Reasons for using mercury as a thermometric liquid

Mercury

1. Mercury is opaque and a shining substance. It can be easily seen through glass.

2. Mercury has a uniform rate of thermal expansion.

3. Mercury is a good conductor of heat.

4. Mercury does not wet to the glass.

5. Mercury has a high boiling point  (357 °C)  and a low melting point (-39 °C), so that both high and low temperatures can be measure it.

6. Mercury quickly assumes the temperature of the object in contact with it by taking the least amount of heat.