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History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c36: Book Xi. On the Purification of Mercury

History of Chemistry in Ancient and Medieval India, Incorporating the History of Hindu Chemistry by Acharya Prafulla Chandra Ray c36

Language
English

Contents

Book Xi. On the Purification of Mercury

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I am now going to describe the various processes for the purification of mercury after having consulted Rasarnava and other works. 10

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There are three natural impurities in quicksilver, *visha* (poison), *vahni* (fire) and *mala* (dirt, dregs), and two artificial, due to its being alloyed with lead and tin. 14-15

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[In Rasendrachintamani also we find; "Trades-people fraudulently adulterate quicksilver with lead and tin, hence it is to be freed from these artificial defects or impurities by means of three distillations".]

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Hence for the purification of mercury, the operations (named below) are to be undertaken with the aid of appliances and skilled assistants. 20

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On an auspicious day and under the influence of a benign star, a quantity of mercury weighing 2000 or 1000 or 100 or 18 or 10 *palas* is to be taken and the operation begun. 21-22

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*Pātanavidhi*.—Purification of mercury by distillation. 33

Fixation of Mercury

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*Rasabandha*:—Processes for destroying the fluidity of mercury :.

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Take mercury and one-fourth its weight of *killed* gold and with the addition of sulphur make a ball. Now add an equal weight of sulphur and roast the mass in a covered crucible. 72

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The mercury thus treated is afterwards killed with six times its weight of sulphur. 73

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[The shining reddish-brown crystalline sublimate of sulphide of mercury thus obtained is a favourite and frequently used remedy with the Hindu physicians It is reputed to be a panacea for a variety of ills that human flesh is heir to. In the Rasendrachintamani and Rasendrasarasamgraha and other treatises, this preparation is described as *makaradhvaja* and *rasasindura* (lit. minium like mercury). From the supposed presence of gold it is often named *svarnasindura* (lit gold and vermilion). During sublimation, the gold, of course, is left behind. The general belief is that by association with gold the mercury acquires the most potent efficacy. A later work, Rasapradipa, is sceptical about the part which gold plays and recommends its being left out.]

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Incineration of Mercury

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(The chapter concludes with certain recipes for the *killing* of mercury, with the aid of purely vegetable products)

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Mercury, roasted in a covered crucible with asafoetida, which has been previously digested in the milky juice of *Ficus oppositifolia*, is reduced to ashes 111

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*Andropogon serratus* and *Clitoria ternatea* are to be pounded in a mortar with sour gruel and with the paste thus formed, mercury is to be triturated and digested seven times and finally roasted in a covered crucible after addition of fresh quantities of the above paste. The mercury is reduced to ashes, resembling salt. 112-113

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The seeds of *Achyranthes aspera* and *Ricinus communis* are to be pounded together The mercury is to be placed inside the powder and the mass roasted as before. The mercury is reduced to ashes. 114

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Purified mercury is to be preserved in the hollow of a horn or tooth or of bamboo. 119

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Here ends Chapter XI of Rasaratnasamuchchaya which treats of the purification, fixation and incineration of mercury.

Chemistry in Rasarajalakshmi of Vishnudeva.

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It gives an account of common *rasas* and *uparasas*

Chemistry in Rasanakshatramalika of Mathanasimha

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There are several prescriptions given in this work in which mineral preparations play a conspicuous part. In the Sanskrit texts two such have been quoted. In the first, among other ingredients, opium occurs; in the second, the Svachchhandabhairavarasa, probably named after the celebrated alchemist, we have the calces of tin, iron and mercury along with other drugs

Chemistry in Rasaratnakara of Nityanatha.

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*Test for killed mercury*—When the substance, being heated over a fire of paddy husks, remains unaltered in weight, it should be considered as reduced to a calx

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Purified mercury should be stored in the hollow of a tooth or horn or bamboo

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Directions for making factitious cinnabar (*makaradhvaja*) are here given.

