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110<br />
like gold, silver, zinc, copper, arsenic, were also used, as well as<br />
various acids.<br />
An important tantric treatise, Rasaratnakara, ascribed to<br />
Nagarjuna (c. AD 800) is a repository of much chemical<br />
information and many alchemical recipes. The text provides<br />
valuable information about the various preparations of mercury,<br />
including red crystalline sulphide of mercury, and techniques for<br />
extracting mercury and zinc from zinc ore. It also describes more<br />
than two dozen apparatuses for experiments in physico-chemical<br />
processes. Another significant tantric treatise, Rasarnava (AD 1200)<br />
has important information on chemistry and is a direct precursor<br />
of iatrochemistry. An elaborate description of the location,<br />
construction and equipment of chemical laboratories is available in<br />
Rasaratna-samuccaya, an iatrochemical treatise of the 13 th century.<br />
A later work, Rasasara (whose name literally means 'sea of<br />
mercury'), is a purely chemical work and describes eighteen<br />
mercurial processes.<br />
Several special operations involving mercury and examples of<br />
chemical composition and decomposition, by processes of<br />
calcination, distillation, sublimation, steaming, fixation, and so on,<br />
were elaborately discussed in the texts devoted to alchemy and<br />
chemistry, as also were various metallurgical processes -<br />
extraction, purification, killing, calcination, incineration, powdering,<br />
solution, precipitation, rinsing or washing, drying, steaming,<br />
melting, casting, filling. Here is a typical example of a recipe, for a<br />
mercury potion, and the apparatus for reducing it to ashes:<br />
Mercury is to be rubbed with its equal weight of gold and then [the<br />
amalgam] further admixed with sulphur, borax, etc. The mixture is then<br />
to be transferred to a crucible and its lid put on, and then submitted to<br />
gentle roasting. By partaking of this elixir [i.e., the sublimate] the devotee<br />
acquires a body not liable to decay. . . . [The apparatus, the Garbha-<br />
Yantram, is described thus:] Make a clay crucible, 4 digits in length and 3<br />
digits in width, with the mouth rounded. Take 20 parts of salt and one of<br />
bedellium and pound them finely, adding water frequently; smear the<br />
crucible with this mixture. Make a fire of paddy husks and apply gentle<br />
heat.<br />
One text speaks of 'killed mercury':<br />
When the mercury assumes colours after having given up its fluidity, it is<br />
known as 'swooned'. Killed mercury is that which does not show signs of<br />
fluidity, mobility or lustre. When the quicksilver, which has acquired the<br />
colour and the lustre of the rising sun, stands the test of fire [i.e., is not<br />
readily volatilized], then it to be regarded as fixed. (Rasaratnakara of<br />
Nagarjuna.)