Thursday, 1 November 2012

Getting Romans hot



In the recent post 'Steeling Yourself' you may have noticed that Roman metal production was barely matched anywhere else in the world until the beginning of the 19th-century. But the thing is 80,000-tons of lead and 82,500-tons of pig iron needed a whole lot of heat. In modern steel production you need two tons of coal to turn a ton of iron into steel...so presumably, the Romans had to find 165,000-tons of hot stuff just to make all that smeltered iron useful. But what kind of hot stuff was it? Traditionally it's believed Roman metal makers - and bathhouses for that matter - relied on wood and charcoal for their furnaces, just like the other contemporary iron age empires. Much of central China and India remain largely denuded of forests because of their charcoal industries. However there's increasing evidence the Romans turned to another well known heat source during the 1st and 2nd-centuries AD. Coal. In Britain several Roman villa excavations and some ancient smelters have turned up traces of coal dust or broken coal on site - some of which have previously been dismissed as glacial deposits by traditionalists. There's also evidence of bituminous coal being used in the Roman Rhinelands by Germanic steel-makers. British coal was also being shipped across the North Sea to the ports the Rhine iron workings as well. So it looks like the global seaborne trade of coking coal is nothing new and Roman industry was just as complex as the Industrial Age we've just had. And perhaps...just perhaps, this explains why European forests survive to the present day. After all, if the charcoal industry was Rome's only way of making steel and water pipes, then its hard to explain why the demand-supply cycle didn't see the Black Forest disappear - no matter what the Germans said or how many legions it took.

Find out what Calvus stoked his fire with