Allttxx~gl~ numerous methods have been clevelopcd for the determination of water and other vapors or gases by sorption on solids, it is frequently supposed that the apparatus required for sorption measurements is too complex for ordinary laboratory use. A simple method is described here for the determinatjon of water by sorption on a desiccant, using a modified &%dhIN' sorption balance. The apparatus is sketched in Fig. I. A helical silica spring (100 mg total capacity; sensitivity, approximately o&j mm/m6obtained from Worden Laboratory, Houston, Texas) is suspended from the glass hook, A, attached to the inside of the standard taper cap, I3, Approximutely 30 mg of desiccant are contained in the aluminum foil bucket, C.
To operate the apparatus, the system is first evacuated through the three-wa3 vacuum stopcock, 1.. By means of a cathetomctcr, the blackened tip of the hook, E, is observed until it remains stationary, and its height is recorded, With the stopcock closed, a liquid sample is introduced through the valve, I;, using a graduated pip&. The valve consists of a medium-porosity sintercd glass disc covered with