The technology of glass making was possibly an accidental product during some
type of metallurgical or similar operation. The term "glass" includes
a wide range of products that are characterized chiefly by their desired rate
of cooling from a state of fusion to a solid state. But it should be in such
a way that it does not undergo crystallization during the process of cooling
from fusion to the solid state. Generally, glass is produced by melting a mixture
of silica (sand: about 75%), soda (about 15%) and calcium compound
(lime: about 10%) with the desired metallic oxides that serve as colouring agents. Although, these glassy products are a mixture of silicates with different compositions, they are better known their physical properties. Some glasses, such as borate and phosphate glasses, are also made for specific purposes.
Subbarayappa, the indefatigable historian of Indian science, has come out with a summary of glass technology in ancient India, in a global context. We summarise the main points below.
The Egyptian and Mesopotamian regions (particularly ancient Assyria) had glass-makers even in the third millennium BC. There is evidence of glass beads from the cemeteries of Ur III (c. 2100 BC) and also from Assur under the Ziggurat (c. 1800 BC) in Mesopotamia. Some archaeological evidence indicates that there were glass-producing factories in Egypt during the XVIII Dynasty in the reign of Amenhotep II (1448-1420 BC). Some remains of a glass house and fragments of glass in several stages of manufacture have been found at Tell el Amarna (1450-1400 BC). A series of Assyrian clay tablets, which are now preserved in the British Museum, London, also provide some details of glass making at that time. However, glass industry began to be developed only during the Graeco-Raman times, especially by the Romans who were well versed in the art of glass blowing and sheet making. Glass also started to be used as a medium of artistic objects, from about the 11th to 16th century AD in Europe. Venice was regarded as the home of the art of fabricating exquisite glassware and art objects.
It seems that the Indus Valley Civilization or Harappan settlements did not have glass, although Harappans had contacts with the Mesopotamian region. Perhaps the Harappans preferred faience, which was a type of proto-glass. The Painted Grey Ware (PGW) Culture of the Ganga valley (c.1000 BC) did have elegant glass beads. There is some archaeological evidence in the form of glass beads found at Maski, a Chalcolithic site in the southern Deccan; it is older than the beginning of the first millennium BC. Kaca is a Sanskrit term used for glass by the Vedic text, Satapatha Brahmana. It was, however, in the three or four centuries before and after the Christian era that Indian glass industry began to gain momentum, although its knowledge being limited to beads, bangles, ear-reels, 'eye-beads' and various types of similar small objects. About 30 archaeological excavated sites in different regions of India have produced several glass objects in different colours such as green, blue, red, white, orange and some other shades. In certain places, a few tiles and fragmented parts of vessels also have been found.
Black and brownish coloured glass beads found at Hastinapur (c. 1000 BC) are mainly of soda-lime-silicate composition with traces of phosphates and potassium, as well as with varying amounts of iron compounds which are responsible for their colour. A number of glass beads of different shapes and colours like blue, red, green, amber, orange and black, dark green, ear-reels with a floral design, 'eye-beads', bangles and seals have been found in the Bhir mound at Takshashila (sixth-fourth century BC). Takshashila was an important centre of the North-western province of the Mauryan Empire. The later town of Sirkap in this area shows evidence of international trade in glass as it has yielded remnants of foreign glass objects like mosaic and milleflori ((it is a Latin word that stands for "thousand flowers"), lace glass, ribbed and swirled ware, blue and white cameo. The milleflori with its floral and cellular structure was generally produced by Roman glass-makers. Some glass flasks unearthed at Sirkap do not seem to be indigenous, but appear to be from the Graeco-Roman culture area. Similarly, the technique of making 'stratified eye-beads' of glass found at Sirkap, was possibly an imported one. Among the protohistoric archaeological sites, which have produced glass objects, special mention needs to be made of Ahichchhatra, Maheswar, Nasik, Nevasa, Prakash, Ter, Kaundinyapura, Ujjain, Sravasti, Nalanda and Kopia, and in South India, Brahmagiri, Maski and Arikamedu.
The data available about the technique of glass production in India is deficient in quantity. A circular oven of about 75 cm in diameter and 37 cm in depth, which has been found in Nevasa is made of burnt clay and is an open-fired type of furnace.
Kopia, situated on the bank of the river Anoma in the Basti district of Uttar Pradesh, had perhaps a glass factory as a large number of glass objects were found there (c. third century BC to third century AD). Blocks of glass, weighing more than 50 kg and measuring 45 cm x 30 cm x 23 cm were found at Kopia. These probably give an indication about the massive scale of operations in vogue at that time.
Indian glass-makers had well developed technological skills in the manufacture of beads, bangles and a few other articles. After observing the various objects excavated at different sites, it may be inferred that glass-makers employed methods such as moulding, folding, twisting and double-stripping. Perhaps, a method known as wire-winding method was also adopted for preparing beads of various types. On the basis of various beads found at Brahmapuri, it is indicated that the beads were probably made by this method by coiling the fused glass rod around a wire or spoke, and twirling it to obtain the desired shapes. The technique of preparing the 'multiple-wound beads' of opaque glass of different colours was also known. The archaeological excavations in Brahmapuri and Kolhapur in Maharashtra State (second century BC-second century AD) reveal that there was also a glass industry in that area, especially for the production of lenticular beads. Some drawn cylindrical beads were also noted in the Kolhapur area. Even in the sixteenth-seventeenth century AD, the Portuguese used to trade in these glass objects with East Africa. Some Satavahana sites have produced folded beads, twisted beads as well as cane-glass beads from Arikamedu, Nevasa, Ter, Prakash etc. in the Deccan region.
