It was (is still?) claimed that at Nazi
concentration camp Mauthausen in Austria,
the Nazis employed the unique method of
placing Zyklon B crystals upon a brick
which had been heated in the crematory
oven, then shoving it in the gas
chamber.
At the 1988 trial of Ernst Zündel in
Canada, under cross examination
by the prosecution, it was put to
American gas chamber expert Fred
Leuchter, that the brick
method may also have occurred at
Auschwitz.
From Barbara Kulaszka's book on the
trial:
The Crown suggested that a
red-hot brick had been thrown
into the chamber (Birkenau's
Krema II & III's gas chambers)
to increase the
temperature around the Zyklon B.
Leuchter replied that bricks did
not get red-hot,
only metal did. A brick might be
too hot for a person to handle,
but would still not
be of sufficient temperature to
cause an explosion with the gas,
although it would
probably raise the temperature.
SOURCE
Did Six Million Really Die?
Report of the Evidence in the
Canadian
'False News' Trial of Ernst Zündel –
1988
by Barbara Kulaszka, published in
1992
page 746