46 GAS WORKS, PLYMOUTH. 



retort, and is then lifted by three men, two at the front 

 with a bar, and one at the handle, pushed into the 

 retort, and turned upside down ; the charge of coals is 

 thus left in the retort, and the scoop is withdrawn to 

 be filled again for the next, and so on till the whole 

 series is charged. It is really amusing (if not inter- 

 esting) to see with what an almost military correctness 

 the men perform this work, the whole of which does 

 not occupy more than about two minutes to each retort. 

 When the coals are introduced "into the retort a lid 

 is immediately applied to the mouth luted on, air tight, 

 and secured by means of a cross bar and centre screw, 

 the ends of the bar dropping into a lug at each side of 

 the mouth. This done, the distillatory process com- 

 mences immediately ; and the gas begins to ascend 

 through the upright pipe, inserted in the mouth of the 

 retort, about three inches from the end or just within 

 the lid. The time required to distil, or, to use the 

 technical term, to carbonize a charge of coals is six 

 hours, by which time, if the process be properly con- 

 ducted, the whole of the gas will be drawn off, mid 

 all that is left in the retort, is the coke, a mere ciiput 

 mortuum. The lids are now removed, the coke with- 

 drawn by means of a long iron rod with a hook at the 

 end, and the recharging with fresh coals commences 

 again ; and so on without intermission. The whole 

 range as will be seen by reference to the engraving 

 consists of 44 retorts of 5 each, except the two end 

 ones, which are sevens. When we last, visited the 

 works the whole of these, except the seven at the right 

 hand, were in full operation; of course the quantity of 

 coals carbonized per diem will be 222 bushels, imperi- 

 al, or 2 bushels less than 14 quarters. 



Just above the retorts is a large pipe, running in a 

 parallel line with, and along the whole length of, the 

 range of retorts ; this is called the hydraulic main, being 

 charged with coal tar, or other liquid, to about half 

 its diameter. Into this pipe the bent ends of the up- 

 right, or, as gas men call them, the ascension pipes, 

 which rise from the mouths of the retorts, to carry off 



