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332 USEFUL PROPERTIES OF BENZOLE, ETC. 
The promises which benzole makes of utility are suf- 
ficiently numerous to encourage a belief that it may form a 
special object of manufacture and of commerce. It may be 
procured to any extent from coal tar or from the light 
naphtha in which it has hitherto been " wasting its sweet- 
ness on the desert air." If absolute purity be not required, 
it may be prepared, with very little expense and trouble, 
either in the laboratory or on the large scale in vast quan- 
tities; and by a further slight outlay of time, any required 
degree of purity may be ensured in the product. The de- 
scription of a method which has been found to yield very 
satisfactory results may be not devoid of interest. 
The boiling-point of benzole is the same as that of alco- 
hol of spec. grav. 0.825, (176°F. ;) it is evident therefore 
that any of the summary processes of rectification which 
are practised by distillers in the manufacture of alcoholic 
spirits, are applicable to the separation of benzole from the 
ess volatile fluids of the naphtha. The method now to be 
described is one which extracts nearly the whole of this 
spirituous hydrocarbon by a very slight expenditure of 
time. 
The light coal naphtha (of which it is best to take that 
which came over at the commencement of the distillation 
of the tar, and contains the benzole less diluted with sub- 
stances having higher boiling-points) is placed in a metal 
retort, which is surmounted by an open vessel filled with 
water, and containing a worm or chamber, into which the 
vapor of the naphtha passes directly from the retort, and so 
arranged, that the less volatile fluids, which will be con- 
densed in it, will flow back into the retort, or into a sepa- 
rate receiver, while the fluids more volatile than water will 
pass on in vapor to another condenser, which is kept as cold 
as possible. The water surrounding the still-head will 
gradually rise in temperature as the operation proceeds, and 
will at last boil ; and when this takes place (or if the heating 
of the water be checked at any period of the process by 
