How to mix Chemicals

[stAtic15]

I have completed the game but I never found out in what order to mix the chemicals. I had the note and all, but still couldn't figure it out, so I just added all the chemicals to the "keypad" and pressed randomly. I got the right potion in a few seconds (and I've done it twice).

1.magnesium
2.calcium
3.barium
4.chloride
5.phosphorus
6.sodium

So in what order is it, really?