When sulphur to which after recrystallisation no air has had access is melted, or when ammonia is led for a few minutes through ordinary sulphur after it has been melted, the two forms of liquid sulphur (yellow, mobile Sλ, and brown, viscous Sμ) adjust themselves very rapidly to those proportions which are in equilibrium at that temperature to which the liquid may have been raised. The adjustment occupies but a few moments. When specimens thus prepared are then chilled by plunging into water, the reversion of the Sμ to Sλ is equally rapid, and therefore the product is wholly brittle, crystalline, monoclinic sulphur. This behaviour is observed whether the liquid has been heated at, say, 155°, where the amount of Sμ, at equilibrium is 7·2 per cent., or at 448°, where the amount is at least 34 per cent.