ures so far as the actual discovery of true coal
was concerned, yet there can be no doubt as to the future value of the
lignite in these parts, when England's supplies of coal approach
exhaustion, and attention is turned to other directions for the future
source of her gas and paraffin oils.

Beside the Bovey Tracey lignitic beds to which we have above referred,
other tertiary clays are found to contain this early promise of coal. The
_eocene_ beds of Brighton are an important instance of a tertiary
lignite, the seam of _surturbrand_, as it is locally called, being a
somewhat extensive deposit.

We have now closely approached to true coal, and the next step which we
shall take will be to consider the varieties in which the black mineral
itself is found. The principal of these varieties are as follows, against
each being placed the average proportion of pure carbon which it
contains:--

Splint or Hard Coal, 83 per cent.;
Cannel, Candle or Parrott Coal, 84 per cent.;
Cherry or Soft Coal, 85 per cent.;
Common Bituminous, or Caking Coal, 88 per cent.;
Anthracite, Blind Coal, Culm, Glance, or Stone Coal, from South
Wales, 93 per cent.

As far as the gas-making properties of the first three are concerned, the
relative proportions of carbon and volatile products are much the same.
Everybody knows a piece of cannel coal when it is seen, how it appears
almost to have been once in a molten condition, and how it breaks with a
conchoidal fracture, as opposed to the cleavage of bituminous coal into
thin layers; and, most apparent and most noticeable of all, how it does
not soil the hands after the manner of ordinary coal. It is at times so
dense and compact that it has been fashioned into ornaments, and is
capable of receiving a polish like jet. From the large percentage of
volatile products which it contains, it is greatly used in gasworks.

Caking coal and the varieties of coal which exist between it and
anthracite, are familiar to every householder; the more it approaches the
composition of the latter the more difficult it is to get it to burn, but
when at last fairly alight it gives out great heat, and what is more
important, a less quantity of volatile constituents in the shape of gas,
smoke, ammonia, ash and sulphurous acid. For this reason it has been
proposed to compel consumers to adopt anthracite as _the_ domestic coal
by Act of Parliament. Certainly by this means the amount of impurities in
the air mi