AMOUNTS OF BOUND AND FREE WATER IN AN ORGANIC COLLOID AT DIFFERENT DEGREES OF HYDRATION

Abstract

Calorimetric determinations were made in the stipe of the Elk kelp, Pelagophycus porra, at hydrations of 30-1015%. At 30% hydration, 0.283 gm. of water (95.83%) was bound per gm. of dry material. As the hydration was increased the amounts of both bound and free water per gm. of dry material showed consistent increases, the bound water increasing more rapidly than the free water, until a hydration of 156.6% was reached, when the amounts of bound and free water were approximately equal. Above this hydration the amt. of free water per gm. of dry material increased more rapidly than the amt. of bound water per gm. of dry material but both showed continuous increases until a hydration of 1015% was reached. This represents nearly the max. hydration for this material. At this hydration 3.305 gms. of water (32.52%) were bound per gm. of dry kelp. These values indicate that the proportion of dry material in a colloidal system is a factor which greatly affects the weight of water bound per gm. of dry material.