coal gas

Cooking on coal-gas stoves, lighting pipes with matches, and driving horses?

This is known as Pole's formula, and has been generally used for determining the sizes of mains for the supply of coal-gas.

Long before this Dr. Clayton described some observations on coal-gas, which he called "the spirit of coals."

It was this form that survived as it came on the threshold of the era of illumination by coal-gas.