This Saturday I'll be heading to Oxford to overdose on homeopathic medicines as part of the 1032 campaign with the Oxford Sceptics in the Pub. The non-potion I brought yesterday and will be enjoying soon is marketed by Boots as Silicea C30 (it's not listed on their website). What do the homeopaths claim is in there, and what's really in there?
Silicea is a slightly made up name for what the rest of us call Silica, chemically SiO2, the most abundant compound on (well, in) the Earth. It turns up as sand, quartz, flint and other rocks and gems. Eating those would be harmless so long as they weren't too sharp. It's also used in silica gel as a desiccant, for instance packed in with new trainers, which you wouldn't want to swallow as there's often other stuff in there with the silica. You can obtain food grade silica gel, without the extra chemicals, and eat that, with no toxic effects (in fact it's available as a dietary supplement). The one thing you shouldn't do is grind up sand or quartz very fine and breath it in, as the teeny particles will stick to the walls of your lungs and irritate them for the rest of your life.
According to the homeopaths, though, whatever contact silica once had with the solution that was dripped onto the pills has been long washed away by 30 repeated 100:1 dilutions. This, they say, only makes it more powerful. As an aside, even if you buy the top of the range Millipore Milli-Q ultrapure water supplies you're specified to have no better than 3 ug / L of silica, or a concentration (by mass) of 3e-9. In homeopathic terms this is only a C4.5 dilution, so anyone advertising or selling something at C30 is clearly doing something misleading.
By the internal logic of homeopathy you treat a symptom with an overdilute solution of something that causes the same symptom. To me it seems that high doses of silica do nothing, so this C30 dilution of it should do nothing only better. According to http://abchomeopathy.com/r.php/Sil (which you really don't need to read), though, Silicea is active against a huge list of things, including, to my amusement, impaired thinking. So there you go.
What's really in there? Little balls of fructose and glucose. A double dose of woo, if you will.
(Flint from the Wikimedia commons.)