The Dola-Yantra is a purification device. Materials of construction include clay, iron, and stainless steel. In this process a drug is wrapped in banana leaf or a muslin cloth which is then suspended in the yantra by string and stick. Bolus should not contact any surface of the yantra. The liquid suited to the purpose is poured into the yantra until one-half of the muslin bolus (poultice) has been covered. The container is heated from below and as the liquid evaporates the liquid in the yantra is replaced-always keeping the poultice half covered (or the poultice may be lowered, too). Tradition permits covering of the yantra to capture the evaporate and to allow it to fall back into the fluid below. Either process is acceptable. Generally, there is a prescribed period for this cooking, upon completion of which the muslin sack is removed. The contents are water washed and sun dried. Note that the drug in the cloth has been potentiated by cooking in some prescribed herbal mixture. In some respects this resembles the (Skt.;treatment) process done in a Kharal (Skt.; Mortar).