FIG. 1. The Retort Furnace. The retorts are placed over each other in one or more rows; so that a certain number of them may be heated by separate fire-places. A, A, shows two of the retorts placed horizontally above each other; B, the fire-place; C, the flue which causes the fire to circulate round the retorts so as to heat them equally in every part; D, the opening of the flue where the fire passes into the chimney; E, the ash-pit; F, a chamber in front of the retort furnace, into which the orifice or mouth of the retorts project; G, G, the doors of the chamber, to enable the workmen to charge and discharge the retorts; H, a funnel shaped hole at the floor of the chamber F, through which the red hot coke as it is discharged from the retorts passes into the arched vault I; K, the syphon tube; L, the horizontal condenser[41]--the action of both of these pipes have been already explained, p. 168; M, main pipe, which conveys the liquid substances from the condenser, to the tar cistern, fig. 3, and which conducts also the gazeous products into the lime machine, fig. 2; N N, shows that part of the pipe which is interposed between the tar cistern, fig. 3, and the condensing pipe M,--it passes in a serpentine direction along the inner sides of the gasometer cistern, and, like the so-called _worm_ in a distillatory apparatus, condenses the products which escape in a vaporous state from the condenser L; O, shows the place where the serpentine pipe N N, passes again out of the gasometer cistern, and its communication with the lime machine, fig. 2, and tar chamber, fig. 3. The action of the lime machine is as follows: The liquid products evolved from the coal, having been deposited in the tar cistern, fig. 3, by means of the serpentine pipe N, N, the gazeous products which accompany it, are conveyed by means of the pipe P, which branches out from the pipe O, into the interior receptacle of the lime machine marked Q, which consists of a vessel open at the bottom, and closed at the top, where it communicates with the pipe O. As the gas accumulates in the interior part Q, of the lime machine, it is made to pass through the liquid which it contains, namely, slaked lime and water; and escapes through appertures made in the horizontal partitions R, R, R, R, into the outer vessel, S, of the lime machine and from thence it is conducted away by the pipe T, T, T, into the additional washing apparatus, of the gasometer; fig. 4, the construction of this apparatus, greatly resembles the lime machine, fig. 2, namely, V, is a water pipe, proceeding from a cistern U, placed 3 or 4 feet above the orifice of the pipe V; T, T, is the gas-pipe, covered with a hood, marked W, and immersed in a small cistern, having horizontal perforated shelves, like those in the lime machine--they fit close to the hood. The gas which enters the hood W, meets with a shower of water delivered by the pipe V. The gas, as it passes through the holes in the horizontal partitions, is, therefore,