Original description: "The retort e, e, is seen charged with coke, which is in the first instance raised to a bright red heat, by means of the furnace beneath. The common brown rosin of commerce, which is deposited in the tank a, is mixed with essential oil, in the proportions of one hundred pounds of the former, to ten gallons of the latter. A portion of the flame and heated air beneath, serves to preserve this in a fluid state, and a damper passing across the aperture in the chimney, exactly regulates the temperature of the fluid. A wire gauze screen at f, reaches to the bottom of the tank, and prevents the solid rosin, or any impurity with which it may be mixed, from choking the stop-cock. The melted rosin having passed by the funnel c, and the syphon d, into the retort, falls on the coke, and in its passage through the ignited mass, becomes decomposed. On arriving at the other end of the retort, a large portion of the oil of turpentine in the form of condensible vapour, is separated by the refrigerator g; this is supplied with water from a cistern above, and the non-condensible vapour or gas passes up the tube h, and dips beneath the surface of the fluid in the vessel i. This completes the condensation, and the gas proceeds in a perfectly pure state by the pipe k, to the gasometer, or rather to the floating reservoir for use. The essential oil, when it leaves the refrigerator, is conveyed by the syphon b [sic!], to a cistern beneath. The necessity for employing a syphon, will be apparent, when it is borne in mind that the tube prevents the escape of the gas, which would otherwise pass away from the box, with the essential oil. Another syphon and pipe m, serve to convey the condensed essential oil from the top cistern."