A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v2.c33.s2: The Metals and Their Loss in Weight After Calcination
A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v2.c33.s2
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The Metals and Their Loss in Weight After Calcination
v2.c33.s2.1
Very vague ideas prevailed among the Hindu philosophers on the constitutions of a metal and its fate after calcination. We are reminded of the diversity of opinion in Europe before the time of Lavoisier. A metal like every material substance was supposed to be formed of one or more of the five bhūtas; in fact the earthy or saline element was taken to be predominant in it,[*] and hence it felt itself so readily to calcination.[†] It should be noted here that by "bhūta" was understood not so much an *element* in the modern connotation of the term as certain qualities of individual substances. Even mercury was regarded as composed of the five bhūtas.[‡] When a metal was submitted to calcination some of its component bhūtas escaped, leaving the earthy or saline portion behind; hence the ash (calx) must weigh less than the original metal itself.
v2.c33.s2.2
[*] पार्थिवाः सुवर्णरजतमाणिक्यमुक्तामनःशिलामृतकपालादयः । Ch. I., 24. Again in Ch. XLVI (Sūtra) 345 et seq. the metals are included among the saline ingredients.
v2.c33.s2.3
[†] Cf. "For some maintain that gold is solid light, or, at least that the chief ingredient is light, which is rendered solid by mixture with some particles of earth. Were it mere earth it might be calcined by fire strongly urged."—Vol. I. p. 9.
v2.c33.s2.4
[‡] पञ्चभूतात्मकः सूतस्तिष्ठत्येव सदाशिवः । इति रसाणवे ।
v2.c33.s2.5
There is, however, no direct reference to be met with anywhere as regards the quantitative aspect of the question so clearly established by Lavoisier.
v2.c33.s2.6
The proportion of loss which a metal undergoes on ignition was made the basis for determining its purity and we find in the law-books an arbitrary scale fixed. Thus according to Yājñavalkya, "gold is unaffected by fire, while one hundred parts by weight of silver, tin and copper lose (lit. undergo decay to the extent of ) two, eight and fifteen parts respectively.* This is to be taken as referring not to the roasting (killing) of a metal but simply as allowance made to goldsmiths and other artisans for loss incurred in the shape of dross &c. when it is melted in a crucible.
v2.c33.s2.7
That copper, lead, tin and other base metals (हीनधातवः) when repeatedly calcined are completely reduced to their calces was well known as will be seen throughout the body of the texts. The passage from Rasendra-chūḍāmani (p. 14) deserves some notice. Lead of the weight of 30 palas is to be calcined till its weight is reduced to a karsha (=1/4 pala). Even if it be calcined now one thousand times, it will not undergo further reduction in weight. Our author evidently had his experience of lead derived from argentiferous galena, which would leave a residue in the shape of a "button" of silver after the lead had been cupelled off.*
v2.c33.s2.8
∗ अग्नौ सुवर्णमक्षीणं द्विपलं रजते शते । अष्टौ वपुषि सीसे च ताम्रे पञ्चदशायसि ॥
v2.c33.s2.9
∗ Similar confusion prevailed in Europe up till the end of the 17th century. The following extract from Robert Boyle's "Concerning the Unsuccessfulness of Experiments" will make the point clear.
v2.c33.s2.10
"Having, upon occasion, had the curiosity not long since to visit some mines of lead and other metals, I find that there is a great difference, and discernible even to the eye, betwixt the several ores ; for instance, of lead, some of which I can show you so like steel, and so unlike common lead-ore, that the workmen upon that account are pleased to call it steel-ore, which being of more difficult fusion than ordinary, they are wont to mix it with other ore, which they call firm-ore, to facilitate the melting of it. And I likewise took notice of an ore, which for its aptness to vitrify, and serve the potters to glaze their earthen vessels, the miners call pottern-ore, and sell it (at least where I saw it digged up) dearer than other ore, from which it differs both visibly enough, and as the workmen affirm in divers other (and those less obvious) qualities ; and yet all these ores, after fusion, do pass indiscriminately under the name and notion of lead. In which therefore it is no wonder, that severer inquiries find a great deal of disparity. I remember I did not long since cause some lead-ore to be tried, which being the most promising that ever I saw, made me suppose it might contain some considerable quantity of silver : but though it proved so rich in lead, as to yield after the rate of seventy pound to the hundred, yet one of the most expert artists in Europe could not extract one grain of silver out of it ; whereas the lead of very many mines, being skilfully examined, will leave behind it, upon the test, a proportion of pure silver. And though this quantity of silver be not considerable enough to make such mines as yield it pass for silver mines
Linked texts (4)
- Carakasaṃhitā — Agniveśa (Āyurveda) & Caraka, Sanskrit
- Rasārṇava — Sanskrit
- Rasendracūḍāmaṇi — Somadeva (alchemist), Sanskrit
- Yājñavalkyasmṛti — Yājñavalkya, Sanskrit