This paper contains the results of further studies (FOOTNOTE 4) on the variations in the composition and properties of natural gas by geologic and geographic distribution.

New data corroborate the composite regional variations previously published.(FOOTNOTE 5) The regional map has been extended to include the gas and oil fields in Canada which lie in the Appalachian Province north of Lake Erie.

Well-to-well variations in the composition of the gas in several individual reservoirs are given. Definite relationships exist between the composition of natural gas and associated oil, both areal and quantitative.

Numerous samples of near-surface gases and gases from coal seams have been analyzed.

A resume of the geologic occurrence of methane, ethane, and higher-boiling saturated compounds, nitrogen, carbon dioxide, and hydrogen sulphide is given. Also the relationship of these gases to their associated constituents--sand, shale, limestone, coal, water, brine, calcium sulphate--are discussed.

The origin, migration, and natural storage of gas and oil are discussed in the light of these data.