CONSTITUTION OF ANTHRACENE OR PARANAPHTHALINE. 683 
but still more to the oil with which it is contaminated, and which it loses on purifi- 
cation. It is soluble, though not abundantly, in alcohol, but dissolves with toler- 
able facility in ether, turpentine, and still better in benzole. Methylated spirit 
was in the first instance used for its purification, and the first solution, on cooling, 
deposited thick oily globules, along with a small quantity of crystals; but after 
several successive quantities of spirit had been used, crystals were deposited free 
from oil, but still retaining the yellow colour of the original substance, and appa- 
rently, owing to the removal of the oil, they were much less soluble in new 
quantities of spirit. By repeated crystallisations, it was found possible to obtain 
the anthracene quite colourless; but the process was too tedious to be employed 
for preparing it on the larger scales. Other solvents, and more particularly 
benzole, were likewise tried ; but, though preferable, the complete removal of the 
colouring matter is difficult with them also, and it was found necessary to com- 
mence by distilling the crude substance in a small iron still. The first portions 
which passed over during the process contained much naphthaline and oil, but 
they were quite free from colour. As the distillation proceeded, however, the 
colour gradually increased, and at the end a small quantity of a dark green 
substance remained in the retort. The first portions of the distillate were pressed 
to remove the oil, and the last portions redistilled so as to get rid of the colour 
as completely as possible, and the purification finished by repeated crystallisation 
from benzole, and sometimes by sublimation. 
Anthracene is deposited from its solutions in perfectly colourless scales, — 
generally of very small size even when large solutions have been allowed to cool. 
Those obtained from spirit are generally the best, and when suspended in the 
solution have a fine satiny lustre, which they lose to some extent when dried. 
From benzole its crystals are somewhat granular, and less brilliant in appear- 
ance. By sublimation, it is got in thin plates resembling those of naphthaline, 
but smaller and of inferior lustre. When quite pure it has no smell, but it is 
apt to retain a trace of oil, which communicates to it a faint empyreumatic odour. 
It is entirely devoid oftaste. It is not volatile at ordinary temperatures, but is 
slowly volatilised in the water bath. At higher temperatures it sublimes freely. 
It melts at 416° F. into a transparent colourless fluid, which, on cooling, solidifies 
into a foliated crystalline mass, and at a higher temperature distils unchanged. 
It is insoluble in water, sparingly soluble in alcohol, but more so in ether, benzole, 
and the volatile oils. The alkalies are without action upon it, but sulphuric acid 
dissolves it, and acquires a green colour, with the formation of a sulpho-acid; and 
nitric acid, even when moderately dilute, acts rapidly upon it. Chlorine and 
bromine form substitution products. 
The analysis of anthracene at first presented some difficulties. When oxide 
of copper was employed in the usual way, the carbon was always deficient, while 
chromate of lead gave an accurate result with that element, but a marked excess 
