FLUORENE (a-diphenylene methane), C 13 H 10 or (C6H4)2CH2, a hydrocarbon found in coal-tar.
The relation between the heat of combustion of a hydrocarbon and its heat of formation may be readily seen from the following example.
It thus possesses the same composition as the hydrocarbon of gutta-percha and as that of oil of turpentine and other terpenes which are the chief components of essential oils.
BENZENE, C 6 H 6, a hydrocarbon discovered in 1825 by Faraday in the liquid produced in the compression of the illuminating gas obtained by distilling certain oils and fats.
ANTHRACENE (from the Greek civOpa, coal), C 14 H 10, a hydrocarbon obtained from the fraction of the coal-tar distillate boiling between 270° and 400° C. This high boiling fraction is allowed to stand for some days, when it partially solidifies.