I think we all know the first part of this one, but the second part is new to me.
ASHES:
a. Do not empty ashes into a wastepaper basket as they can easily start a fire. A large tin is much more suitable .
b. To prevent cigarette ends from burng in an astray and to reduce the smell of stale tobacco, coat the bottom of the ashtray with baking powder.
** Could have used the part 'b' info years ago when I filling up the ashtrays as fast as time would allow me..