An Apparatus for Thermometric Determination of the Activity of Water in Solutions and in Biological Fluids

Abstract

An apparatus for thermometric determination of the activity of water in solutions and in biological fluids is described, based on measurement of the temperature differences between the solutions or fluids and water suspended on thermistors in a saturated gas phase with forced convection. Thc precision and accuracy of the equipment is evaluated by determining the activity of water in sodium chloride solutions. The ratio between the measured temperature differences and the differences of the activity of water in these solutions was in this study found to be constant, extending the rangc of concentration in which Raoult's law is valid.

Key Words:

• Chemistry, physical
• electronics
• heat
• partial pressure
• temperature
• thermodynamics
• water
• water-electrolyte-balance