• Tin plate box - 13cm sides
• Top opening fitted with a stopper

Tin plate box with 130 mm sides. The vertical faces of the box areblackened, roughened, varnished and polished respectively. The top openin is fitted with a stopper. The apparatusis filled with water maintained at boiling point by a low bunsen flame Infrred sensors may be used to compare the relative radiant heatoutput from each of the four faces.