Assertion: gas | /r/MadeOf | coal
Facets:
Source sentences:
text: The gas was made from coal up to 1937 when the high cost of operating the old coke oven and coal-gas generating sets forced a change-over to oil.
text: The gas was made from coal up to 1937 when the high cost of operating the old coke oven and coal-gas generating sets forced a change-over to oil.