@Texaspyro, I may be mistaken but I read somewhere that they can vent hydroflouric acid, or was that only for lithium primaries?
If there was HF in there, the shell and copper and aluminum electrodes would be dissolved. You might get some HF if the electrolyte torched off… would depend on the electrolyte.
I have a friend that tortures batteries for a living. He would be long dead by now if there was something really nasty going on.
Well of course it is not actually in the battery, but I know there were a few HF incidents on CPF due to vents.
Scaru, I believe it was a CR123 primary cell in the thread at CPF.
Here’s the thread: Inhaled vapors from battery!!! | Candle Power Flashlight Forum!!!
Edit: More info about HF:
HF is produced at burning. No flames/smoke, no HF
Call the fire brigade.
They have specialist hazchem units who will let you know if it’s actually dangerous,
and how to safely dispose of it.
How the hell can a cell start to bubble? Are we sure its venting or just getting really hot?
I'd let it sit outside for a few days (dont throw it onto the lawn and run over it with a lawnmower though) and then try the saltwater method. If you have something like this, you should be really safe:
Pressure differences pushing electrolyte out of a tiny leak in the seal/can.
Could be expensive if emergency services later sends you a $1,000 bill for their visit. However, I suppose just calling them to ask for info should be free.
Will try and resist doing that….
Thanks for the suggestions, both dodgy cells are currently now sitting under a 20kg solid conrete plant pot, will dump them into salt water in a few days time.
Good idea I might call the fire brigade and ask them where to dispose of them.
Off to the snickers wrapper they go then 
You could send it to the guy who posted on here yesterday about how to disassemble a li ion cell, he already cut the top off one, he is a graduate student or something.
+1 Very well Said.
Send it to me :P
I think if you tested it at zero voltage it's a door stop why does anyone freak out about a dead cell .unless he went back and edited his post .
It says he tested it at zero volts ..That doesn't scare me ..Should it ? check voltage and if it's dead or very dang dead ..Wrap them separately in little plastic tape them up and recycle them . killer gases comes from the batteries on fire not sitting there doa with no voltage . i ain't scared
If i saw a battery bubbling ... it might get my attention
if I'm wrong ....i'd like to know
Tell me Cat eyes, you use “LSD” Cells to keep you going, don’t you. Just curious, do you insert them Nasally, Intravenously or Rectally. 
just because theres no voltage doesn’t mean everything inside is in its lowest energy state, it just means the chemical reaction isn’t producing electricity, i don’t know much about lithium battery construction, but if there are chemicals that are reactive then you could have a problem, say acids, hydrogen, pure oxygen, materials incompatible with water, air, calcium, magnesium etc.
Hydrofluoric acid is a good example, i’m not getting into the debate of if its in batteries or not, but its an example of something that may not produce electricity, but is still harmful no matter if its sourced from batteries or aluminium etching solutions.
Plutonium is also a good example, I’m not getting into the debate of if it’s in batteries or not, but it’s an example of something that may not produce electricity, but is still harmful ….
CPF meh, they’re drama queens any way…
Awww, now where’s the fun in doing it safely… just boldly go! J)
It’s prolly a bit hard to do that as every pack is slightly different, plus I wouldn’t really call my method ‘safe’ as essentially I’m using a large blunt flathead screwdriver to pry the cases open using excessive force combined with a light careful touch if that makes sense…
DON’T use a knife to try and run around the seam!!! I have seen several packs where people have tried this and they have actually ended up almost cutting through the actual cells (can show you pics of this if you like as I had some in this batch)
One thing I would suggest though is starting in the area the battery connector is, it’s the weakest point to get it started, plus there’s less risk you’ll accidently go through the casing initially and stab a cell :~ Once you have a leverage opening then slowly (and carefully) work your way around the pack until you can pull the two halves apart. I work around cracking the case open by twisting the screwdriver head, bit by bit.
Once you have it open the cells are normally stuck to the bottom half with double sided tape, I use a plastic ipod opening tool that has no sharp edges to gently work under the cells to lift them, once unstuck the cells and circuit board lift right out.
Then cut away the circuit board (one wire/connection at a time) while being careful not to short the pliers against anything else on the board/battery contacts.
I would suggest you wear eye protection and do this outside given my recent experience lol……
If it’s an HP pack, some of these seem to be plastic welded, with a strip that runs around the side the connector is on, these are really hard to open.