iron
pyrites, which yield a red ash. There are, however, several striking
exceptions, as for instance in the anthracite from Peru, given in Table
I., which contains more than 10% of sulphur, and yields but a very small
percentage of a white ash. In this coal, as well as in the lignite of
Tasmania, known as white coal or Tasmanite, the sulphur occurs in
organic combination, but is so firmly held that it can only be very
partially expelled, even by exposure to a very high and continued
heating out of contact with the air. An anthracite occurring in
connexion with the old volcanic rocks of Arthur's Seat, Edinburgh, which
contains a large amount of sulphur in proportion to the ash, has been
found to behave in a similar manner. Under ordinary conditions, from 1/8
to 1/4 of the whole amount of sulphur in a coal is volatilized during
combustion, the remaining 3/4 to 7/8 being found in the ash.

TABLE II.--_Composition of the Ashes of Coals._

+----------------------+-------+--------+--------+-------+---------+-------+---------+----------+--------+
| | | | Ferric | | | |Sulphuric|Phosphoric| |
| |Silica.|Alumina.| Oxide. | Lime. |Magnesia.|Potash.| Acid. | Acid. | Total. |
+----------------------+-------+--------+--------+-------+---------+-------+---------+----------+--------+
| True Coals. | | | | | | | | | |
| Dowlais, South Wales | 39.64 | 39.20 | 11.84 | 1.81 | 2.58 | .. | .. | 3.01 | 98.08 |
| Ebbw Vale, " | 53.00 | 35.01 | .. | 3.94 | 2.20 | .. | 4.89 | 0.88 | 99.92 |
| Konigsgrube, Silesia | 55.41 | 18.95 | 16.06 | 3.21 | 1.87 | 2.05 | 1.73 | 0.36 | 99.64 |
| Ohio | 44.60 | 41.10 | 7.40 | 3.61 | 1.28 | 1.82 | 0.59 | 0.29 | 100.69 |
| | | | | | | | | | |
| Lignites. | | | | | | | | | |
| Helmstadt, Saxony | 17.27 | 11.57 | 5.57 | 23.67 | 2.58 | 2.64 | 33.83 | .. | 97.13 |
| Edeleney, Hungary | 36.01 | 23.07 | 5.05 | 15.62 | 3.64 | 2.38 | 12.35 | .. | 98.12 |
+----------------------+-------+--------+--------+-------+---------+-------+---------+----------+-