CHEMICAL PRODUCTS FOR REMOVING HYDROGEN SULPHIDE FROM GASES FOR USE IN THE PURIFICATION OF NATURAL GAS, COKE OVEN GAS, GAS FROM COAL GASIFICATION, SEWER GAS, SYNTHESIS GAS, CARBON DIOXIDE RECYCLE GAS FROM ENHANCED OIL RECOVERY, WASTE GAS AND WASTE AIR FROM CELLULOSE AND VISCOSE PLANTS, GAS PROCESSING PLANTS, REFINERY OFF-GASES AND THE LIKE