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Copper in Ancient India c10.s3: Earlier Discovery of Zinc in India Than in Europe

Copper in Ancient India c10.s3

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English

Earlier Discovery of Zinc in India Than in Europe

c10.s3.1

Zinc appears to have been prepared in India, as has been stated above, at a much earlier period than in Europe. In Europe "the word zinc is first found in the writings of Paracelsus (16th century) who has pointed out that zinc was a metal." According to W. Hommel, however, "the name zinc is erroneously attributed to Basil Valentine and the discovery of the metal to Paracelsus, for the identification of zinc as the metal from blende was only accomplished by Homberg in 1695."¹

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It would even appear that the acquaintance of European alchemists with zinc began when it was being imported from India or at any rate from the East Indies by Dutch merchants in the 17th century, as Libavius "who was the first to investigate the properties of zinc more exactly, although he was not aware that the metal was derived from the ore known as calamine" stated "that a peculiar kind of tin is found in the East Indies called caloem. Some of this was brought to Holland and came into his hands."¹

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¹ Roscoe and Shcorlemmer, Treatise on Chemistry, Vol, II, pp. 643-644.

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In India, zinc appears to have been extracted from calamine (Sanskrit "rasaka" or "kharpara") by heating it in a covered crucible with substances rich in carbon at least as early as the 7th century. We find the description of a process of the extraction of "essence of calamine" in the alchemical work of the 7th century named Rasaratnākar, ascribed to Nāgārjuna which gives the following recipe—calamine is macerated, amongst other things, with carbonated alkali lac, soot and borax and then heated in a covered crucible in a furnace when an essence of the colour of tin is obtained.¹

c10.s3.5

In this process carbonated alkali and the carbon obtained by the destructive distillation of such carbonaceous substances as lac &c. supply the reducing agents in the extraction of zinc from calamine. In later alchemical treatises the covered crucible is provided with a tubulure so that the completion of the reaction may be ascertained when the blue flame at the mouth of the tubulure suddenly changes to white owing to the volatilisation of zinc. The description of the distillation of zinc in tubulated covered retorts or crucibles in *Rasaratna-samuchchaya*, *Rasaprakāsh-sudhākar* and other alchemical treatises of the 12th and 13th centuries is "so exact that it will bear repetition in any text-book of metallurgy." We give below the description of the process as given in *Rasaratna-samuchchaya*²:—"Rub calamine with turmeric, the chebulic myrobalans, resin, the salts, soot, borax and one fourth its weight of semicarpus anacardium and the acid juices. Smear the inside of a tubulated crucible with the above mixture and dry it in the sun and close its mouth with another inverted over it and apply heat..

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1. क्षार क्षइज घान्दाञ्ज रसकं भवितं दडं । उचीलाक्षा तथा पथ्या भूखता धूमसंयुतम् ॥ मूकलूषायत घ्रात टणेन समन्वितम् । सत्वं कुटिलसङ्कशं पतते माल सशय ॥ Rasaratnākar.

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हरिद्रासिकलालारसिन्धु धूमैः सटङ्गणैः । सारुकैरैव पादांशै सास्त्रैः संमही खर्पर ॥ खिजं घ्नाकमूषां शोषयित्वा निरुध्य च । मूपा मूयोपरि खर्परं प्रधमेत् ततः । खर्परे प्रकृते ज्वाला भवेन्तीलासिता पदि । तदा सन्दज्ञतो मूपां घृत्वा कृत्वा त्व धोमुखीम् ॥ शमैरख्याखयेद् भूमौ यन्त्रा वालं अ भज्येत । वङ्गाभं पतितं सत्वं समादाव नित्योजयेत् ॥ Rasaratna-samuchchaya, II, 157—161.

c10.s3.8

When the flame issuing from the molten calamine changes from blue to white, the crucible is caught hold of by means of a pair of tongs and its mouth held downwards and it is thrown on the ground, care being taken not to break its tubulure. The essence possessing the lustre of tin which is dropped is collected for use.” The chemical reaction that takes place in the above process is easily understood and is the same as takes place in the modern process of the extraction zinc. In the first place calamine is converted by heat into zinc oxide, which when heated with soot and carbon obtained by the destructive distillation of carbonaceous substances such as lac is converted into metallic zinc whilst carbon monoxide is evolved which burns at the mouth of the tubulure with the characteristic bluish flame. When the reduction is complete and the zinc vaporises, the bluish flame is replaced by the white flame of burning zinc vapour. At that time the molten zinc is poured out from the crucible by holding its mouth downwards.

