Many herbs and minerals require special purification processes in order for their beneficial properties to be usable and their side effects removed. For purification of herbs, many methods exist including to cleanse, sort, peel, unhusk, polish, strain, filter, distill, or dehydrate the substance. For purification of metals and minerals, complicated and time-consuming processes are necessary like trituration, boiling in milk or cow’s urine, soaking in vinegar, or keeping the substance for a long time in dairy products like buttermilk.
The modern medical pharmaceutical industry requires a range of various chemicals or solvents in its preparations. The Ayurvedic pharmaceutical industry, on the other hand, uses the contact of minerals with heat along with certain purifying herbal substances or juices. The simplest procedure for preparation of medicines in Ayurveda consists of crushing the leaves and taking out the juice of the herb. Complex procedures may involve sequential processes spread over a period of up to thirty years, like the preparation of Abhrak Bhasma (oxide of mica).
Ayurveda does not use heavy metals or minerals without extensive processes to render them fit for human consumption. In this regard, it uses drugs medicinally but in a careful, complex and safe manner. Mercury or gold preparations (rasas), for example, require many physical and subtle chemical processes before their final stage is achieved and they are able to be consumed. Such Ayurvedic drugs do not accumulate in the tissues but are eliminated from the body once their work is done. In this way, Ayurveda can employ the great healing power of minerals while avoiding their side effects. Ayurvedic medicines thus are much more complex than simple herbal or drug preparations. They have an efficacy greater than either, while preserving the benefits of both.
The most important factor in the preparation of an Ayurvedic medicine is Agni, or heat, which transforms the substance so that it can be accepted by the human body and become easily absorbed. Agni is important for bringing about the transformation of qualities required in various pharmaceutical processes. With the help of heat or Agni, many processes like heating, frying, melting, burning, smoking, cleansing, drying, distillation, digestion and oxidation are carried out.
During ancient times, although there was no equipment to measure heat gradations, various grades of heat were specifically described like low, medium, high, very high and extremely high. For these, certain parameters were used like the temperature at which hay burns, at which ammonium chloride melts, or at which borax crystallizes, For controlling temperature at various levels, different heating methods were used like sand bath, water bath, oil bath and sulphur-melting bath. These are still in use today. Various qualities of heat were obtained from different sources like cow dung, sheep dung, horse dung, woods like catechu, coal of different woods, and the husks of rice.
Ayurveda uses elaborate purification procedures to make toxic substances safe for internal usage. Procedures like triturating, contact heating, closed-shell heating, and heating in boiling liquid sulphur also indicate the portion of .the body in which the medicine’s action is likely to take place.
In Khalvi preparations, minerals are triturated with liquid extracts of herbs. A powder of the mineral is placed into a mortar and pestle with the juice of an, herb and it is triturated (stirred in a clockwise motion with the pestle) until completely dry. This is one Bhavana or procedure. Bhavanas are done at least seven times but, in some instances, may occur over a thousand times. Such medicines act mainly on the upper part of the gastrointestinal tract, because the heat applied in this process is nothing but friction between mortar and pestle during trituration. This process of trituration is also the basis for the other preparations that follow.
In Parpati preparations, first Kajjali or “humanized” Rasa (sulphur and mercury) is prepared. Other herbs and minerals are then added one by one and triturated to create Kajjali powder. The components are next heated on an iron plate, which is just hot enough to liquefy the combination. Thel1 the mixture is taken out and put on a banana leaf and allowed to cool. As this process requires more heat than the Khalvi group, these medicines do not break down as quickly. They dissolve in the middle portion of the gastrointestinal tract and therefore act on the small intestine. Hence, medicines to improve absorption are prepared in this manner.
Still further micro-refined products materialize in the process of preparing the Kupipakva group. Kajjali is taken, along with certain medicines triturated in it, put into a glass shell and fired together usually in sand for a period of twenty-four to seventy-two hours. This produces Rasa or, alchemical preparations using Kajjali or humanized mercury-sulphur as a base. Here the heat contact is such that the ingredients must be put into a closed glass shell. The heat applied is much higher than that for the Khalvi group. Two different products result from this process, one at the sublimated portion at the neck of a glass shell or bottle, and ‘the other in the sedimented portion at the bottom.
Even though both these products arise from the same initial ingredients, the substances in the sublimated’ portion and those in the sedimented portion differ in their elemental constituents. Those found in the neck portion act on the lung, heart, and brain, or upper part of the body, while those at the bottom are more compact and act on pelvic organs like the uterus and kidneys and the lower part of the body.
Kupi prepared medicines are refined further, which produces yet a stronger bond between the medicines (sulphur and mercury). In the Pottali group, a sulphur cooking medium is used. The medicines are placed in a cloth bag and immersed in boiling sulphur for up to six hours. Sulphur imparts heat from all sides to the particles of the formula suspended within ii. These drugs are meant for quick action, which may be sublingual. Their action is on deeper tissues and works directly through the brain. The best example is Hemagarbha or purified gold.