[stansfield] carbonization OF LIGNITES • 123 



to remove the last traces of tar fog, but the condensate was usually 

 in the form of a watery emulsion, very difficult to handle. 



The method employed is as follows: the hot gases leaving the 

 retort pass down through the centre tube of a small scrubber D, made 

 of iron pipe and containing three interlacing coils of wire, passing up 

 again through a surrounding annular space; the whole being jacketted 

 with superheated steam. The heavy tar oils are here condensed in 

 a practically water free condition, and drop into a weighed glass 

 beaker. The lighter oils, steam, and gases pass on and down through 

 a simple tubular condenser E where the two former condense and 

 collect in a receiver, the oils floating on the water and showing only a 

 slight tendency to emulsify. The cool gases leaving the condenser 

 still contain some tar fog; they are therefore passed down through a 

 tube scrubber F filled with glass beads (and a short layer of glass 

 wool shown shaded) through which a jet of steam from a weighed 

 boiler is also passed. The bottom half of this scrubber is water cooled. 

 This scrubber completely removes the tar fog from the gas; the oil 

 first condensed on the beads acts as an oil scrubber collecting more 

 of the tar, the steam prevents the clogging of the scrubber by keeping 

 the tar hot and fiuid, and also, when condensing at the bottom, 

 carries down with it any vapours still remaining. The gases are thus 

 completely cleaned, and all the liquid products as well as the am- 

 monia from the lignite are collected in the vessels and can be readily 

 weighed and examined. The tar oils thus collected are reasonably 

 free from water and can be redistilled without excessive bumping or 

 frothing. The gases leaving the scrubber F pass through a final 

 cooling tube G, through a gas meter H, and into a gas holder which is 

 not shown. 



Regular Series of Tests 



In the experiments the retort was charged, usually with pea 

 sized lignite contain'ng about 34% moisture but in a few experiments 

 with dried lignite, and connected to the purifying train which was 

 then swept out with gas from a previous run. The lead bath, heated 

 to temperature higher than that desired for the test in order to allow 

 for the cooling effect of the retort, was then raised to surround the 

 retort. The temperatures and pressures at the different parts of the 

 system, and also the meter readings, were recorded at frequent inter- 

 vals, and the experiment continued until the evolution of gas had 

 practically ceased. The volumes of gas collected were corrected for 

 temperature, pressure and moisture content, being reduced to moist 

 gas at 60°F. and 30" of mercury pressure. All other products were 

 weighed, and all the products were carefully analysed. In a number 



