NAPHTHA, COAL 



393 



by a steam-jacket, is connected at its upper extremity with a head, b, answering to the 

 worm c in fig. 1545. The head plays into the worm-tub d; the benzole being con- 

 veyed by the exit-pipe, e, to the reservoir, or close tank, in which it is to be stored. The 

 tub, c c c c, contains water to condense the hydrocarbons which are to be removed from 

 the benzole. In order to save time, it is convenient at the commencement of the 

 operation to heat the water in c c c c to about 170 ; this is effected by means of the 

 steam-pipe III, which is connected with the boiler/. The steam is admitted to the 

 jacket of the still by means of the pipe g. The steam can be regulated or stopped 

 altogether by means of the stopcock n. The cock m, is to regulate the admission of 

 steam to the vessel c c c c. The man-hole is represented at k, A small cock to allow 

 the condensed water in the jacket to be run off, is seen at i. Unless the naphtha is 



1547 



of the best quality the benzole will be difficult to extract by the heat of the jacket 

 alone. It will then be necessary to send direct steam into a a. When no more 

 benzole comes over, the remaining naphtha is to be run out of the still by the stop- 

 cock h. Although the boiler/ is, for the sake of space, represented in the figure as if 

 placed beneath the support of the condenser or worm-tub, it should in practice be 

 removed to a considerable distance for fear of the vapour of the hydrocarbon reaching 

 the stoke-hole and causing an explosion. The condenser b may be arranged in the 

 form of a worm like c in fig. 1545, but the precaution is scarcely necessary if the 

 chamber at b, fig. 1547, be made sufficiently capacious. The benzole obtained in the 

 above apparatus is, of course, contaminated with toluole ; if, however, the rectification 

 be repeated, the water in the chamber c c c c not being permitted to become hotter 

 than 180 Fahr., the resulting benzole will be almost pure. One distillation is amply 

 sufficient for the preparation of the commercial article. 



A rectifying column somewhat like Coffey's still may alse be employed for pre- 

 paring benzole. 



The less volatile naphtha remaining in the still is by no means valueless ; it is 

 adapted for almost all the purposes for which ordinary coal-naphtha is applicable. By 





