The ones with a second "solid-fuel" oxidizer cartridge work GREAT!
They have a tiny flame, are totally portable, and are more than
hot enough for a good seal. I don't know where one would go to
acquire one in the UK, but Radio Shack in the US has an inexpensive
one which I use all the time.
cheers,
Rich Shoemaker
-- Richard Shoemaker, Ph.D. Phone--(402) 472-6255 Instrumentation Director, Chemistry FAX---- -6964 Research Associate Professor, Chemistry University of Nebraska-Lincoln URL: http://wwitch.unl.edu/nmrlab.html