72 hours and a polypropylene oil adsorbent became submerged after 78 hours in a ratio of 1 4 1 10 table 4______________________________________mat time to complete time to finish ratio of submergenceno submergence hr of the test hr of the maps tested______________________________________a 28b 30c 78 about 9 10d 75e 78 about 3 4f 78 about 1 2g 78 about 1 10______________________________________ the above data indicate that the mat g produced according to the method of the present invention i e a mat made of grass peat fibers for which 4 of paraffin and 0 5 of a carboxyl modified mbr have been used has a floatability of at least 78 hours as a result of wave resistance test and that the mat is equivalent in floatability and wave resistance to a commercially available polypropylene mat an oil adsorbent designated as mat g in example 3 and produced from grass peat fibers according to the method described in example 2 was subjected to the tests a and b stipulated in article 33 2 par 2 no 3 of the marine pollution inhibition law enforcement rules enforced since july 13th 1974 in accordance with the method remarked in the annexed notes of the above enforcement rules a result of the tests for the amounts of water and oil adsorbed was as shown in table 5 table 5______________________________________1 apparent specific gravity 0 08.