Hydrogen gases 0
Carbon dioxide 0.1
Oxygen 0
Heavy hydrocarbons 0
Carbon monoxide 0
Methane 81.8
Ethane 16.8
Nitrogen 1.3

The volume of gas used is measured by an accurate test meter reading to
one-twentieth of a cubic foot. The required amount is admitted near the
bottom, to one or more of the 20-ft. divisions of the gallery, from a
2-in. pipe, 14 ft. long. The pipe has perforations arranged so that an
equal flow of gas is maintained from each unit length.

Each 20-ft. division of the gallery is further equipped with an exterior
circulating system, as shown by Fig. 1, thus providing an efficient
method of mixing the gas with the air. For the first division this
circulating system is stationary, a portion of the piping being equipped
with heating coils for maintaining a constant temperature.

The other divisions have a common circulating system mounted on a truck
which may be used on any of these divisions. Valves are provided for
isolating the fan so that a possible explosion will not injure it.

In the center section of each division is an indicator cock which is
used to provide means of recording pressures above and below
atmospheric, or of sampling the air-and-gas mixture. The first division
of the gallery is equipped with shelves laterally placed, for the