PRIYADA RANJAN RAY University College of Science and Technology Calcutta, India
T H E ORIGINS OF CHEMISTRY, in India as in other p a ~ t s as high as 9.38 per cent, forming an alloy with copper. of the world, are bound up with the early developments Lead was possibly obtained from mines near Ajmere in of the practical arts as well as with the philosophical Rajputana. Bronze was preferred t o copper for making speculations on the nature of matter and its behavior. weapons and implements with extra sharp cutting The present article will concern itself with the first of edge. these and will deal particularly with the achievements An alloy of copper and arsenie(34.5 per cent) was of the early Indians in the fieldof practical chemistryalso used a t Mohenjo-daro in place of bronze. It has the handling of minerals, metals, metallurgical proces- got almost equal hardness to low grade bronzes. Whether the alloy was a natural one derived from arses, metallic compounds, acids, alkalies, etc. In a previous communication a general survey of the senical copper ores, or artifically made, is however a knowledge of chemistry in ancient India has been made, moot point. and an account has been given of the theories and methCopper was possibly smelted from ores near the odology of science as was developed in those early days. mines, the metal being afterward refined in clay cruciThe present article will, therefore, he exclusively de- bles. A fragment of such a crucible with the slag stickvoted to a description in more details of the achieve- ing to the edges has been found a t the excavation a t ments of the early Indians in the field of practical chem- Mohenjo-da~o. From an examination of the analytical istry, particularly dealing with minerals, metals, metal- results, given below, of specimens of various copper arlurgical processes, metallic compounds, alkalies, acids, ticles found a t Mohenjo-daro, it has been concluded etc. that the people of the Indus Valley at that time were So far as minerals, metals, and metallurgical processes acquainted with four distinct varieties of copper and are concerned, their knowledge can be traced beyond its alloys: viz., (a) crude copper, (h) refined copper, (e) the Vedic period t o the time of the Indus Valley Civiliza- copper-tin alloy or bronze, (d) copper-arsenic alloy. tion of 4000-3000 B.c., as revealed by the excavation a t The following table gives some typical analyses of Mohenjo-daro (I) in Sind and Harappa in the Punjab. copper and bronze found a t Mohenjo-daro (3). This pre-Aryan civilization of ancient India is believed t o be allied to the Surnerian culture of Mesopotamia Fmgment and that of the Egyptians in the valley of the Nile. of The findings a t Mohenjo-daro prove that the residents Copper Coppw some Bronze lump impleCopper Bronze lump of the ancient cities of those days were skillful metal I II mat chisel button slab workers, who had a t their disposal a plentiful supply of gold, silver, and copper. Uses of lead and tin also were 92.49 92.41 88.05 82.71 0.37 95.80 0.0 0.0 8.22 13.21 not uncommon, though the latter metal was found Sb 0.88 Trace 0.72 0.10 2.60 0.33 mostly alloyed with copper in the form of bronze, per- As 0.15 1.30 0.74 3.42 Trace 1.17 Fe 0.03 1.51 0.12 0.59 0.29 0.42 centage of tin varying from 6 to 13 in the alloy. Ni 1.27 1.06 0.25 0.15 Trace 0.56 The use of gold was confined to jewelry. Silver was Pb 0.02 Trace 1.58 3.28 0.0 0.11 used for jewelryand also for ornamental vessels. Gold 0.98 2.26 0.61 0.05 0.84 O.O ... 1.01 0.18 ... ... 1.49 a t Mohenjo-dqro was obtained from south India goldfields in Mysore and Madras. Silver might have been obtained with go!d from the samesource or from argenA sample of silver found a t Mohenjo-daro has been tiferous lead of Burma. Articles made of a gold-silver found to contain: Ag, 94.5; Pb, 0.42; Cu, 3.68; inalloy, electrum, have also been found a t Mohenjo-dqo. soluble, 0.85 per cent. This indicates that the silver Copper and bronze were used for making weapons, was obtained by smelting argentiferous lead ore associtools, and vessels or utensils, as well as for cheaper or- ated with cuprite, of which the cerussite, found at Balunaments. Copper found a t Mohenjo-daro contains an chistan, might be a probable source. The process of appreciable amount of lead, suggesting that it must extracting silver from lead was undoubtedly known to have come from Rajputana, Baluchistan, or Persia, as the people of the Indus Valley a t Mohenjo-daro. It copper ores in all those areas are found to be associated furnishes an evidence of considerable knowledge of with lead. It deserves particular mention here that metallurgypossessed by them. some of the copper objects found a t Mohenjo-daro conTm was also found a t Mohenjo-daro; but it waa postain nickel. In one case it was found on analysis t o be sibly imported from outside. The Indus people had
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sufficient experien'ce and ability in working of metals. They were also using an alloy of copper and arsenic for making tools and weapons. ,Evidences have been ohtained that the copper articles a t Mohenjodaro, such a;;; axes, were made both by casting and hammering; the edges were usually hammered out after plain blades had heen cast. Copper dishes were also made by similar methods. A large number of minerals, ores, and rocks were known too, and in use among the Indus Valley people. Mention may he made of lapis lazuli, turquoise, rock crystal, lime stone, soap stone, alabaster, hematite, amethyst, slate, agate, jasper, chalcedony, onyx, bitumen, red ochre, basalt, steatite, sodalite, jade, lollingite, arsenical pyrites, etc. Most of these were found a t Mohenjo-daro in the form of beads, pendants, etc., used for ornamental purposes, and some were often coated with a glaze. Lollingite and leuco-pyrite were also utilized for the preparation of arsenious oxide and arsenic. Cerrusite and cinnabar have also been found 'at Mohenjo-daro. They were possibly used for cosmetics and medicinal purposes. White lead was utilized for plasters, eye-salves, and hair-washes. Ga.lena also was used for the preparation of eye-salves and paints. Gypsum and lime were used for plastering work and for making floors of drains.. Besides, brick, pottery, faience, and miscellaneous terra-cotta objects have been found in abundance a t the Indus Valley sites. Brown glazed pottery articles are t,he most common variety. Specimens of polychrome pottery, bedecked with floral and geometric patterns in Hack and white on a red ground, have been found. The base of some vases are found to he adorned with a row of lotus petals. Potteries were in some cases slip glazed, hut mostly painted. Painted potteries were made hy decorating or painting on a slip applied to the hody. Slips used were also colored: buff, cream, pink, and red. These were made mostly of ferruginous clays, or by mixing red ochre with clay. The articles were finally burnt. Manganiferous hematite was used for black color, and gypsum for producing white pottery. We thus find that the art of glazing on pottely flourished at Mohenjo-daro, as evidenced b y - a large number of pieces of broken pottery and faience found on excavation. But, curiously enough, no true glass has yet been found either a t Mohenjo-daro or at Harappa. After the decline of the urban civilization of the Indus Valley people, there followed a dark age in Indian history till the advent of the Aryans in near about 2500 KC. The Aryans developed a new civilization of a more or less pastoral type, based on high spiritual and philosophical ideas with their numerous religious rites and ceremonies. The Vedas, Upanishadas, and the various systems of philosophies are the great and glorious intellectual products of this civilization. The practical aspect of chemistry, as we have seen, was pursued by them mostly as a handmaid of medicine and alchemy. In the Vedic literature we find mention of six metals: White Yajurveda writes of ayas (gold), hiranya (silver), loha (copper), shyama (iron), sisa (lead), and tmpu (tin).
