atz, _Palaeontographica_, xxix. (1882); J.J. Quelch,
"_Challenger_ Reports," _Zoology_, xvi. (1886); * P.S. Wright and Th.
Studer, "_Challenger_ Reports," _Zoology_, xxxi. (1889).
(G. C. B.)

ANTHRACENE (from the Greek [Greek: anthrax], coal), C14H10, a
hydrocarbon obtained from the fraction of the coal-tar distillate
boiling between 270 deg. and 400 deg. C. This high boiling fraction is
allowed to stand for some days, when it partially solidifies. It is then
separated in a centrifugal machine, the low melting-point impurities are
removed by means of hot water, and the residue is finally hot-pressed.
The crude anthracene cake is purified by treatment with the higher
pyridine bases, the operation being carried out in large steam-jacketed
boilers. The whole mass dissolves on heating, and the anthracene
crystallizes out on cooling. The crystallized anthracene is then removed
by a centrifugal separator and the process of solution in the pyridine
bases is repeated. Finally the anthracene is purified by sublimation.

Many synthetical processes for the preparation of anthracene and its
derivatives are known. It is formed by the condensation of acetylene
tetrabromide with benzene in the presence of aluminium chloride:--

Br.CH.Br /CH\
C6H6 + | + C6H6 = 4HBr + C6H4< | >C6H4,
Br.CH.Br \CH/

and similarly from methylene dibromide and benzene, and also when benzyl
chloride is heated with aluminium chloride to 200 deg. C. By condensing
ortho-brombenzyl bromide with sodium, C.L. Jackson and J.F. White
(_Ber_., 1879, 12, p. 1965) obtained dihydro-anthracene

/CH2Br Br\ /CH2\
C6H4< + 4Na + >C6H4 = 4NaBr + C6H4< >C6H4.
\Br BrCH2/ \CH2/

Anthracene has also been obtained by heating ortho-tolylphenyl ketone
with zinc dust

/CH8 /CH \
C6H4< = H2O + C6H4< | >C6H4.
\COC6H5 \CH /

Anthracene crystallizes in colourless monoclinic tables which show a
fine blue fluorescence. It melts at 213 deg. C. and boils at 351 deg. C.
It is insoluble in water, sparingly soluble in alcohol and ether, but
readily soluble in hot benzene. It unites with picric acid to form a
picrate, C14H10.C6H2(NO2)3.OH, which crystallizes in needles, melting at
138 deg. C. On exposure to sunlight a solution of anthracene in benzene
or xylene d