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Similar descriptions are to be found in other alchemical works of this and later times, showing that by the 13th century the process was quite common, though it must be conceded that the process was discovered as early as the 7th century, if not earlier.

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The Indian process of distillation of zinc described above is thus an anticipation by several centuries of the old English process termed ‘distillation of zinc per descensum’, in which “the mixture of ore and coal was heated in curcibles closed at the top, but having a pipe leading from the bottom stopped by a wooden plug. The latter was quickly carbonised, thus becoming porous and allowing the vapour of the reduced zinc to pass down the tube where it was condensed.”¹ In the Indian process the molten zinc is poured out.

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¹ Roscoe and Schorlemmer’s Treatise on Chemistay, Vol. II, p. 645.

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Zinc was recognised as a metal for the first time under the designation of its modern name, *Jasada*, as pointed out by Dr. Ray, in the lexicon ascribed to king Madanapāla written about the year 1374 A.D.¹ But this fact was not universally recognised until the sixteenth century. Sārangadhar, the well known alchemist has not mentioned zinc in its list of nine metals. Rasendrachintāmani, Rasakalpa, Nityanātha's Rasaratnākar and other alchemical works of this period do not mention zinc in the list of metals. It is only in the works of the sixteenth century that zinc finds a permanent place in the list of metals. Dhātukriyā, Bhābaprakāsha and other alchemical works of this century mention it in the list of metals and the Ayeen Akbari also mentions "ruh-i-tutia" (essence of white tutia) or zinc as one of the seven metals. It must therefore be acknowledged that though zinc was universally distilled in India by the 13th century and its metallic nature recognised by Madanpāla in the fourteenth century, it was not until the sixteenth century that it was universally recognised as a metal. Even in this respect India's knowledge of the metallic nature of zinc was more in advance than in contemporary Europe as "the identification of zinc as the metal from blende was only accomplished by Homberg in 1695."²

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¹ जमदं वङ्गसदृशं दितिहेतम—Madanpāla-Nirgghantu.

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² It is often remarkable how truth is arrived at by different peoples through almost identical channels of surmises and mistakes. We have already pointed out that in India a good deal of confusion existed regarding the chemical nature of zinc from the fourteen to the sixteenth century. In Europe also "the exact nature of zinc and its ores continued doubtful during the seventeenth century. Glaubey it is true, stated that calamine was an ore of zinc, but Lemery, so late as 1675, believed that zinc was identical with bismuth, and Boyle often employed the names zinc and bismuth indiscriminately for the same substance." Then again in India there was a good deal of confusion for a long time regarding the equivalents for zinc and its ore calamine (rasaka or kharpara). Both the equivalents of calamine were used to designate the ore as well as the metal. In Europe also "the word zinc occurs in many subsequent authors and sometimes it is employed to denote the metal, at other times the ore from which the metal is obtained" It would be rash to suggest from the similarity in the development of the ideas regarding the chemical nature of zinc that Europe borrowed them from India. It often happens that different countries often arrive at a particular truth after pursuing a similar train of reasoning.

c10.s3.15

1. जमदं वङ्गसदृशं दितिहेतम—Madanpāla-Nirgghantu.
2. It is often remarkable how truth is arrived at by different peoples through almost identical channels of surmises and mistakes. We have already pointed out that in India a good deal of confusion existed regarding the chemical nature of zinc from the fourteen to the sixteenth century. In Europe also "the exact nature of zinc and its ores continued doubtful during the seventeenth century. Glaubey it is true, stated that calamine was an ore of zinc, but Lemery, so late as 1675, believed that zinc was identical with bismuth, and Boyle often employed the names zinc and bismuth indiscriminately for the same substance." Then again in India there was a good deal of confusion for a long time regarding the equivalents for zinc and its ore calamine (rasaka or kharpara). Both the equivalents of calamine were used to designate the ore as well as the metal. In Europe also "the word zinc occurs in many subsequent authors and sometimes it is employed to denote the metal, at other times the ore from which the metal is obtained" It would be rash to suggest from the similarity in the development of the ideas regarding the chemical nature of zinc that Europe borrowed them from India. It often happens that different countries often arrive at a particular truth after pursuing a similar train of reasoning.

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