e neighbourhood of 40%
of alcohol. Some bitters, although possessing tonic properties, may be
regarded as beverages pure and simple, notwithstanding the fact that
they are seldom consumed in an undiluted state; others again, are
obviously medicinal preparations and should be treated as such.

BITUMEN, the name applied by the Romans to the various descriptions of
natural hydrocarbons, the word _petroleum_ not being used in classical
Latin. In its widest sense it embraces the whole range of these
substances, including _natural gas_, the more or less liquid
descriptions of _petroleum_, and the solid forms of _asphalt, albertite,
gilsonite_ or _uintahite, elaterite, ozokerite_ and _hatchettite_. To
distinguish bitumen intermediate in consistency between asphalt and the
more liquid kinds of crude petroleum, the term _maltha_ (Latin) is
frequently employed. The bitumens of chief commercial importance may be
grouped under the three headings of (1) _natural gas_, (2) _petroleum_,
and (3) _asphalt_, and will be found fully described under these titles.
In the scriptures there are numerous references to bitumen, among which
the following may be quoted:--In Genesis ix. 3, we are told that in the
building of the tower of Babel "slime had they for mortar," and in
Genesis xiv. 10, that the vale of Siddim "was full of slime-pits," the
word _slime_ in the latter quotation from our version appearing as
_bitumen_ in the Vulgate. Herodotus alludes to the use of the bitumen
brought down by the Is, a tributary of the Euphrates, as mortar in
building the walls of Babylon. Diodorus, Curtius, Josephus, Bochart and
others make similar mention of this use of bitumen, and Vitruvius tells
us that it was employed in admixture with clay.

In its various forms, bitumen is one of the most widely distributed of
substances. It occurs, though sometimes only in small quantity, in
almost every part of the globe, and throughout the whole range of
geological strata, from the Laurentian rocks to the most recent members
of the Quaternary period. Although the gaseous and liquid forms of
bitumen may be regarded as having been formed in the strata in which
they are found or as having been received into such strata shortly after
formation, the semi-solid and solid varieties may be considered to have
been produced by the oxidation and evaporation of liquid petroleum
escaping from underlying or better preserved deposits into other strata,
or into fissures whe