From Jan Meulendijk, Walwyn's Castle, Pembrokeshire, UK
Thomas Patrick Reid wonders whether an object’s density fools our perception of its weight (Letters, 22 June). I sometimes carry bags of cement and of hydrated lime, both with a mass of 25 kilograms. The lime is approximately half as dense, so its bags are twice as large. Against all knowledge to the contrary, I find them much less heavy.