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Atharva-veda names gold as harita (yellow), silver as rajata (white), and copper as lohita (red). In Rig-veda, the earliest of the Vedas, there are numerous mentions, of gold and iron. In the Ayurvedic period mentions of brass and bronze articles are found in the writings of the Hindu Lawgiver, Manu (circa fourth century B.c.), as well as in the treatise of Charaka. Mercury has been mentioned for the first time in the Artha-shastra (treatise of polity) of Chanakya or Kautilya in the fourth century B.C. The author has also given descriptions of ores and mines of gold, silver, copper, iron, lead, tin, and many precious stones. Ores of iron have been descrihed as orange, faint red, and red like vermilion. These obviously relate to red and brown hematite. Copper ores have been descrihed as heavy, and green, grey, or red in color, which might be attributed to malachite, pyrites, and red copper ore, respectively. The use of copper for making alloys, for gold and silver coins, has also been mentioned in the same treatise. It also describes the process of gilding copper articles by covering with gold leaf and then polishing the outer surface and sides. We shall first give a more detailed account of the knowledge of the two most useful metals, copper and iron, as acquired by the ancient and mediaeval Indians. This is best done by considering some ancient archaeological specimens of copper and iron of historical importance. Such specimens are, however, abundant in India in the shape of statues, pillars, plates, caskets, beams, weapons, and implements. COPPER AND IkON
A solid copper holt, apparently shaped into form by hammer after being cast, has heen found in the Rampurwa Asoka pillar near the Nepal frontier. Historical evidences indicate that the holt is a product of the third century B.C. Its size is given by the length 24.5 inches and the circumference varying from 12 inches a t the extremities and 14 inches a t the center. It is very heavy and furnishes undoubtedly a strong evidence of the high metallurgical skill of the ancient Indians. In the ruins of an old Buddhist monastery, situated at Sultangunge in the d~strictof Bhagalpur (Bihar) and believed to be of the fifth century A.D., a copper statue of Buddha, 7 ft. 6 in. in height and weighing 1 ton, has been found. This huge statue was constructed by casting in two layers. The outer layer consists of a very thin and transparent garment laid over the inner body, made up of segments held together by iron hands. The inner hody is thus visible through the outer layer. There can be no better illustration of the perfection attained by the early Hindu workers on metals in smelting and casting operations. The well-known Chinese traveler Hiuen-Tsiang has left a description of a colossal copper statue of Buddha, 80 ft. in height, which he found standing upright near about the famous Nalanda convent in Bihar. I t was constructed in the seventh century A.D., hut disappeared possibly after a few centuries, as no mention of it is found in later chronicles.
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There are numerous evidences about the use of copper in India in the form of coins in early days by the Greek and Bactrian kings of the third century B.c., as well as by the Kushan kings like Kanishka and his successors in the first century A.D., and by the Gupta kings of the following period. We have seen that there are ample evidences of copper being smelted on an extensive scale in ancient India. In the, Singbhum and Hazaribagh districts of Chotanagpur it is believed that copper was mined and extracted some two thousand years ago. Deposits of copper slags were abundantly found on the hills all around these places. Copper is now mined and extracted a t Singbhum on a large scale by an English company, The Indian Copper Corporation, Ltd. In various states of Rajputana many extinct copper mines are found from which copper was obtained in ancient times. Some of these .mines are worked even now on small .scales following the old indigenous methods. Nepal was an important source of copper in ancient India. Copper is manufactured in Nepal even a t the present time according to the old methods. On account of its purity Nepal copper was highly valued in old days. Copper mines were also worked in the Central Provinces, the Kumaun district, the district of Gharwal, and also in some places of Madras Presidency. The Ayurvedic treatise, Susruta-samhita (circa' 5th century B.c.) has made mention of two copper ores: makshika (pyrites) and vimala (copper glance.) It has been noted further that makshilca occurs in two varieties: hema-makshika (hema means gold, hence signifies copper pyrites), tara-makshika (tars means silver, hence signifies iron pyrites). The extraction of the metal from these ores by heating with carbonaceous matter, alkali carbonate and borax, has been described a t a later age in various alchemical and iatro-chemical treatises like Rasaratnakara, Rasarnava, and Rasaratnasamuchchaya (800-1300 A.D.). COPPER ALLOYS
Among the alloys of copper, bronze has been mentioned in the Ayurvedic treatises, Charaka and Susruta of the pre-Buddhistic era. In the latter, directions are given for drinking water in bronze vessels.. In the mitings of the Hindu Law-giver, Manu, of the 4th century n.c. there are mentions of household utensils made of bronze. The alloy was also employed in making gongs or bells in those days. Hence, no distinction was made a t that time between bronze and bell-metal. Both were designated by the same term kamsya. Large quantities of ornamental bronze articles, found in the excavation at Tinnevelly in the Madras Presidency (vide infra), furnish an irrefutable evidence of its use in ancient India (circa 4th century B.c.). An alloy made of two parts of silver and one of copper has been mentioned in Kautilyas Arthashastra (circa 3rd century n.c.) as triputaka. Preparation of kamsya, consisting of eight parts of copper and two parts of tin, has been described in detail in Rasaratnasamuchchaya of the 13th century AD. Brass was prepared in early days by heating copper and cala-
