The portion in Susruta Samhita, which explains the preparation and use of alkalies, occupies a prominent place in Indian medical chemistry. It is said that alkalies were used to clean surgical instruments, which were used to cut the diseased parts of human body. (the term СksaraТ itself means Сthat which removes away the affected parts of the bodyТ). Plates of iron, silver and gold were dipped in alkaline liquids before mixing with medicines.
Susruta classifies alkalies into mrdu, tiksna and madhyama. He gives the preparation of each category. Some of them are used for external application and some for internal administration. They are used externally for skin diseases like kusta, tumors, piles etc. and internally for abdominal tumors, indigestion, urinary deposits, intestinal worms etc. devices to store them are also advised. According to him, the sharp, saline taste of alkali when mixed with acid becomes very mild and gives up its sharpness. That is why acid neutralises alkaly.
Different metals like bronze, iron, gold, silver, lead, copper, tin and different salts like rock salt, sea salt etc are enumerated in the Samhita. Roasting of iron and other metals so as to render them fit for internal administration has been described. The thin leaves of metals were plastered with a paste of the salts and afterwards subjected to roasting and were converted into their respective oxides, chlorides or oxichlorides. This can be considered a crude process for the preparation of the metallic salts.
Brhatsamhita (6th Century AD)
Varahamihira, in his Brhatsamhita, refers to mordants like alum and sulphate or iron for the fixing of dyes on textile fabrics. It also alludes to cosmetics, scented hair dyes, perfumes etc. It also contains information on various cement preparations, which may be classified under two heads: rock cement (vajralepa) and metal cement (vajra samghata). These varieties of cement were applied to the walls and roofs of temples and other buildings.
Alchemy in Tantric Period (800 AD to 1600 AD)
The flourishing of chemistry in India, especially alchemy, has an interesting phase during the period of tantra. The tantric cult in India was an admixture of alchemical processes on the one hand and grotesque rites on the other, centred on the worship of Siva and Parvati. We also have a class of tantras, which is an admixture of Buddhist and Saiva cults. Rasaratnakara ascribed to Nagarjuna belongs ato this category. According to tantric cult, a man should preserve his body by means of mercury and medicaments. According to tantrics, mercury was produced by the creative conjunction of Siva and Parvati and mica was produced from Parvati. The combination of mercury and mica was believed to be destructive of death and poverty.
Sarvadarsana Samgraha of Madhavacarya which elaborates the sixteen philosophical systems current in 14th Cent AD, includes raseswara darsana or mercurial system as one among them. According to this darsana, different preparations of mercury can enable a man to be free from old age and death, ie to obtain jivan mukti. Rasa is called parada because, it enables one to overcome the worldly affairs.
Rasarnava (asked in UPSC GS MAINS 2012) of unknown authorship, Rasaratnakara of Nagarjuna and Rasaratna samuchaya of Vagbhata are some of the important works of Indian alchemy written during the tantric period. Rasaratnakara and Rasarnava are tantras pure in which alchemy is incidentally dealt with. Rasaratnasamuchaya is a systematic treatise on pharmacy and medicine. Rasaratnakara of Nagarjuna contains descriptions of alchemical processes and preparations of mercurial compounds. Extraction of zinc, mercury and copper are described by him. He also elaborates on the preparation of crystalline red sulphide of mercury (swarnasindura or makaradhwaja) which is used as medicine for many ailments.
There are also works written in regional languages like Tamil, Telugu, Kannada, Malayalam, Bengali, Marathi, Oriya and Gujarati on alchemy. Here, Tamil works on siddha vaidya, about two hundred in number, deserves mention. Works of Agastya, Nandiswara, Romarshi and Kailasamuni are important among them. A comparative study of the alchemical ideas of these Tamil and Sanskrit works has not yet been initiated.
According to tantric cult, siddhis are of two types - dehasiddhi (development of the body) and loha siddhi (development of metals).
- The first pertains to making mercury capable of changing the molecules of lower metals into molecules of higher metals. Mercury, which is capable of this, can certainly transform human molecules also. This is dehasiddhi.
- Lohasiddhi is called alchemy or dhatuvada. Dehasiddhi is obtained through lohasiddhi. Gradually, devices to refine metals led to the making of their powders, which were used as medicines.
As part of these alchemical processes, there are certain methods to purify mercury. Indian alchemists had adopted 18 methods for this purpose. They also make classification of chemical substances into maharasa, uparasa, datu, ratna and visa. Certain refining processes of metals and mine products, mixtures of mercury also deserve special mention.
An important feature of Indian alchemy is the description of certain plants used in alchemical processes. About two hundred plants are referred to in this connection. We get an elaborate description of the laboratories and the instruments from these alchemical works.