Abstract
The surface tensions of 1,16-hexadecane disodium sulphate in 0.001, 0.2 and 1.0M l.−1 sodium chloride solutions have been determined by the Wilhelmy plate method. Considerable ageing effects were noted. The minimum molecular areas calculated were 95, 88 and 86 sq. Å respectively in the three salt solutions. The lowering of the surface tension was not as great as that caused by sodium dodecyl sulphate, and the hydrocarbon chain linking the two head groups in 1,16-hexadecane disodium sulphate appeared to prevent very close packing in the surface layer.