The Materia Medica of the Hindus, compiled from Sanskrit Medical Works c4.s4.36

c4.s4.36

For the sublimation of metals and metalic preparations, two sorts of apparatus are used. The first, called उर्द्धपातनयन्त्र *Urddha-pátana yantra*, consists of two earthen pots placed one above the other with their rims luted together with clay. The lower pot containing the medicine is put on fire while the upper one is kept cool with wet rags. The sublimate is deposited in the interior of the upper pot. Sometimes the lower pot is covered with a concave dish and water poured into its hollow to keep it cool and changed as often as it gets hot. The second plan consists in placing the medicines to be sublimed in the bottom of a glass bottle which has been strengthened with layers of clay and cloth wrapped round it, and then exposing it to heat in a sand-bath. The sublimate is deposited in the neck of the bottle, whence it is extracted by breaking the latter.