Zane does the same thing; he is never seen swallowing Atium
He probably carried a bead in his mouth like he did with coins. That way digestive juices didn't ruin it and he'd be able to swallow and burn instantly. If it's a big enough bead he wouldn't need water to wash it down like you would with metal flakes.
The problem with that thought, VegasDev, is that saliva is incredibly acidic, too. It essentially acts the same as regular digestive juices in breaking down food.
I didn't read all the comments on this thread, but something seems odd to me.
Why do people thinks that Vin is using Hemalurgy? Inquisitors have eleven spikes of metal in theirs bodies and Zane had one in the back. Why on earth would Vin be an hemalurgist? Because of her earring?
I recall marsh saying that the process to create an new Inquisitor was messy (it involved, as far as I know, big metals spike in the body and lot of deads, since marsh said there was several corpses used in his fabrication). The smalls earring of vin and the death of her sister, in my humble opinion, aren't enough to create an hemalurgist. I mean, compare the size of the spike versus the earrings of vin, the death of her sister (who was a child) with the amount of corpses involvend im Marsh creation.
The connection is interesting, but Vin seemed to lack....proper transformation. I mean, every hemalurgist seen had spikes , why would she make an exception?
The importance in that, I believe, is simply that metal was inside her body, as a piercing would. A spike would just be, essentially, a far bigger "piercing".
Also, there is the fact that Vin's earring is bronze, which coincidentally is the metal that finds Allomancy. But it isn't a coincidence. Honestly, we don't really know the direct effects of Hemalurgy, other than the mists being repelled, but it appears that it is some kind of enhancement to Allomancy (that is just what is seen right now, not my actual opinion. I personally believe that Hemalurgy is a separate magic from Allomancy, so it is more than just an enhancement of Allomancy. Just, we haven't seen those different powers yet). The metals, in both Allomancy and Hemalurgy, must, logically, have similar powers. Vin can pierce copperclouds, so why is that? The earring, Hemalurgified, provides an explanation. Most Allomancers don't wear metal on their body... but Vin has that earring. And it's bronze.
It would be too coincidental if that wasn't the explanation.
On another note, it's important to realize that whatever Vin uses, Hemalurgy-wise, pales in comparison to what Inquisitors have. Inquisitors are far different creatures than Vin, in most conceivable ways, the most clear example being that Inquisitors have incredible healing abilities. Vin does not have anything close to the Inquisitors in that respect.
Finally, in the last part of book 2, Elend notices that Vin is repelling the mists, something that EUOL has confirmed is a result of using Hemallurgy.
Page number, please? I don't remember that
at all. How could I have missed that, lol? (But asking that is like wondering why I missed crucial details about Zane, but whatever...)