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mine with carbonaceous substances. Later on, in the iatro-chemical period (circa 14th century A.D.) copper and metallic zinc were used for the purpose. But, brass vessels, belonging to the first century B.C. or near about, have been unearthed by excavations of ancient Buddhistic stupas. According to archaeological evidences, brass coins were also in common use in those'days. The Ayuwedic treatise Charaka also makes mention of brass. The alloy has been largely used in ancient and mediaeval India for making statues of gods and goddesses. A very remarkable use of brass for a very large scale constructional purpose has been mentioned by Hiuen-Tsiang. It Tefei-s to an unfinished brass "vihara" (convent) near Nalanda, made during the reign of King Siladitya, known also as Harshavardhana, in the seventh century A.D. It is mentioned that this vihara would measure 100 ft., when finished in accordance with the plan. This undoubtedly hears an eloquent testimony to the remarkable skill displayed by the ancient Indians in large-scale brass work. In a later age, during the Mogul period, large size guns and cannons were also made of brass and bronze. The great gun of Agra has a length of 14 ft., a bore of 22.5 in., and weighs 1049 cwt. But the famous bronze gun of the Moguls, known as "malik-i-maidan" (monarch of the plain) is possibly the largest of the kind still in existence. It has a length of 14 ft. 3 in., with an enormous diameter of 4 ft. 10 in. at the mouth. It was cast a t Ahmednagar in 1548 A.D. and now lies a t Rijapur. Handling and working of such a large amount of alloy with little mechanical power available in those days reflect a great credit on the ability and skill of Indian metal workers. Brass was recognized as an alloy (misra loha) in the 13th century A.D. in India. A!fisra loha literally means mixed metal. Alchemical treatises like Rasaprakasha-sudhakara and Rasaratnasamuchchaya have described it as such. In many alchemical writings alloys have been designated as upadhatus (semimetals). Of the compounds of copper, the preparation of copwer sulfide in a wure state has been described bv Chaki.apani (1060 A:D.) in the alchemical treatise named Chakradatta after him. It was called tamrayoga or tamra-parpati, and was mad6 from metallic copper and sulfur, or from copper ama1ga.m and sulfur by heat. Conversion of a metal into its sulfide by heating with sulfur is described as vida or killing by many Indian authors of the transition and alchemical period. Thus in Rasanarva it is written: "There is no such elephant of a metal which cannot be killed by the lion of a sulphur." Copper sulfate has been known as tuttham from the days of Charaka and Susruta as a remedy for diseases like ulcers, leprosy, etc. I t was also called mayuratuttham and'sasyakam in iatro-chemical treatises like Rasaratnasamuchchaya, Rasendrasarasamgraha, and Sarangadhara. The word mayura-tuttham indicates that its color resembles that of the throat of the peacock. That copper can be obtained from blue vitriol has been mentioned in several places in Rasarnava and Rasaratnasamuchchaya. The substance has also been prescribed as an emetic and an antidote to poisons.
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Preparation of copper sulfate from copper and sulfuric acid (&ha jal-lit. burning water) has been described in Dhatukriya, a treatise of the 16th century A.n. on reactions of metals. Preparation of copper chloride by heating copper with common salt and of copper oxide by heating the metal in air have also been given in the same book. It may be &ted here as a significant fact that the I n d i alchemists did not fail to make the observation that copper and copper compounds give a blue color to the flame. The fact has been recorded in Rasarnava of the 12th century. IRON PRODUCTS
The metal iron appears to have been known to the ancient Indians of the Vedic age, for the word ayas frequently occurs in Rig and other Vedas. But the selfsame word has also been used in Vedas to denote gold, as well as metals in general. In White Yajurveda the word shyama has been used to mean iron. In the Brahmans and Upanishad@ (circa 1000-500 B.c.) iron has been given the name of krishnayas or black metal, while copper has been termed lohitayas or red metal. Later on, in the epic age (circa 500-200 B.c.) we find that the Hindu Law-giver, Manu, in his Dharmashastra mentions household utensils made of copper, iron, brass, bronze, tin, and lead. In the Ayurvedic treatise, Susruta, we find description of about one hundred varietieswf surgical instruments, made possibly of best steel. Iron implements and weapons in the form of swords, daggers, tridents, spears, javelins, arrows, spades, hangers, beam rods, and tripods have been found in the excavations of numerous bu&l sites in the gravelly mounds of the Tinnevelly district of the Madras Presidency, particularly a t Adittanattur. These must have been buried under the earth in an age when the of was unknown in southern l,,dia, i. e., before the 4th B.c. Iron at the Bodh-Gaya temple, and the iron slag, found on excavation of the foundation of the s t u ~ a t the same place and now preserved a t the Calcutta museum, furnish evidences regarding the knowledge of the process of manufacturing iron in ancient Indiaas as the 3rd century B.C. The famous iron Dillar near Delhi by the side of the Kutab Minai-, whici, from a consideration of the script and the test of the inscription on the pillar, is believed to have been constructed sometime in the 4th century A.D. during the reign of Chandra Gupta 11, as a pillar of victory, and may be viewed as a standing monument of the achievement of the early Indians in metallurgical work. It is about 24 ft. long, 16.4 in. in diameter a t the bottom, and 12 in. in diameter a t the top. The engraved capital a t the top is 3 ft. 6 in. in length. The weight of the pillar has been estimated to be about: six tons. Analyses of specimens of the material of the pillar have proved that it is made of wrought iron without any alloy. Specific gravity of the metal is 7.81, that of the purest wrought iron being 7.84. We quote here the results of analysis given by Hadfield (3) in the
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Journal of Iron and Steel Industries: Fe, 99.72; C, 0.08; Si, 0.046; S, 0.006; P, 0.114; Mu, nil; total, 99.996. Absence of managanese is significant. Low percentage of sulfur indicates the use of charcoal as fuel. The pillar has wonderfully withstood the influence of rain and water for over fifteen centuries without giving any sign of rust formation. Expert observers of all classes are of opinion that this pillar presents an indisputable and permanent record of a very high metallurgical skill and engineering ability of the ancient Hindus, which can reasonably claim unstinted admiration even of our present time. It will. therefore. be not out of place here-to quote extracts from the opinions of some of these observers. "The dexterity exhibited by the Hindus in the manufacture of wrought iron may be estimated from the fact of the existence in the mosque of the Kutab ness Delhi of a wrought iron pillar . . . belonging to the 4th century. I t is hot an easy operation a t the present day to forge such a mass with our largest rolls and steam hammers; how this could he effected by the crude hand labour of the Hindus we are a t a loss to understand." . Roscoe and Schorlemmer (4). "Taking A.D. 400 as a mean ddste--and it certainly is not far from the truth-it opens our eye to an unexpected state of affairs ta find the Hindus a t that age capable of forging a bar of iron larger than any that have been forged in Europe up to a very late dttte, and not frequently even now. As we find them, however, a few centuries afterwards using bars as long as this in roofing the porch of the temple a t Konarak, we must now believe thttt they were much more familiar with the use of this metal than they afterwards became. I t is almost equally startling to find that sfter an exposure to wind and rains for fourteen conturies, it is unrusted, and the capital and inscription are as clear and as sharp now as when put up fourteen centuries ago," . . . Fergusson (6).
