Natural gas and oil have been burned with no regard for the future.
Of all the fuels, natural gas may be said to be the ideal one.
The decrease of natural gas is strikingly illustrated in Indiana.
Suggest a probable way in which natural gas has been formed.
The natural gas has been shut off, owing to the many leaks in Johnstown.
In the fall of 1886 natural gas was introduced into the works.
Natural gas is used both for lighting and for fuel purposes.
Natural gas was, and had been for a long time, the fuel used in these works.
Give some facts about natural gas and its use in Pittsburgh.
The most perfect fuel with which nature has provided us is natural gas.