1068 LAWS OF MARYLAND. [CH. 437

tained in such quantity that the incombustible content of
the mine dust will riot be less than 65 percent.

MISCELLANEOUS SURFACE CONDITIONS

141. Surface fire prevention, (a) Oil, grease, and simi-
lar flammable materials shall be stored in closed contain-
ers, separate from other materials so as not to create a
fire hazard to nearby buildings or mines. If oil or grease is
stored in a building, the building or the room in which it
is stored shall be of fire-resistive material and well ven-
tilated no oil, grease or other similar inflammable mate-
rials shall be stored within any fan-house. Tight metal
receptacles shall be provided for oily waste. Smoking in
or about surface structures shall be restricted to places
where it will not cause fire or an explosion.

(b) If a gasoline engine is used to propel any ventilat-
ing fan, the fuel tank of said engine shall not be placed
immediately above said gasoline engine but shall be placed
outside of the fan-house. When placed outside of the fan-
house, it may be placed in such a position as to allow
gravity feed.

(c) Unless existing structures located within 100 feet
of any intake mine opening are of reasonably fireproof
construction, fire doors shall be erected at effective points
in such mine openings to prevent smoke or fire from out-
side sources endangering men working underground. These
doors shall be tested at least monthly to insure effective
operation.

UNDERGROUND FIRE PREVENTION, FIRE CON-
TROL, AND MINE DISASTERS

142. Fire prevention and control, (a) Each mine shall
be provided with suitable fire-fighting equipment, adequate
for the size of the mine as prescribed by the Bureau of
Mines, such as supplies of rock dust at doors and at other
strategic places, water. lines and hose, water or chemical
trucks, and fire extinguishers.

(b) Clean dry sand, rock dust, or fire extinguishers,
suitable from a toxic and shock standpoint, shall be pro-
vided and placed at each electrical station (substations,
transformer stations permanent pump stations) so as to
be out of the smoke in case of a fire in the station.

(c) After every blasting operation an examination shall
be made to determine whether fires have been started.
Should a fire occur, the person discovering it and any per-