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The following excerpt from the opinion of an engineer is also worth quoting here : . .. while considering forging of large masses of iron and steel,
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easy to forget the impression caused by first seeing the iron pillar a t Delhi. This column of wrought iron, which is 16 in. in diameter and of which 22 ft. are above the ground, is finished perfectly round and smooth, with an ornamental top, and was made many centuries ago from iron produced direct from the Ore and built up piece by piece. Remembering the lack of facilities men had in those days for first forging and then welding together an enormous mass makpg one wonder at the iron worker of those davs. - , who must have ~ossessedenzineerinn ability.eleiming the admiration of our times. It is questionable whether the whole of the iron works of Europe and America could have produced a similar column of wrought iron so short a time ago as the exhibition of 1851."
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Numerous iron beams and clamps in the temple at Bhubaneswar (640 A.D.),similar beams of larger dimension in the temple a t Konarak (900-1000 A.D.),and huge iron girders in the temple a t Puri (1174 ~ . n . ) in , the province of Orissa, are other striking instances which speak highly of the achievements of the Hindu workers of the time in the art of manufacturing iron and steel. Of the beams a t Konarak the largest one has a measure of 35 ft. in length, 7-7.5 in. square, and weighs about 6000 pounds. In the garden temple a t Puri there are as many as 239 beams ranging up to 17 ft. in length and 6 X 4 or 6 X 6 in. in cross section. All these beams are made of pure wrought iron, as the analysis of a speci-
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men of Konarak beam piece given below, indicates (7): move about is called bhramaka; one which kisses iron is Fe, 99.64; C, trace; S, trace; P, 0.15; Mn, nil; total, named chumbaka; one that attracts iron is called kar99.79. Specific gravity, 7.8. The nature of the iron is shaka; that which helps melting iron is called dravaka; thus very similar to that of the Delhi pillar. and that which, when broken, shoots forth hair-like The iron pillar a t Dhar, the ancient capital of Malava, filaments is termed romakanta. is the most massive of its kind. It has been lying broken From what has been said about the properties of in three pieces. The total length is 43 ft. 8 in., with an different varieties of iron, it is apparent that munda average width of 10.25 in. The cross section of the represents cast iron owing to its brittleness and black pillar is not uniform throughout, but partly square, fracture; tikshna can he identified with steel in view of partly rectangular, and the rest octagonal. Its esti- its strength, elasticity, and sharpness; and kanta mated weight is approximately 7 t,ons. It is believed stands for wrought iron being the purest and the best to have been constructed in the 12th century A.D., pos- form of iron. sibly as a victory pillar. One very striking property of the wrought iron manuA third iron pillar, 12 ft. 9 in. in height, ending in a factured by the ancient Hindus is its remarkable 1.eSiva's tn'sul (trident) a t the top stands in the courtyard sistance to corrosion, as has been particularly noticed of the temple Achaleswar on Mount Abu in Rajputana. in the case of the famous Delhi pillar. It is difficult It is stated that the pillar was built in the early part of to account for it. Dr. A. S. Cushman and Prof. H. Le the 15th century A.D. as a monument of victory. Chatelier (8)are of opinion that the absence of mangaMention may now be made of some huge hammered nese with low sulfur and high phosphorus content is priwrought iron guns of the Mogul time (16th and 17th marily responsible for the strikmgly high corrosion recentury A.D.). Most of these weigh about 30-47 tons. sistance and the exceptional durability of the Delhi The maximum length found is 31 ft. and the largest pillar and the other specimens of the ancient Indian iron. bore reaches about 1 ft. 7 in. in diameter. These guns It is, however, more likely that their resisting power is were manufactured by Hmdu mechanics and were con- due to a thin Jihn of magnetic oxide of iron mixed also structed of iron bars of square section laid longitudin- with some sulfide of iron, produced on the surface of the ally alongthe bore, over which iron rings were slipped, metal by treatment like heating and quenching after one a t a time, while red hot. On cooling they shrank being painted with a mixture of differentsalts and orand fastened the iron bars strongly together. Near the ganic substances. There are evidences of iron being breech the guns were often strengthened by a second subjected to such treatment for improving their qua'ity layer of rings. in some of the Indian alchemical treatises. A Sanskrit alchemical manuscript, Yuktikalpataru, Iron produced in ancient India .was mostly wrought of the 11th century A.D. classifies iron into different iron. For, with their use of charcoal as fuel, the temperavarieties and describes their relative qualities as fol- ture raised in the furnace could not have been high lows: . enough to melt the metal and thus to ensure absorption' Crouncha iron is twice as good as samanya (ordinary) of carbon 'for the production of cast iron. At the low iron, kalinga (Orissan) iron is eight times as good as temperature thus prevailing in the furnace, the whole erouneha iron, bhadra iron is one hundred times as good of the ore used, however, was never completely reduced, as kalinga, bajra iron is one thousand times as good as and a large portion escaped reduction. Furnaces embhadra, pandi iron is again one hundred times as good ployed resemble those of the Catalan type. as bhadra, niranga iron, on the other hand, is ten times Steel has been prepared and used in India from very as good as pandi, and finally the kanta iron is one billion early times. We find its use in the making of a large times as good as niranga. number of surgical instruments described in the AyurThe iatrochemical