This is because Hg is an abbreviation of the Latin name of the element, which was hydrargium. With this name the Greeks were referring to the fact that mercury is a silvery liquid at room temperature, rather than a solid like other metals.
We've looked at the three types of heat transfer. Conduction and convection rely on temperature differences; radiation does, too, but with radiation the absolute temperature is important.
Thermal conductivity-Hence, heat can only be transferred through three means: conduction, convection and radiation. In addition, conduction is perhaps the most common, and occurs regularly in nature. In short, it is the transfer of heat through physical contact.