THE RETORT OVEN.

75

moniacal fluid reach the reservoir destined toreceive these products.

iThe gaseous fluid which accompanies the con-densible products, are then made to pass into thelime machine, of which we shall speak hereafter,in order to be deprived by means of quick-limeand water, from the portion of sulphuretted hydro-gen and carbonic acid gas which was combined withthe gas. And when this has been accomplished,the purified gas is conveyed into the gas-holder,where it is stored up for use. This part of theoperation will be rendered more obvious hereafter.In some establishments, the hydraulic main isfurnished with two discharging pipes, the onecarries away the condensible fluid, into which theperpendicular pipes P, fig. 2, plate IV. dip, whilstthe other serves to convey away the gaseous fluidsto a condensor, in order to deposit the vaporousportion of condensible liquid it may contain, andfrom thence the gas passes into the purifying appa-ratus, or lime machine. X, fig. 2, plate IV., isa small screw plug, which, when opened, restoresthe equilibrium of the air within and without theretort previous to the lid being taken off, to pre-