Concentrated formaldehyde solution

Claim 1

IN THE ABSORPTION OF FORMALDEHYDE, THE PROCESS WHICH COMPRISES PASSING FORMALDEHYDE IN GASEOUS FORM UPWARDLY THROUGH AND IN INTIMATE CONTACT WITH A SOLUTION OF A FORMALDEHYDE ACCEPTOR SELECTED FROM THE GROUP CONSISTING OF UREA AND MELAMINE AND DISSOLVED IN A WATER-ALCOHOL MEDIUM, THE ALCOHOL BEING WATER SOLUBLE AND OF BOILING POINT LOWER THAN WATER AND THE SAID SOLUTION DESCENDING IN A COLUMN UNDER FRACTIONATING CONDITIONS COUNTERCURRENT TO THE UPWARDLY RISING FORMALDEHYDE, MAINTAINING THE PROPORTION OF THE SELECTED ALCOHOL HIGHER THAN THAT OF THE WATER IN THE UPPER PART OF THE COLUMN AND BELOW THAT OF THE WATER IN THE LOWER PART OF THE COLUMN, HEATING THE SAID COLUMN AT A LOWER PART THEREOF AND MAINTAINING THE SAID MEDIUM AT THE TOP OF THE COLUMN AT ABOUT THE TEMPERATURE OF REFLUXING FOR THE SAID ALCOHOL AND AT THE BOTTOM OF THE COLUMN AT A POINT BETWEEN THE SAID TEMPERATURE AND THE BOILING POINT OF THE WATER IN THE SOLUTION AT THAT LEVEL, CONTINUING THE PASSING OF THE FORMALDEHYDE THROUGH THE ACCEPTOR SOLUTION AND THE SAID HEATING SO THAT A CONCENTRATED FORMALDEHYDE-ACCEPTOR SOLUTION RESULTING FROM THE ACTION OF THE FORMALDEHYDE ON THE ACCEPTOR COLLECTS IN THE LOWER PART OF THE COLUMN AND THE ALCOHOL BECOMES CONCENTRATED IN THE UPPER PART OF THE COLUMN, WITHDRAWING THE CONCENTRATED SOLUTION FROM THE SAID LOWER PART AND THE ALCOHOL IN VAPOR FORM FROM THE UPPER PART OF THE COLUMN, AND SUPPLYING TO THE SAID COLUMN ADDITIONAL AMOUNTS OF THE ACCEPTOR AS REQUIRED FOR ACCEPTING THE FORMALDEHYDE, THE ACCEPTOR BEING INTRODUCED AT A POSITION ABOVE THAT OF INTRODUCTION OF THE GASEOUS FORMALDEHYDE.