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A TREATISE ON GAS-LIGHT.

w av. This retort rests upon a tripod of ham-mered iron, placed upon the bars of the grateof the chemical furnace. Into this retort thecoals are put for furnishing the gas. It is pro-vided with a solid iron stopper ground air-tight into the mouth of the retort, and the stop-per is secured in its place by an iron wedgepassing over it in the centre; by means of whichthe mouth of the retort when charged withcoal is readily made air-tight, and the stoppermay easily be removed by knocking out theiron wedge, b. is a metal pipe which conveysall the distillatory products from the retort intothe purifier tig. 2 . This tube is bent at rightangles at the extremity where it enters the in-termediate vessel fig. 2. The purifier fig. 2, isdivided into three compartments marked c. d. e.The first compartment is filled with water, andby means of it an air-tight communication isestablished with the retort which furnishes thegas. The second compartment, d, contains asolution of caustic pot-ash composed of about2 parts of caustic pot-ash and 16 of water, ora mixture of quick-lime and water of the con-sistence of very thin cream. The object ofthis compartment is to separate the non-inllam-