 From the hopper, the coal was fed via a single chute into the vertical retort block which was then divided into 8 separate retorts, where it was heated by furnaces (and later an additional steel furnace in the back room) located on the first floor (ground level).The extracted gas was collected in two parallel "Collector Mains" running along the top of the retort block.Accumulated tar and liquor was drained from the collector mains into a small liquor separating tank on the 3rd floor on the western side of the building.