AbstractThio‐compound collectors and frothers produce, in aqueous solution, a smaller lowering of surface tension than other collectors. the surface tension of a solution of a collector‐frother mixture is intermediate between those of the individual reagent solutions, when the concentrations of both are in the vicinity of surface saturation, but when the mixture solution is very dilute, the lowering of the surface tension may be equal to the sum of the lowerings due to both reagents.