Two temperature on the Kelvin scale are to each other as the heats trasnferred between the same two reversible adiabatic surfaces at these two temperatures.

• 上式说明凯式温度的定义是与在等温面上一等温过程由一可逆绝热面转换至令一个可逆绝热面所吸收之热量有关。由此定义的凯式温标与物质的特性无关。