Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
Rough Science Photo of the Rough Science cast
 Home | New Zealand | Scientists | Mike Bullivant | Diary | Day 32
Series 3:
New Zealand
Gold Rush
Shakers
Quakers
Ice
Treasure Hunt
The Big Smelt
   
The Scientists
The Location
Tune In
 
Series 1:
Mediterranean
Series 2:
Carriacou
Series 4:
Death Valley
   
  About the Show
  Discover More
  Feedback
Site Map
Mike Bullivant's Diary

Day 32: Smelting Gold

I'm feeling a lot more mobile than I did at the end of the last challenge. Even with rest, it's going to take 5 or 6 weeks for my ribs to mend, and I plan to take things easy in this final programme.

My final challenge is to purify all the gold that we've amassed - ‘amassed' seems a rather grand word for the 6g that we've managed to extract over the last 5 weeks. Kate tells me that I'm in charge of building a furnace to smelt the gold. Once we've done that, Jonathan, Ellen and Kathy have the job of designing and making something from the pure gold that we manage to recover.

Kathy and Ellen making clay 'pizzas' We all set about designing a furnace that we hope will give us the 1200 or so degees Celsius that are needed to melt the gold. In the kit for this challenge, we've been given a pile of firebricks, which will help enormously. We decide that we need to insulate the firebricks with clay mixed with charcoal, so that as much of the heat that's generated by the burning coals will stay inside the furnace and not be lost to the outside world. There are enough firebricks to build a double-walled furnace, but we won't be able to build the outer wall until the inner wall of firebrick (lined with clay/charcoal) has dried out. We set about constructing the inner furnace, with Kathy and Ellen doing a great job of churning out loads of clay/charcoal ‘pizzas'.

inner furnace charged with hot coalsIt really is a team effort, with Mikey L making a wonderful pair of leather and plywood bellows, and Jonathan and Mike working on a way of ‘measuring' the temperature inside the oven. By the end of the day, we have a lined, inner furnace, which we charge with hot coals and leave gently simmering overnight to dry out. This is a process that usually takes two to three weeks to do properly, so we're all feeling a little apprehensive as we leave the sawmill at the end of Day 1 with our little furnace glowing away in the rear-view mirror. What will greet us tomorrow morning? Perhaps drying the clay/charcoal liner so quickly will prove to be too much, and all we'll succeed in doing is cracking the clay, which won't help at all. There are already strong doubts as to whether the furnace can generate the temperatures we need, even if all goes well tonight. We shall just have to wait and see.

Back to top



Photo: Mike Bullivant
Metal Detector Interactive