[IAmBroom]

> I stumbled on reviews with photos showing products that had no mercury inside and actual blobs of mercury stuck to the tip that goes in your mouth.

I played with mercury a bit when I was a kid, as did every kid who could - it was COOL! From that I learned: mercury is almost omniphobic. Oil avoids mixing with water. Mercury avoids mixing with, holding on to, and generally touching anything.

So how could a blob of mercury stick to a glass tip???

Sincere question.

[LorenPechtel]

It's inside the tip.

Bulb of mercury. Fine tube extending up from it. Thermal expansion of the bulb produces a big effect on how far up the tube it goes.

They work. They're safe unless you break them. But they can break.

[noduerme]

In the photo I saw, the tip was metal and had a blob resembling an amalgam on it so it may not have been pure liquid mercury there.