12 CORRUGATED PAPER IN SHEET FORM THAT HAS BEEN HARDENED AND STRENGTHENED BY IMPREGNATION WITH AN INTROFYING AGENT SUCH AS SULPHUR, THE SAME BEING USED BY VIRTUE OF ITS STURDINESS AS A RAW MATERIAL FOR THE BUILDING TRADES, FOR THE CONSTRUCTION OF STIFF-WALLED CONTAINERS,FOR RIGID PARTITIONS, DIVIDERS, ETC