Water content of saliva dried at various humidities.

Abstract

IN calculations relating to the aerial bactericidal action of certain α-hydroxy acids, it was noted that the calculated rates of diffusion of these acids into air-suspended salivary particles, when plotted against the water content of the particles, did not appear to extrapolate to the expected diffusion-rate in pure water at 100 per cent water content1. It was suggested that this might be due to the formation of a shell of dried material on the outside of the particles so that the water content of the particle as a whole, some minutes after its formation, exceeded that of the outer layers, the estimated diffusion-rates being largely determined by the water content of these layers. Measurements of the equilibrium water content of saliva dried at various relative humidities confirm that, at relative humidities greater than 50 per cent, the water content of the salivary particles some minutes after their formation exceeds the equilibrium value.