treatise, Rasaratnasamuchchaya, vedic treatise Susruta of the pre-Buddhistic era. It has describes three variet,icsof iron, distinguished as munda been also mentioned by some ancient writers that about (cast iron), tikshna (sharp iron or steel), and kanta 40 lb. weight of steel was presented by King Porus to (wrought iron). Alexander the Great, who conquered his kingdom. It is Munda again is subdivided into three types: mridu, believed that the Indian steel was exported to the westkuntha, and kadara. That which melts easily, does not ern countries as early as 2000 years ago. It was known break, and has a glossy appearance is called mn'du; in Europe as "wootz." This seems to have been mauuthat which expands with difficulty when hammered is factured from a very early time in Nizam's dominion, known as kuntha; while one which breaks when struck Mysore, Salem, and other parts of the Madras Presiwith a hammer and shows a black fracture is described dency. This was the metal from which the famous as kadara. Damascus blades were prepared. The Indians were Tilcshna has also got six varieties: viz., khara, sara, noted for their skill in the tempering of steel, and it was hrinnala, tarabatta, bajira, and kala lauha (black metal), from them that the secret of the operation was learned distinguished by their diierence in appearance, nature by the Persians and, through them, the Arabs. Steel and appearance of fracture, elasticity, and brittleness. was produced in early days in India by a process resemKanta has also been distinguished into five kinds: bling the modern cementation or crucible process. namely, bhramaka, chumbaka, karshaka, dravaka, and Wrought iron was produced directly from magnetic iron romakanta. The variety which mrakes all kinds of iron ore and charcoal. This was then heated in closed cru-
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cibles with dry wood chips, stems and leaves of plants in a charcoal fire maintained by blowing air with large bellows. The process was completed in 4-6 hours, whereas the modern cementation process generally takes up 6-7 days. The steel first obtained was heated again in closed crucibles whereby the excess of carbon was burned off. Sometimes water was poured on the hot metal which was thus hardened on being quenched. Descriptions of the sulfide ores of iron are given in the ancient Hindu medical treatises like Charaka and Susruta. Their general name was tapya, aa they were obtained from the bank of the river Tapi. Two varieties of tapya, golden and d v e r , were distinguished in the Ayurvedic literature. Latterly the name mnkshika was substituted for tapya, and the two varieties were designated as swarna makshika (golden or copper pyrites) and raupya makshika (silver or iron pyrites). Oxide ores of iron are described in Kautilya's Arthashastra of the 4th century B.c., where it is stated that their color is either orange, or red like vermilion. They evidently refer to hematite, limonite, or ochres. The name gairika was subsequently used for these ores, and the two varieties were distinguished as pashana gairika (hematite), which is hard and copper-colored, and swarna gairika (limonite or yellow ochre), i . e., of the color of gold. Ochres were also used in early days for dyeing clothes. Of the compounds of iron, the methods for the preparation of the oxide and the sulfide have been described by the well-known Indian alchemist Nagarjuna in the 8th century A.D. AS in the case of copper, these processes for preparing the oxide and the sulfide were known a s "killing" of the metal, and the products passed under the name of "killed iron" for use as drugs. Charkapani (11th century A.D.)recognized that killed iron (the oxide variety) and mandura (the rust of iron) possess identical properties. Mandura was as a medicine. A product, obtained by heating iron with a mixture of salts including the common salt, has also been described. It obviously contains ferrous chloride and oxychloride of iron besides the unacted metal and its oxides. The process has been described in the Ayurvedic treatise Susruta as ayaskriti (roasting of iron) which renders the metal fit for internal administration. When the mixture of salts contained vitriols and alums, sulfates and basic sulfates were also formed. The mixture of the salt used was technically called "vida" in the later alchemical treatise Rasarnava, as already mentioned. The process ayaskriti had been applied to all the metals known in those days anand may be viewed as a crude and imperfect method for the preparation of metallic salts in general, as the mineral acids were then not known. Green vitriol or ferrous sulfate has been mentioned in Charaka and Susrnta under the name kasisa. It has been further distinguished in Rasaratnasamuchchaya (14th century A.D.) into two kinds: valuka- or dhatukasisa, the green variety, and pushpa-kasisa, the basic yellowish variety. This has also been mentioned in an earlier tantric treatise, Rasakalpa or Rudraymala Tantra.
JOURNAL OF CHEMiCAir; EDUCATION
Among the other metals gold and silver were hnown from time imn~rmorialin ancient India. They were also used in medicine from very early times after untlergoing processes of purification and killing. Rasaratnasamnrhchaya mentions of a variety of gold which is ohtained by the transmutation of the baser metals I t is difficult to decide what it refers to. Obviously, it cannot be brass or bronze, both of which were well known at the time. The process of killing gold by roasting with saltpeter, green vitriol, borax, salammoniac, salt, etc., in covered crucibles, as described in Rasarnava, possibly led to the partial formation of gold chloride. Roasting or killing with sulfur in the same way evidently gave rise to the sulfide of gold. That silver can he easily alloyed with lead and can be purified by this means has been described in Rasaratnasamuchchaya as follows: "Silver melted with lead and borax undergoes purification . . . . Arrange on an earthen dish a mixture of lime and mhes in a &eular r o s and place in it silver wit,h its equal weight of lead.
Now roast it over fire undil the lead is consumed. Silver, thus purified, is to be used ior medicinal purposes."