Chemistry in Dhaturatnamala.

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In the beginning the author after salutation says: "I shall speak of silver, gold, copper, lead, tin and iron; as also of calamine, mica, pearls, coral, orpiment, realgar, the pyrites, mercury and diamonds, in fact, the properties of all the metals and minerals and the mode of their incineration "

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Directions are given for the *killing* of silver.

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Chemistry in Rasapradipa

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Description for preparing mineral acids by distillation :—*Samkhadravarasa* or liquid for dissolving conch-shells ; this is to be prepared by distilling a mixture of alum, sal-ammoniac, saltpetre and sulphur. Cowrie-shells and metals dropped into the liquid are at once dissolved.

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Preparation of calomel for the treatment of *phirangaroga* (syphilis) with its application.

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Chemistry in Dhatukriya or Dhatumanjari (Rudrayamala Tantra)

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Tin, iron and copper are to be classed among the superior metals

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In general a metal being alloyed with silver is improved in quality. *Sattvaja* metal (i.e. an alloy of tin and copper) is of middle quality. 12-14

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Couplets 39-49 give synonyms of the different metals.

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Synonyms of zinc :—*Jasatva*, *yasadayaka*, *rupyabhrata* (lit. brother to silver), *charmaka*, *kharpara*, *rasaka*, etc. 50-51

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*Pittal* is an alloy of copper and zinc. 63

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*Kamsyaka* is an alloy of tin and copper. 65

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Zinc being amalgamated with mercury gives rise to *rasaka*. 68

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[N.B.—*Rasaka* and *kharpara* are the names generally applied to the mineral calamine, but here they stand for the metal zinc or its amalgam.]

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Lead being *killed* with the aid of gentle heat gives rise to minium (red lead). 69

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Copper in combination with the "burning water" gives rise to *tuttha* (blue vitriol). Thus manifold operations are performed with the aid of *mantras* and apparatus: all these belong to the province of chemistry. 70-71

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Synonyms of *haritāla* (orpiment):—Orpiment is a consumer of mercury and also a clipper of its wings 79

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[Mercury, being rubbed and gently heated with orpiment or sulphide of arsenic, is itself converted into its sulphide. It is thereby *killed* or *fixed*, i.e. loses its volatility or clipped of its wings.]

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Synonyms of realgar, cinnabar, mica, etc. are given. 81-89

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Synonyms of pearl, coral, tortoise-shell, conch-shell, tusk of elephants, the tail of the peacock are given.

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Commonplace information about the localities of different metals.

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Localities for copper specified:—Nepal, Kamarupa, Bengal, the country of the *mlechchhas*, Ruma and the country of the *phirangas*, etc.

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Localities for zinc—Kamboja, Ruma (Istambul), Balkh etc. 146

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Metals in combination with mercury and sulphur become fit for administration as medicine. 153

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Process of roasting a substance in a stout glass vessel using goat- and cow-dung cakes and husks of paddy grains as fuel, is described. 9-10

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One part of gold and four parts of zinc are to be melted together and the alloy roasted in a closed crucible.....the process repeated with the addition of alkalies.....gold of a reddish-yellow colour will thus be generated. 11-17

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A process for making factitious cinnabar by pouring mercury into its own weight of molten sulphur and then adding three-fourths its weight of orpiment.....The mass is to be rubbed in a mortar and subjected to sublimation. 28-30

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By using the augmented (weight increased by the addition of inferior metals) gold as a means of exchange one can amass wealth. 52

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Tin is to be melted and one-hundredth part its weight of mercury to be amalgamated with it. This (fraudulent substitute for) silver can be used for purposes of exchange, and one can thus amass wealth. 85-86

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Pure gold is to be alloyed with one hundred times its weight of copper and this (imitation) gold will resemble native gold. 88

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Lead and copper being alloyed together will give rise to gold. 97-98

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Here ends the chapter on the extolling of gold in Rudra-yamala.

