A Leslie cube is a small hollow metal box with different painted sides. One is bare metal, the others are matt black, gloss black and gloss white.
The cube is filled with water and then heated until it boils.
Using an infrared thermometer we look at the temperatures of the different surfaces. Each is a different temperature as seen in the pictures.
With a burner under the cube the water is heated until it is boiling. and the temperature of each surface is measured.
The bare metal surface came out as 49.3C
The Matt black surface came out as 97.9C
The smooth black surface as 95.9C
And the white surface as 97.0C
There is a difference. The bare metal was cooler by far. Now why might that be?