1. A PROCESS FOR THE PREPARATION OF WATER-SOLUBLE SALTS SELECTED FROM THE GROUP CONSISTING OF METAL AND AMMONIUM SULFATES, PHOSPHATES AND NITRATES, COMPRISING REACTING THE CORRESPONDING CHLORIDES WITH AN ACID SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF FREE SULFURIC, PHOSPHORIC AND NITRIC ACIDS, ACID SULFATES AND ACID PHOSPHATES, BY PREPARING AN INITAL AQUEOUS SOLUTION CONTAINING THE CHLORIDE AND THE ACID SUBSTANCE USED AS REACTANT, IN WHICH SOLUTION THE IONS PRESENT ARE IN A STATE OF EQUILIBRIUM; CAUSING DISPLACEMENT OF SAID EQUILIBRIUM BY EXTRACTING SAID INITIAL SOLUTION WITH A SOLVENT SELECTED FROM THE GROUP CONSISTING OF ALIPHATIC MONOHYDRIC ALCOHOLS HAVING 4-5 CARBON ATOMS, AND BEING OF LIMITED MUTUAL MISCIBILITY WITH WATER, IN ORDER TO EXTRACT HYDROCHLORIC ACID FROM THE AQUEOUS SOLUTION AND TO PRODUCE AN EQUIVALENT AMOUNT OF DESIRED PRODUCT; SAID EXTRACTION BEING CARRIED OUT AT A TEMPERATURE BELOW BOILING TEMPERATURE OF THE AQUEOUS SOLUTION AND OF THE SOLVENT USED FOR EXTRACTION; SEPARATING THE AQUEOUS SOLUTION AND SOLVENT EXTRACT FROM EACH OTHER; KEEPING THE AQUEOUS SOLUTION AT A TEMPERATURE AT WHICH DESIRED PRODUCT SEPARATED AS A SOLID PHASE FROM THE AQUEOUS PHASE; SEPARATING THIS SOLID PHASE FROM THE AQUEOUS SOLUTION; RESTORING THE INITIAL COMPOSITION OF THE AQUEOUS SOLUTION BY ADDITION OF SALT AND ACID THERETO, THE RESTORED AQUEOUS SOLUTION BEING THEN TREATED AGAIN BY SOLVENT EXTRACTION IN ORDER TO BRING ABOUT FURTHER FORMATION OF DESIRED PRODUCT.