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Chemistry in Suvarnatantra or Svarnatantra

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The origin of the Tantra is explained in the opening lines. Parasurama having given away his worldly possessions to Kasyapa is rendered destitute, and thus has to invoke the aid of the god Siva for his very maintenance.

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Siva said: Listen! I shall now reveal to you the most wonderful mysteries of Svarnatantra. 1-10

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A kind of oil is exuded from the bulbous root of a plant; all around it within a radius of ten cubits oily water is exuded and a venomous snake lives under it. If you want to test the properties of the bulb, you should thrust a needle into it, and the needle at once dissolves. Having procured this bulb, rub it with mercury in a mortar and add the oil and subject the mixture to heat in a crucible. The mercury is at once *killed* and acquires the property of converting one hundred thousand times its own weight of the base metal into gold. 14-18

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Pure orpiment is to be rubbed with this oil for 20 days, and the former is *killed* thereby and losses its volatility. The eight metals in the molten state being treated with this prepared orpiment acquire the power of transmutation. When the above oil is thrown into molten copper, it is turned into gold of beautiful lustre Tin and bell-metal similarly treated are turned into silver ; and copper, iron, brass and silver similarly turn into gold. 19-24

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*Śaṅkhadrāvaka* (aqua regia) is spoken of as universal solvent ..... The solvent with mercury is to be placed in a glazed crucible and subjected to heat ; the mercury, thus *killed*, can convert the eight metals into gold. By partaking of this mercury one becomes immortal ; even his urine and faeces can convert copper into gold 1-10

Minerals

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*Diamond* :—Belief in the combustibility of diamond and in its being *killed* or reduced to fine ashes, as has been already referred to (*cf.* Rasaratnasamuchchaya, Book IV. The Gems; p. 178), was an accepted creed with the Hindu Iatrochemists.

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*Vaikranta*.—It is described to possess eight faces and six angles and to exhibit a great range of colours. This possibly refers to a mineral crystallizing in the octahedral form, viz., the family of spinels, or to one crystallizing in hexagonal prisms like corrundum. But neither of these minerals are liquefiable as stated in Rasaratnasamuchchaya (The Gems, loc cit.).

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*Makshikam* (pyrites) :—Pyrites is of two kinds: golden and silvery; FeS₂ is brass yellow in colour, but there are other pyrites-like minerals which are silver-white; for instance, cobaltite, CoS₂.CoAs₂; lollingite, FeAs₂ (S); leucopyrite, Fe₃ As₄. Copper pyrites has a deep yellow colour.

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*Gairika*.—Haematite, which is red and often hard, and limonite, which is yellow or brown; both occur in the form of ochres.

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*Kankushtham* is produced at the foot of the Himalayas. It is of white and yellow colour, and is a strong purgative. Possibly an efflorescence of magnesium sulphate or sodium sulphate; both are not uncommon. The yellow colour might be due to admixture with ferruginous dirt.

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*Vajram* :—The mention of 8 faces and 6 corners seems to suggest an octahedral crystal of diamond

Gems

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Among the sixty-four branches of arts and sciences recognized in the ancient Kamasutra of Vatsayana* (5th century A D) occur the following: (a) testing of gold and the gems, (b) knowledge of the colouring of gems; as also knowledge of mines and quarries. Varahamihira (6th century A.D) in his Vrihat Samhita, as already stated, conveys much useful informations on the subject, and refers in his turn to experts who preceded him

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The Garudapurana (circa 9th century A.D)* under the heading of *Ratnapariksha* (examination of the gems) devotes several chapters to a detailed and exhaustive description of the gems.

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From time immemorial the gems have been valued in India not only for purely decorative and ornamental purposes, but also as agents for warding off perils and the malignant influences of the planets, and for securing luck and longevity Hence, particular attention is paid to the testing of gems, as their virtue increases in proportion as they are faultless and flawless.

