Green Fireworks

I suspect anyone who has spent time in a chemistry lab – or seen one of the many programmes affording a brief glimpse of Dr Andrea Sella on the television (he seems to be very much the go-to guy for chemistry experiments these days) – will be familiar with the flame test.  You place a small sample of a metal or compound in the flame of a bunsen burner and admire the pretty colours.  Well, you did in my day – but we did only have black and white television and were use to making our own fun – perhaps young people today just yawn or are too busy texting to notice.

Green was always a tricky colour to obtain – we were taught that barium produces an apple-green flame but we weren’t allowed to play with barium (whether as a result of cost or the rather limited health and safety concerns present in the late 70s, I don’t know) and my teachers never indicated what kind of apple.  There is a huge difference in green between an Egremont Russet and a Blenheim Orange or Rev. W Wilkes.

This effect is really rather important and led to the science of spectrometry, by which we can tell of what chemical elements distant stars are made.  It also explains the colour of sodium street lamps and contributes to the beautiful colours obtained from the fireworks launched to celebrate the capture (and subsequent execution) of a chap with a name homophonous to mine when he tried a rather extreme vote of no confidence in the government of his day.

Green fireworks use barium chloride (BaCl2), but there are concerns that this can build up to toxic levels at sites where fireworks are frequently used – Lewes you have been warned!  I had always assumed barium was harmless – perhaps even tasty – as patients are often given a barium meal in hospital, but further research suggests this process only involves insoluble barium salts.

However, military scientists in the US – I think looking at flares or tracers, rather than celebratory explosions – have discovered that boron carbide also produces a green firework and is non-toxic (no data yet on its flavour when used as a seasoning or spice).

Boron carbide has (more-or-less, it tends to be a slightly carbon deficient in bulk) the chemical formula B4C (apologise for the failure to subscript the 4, not yet sure how to get WordPress to subscript – I rather think it requires more knowledge of HTML than I currently possess) or homophonically, before sea.  This leads me to wonder if one could use words like Beach or Shore (or the Morning of the Second Day) as a brand name for boron carbide.  Boron carbide is incredibly hard – I think the water in Cambridge is pretty hard, but that is nothing to boron carbide – on the mohs scale where diamond is 10, B4C comes in at a very respectable 9.3 (however, it would only satisfy a rather niche taste for jewellery, I fear).  It can stop neutrons, bullets and even shells (ordnance rather than mollusc related, but it could probably stop those as well – let’s face it, snails and their ilk are not known for being all that fast moving) and so is used in armour of all kinds. Presumably when B4C armour is struck by ordnance, one obtains lovely green sparks?

So, let us raise a glass (of crême de menthe or listerine, perhaps) to the US Army scientists of the Picatinny Arsenal.  Green fireworks can now truly be green!

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4 thoughts on “Green Fireworks

  1. Semibreve says:

    But snails are fast moving. At least, they are when I give them flying lessons by lobbing them over the hedge onto the pathway beyond.

  2. Stuart Ffoulkes says:

    True enough – though generally speed records achieved at altitude are not recognised (at least for human athletes – and so, I presume by extension, for their mollusc counterparts). Even so, I’m sure any users of the pathway beyond your hedge would appreciate the benefits of snail-proof armour made of B4C (assuming they were wearing such prophylactic garb when assailed by airborne gastropods).

  3. matathew says:

    Sorry to pick up on this characteristically profound post at a trivial level, but “sub” works as the HTML tag you’re after in my browser. But will it work in WordPress? Here goes:
    X20: Curse you, terraneans!

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