The process practically resembles that of cupellation and is mentioned also in the earlier treatise Rasaratnakara of Nagarjuna (8th century ~ . n . ) . Ths method employed for killing silver by heating it with sulfur or orpiment in a covered crucible over a sand bath obviously leads to the formation of sulfide. Two varieties of tin have been distinguished by the author of Rasaratnasamuchchaya: kshurakam and misrakam. The former is white, soft, readily fusible and bright, and does not clink when struck. The latter is dirty white. This reminds one of white and grey tin. The same author gives a method of reducing tin to ashes by heating it with orpiment and plant ashes. This obviously leads to the forma.tion of tin sulfide. Another recipe given in Rasendrasarasamgraha, which consists in heating the metal with plant ashes over fire with constant stirring of the molten mixture, is likely to yield the oxide of tin. Lead has been described in Rasaratnasamuchchaya as a readily fusible, very heavy metal with a black and bright appearance on fracture. It was supposed to possess a fetid odor. The author gives a recipe for obtaining a bright red ash of the metal by heating it strongly with plant ashes and mercury in air while stirring the mixture continuously with an iron spoon. Both Rasendrachintamani and Rasendrasarasamgraha describe a process for converting lead into a vermilionlike powder, in which the metal is heated with plant ashes repeatedly for seven times as described above. The process evidently yields red lead. The method described for killing the metal by heating with orpiment in a closed crucible leads, as in other cases, to the formation of its sulfide. An alloy made of lead, iron, copper, kamsya (bronze), and pittala (brass) has been described in Rasaratnasamuchchaya under the name of uartaloham. It may, therefore, be regarded as an alloy of five met,als: lead, iron, copper, tin, and zinc.
JUNE, 1948
333
MERCURY
The shining reddish brown crystalline sublimate of the sulfide of mercury, thus obtained, is a very wellknown remedy in the Hindu system of medicine. I t is reported to be a panacea for all the ills that human flesh is heir to. In the Hindu medical treatises the red sulfide of mercury, prepared by heating mercury with sulfur, is desc~ibed as "Makaradhwaj" and "Rasasindzcra" (minimum like mercury). When prepared as described above with the use of gold, it is often called "Swarnasindura" (gold vermilion). Of course, the sublimate of mercnry sulfide cannot contain any gold which is left behind. But t,he product, prepared in the presence of gold, is believed to be much more efficacious than when made in its absence. Preparation of the black modification of mercury sulfide under the name of kajjali or rasaparpati has also been described in Rasaratnakara, Siddha Yoga of Vrinda, and in Chakrapani. The process consists in rubbing together mercury and sulfur in a mortar. A process of killing mercury has been described in Rasarnava, which evidently yields calomel. In this, green vitriol, alum, salt, borax, and some other vegetable drugs are heated toget,her with mercury in a covered clucible. The white sublimate is to be collected. Similar descriptions are found also in various other Iatsr alchemical and iatrochemical trea.tises: uiz., Rasaprakasa Sudhakara, Rasapradipa, Rasendrachintamani, Fhendrasarasamgraha, and Bhavaprakasa. The product rasakarpura (calomel) was recommended as a remedy for leprosy 2nd syphilis. Killing of mercury with the aid of purely vegetable products has been described in Kasaratnasamuchchaya. This obviously gives the oxide of mercury (yellow or red), as the metal, on being heated with plant ashes, is finally converted into the oxide. The processes described for killing or fixingmetals by the ancient Indian workers lead evidently to the formation of their oxides, sulfides, or chlorides. The products were generally known as b h a s m s (ashes). According to Hindu workers there are thus four kinds of mercury bhasma, namely, black (kajjali),red (rasasinduravermilion), white (rasakarpzcm, calomel), and yellow (mercuric oxide). Zinc has been extracted in India from calamine as early as the 8th century A.D. Preparation of zinc as the essence of calamine, by heating the latter in a covered crucible with carbonaceous matter, has been described in Rasaratnakara by Nagarjuna. Calamine was known in India as rasaka or kharpara in the Ayurvedic age and was emdoved for makiue brass. Both Rasarnava and ~ a s ~ r a ~ ~ i a s a m u c h give c h a ya ~detailed account of the extraction of zinc from calamine. The process described in the latter treatise is so elaborate that it may be transferred bodily without any change into any modem textbook of chemistry. It utilizes the principle of distillation per descensum and takes note of the bluish flame of burning carbon monoxide. The following gives a literal translation of the original text:
Mercury (Parada) has been mentioned in Susruta Vagbhata. But i t was particularly studied by the Indian alchemist, Nagarjuna, and in his treatise Rasaratnakara the detailed recipes for the preparation and purification of mercury and of its compounds are given. i\fercury has been described by Nagerjuna as the king of rasas (minerals). The word rasa was subsequently reserved for signifying mercury, the study of whose propert,ies became the central theme of Indian alchemy. Preparation of mercury by distillation from cinnabar has been described in Rasaratnakara and Hasaratnasaniuchchaya. Cinnabar was known as darada from Dardistan, the mountainous region about Kashmir, from rvhere it was obtained. Mercury was, therefore, regarded as an essence of darada, of which the latter was also known as hinyula. Purification of mercury from lead and tin by digestion with sour gruel, followed by distillation, has been described in the alchemical treatise, Rasahridaya of Bikshu Govinda. A description of the apparatus for t,he sublimation and distillation of mercury has also been given by the author. The appa? ratus employed for the purpose and known as "Patana Yantram" consists of two vessels, so adjusted that the neck of one fits into that of the other, the junction being luted airtight with a composition made of lime, sugar, iron, and milk. The lower vessel is heated over a fire, when the sublimate collects on the under surface of the upper vessel. The description of this process and the appa~atushas been quoted verbatim in later works like the alchemical treatise, Rasendrachndamani by Somadeva and the iatrochemical treatise, Rasaratnasamuchchaya. In these latter there are descriptions of iniproved apparatnses for the purpose. These are called "Dheki Yantram" and "Vidyadhara Yantram," In the former the distilling vessel is a closed pot below the neck of which there is a hols, and into this is introduced the upper end of a bamboo tube, the lower end of it fitting into a brass vessel filled with water and made of two hemispherical valves. Vidyadhara Yantram consists of two vessels, one placed over the neck of the other. The upper one contains cold water, and the mercury condenses a t its bottom when the lower one containing cinnabar is heated over a fire. Killing or fixing of mercury by heating with sulfur in closed vessels, which obviously yields its sulfide, has been described in Rasarahakara, Rasarnava, and Rasaratnasamuchchaya. The process of fixation as described in t,helatter two treatises is given below. (1) "Mercury is to be rubbed with its equal weight pf gold and then further admixed with sulphur and borax, etc. The mixture is then to be transferred to a crucible, which is then covered with its lid and submitted to gentle heating. By partaking of this elixir (sublimate) thedevotee aequircs a body not liable to decay." (2) "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 oruoible. The mercury thus trerttcrl is afterwards killed with six times it,s weight of sulphur."
