Abstract
In recent simulated diving experiments, subjects have experienced intense itching, confluent maculopapular skin lesions and a severe vestibular derangement with vertigo and nystagmus. These effects have been observed when a gas mixture containing nitrogen or neon is being breathed while a second inert gas, helium, is present in the surrounding environment. Attempts to explain this phenomenon led to a study of counterdiffusion through two-layer composites. When the two layers differ in their relative permeabilities to the two diffusing species, and when the layers are arranged in the proper sequence in a counterdiffusion system, a steady-state supersaturation results within the two layers. Bubble formation in an oil-water system and continual flow of gas into an intermembrane space in a two-membrane system are demonstrated experimentally: both effects were predicted from diffusion theory. In addition to providing a possible explanation for the itching phenomenon and vestibular derangement, the theory has a wide range of applications to physical and biological processes.