Coal
Anthracite or hard coal has been used in certain districts in the United States, especially in New Jersey and eastern Pennsylvania. It is not an ideal fuel as it is too solid to burn rapidly, spalls or cracks under heat and interferes with the blast. Since 1860 when coke became available here much less coal has been used, though some is yet used in admixture with coke. Some bituminous coals which contained little tarry matter also have been used in this way.