[bobqu]

Hi All!
I have broken a thermometer and I don't know whether it is a mercury one or gallium one. This is how it looks like. It sticks to glass but not easily had to smudge it few times. My guts says it is gallium one... but just to sleep calmly I want double check with you all. Picture in attachment.

Thanks for help in advance!

[Orcio_87]

Try adding few drops of HCl. Galinstan (alloy of gallium, indium and tin) should react and H₂ should be visible. Mercury does not react with HCl.