将肥皂溶解在乙醇中，过滤，并称量未溶解的残渣。未溶解的成分对应于添加剂和杂质，低溶解度或不溶于95%（V/V）乙醇，添加到肥皂中，以及添加到所有肥皂配方中的物质，如碱碳酸盐和氯化物、硼酸盐、过硼酸盐、超磷酸盐、硅酸盐、磷酸盐等。它也可能由淀粉、糊精、酪蛋白、糖等有机物质组成，纤维素衍生物、褐藻酸盐等。

The soap is dissolved in ethanol, filtrated and the undissolved residue is weighed. The constituents not dissolved correspond to the additives and foreign matter, of low solubility or insolubility in 95 % (V/V) ethanol, added to soaps and also to substances in all soap formulations, such as alkali carbonates and chlorides, borates, perborates, suphates, silicates, phosphates etc. It also may consist of organic substances like starches, dextrins, caseins, sugars, cellulose derivatives, alginates, etc.