ตำรายาของประเทศไทย
Thai Pharmacopoeia
สำนักยาและวัตถุเสพติด กรมวิทยาศาสตร์การแพทย์ กระทรวงสาธารณสุข
Bureau of Drug and Narcotic, Department of Medical Sciences, Ministry of Public Health7.11 WATER-SOLUBLE ASH
Boil the total ash for 5 minutes with 25 ml of water, collect the insoluble matter in a sintered-glass crucible or on an ashless filter paper, wash with hot water and ignite for 15 minutes at a temperature not exceeding 450º. Subtract the weight of the residue from the weight of the ash. The difference in weight is taken to be the water-soluble ash. Calculate the percentage of watersoluble ash with reference to the air-dried drug.