.
"Calan~ineis to be powdered with lac, treacle, white mustard, myrobalan, nstron and hbrax, and the mixture boiled with milk
JOURNAL OF CHEMICAL EDUCATION and clarified butter. This is then m a d e into balls. The balls me dried and afterwards heated in a. 'Kosthi' apparatus. The apparatus consists of a vessel closed with a perforated saucer over which is inverted another vessel charged with the balls as prepared above. The lower vessel contains cold water and is plt~cedin position in a hole under the ground; the upper vessel lying over the ground is strongly heated by means of charcoal fire. Metallic zinc drops ar distils into the water below. In ¬her method B tubulated crucible is filled with the above mixture made of calamine. The mouth of this orucible is then closed with another inverted over it. On the application of heat, when the flame issuing from the molten calamine changes from blue to white, the crucible is caught hold of by a. pair of tongs and is thrown on to tho ground with its mouth downards. The essence, possessing the lustre of tin, which is dropped, is collected ior use."
the color of madder. Generally it was used in medicine. Sodium sulfate and magnesium sulfate were both denoted by the same term kamakustham in the alchemical treatises Fhsakalpa and Rasarnava, and no distinction seems to have been made between them. Saltpeter or niter was known in the time of Snkraniti and Rasarnava, and the term sauvarchala was applied to it. It is one of the five salts mentioned in Charaka. Tre.ttises of the alchemical period make mention of another salt under the name of navasara or chulikalavana, which means sal ammoniac. Chulika-hvana is literally salt deposited in the hearth. Rajavarta is the term which was applied to lapis lazuli by the Indian alchemists. Among the other minerals known to the early Hindus mention may be make of abhra or kechara (mica) and vaikranta (spinels). Their different varieties and color have been described in some details in Rasaratnasamuchchaya. A fairly detailed knowledge of physical and chemical properties of a large variety of minerals, valued as gems or precious stones, was acquired by the ancient Indians as early as the 3rd or 4th century A.D. Testing of genuineness or otherwise of gold and gems, and a knowledge of their coloring, constituted one of the sixty-four branches of arts and sciences recognized in the ancient treatise, Kamasutra of Vatsayana. Much useful informations on the subject are found also in Vrihatsamhita of Varahamihira, composed in the 6th century A.D. Gems were valued in India from time immemorial not only for decorative and ornamental purposes as jewels, but they were also largely used as an antidote against bad luck and evil influences of unfavorable planets. Since their values were believed t o depend upon their purity and freedom from all physical defects, methods for their testing were fairly well developed. These related to their relative weight, hardness, lnstei, transparency and color, fusibility-particularly when heated with alkalies, presence of impurities or adulterations, crystalline character, etc. Diamond was recognized as the hardest of all, for a diamond alone will scratch a diamond. After diamond, corundum was placed next in order of hardness. Both ruby and sapphire were regarded as varieties of corundum only. Change in color undergone by some of the gems, such as ruby and sapphire, under the influence of heat has also been carefully observed. The octahedral character of diamond crystals has been described by many workers of those days as having six angles, eight faces, and twelve edges.
In the beginning the Indian alchen~istsdid not quite recognize the essence of calamine as a separate metal. But, later on in the 14th century, it came to be classified as a new metal under the designation of Jasada. Killing of zinc by heating it with orpiment has also been mentioned in Rasaratnasamuchchaya. This evidently yields a mixture of sulfide and arseuide. There is no mention of antimony as a distinct metal in Indian alchemical treatises. Naturally occurring sulfide of lead and of antimony were, however, distinguished as sauwil.anjana and nilanjana, respectively. They were both regarded as uparasas or inferior minerals m d valued for use as anjanas (collyrinm). We find, however, in Rasendrachudamani of Somadeva that nilanjana mixed with tikshna (steel) and heated several times yields a superior kind of lead, which is readily fusible and is of mild black color. The metal antimony was thus confounded with lead, and particularly nilanjana (stibnite) was often mistaken for sauviranjana (galena). The use of stibnite and galena has been mentioned even in the Ayurvedic treatises of Charaka and Susrnta. Color of Flames. That flame is colored by many metals and metallic compounds was known to the metal workers in early India. The blue color, produced in a flame by copper and its compounds, has already been referred to. The tantric treatise Rasarnava thus writes: "Capper yields a blue flame . . .that oi tho tin is pigeon colowed, that of the lead is pale tinted, . . .that of iron is tawny,. ." OTHER MINERALS AND METALS
A few more minerals and metallic compounds with which the ancient Indians were familiar may now he mentioned here. Sulfur has been used as a medicine in ancient India from the Vedic age. It is, however, mentioned in the alchemical and iatrochemical treatises that there are four kinds of sulfur: yellow, white, red, and black, the last one being rare. Both realgar (manassila) and orpiment (harital) have been freely used as medicines in ancient India from the Ayurvedic age. Alum has been mentioned in Susruta and Rasarnava as saurashtri from Saurashtia (modern Snrat) where it was found. Its other name is tuvari. It is stated in Rasaratnasamuchchaya that tuvaf-i dyes cloth and fixes
KNOWLEDGE OF ALKALIES AND ACIDS
.
