During the transport of <i>objets d'art in closed containers, the atmosphere inside the containers may undergo large changes in humidity resulting from changes in the surrounding temperature. This paper describes a method used to lessen these changes in the containers used for the recent travelling exhibition of Japanese art. Kaken gel, a drying agent similar to silica gel but for this purpose slightly superior, was placed in the containers. The Kaken gel had originally been brought into equilibrium with the humidity which it was desired to maintain in the containers. A formula is given for calculating the quantity of Kaken gel necessary to limit changes in humidity.