Measurement of calcium ion suppression by protection of foam of sodium cetyl sulfate solutions

Abstract

Summary Relative protection of various compounds against calcium salts was determined by a pour‐foam test, using sodium cetyl sulfate as a foam‐producing indicator. The sensitivity of the test corresponds to less than 2 p.p.m. of calcium salt. Some of the data are compared with similar tests, using sodium oleate as an indicator, and advantages of the cetyl sulfate test are noted. The test is discussed from the point of view of a competition for calcium ion by the cetyl sulfate anion to precipitate calcium cetyl sulfate and by the compound tested to precipitate a calcium salt or form complex calcium ions. On the basis of the equilibria involved an estimate is made of the approximate solubility of calcium cetyl sulfate in the salt solutions tested.