Development of Chemistry

Development of Chemistry

Chemistry is the branch of science that studies the composition, structure, properties, and reactions of matter. Science as a whole is conventionally divided into disciplines such as chemistry, physics, biology, and geology for convenience -- but the practical knowledge that eventually became chemistry is ancient, and a great deal of it developed independently in India, long before the subject had a name.

Why Chemistry Developed: Two Old Motivations

Historically, the pursuit of what we now call chemistry did not begin as a search for scientific understanding for its own sake. It grew out of two much more colourful human obsessions:

• The search for the Philosopher's Stone (called Paras in Indian tradition) -- a legendary substance believed capable of turning ordinary metals such as iron and copper into gold.
• The search for an Elixir of Life -- a preparation believed to grant immortality.

These pursuits, though never successful in their original aims, drove centuries of experimentation with metals, minerals, and reactions -- experimentation that laid the groundwork for real chemical knowledge. This phase of proto-chemistry is generally called alchemy, and a related medical tradition that used chemical preparations for treating disease is called iatrochemistry. Both flourished roughly between 1300 and 1600 CE. Modern chemistry, as a systematic experimental science, took shape later still, emerging in 18th-century Europe after centuries of alchemical tradition -- much of which had itself reached Europe through Arab scholars.

India's Own, Much Older, Chemical Tradition

Long before the European alchemical period, people in ancient India already possessed considerable practical chemical knowledge, applying it across metallurgy, medicine, and craft industries. In ancient India this body of knowledge went by several names -- Rasayana Shastra, Rastantra, Ras Kriya, or Rasavidya -- and covered metallurgy, medicine, and the manufacture of cosmetics, glass, and dyes.

Archaeological excavations at Mohenjodaro (in present-day Sindh) and Harappa (in Punjab) show that mass production of baked bricks and glazed pottery -- among the earliest genuinely chemical processes, involving mixing, moulding, and controlled heating -- was already established. Harappan artisans also produced faience (a glass-like material used in ornaments), and worked and alloyed metals such as lead, silver, gold, and copper, deliberately hardening copper by alloying it with tin and arsenic.

Textual and archaeological evidence points to a long, continuous tradition:

• The Rigveda records the tanning of leather and the dyeing of cotton between roughly 1000-400 BCE.
• Kautilya's Arthashastra describes the production of salt from sea water.
• The Charaka Samhita and Sushruta Samhita -- classical texts on medicine -- describe the preparation of sulphuric acid and nitric acid, the oxides and sulphates of metals such as copper, tin, and zinc, the carbonates of lead and iron, and the medicinal importance of alkalies.
• Ink was in documented use in India from around the 4th century CE, and paper-making was known in India by the 17th century. Fermentation was also well understood: the Vedas, Kautilya's Arthashastra, and the Charaka Samhita all describe the preparation of liquors and medicinal fermented preparations (asavas) from barks, flowers, cereals, fruits, and sugarcane.
• Classical texts such as the Atharvaveda (around 1000 BCE) mention dye stuffs — the materials used were turmeric, madder, sunflower, orpiment, cochineal and lac; other substances with tinting properties carried names like kamplcica, pattanga and jatuka.
• Glass-making has deep roots too: a number of glass objects have been found at Maski in South India (1000–900 BCE) and at Hastinapur and Taxila in North India (1000–200 BCE), with glasses and glazes coloured by the addition of metal oxides as colouring agents.
• Copper metallurgy in India dates back to the beginning of the chalcolithic cultures, and there is considerable archaeological evidence that the technologies for extracting copper and iron were developed indigenously. Remarkably, the golden gloss of the black polished ware of northern India has still not been replicated and remains a chemical mystery — these wares testify to the mastery with which kiln temperatures could be controlled.
• Excavations at Taxila indicate that ink was in use in India from the fourth century; the colours of ink were made from chalk, red lead and minimum.
• Indian metallurgists and chemists are also credited with early gunpowder-mixture formulations (described in the Rasopanishada) and, in Tamil texts, recipes for fireworks using sulphur, charcoal, saltpetre, mercury, and camphor.

Nagarjuna, Chakrapani, and India's Craft Chemists

Two names from this tradition deserve special mention — both are asked about in examinations:

• Nagarjuna was a great Indian scientist — a reputed chemist, an alchemist and a metallurgist. His work Rasratnakar deals with the formulation of mercury compounds, and he also discussed methods for the extraction of metals such as gold, silver, tin and copper. A related book, Rsarnavam, appeared around 800 CE; it discusses the uses of various furnaces, ovens and crucibles, and describes methods by which metals could be identified by flame colour — an idea chemistry still uses today in the flame test.
• Chakrapani discovered mercury sulphide, and the credit for inventing soap also goes to him: he used mustard oil and some alkalies as ingredients. Indians began making soaps on a wider scale by the 18th century CE, using oil of Eranda, seeds of the Mahua plant and calcium carbonate.

The craft side of this tradition was equally rich. The paintings on the walls of Ajanta and Ellora, which look fresh even after ages, testify to a high level of applied chemical science. Varahmihir's Brihat Samhita — a sort of encyclopaedia composed in the sixth century CE — describes the preparation of glutinous material to be applied to the walls and roofs of houses and temples, made entirely from extracts of plants, fruits, seeds and barks concentrated by boiling and treated with resins. It also gives references to perfumes and cosmetics, with recipes for hair dyes made from plants like indigo and minerals like iron powder, black iron or steel, and acidic extracts of sour rice gruel; the text Gandhayukli describes recipes for making scents, mouth perfumes, bath powders, incense and talcum powder.

Ancient India's Atomic Theory

The idea that matter is ultimately built from indivisible units also has an Indian origin. Acharya Kanda (born around 600 BCE, originally named Kashyap) is regarded as the first proponent of an atomic theory anywhere: he proposed that all substances are made up of extremely small, indivisible particles he called Paramanu, which he described as eternal, indestructible, spherical, imperceptible to the senses, and always in motion. He held that different classes of substances are made of different varieties of these particles, and that they combine -- in pairs, triplets, and other combinations, driven by unseen forces -- to form the matter around us. This is a strikingly early anticipation of atomic theory, proposed roughly 2500 years before John Dalton (1766-1844) formulated the modern atomic theory that the rest of this book builds on.

Ancient Indian medicine also anticipated ideas we would today associate with nanotechnology: the Charaka Samhita discusses reducing the particle size of metals to prepare medicinal bhasmas, and modern analysis has confirmed that these bhasmas do indeed contain metal nanoparticles.

From Alchemy to a Modern Science

After this long alchemical and iatrochemical period, both traditions eventually declined in India -- accelerated in the 20th century by the spread of Western medicine. The older Ayurveda-based pharmaceutical tradition persisted for a time but gradually declined as well, and it took roughly 100-150 years for Indian science to adopt the newer techniques of modern chemistry. By the mid-nineteenth century, European scientists started coming to India, and modern chemistry began growing here through the later part of the nineteenth century.

From this whole discussion one message stands out: chemistry deals with the composition, structure, properties and interaction of matter, and is of much use to human beings in daily life. These aspects are best described and understood in terms of the basic constituents of matter — atoms and molecules — which is why chemistry is also called the science of atoms and molecules. Can we see, weigh and perceive these entities? Is it possible to count the number of atoms and molecules in a given mass of matter, and have a quantitative relationship between the mass and the number of these particles? This chapter answers some of these questions, starting with how matter is classified and how its physical properties are described quantitatively, with suitable units.