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The typical characters which, according to Garudapurana, are most relied upon for differentiating one species of gem from another are (1) the relative weight, (2) hardness, (3) lustre, transparency and colour, (4) fusibility, specially when heated in combination with alkalies

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1. *Relative Weight.*—The principle of Archimedes being evidently unknown among the Hindus, the measurement of volume could only be roughly approximate Thus it is stated that a stone may be of the same species as, and equal in volume to, a *padmaraga* (oriental ruby), but will differ in weight from the latter. Empirical and arbitrary scales of weight were adopted as standards. A ruby occupying the volume of a *gunja* (*Abrus precatorius*) may be equal in weight to 10, 7 and 3 *gunjas* respectively. In each case the gem which is of greater weight is superior in quality, and the value thereof is enhanced in proportion.

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In the case of precious metals, however, adulteration was detected by an ingenious device, which may be regarded as a near approach to the principle of Archimedes, Thus, for testing the purity of gold the following instruction is given by Garuda. A wire of gold to be tested is drawn through the orifice of a corundum. In a similar manner another wire of the standard gold is drawn through the self-same orifice. As these wires are of equal diameters, equal lengths will have equal weights, provided the sample is pure.

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2 *Hardness* :—The spurious substitute of any precious stone may easily be detected by its difference in hardness and low specific gravity. The suspected gem may also be rubbed on a whetstone; if it simply gains in lustre but does not lose in weight (by abrasion), the specimen is to be regarded as genuine (test of a ruby). Diamond and corundum alone will scratch ruby and sapphire. All the gems occurring in this world, as also the metals, will be scratched by a diamond, but the latter will not be similarly affected by the former. A diamond alone will scratch a diamond.

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3. *Lustre, Transparency, Colour and other Optical Properties* :—Difference in lustre is often regarded as a diagnostic feature of the gems. According to Varaha gems of superior qualities should possess cool (lit. waxy) lustre, be limpid and emit rich rays. Classification according to colour is often enjoined. For instance, a diamond may be perfectly colourless, or it may be yellow, black, red or copper-tinted. Stones which are translucent, opaque and of dull colour are inferior in quality. In the case of diamond special stress is laid on its displaying the colours of the rainbow (due to its high dispersive power). Some gems have only one shade of colour, other again two (dichroism).

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The changes in colour, which the ruby and the sapphire undergo under the influence of heat, had evidently been carefully observed. This test is to be applied with extreme caution, as, in case the proper degree of temperature is exceeded, the stone may be materially injured.

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readily yield sulphuric acid which, with sodium chloride and nitre, might be expected to produce aqua regia.

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*Vida* or *Vit* (now known as *kalanimak* or ‘black salt’):— It is difficult to ascertain what it meant in the Ayurvedic age at the time of the Charaka and the Susruta. An account of the preparation of the black salt is given in Watt’s Dictionary of the Economic Products of India.

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“Black salt is prepared in upper India chiefly at Bhewani in the Hissar district by heating together in a large earthen pot 82 lb. of common salt, one pound of the fruit of *Terminalia chebula*, and one pound of *Phyllanthus emblica*, and one pound of *sajji* (impure carbonate of soda), until by fusion of the salt the ingredients are well mixed; then the pot is removed from the fire and its contents allowed to cool and form a hard cellular mass. This preparation is used medicinally, principally as digestive”

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The salt has a reddish-brown colour and consists mainly of sodium chloride with traces of sodium sulphate, alumina, magnesia, ferric oxide and sulphide of iron. During the fusion, a portion of the sodium sulphate is probably reduced to sulphide by the organic matter (*T. chebula*). This then reacts with the traces of iron salt present to form the sulphide of iron.

