Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic. But it is not those differences between us that are separating us. It also served as a metaphor for the barriers separating different classes of society. It is spoken by separating a word into syllables and reversing the syllables. Different techniques exist for separating out the wavelengths. Wind winnowing is an agricultural method developed by ancient cultures for separating grain from straw. A plastic still is a device for distillation specially adapted for separating ethanol and water. It allows the cheese to melt without becoming greasy by stopping the fats from separating. Azeotropes are useful in separating zeotropic mixtures. They had two sons together before separating in 1971 and divorcing in 1973. The main problem has been separating oxygen from the air. This was one of his solutions for separating the populations. The Curies undertook the arduous task of separating out radium salt by differential crystallization. In the Western world there are centuries of tradition for separating pharmacists from physicians. Goldwater responded by accusing Rockefeller of blurring the line separating the Republican and Democratic parties.