retorts and secondarily as a by-product. The gas bench is thus of the by-product recovering 
order so far as the volatile portion of the coal treated is concerned, but the quality of coke is inferior; 
so in advantages and disadvantages alike it presents the exact reverse of the beehive coking procedure. 
From a model in the United States National Museum. 
