On 12/03/2013 22:42, Chris Hogg wrote:
On Tue, 12 Mar 2013 20:46:25 +0000, Tim+
wrote:

How do they do it? The news picture looked like they were burning an old
car tyre so that accounts for the black smoke. How will they make the
white smoke? Stage smoke machine or something more traditional? ;-)

Tim
A news item on the beeb earlier this evening showed two small
cylindrical stoves, rather like the old fashioned tortoise stoves,
connected to a temporarily erected chimney supported by scaffolding,
the implication being one stove for white smoke, the other for black.
No idea how they make the smoke the correct colour though. I was once
told that smoke screens laid down by warships in WW2 were made by
injecting titanium tetrachloride into the smoke stack, where it
reacted with the steam to produce an aerosol of titanium dioxide and
hydrochloric acid; very white if a little unpleasant.

Burning phosphorous is simple and makes a pretty good white smoke
although it is more than a little unpleasant to handle and the smoke is
toxic and corrosive. But since they only need to do it infrequently.

Lets hope they pick one that lasts a bit longer since there are some who
believe that this will be the last Pope ever.... TEOTW is nigh!

--
Regards,
Martin Brown