| 释义 |
slipper coal
[? f. slipper a.]
A variety of coal (see quot. 1877).
1712Phil. Trans. XXVII. 541 Coal, less black and shining than the former, called Slipper-Coal. 1877Encycl. Brit. VI. 66 A smaller drift for ventilation..is carried above it in one of the upper beds called the slipper coal. Ibid., The coal is first cut to the top of the slipper coal from below. |