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Killing of Metals

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From the time of the Charaka and the Susruta we find metallic preparations in the shape of oxides, sulphides and sometimes chlorides, recommended for internal administration. The various formulas, which will be found scattered throughout above, give us methods for *killing* metals But a *killed* metal is not necessarily a compound; it sometimes means a metal deprived of its well-characterised physical properties, e g. colour, lustre, etc Thus the Ayurvedic *killed* gold and silver often represent the respective metals in a fine state of division. This is illustrated by the following recipe from Rasaratnakara by Nityanathia:

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"Rub gold-leaf with four times its weight of *killed* mercury (i e sulphide of mercury) and sublime the mixture in a closed crucible. On repeating the process eight times, the gold is *killed*."

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As the Hindu Iatrochemists were very particular about the *killing* of the metals being ensured, they had often to hit upon proper tests for securing this purpose Thus Rasaratnakara says:—"In order to examine whether the mercury has been completely reduced to ashes, it has to be heated over a gentle fire for three hours. If the weight remains constant, know then that it has been completely *killed*." In other words, it means that if there be any free mercury present, it would volatilise off and thus there would be a loss in weight.

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According to Hindu alchemists, there are four kinds of the ash (*bhasma*) of mercury; namely black (*kajjali*), red (*vermilion*), white and yellow. The white variety is often spoken of as *rasakarpura* or camphor of mercury; it is often found to be almost pure calomel and sometimes a mixture in indefinite proportions of calomel and corrosive sublimate.

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The chlorides of mercury are found to be medicinally used from the 12th century downwards, and various recipes are given for their preparation. The earliest account seems to occur in Rasarnava (Ch. XI, 24), where we find a mixture, among other drugs, of green vitriol, alum and salt, described as capable of *killing* mercury in an instant (p. 139) A more detailed description is found in Rasendrachintamani, a work which may safely be placed in the 13th-14th century. There the author Dhundhukanatha says: "I am now going to explain the process of preparing *rasakarpura*, which is a remedy for all diseases. Take a strong earthen pot and fill one-fourth of it with common salt and place over it a mixture of brick-dust, alum and rock-salt. Rub mercury with the juice of Indian aloe and an equal weight of the above mixture into a paste, deposit it in the earthen pot and cover it with the same ingredients The pot is to be firmly closed with a well-fitting lid. Now apply heat for three days together."

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Another work of the Iatrochemical Period, Rasendrasarasamgraha, describes the following process for obtaining the *svetabhasma* or white ash. "Rub mercury repeatedly with *pamsu* salt (i.e., *audbhida* salt) and the juice of *Euphorbia neriifolia*: place the mixture inside an iron bottle, the mouth of which is closed with a piece of chalk. The bottle is embedded in a mass of salt, and then fire is urged for an entire day. The white deposit in the neck of the bottle is to be collected."

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The Bhavaprakasa, written about 1500 A.D., prescribes calomel in the treatment of *phirangaroga* (lit. the disease of the Portugese; i.e., syphilis) and gives the following recipe: "Take of purified mercury, *gairika* (red ochre), brick-dust, chalk, alum, rock-salt, earth from ant-hill, *kshari lavana* (impure sulphate of of soda), and *bhandaranjika* or red earth, used in colouring pots, in equal parts; rub together and strain through cloth. Place the mixture in an earthen pot, cover it with another pot, face to face, and lute the two together with layers of clay and cloth. The pots so luted are then placed on fire and heated for four days, after which they are opened, and the white camphor-like deposit in the upper part is collected for use."

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The chemical reactions, involved in the above methods for the preparation of calomel, may be explained as follows: Alum, magnesium sulphate or ferrous sulphate, when heated, yield some sulphuric acid. This reacts with common salt to liberate hydrochloric acid. The latter undergoes aerial oxidation in contact with ferric oxide from the brick dust, *gairika*, clay, etc., acting as a catalyst, and sets free chlorine, which attacks the mercury, giving rise to calomel. Alumina from alum or from clay may also catalyse the reaction to a certain extent like the ferric oxide.

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