I shall now conclude this article after giving a brief account of the knowledge of alkalies and acids as were known to the ancient Indians. So far as the preparation of caustic alkali is concerned it may be stated without any fear of contradiction that the early Himdus attained a high degree of perfection in this respect. This is evident from the following descrip-
JUNE, 1948
tion of the preparation of alkaline carbonates and caustic alkalies from the Ayurvedic treatise Susruta 5th century B.c.). ~plants (their ~ ~ are given i in the ~ original~text) are~ names cut into pieces and then burnt, hi^^^ two seers (about 2 oounds make a seer) of the ashes thus oroduced should be stirred or mixed with six'times their quantky of water and then strained through cloth. This should he repeated twenty-one times. The strained fluid should then he boiled slowly in a large pan and agitated with a ladle. When the fluid becomes clear, pungent and soapy to the feel, it should be removed from the fire and strained through cloth. The residue being thrown away, the strained fluid should be again hoiled. From this alkaline solution take three q m t e r s of a seer. Then take eight p a l a (one oala is about 38 em.) each of burnt limestone. conch shell and bivalve shells, anchehellt them in iron pan till the; are of the colour of fire. Then moisten them in the same vessel with the above mentioned three quarters of a seer of the alkaline water and reduce them to powder. This powder should be thrown on sixtyfour seers of the water, and boiled ~ t c ho n s h tand careful a d a t i o n by the ladle. Care should be taken that the solution neither t o o thick or thin. When reduced to proper consistence, the solution should be removed from the fire and poured into an iron jar. The opening or the mouth of the jar should be covered and it should he kept in a secluded place. This preparation is called mndhyama kshara or alkaline caustic of middling strength. When the alkaline water is simply boiled to the proper consistence (first stage) without the addition of burnt shellsetc., the preparation is eallcd m&du kshara or weak alkaline solution!' t
J~
~
We thus find that a clear distinction was made between alkaline carbonate (mridu kshara) and caustic alkali (mdhyamik and tikshna kshara). Kshara is the term applied generally to alkali. Mridu, madhyamik, and tikshm in the literal sense mean respectively mild, medium, and sharp or strong. Products obtained in this manner are evidently potassium carbonate and caustic potash. But we also find other varieties of alkalies mentioned in the alchemical treatise Rasarnava and in the iatrochemical treatise Rasaratnasamuchchaya. These are, namely, borax (tankanam), sodium carbonate-trona or natron (sarjika-kshara), and potassium carbonate (yava-Kkshara). The early Indians were well acquainted with many organic acids, both naturally occurring and prepared by fermentation from starchy materials. The term kanjika (fermented rice water) has been applied to the latter, which is evgently crude vinegar. The neutalization of acid by alkali was also recognized in those days, and Susruta thus accounts for the process of neutralization: "If you question, my son, how is it that the application of the pungent acid of kanjika relieves the burning of the fire-like hot alkaline caustio, then hear the following explanation from me. Alkalies possess all the tastes except that of the acid. The acrid taste prevails in it and the saline one to a less degree. The sharp saline w r r , whm rnirrd nit11arid, h t m m n very mild, and rim. up its a h r p quality. From this rnodifilat~rmot th+ mlint t w r , r1.v pnln of r ~ w s t id i ~r+lww~Ia s tire is vxtinp~i>hrdby n.nlt.r '
Alkalies have been recommended in Susruta both for external and internal uses as a remedy for a variety of diseases. It is thus stated: ".4lkdies are of two sorts, namely for external application and internal administration. They are used extemslly in the skin
335
diseases called knstha (leprosy), in keloid, ring worm, leucoderma, lep% fistula-in-ano, tumors, unhealthy ulcers, sinuses, moles, warts, piles, external inflammations, diseases of the mouth, throat, gum, etc. Blkaline solutiong are administered internally in chronic or slow poisoning, abdominal tumors, loss of appetite, indigestion, urinary deposits, calculi, intestinal worms, piles, etc.. . "
Of the naturally occurring organic acids we find in Ra~~atnasamuchchaya the mention of citrons and lemons, tarmaind, oxalis corniculata, the acid exudation of Ziziphusjujuba, pomegranata, etc. ~ h ,inera, , were, however, unknown to the lndmns at a later period in the age. The distillation of alum, referred to in Rasamava and of green vitriol in ~as&atnasamuchcha~a, obviously give rise to some sulfuric acid. only in some medical works of the 16th and 17th centuries, the preparation of mineral acids has been described in some details. In these, directions ale given for distilling a mixture of. among other things, alum, green vitriol, sal ammoniac; saltpeter, and borax in a glass retort. A dilute solution of nitro-muriatic acid is thereby obtained, which is recommended in a remedy in derangement of liver and spleen. It is called samkha dravaka (lit. solvent for conch shell) and is described as endowed with the property of dissolving metals. The term dravaka (solvent) seems to have been used for the mineral acids. Recipes for the preparation of the three mineral acids, sulfuric, nitric, and muriatic acid, have been found in the writings of many workers of the Mogul period, particularly during the reign of Emperor Akbar. It is givep there that sulfuric acid is prepared by burning sulfur with a small piece of niter in strong earthen vessels. Nitric acid is prepared by distilling a mixture of saltpeter and alum; and muriatic acid from the distillation of a mixture of common salt and alum. This concludes a more or less synoptic survey of the achievements of the Indians of the ancient and mediaeval ages in the field of practical chemistry; and it can be stated without any fear of contradiction that it is by no means a poor record for that. time.' LITERATURE CITED (1) For a comprehensive account of the Indus Valley Civilization
see: "Sir John Marshall, Mohenja-daro and the Indus Valley Civilization," Vol. I & 11, Arthur Prohsthain, London, 1931. (2) IM., Vol. 11. (3) H A D ~ E LJ. D .IronSteel Ind.. 85. 1.170 (1912). H. E., and C. SCHORLEMMER,'~reitiee on ChemisROSCOE, try," Vol. 11, Maemillan & Co., London, 1907, p. 1146. FERGUSSON, ':History of Indian and Eastern Architecture," Vol. 11, p. 280. Presidential Address, Imt. Mech. Engrs., ond don, 1905. NEOGI, P., Indian Assoc. Cultivation Sn'., Calcutta, India, Bulletin 12 (1914). CU~FIMAN, A. S., J. I ~ o nSleel I d . , 177 (1912); H. Lr Chatelier. ibid.. 180. 1 For a very comprehensive account on the subject of this article special reference should be made to: P. C. RAY, "History of Hindu Chemistry," Vol. I, Chuckervertty, Chatterjee & Co., Ltd., Calcutta, 1925; and P. NEOGI,"Iron in Ancient India"; "Copper in Ancient India," The Indian Assoc. for the Cultiwtion of Science, Calcutta, 1918.