Monochrome as well as polychrome bangles were produced with great care. Certain beautiful patterns were also applied on them through delicate expertise. Though jewellery glass technology was well developed in India, glass vessel making was not popular. Flasks, bowls and even bottles which are found in some archaeological sites, by and large, were made in the Mediterranean (Roman) region with which India had commercial contacts from ancient times. Similarly, the milleflori glass with floral designs, found near Takshashila and Ahichchhatra (UP) appear to be of Roman origin.
Persian glass-makers brought their craftsmanship to India and were engaged in the production of glass dishes and dish covers, spittoons, flat-bottomed vessels, mirrors and other objects like tiles and ear reels. As a result, the artistic glass specimens of the Mughal period, when glass industry received royal patronage, show Persian influence. It shuld however be noted that glass-tiles appeared to be in use in India even as early as the third century BC during the reign of Asoka.
The chemical analyses of glass objects from over 15 sites of different parts of India clearly indicate that Indian glass-makers knew the significance of metallic oxides and other chemical compounds in imparting the desired colours to the glass objects. They also used minerals containing iron like haematite, copper, cobalt, manganese, aluminium, and lead along with silicates in a calculated manner and in appropriate quantity for the production of various types of glass beads, bangles, tiles and bottles.
A distinct role was played by transparent glass of high quality in the history of science, especially from the 17th century onwards. We have to think about lenses and mirrors, which on one hand gave us the telescope, the use of which opened up new vistas in astronomy, while on the other, the microscope that provided rare insight into the invisible world of minute organisms. Therefore, we can say that the glass apparatus of various kinds played an important role in chemistry and enabled chemistry to become a branch of modern science, with its verifiability and reproducibility in a quantitative way.
There was commercial contact, now and then, between India and the Greaco-Roman
world. Some foreign glass objects that were found at Arikamedu (first-second
century AD) reveal not only such contacts but also give a view about their wide
use in the Gracco-Roman culture. Yet, glass played an insignificant role in
the Indian socio-cultural life. They did not generally choose to employ glass
vessels for their chemical operations involving distillation, steaming, mild
heating etc. Thus their apparatus did not permit them to observe the way in
which the chemical operations were taking place within the apparatus, as their
apparatus by and large were earthen. Such an observation would have provided
the rasavadins (alchemical-cum-medicinal chemists) with insights and
stimuli leading to an appreciation of the chemical processes as well as the
fabrication of glass apparatus, as these placed chemistry on a solid foundation
in the West in the 18th century. At that time the West had developed some tank
furnaces for large-scale commercial production of glass of different shades
as well as pot furnaces for the production of smaller quantities of glass. The
glass fabricating methods were also standardized; especially, by using the finest
raw materials silica and compounds of sodium, magnesium as well as calcium.
They also produced optical glass with the required degree of hardness, desired
refraction and depressive powers. Later on, lenses, prisms, mirror, glass tubes
and vessels were developed and they played an important role in the new experimental
methods that led to the growth of physics, chemistry and biology.
At the end I would like to make some observations in a wider perspective.
Most of us often wonder as to why despite more than 1500 years of head-start over Europe, India did not usher in to the modern scientific and industrial revolution. In the 18th Century, India was far advanced than Europe in surgery, medicine, maths, astronomy, hydraulics, architecture, metallurgy etc. I think the story of glass may give us some clues. Though India had close trade and cultural relations with West Asia where glass technology was known even in the 3rd millennium BC, the Indus Civilization did not go for it. It chose the proto-glass faience. Though India was advanced in chemistry in historical times, it preferred to carry out chemical reactions in the apparatus made of clay and not glass, this did not allow close observations of the reactions taking place. In India, glass did not enjoy a social status similar to that of metals and pottery, which were preferred to glass vessels, especially on religious occasions and in iatro-chemical practices as well. In Indian ethos, the importance of glass was hardly recognized, which probably came in its way of development of modern science in India. Indian craftsmen mastered the glass technology, but the society accepted it only for decoration and ornaments, but not for domestic and chemical wares. This taboo continues even today: village elders as also old ladies do not drink water or tea from glass tumblers; they prefer metal glasses. This is reflected even in middle class homes who can easily afford gas oven; instead, they prefer charcoal fire for cooking. Perhaps there was always some resistance to new technology, which came in the way of India beating the West in scientific revolution.
1. Dikshit, M.G.History of Indian Glass, University of Bombay, Mumbai
2. Subbarayappa, B.V.: 'Chemical Practices' in A Concise History of Science in India, Indian National Science Academy, New Delhi, 1991; reprint 1993, pp. 291-6.
3. Sen, S.N. and Mamata Chowdhury: Ancient Glass and India, Indian National Science Academy, New Delhi, 1985.
4. Ghosh, Monoronjan: 'The Use of Glass in Ancient India', Journal of the Bihar and Orissa Research Society, 10, pp.194-201.
5. Annual Reports of Archaeological Survey of India: 1908-1909; 1911-12; 1912-15; 1919-20; 1920-25; 1930-34 (see sections dealing with archaeological glass objects).
6. Indian Archaeology: A Review: 1953-60; 1960-68 (see sections concerning glass).
7. Lal, B.B. (Dr): 'Examination of Some Ancient Indian Glass Specimens', Ancient India, 8, 17-27, 1952.
8. Lele, S.R.: Glass-making in Ancient India, Indian Ceramic Society, Mumbai, 1967.
9. Prakash, Satya and Rawat, N.S.: Chemical Study of Some Indian Archaeological Antiquities, Allahabad, 1965.
Subbarayappa, B.V. (Ed.) 1999, Chemistry and Chemical Techniques in India.
Project of History of Science, Philosophy and Culture, Vol. IV, Part 1. PP.