Weigh a specimen from 8.1.5 of approximately 2 g to the nearest 0.001 g (A)in a tared weighing bottle.Dry for 2 h in an oven at 105+3c , cool in a desiccator,replace stopper,and open the stopper momentarily to equalize the air pressure and weigh.Return bottle to the oven for 1 h;repeat the cooling and weighing as above for successive hourly periods unit constant weigh (B) is reachhed,that is,until successive weighings do not change by more than 0.002 g.