APPARATUS AND MACHINES, NAMELY, MASS-EXCHANGE PLATES FOR USE IN THE CHEMICAL INDUSTRY FOR EXCHANGE OF COMPONENTS BETWEEN TWO OR MORE PHASES IN WHICH THE PLATES CONTROL THE CONTACT TIME BETWEEN ONE PHASE AND ANOTHER, RECTIFICATION PLATES FOR USE IN THE CHEMICAL INDUSTRY FOR SEPARATION OF COMPONENTS OF A MIXTURE IN WHICH THE PLATES CONTROL THE CONTACT TIME BETWEEN PHASES OR BETWEEN A COMPONENT TO BE SEPARATED AND THE MIXTURE; AND COLUMNS FOR MASS-EXCHANGE OR RECTIFICATION AND FOR USE IN THE CHE...