THE WATER SORPTION ISOTHERMS OF CANE (ARU NDO-DONAX L) USED FOR REEDSOF WOODWIND INSTRUMENTS

The water sorption isotherms of cane (Arundo donax L,.), before and af ter water extraction, and isolated extractives were obtained. The equi librium moisture content of cane before extraction was less at relativ e humidities below 40% and larger at those above 50% than that after e xtraction. The extractives scarcely adsorbed water at small relative h umidities, but much at large humidities. The fiber saturation point of cane before extraciton was estimated to be above 35%, whereas that af ter extraction was 21%. By applying the Hailwood-Horrobin's equation t o the isotherms of cane, the hydrated and dissolved waters were separa ted. After extraction, the amount of the hydrated water increased, and that of the dissolved water decreased. This result showed that the ex tractives adsorbed most of water in the from of dissolved water. The i sotherms of the extractives in cane was compared with those of the iso lated one. Both the equilibrium moisture contents were almost the same at small relative humidities, but those of the extractives in cane wa s less at above 50%, especially above 80%. This fact showed that the w ater adsorption of the extractives existing in the cell walls was rest rained.