Studies on the spreading of certain substances on a clean surface of water—Part I

Motion and Dissolution of Drops of Sparingly Soluble Alcohols on Water

“…The dish diameter-to-depth ratio does not appear to be important for the small drops employed here. Ramdas likewise found that the dissolution times for camphor did not depend on the depth of the water bath …”

“…Under these conditions, the concentration of alcohol at the surface will vary with time as: d c d t = D ∇ 2 c − α false( c max − c a false) where α is a constant that reflects the dissolution rate. We further assume that the flux of alcohol from the perimeter of the lens is proportional to the alcohol activity at the perimeter (assumed to be unity) and yields a constant flux per unit perimeter length. ,, The steady-state solutions to eq in the limit of large dishes yield concentration gradients, evaluated at the perimeter of the drop, of the form d c d r = false( c max − c a false) true( α D true) K 1 true( α D R true) K 0 true( α D R true) where R is the lens radius and K 0 and K 1 are zero- and first-order modified Bessel functions.…”

“…In this work, we examine the behavior of small drops (typically 10 μL) of alcohols with modest chain lengths (4 ≤ n < 9, where n is the number of carbon atoms), which show vigorous activity on pure water. – This activity is often similar to the “camphor dance” ,, displayed by pieces of camphor where they spin and dart across a water surface.…”