A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c13.s1: Alum and Green Vitriol

A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c13.s1

Language: English

Alum and Green Vitriol

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Dutt speaking of alum states: "it is not mentioned by Susruta, in his list of metallics, but later writers give its synonyms and uses." This is evidently incorrect. Alum, with green vitriol, is distinctly referred to in the Susruta, *e. g.*:

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कासीसं त्रिवृतादली हरितालं सुराष्ट्रजा।

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Sūtra. xxxvi, 12.

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In the above sloka *surāshtrajā*, lit., begot of Surāshtra (modern Surat), is used in the sense of alum. From the ancient times the "earth of Surat" has been known to yield this mineral. Amara Simha in his Lexicon, written sometime between 400-600 A. D.,¹ gives among others the following synonyms of alum:—*kāmkshī*, *tuvarī* and *surāshtrajā*. "Rasaratnasamuchchya" also gives the same synonyms. (Bk. III., 59-62). The manufacture of alum survives to our own days, as the following description will show:

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¹ The lowermost limit of his age may be taken about 948 A. D. as made out from an inscription in Budh Gaya.

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"Alum shales, so called, are of rare occurrence in peninsular India, and, so far as it known, the only considerable native manufacture is situated in Rājputana; but as will be gathered from what follows, the tertiary rocks of the extra-peninsular regions often contain such shales.

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“In two localities lumps of alum...occur naturally in sufficient abundance to be a regular article of export.

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“Alum is principally used as a mordant in dyeing, but as a drug its employment is extensive in India.

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“BEHAR.—Captain Sherwill in 1846¹ stated that a small quantity of alum was manufactured from slates obtained in the district of Shahabad; these rocks, it is believed, belonged to the Bijigrah pyritous shales of the Kaimur group of the Vindhyan series.

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¹ Journ. As. Soc. XV., p. 58.

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“The alum was sold at the high price of one rupee per tola; it was identical with the salajit of Nepal. Copperas or iron sulphate is obtained in the same region, which is situated to the north of Rotasgarh, and to the west of the Sone.

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“Rājputana, Khetri, and Singhana.—In connection with the copper mines at the above localities there are manufactories which turn out considerable quantities of blue vitriol (copper sulphate), copperas (iron sulphate), and alum. The process has been very fully described and illustrated by Colonel Brooke. In 1864 there were twenty of these factories at Khetri and about double the number at Singhana. The broken shale from the mine which contains the salts is placed in earthen *gharas*, together with the crusts from the refuse heaps of previous lixiviations and water is added. The *gharas* are arranged on ledges prepared for the purpose on the heaps of refuse, as will be seen by reference to the wood-cut (*vide illustrations*).

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"Each charge of shale is exposed to three changes of water and the water itself is changed from one *ghara* to another till it has taken up the sulphates from seven different steepings. It is then of a thick dirty-bluish colour and is taken to the boiling house, where it is boiled in earthen *gharas*; when sufficiently concentrated it is left to cool, and thin sticks being introduced the blue vitriol crystallizes on them. The mother liquor is then poured off and again boiled, and on the addition of saltpetre, the alum crystallizes at the bottom of the vessel. The residual sulphates still in solution, are allowed to crystallize out by exposing the mixture to the sun.
* * * * *

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“CUTCH.—There are numerous accounts of the manufacture of alum in Cutch. The earliest is by Captain Mc Murdo, who states that before 1818 the exports of alum amounted in some years to several hundred thousand maunds, which chiefly went to Guzerat and Bombay to be employed in dyeing. The following account by Mr. Wynne is the most recent and complete. The site of the operations is at Mhurr or Madh.

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“The rock containing the materials is a pyritous dark-gray or black shale, which is in close association with a soft aluminous pseudo-breccia of the sub-nummulitic group.

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“This shale is excavated from pits and is exposed for four months, a slow combustion taking place owing to the decomposition of the pyrites.

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“It is then spread in squares resembling salt pans and sprinkled with water. After about 12 days it consolidates into efflorescing mammillated crystalline plates or crusts called *phitkari-ka-bij* or seed of alum. These crusts are boiled in large iron vessels (luted inside with lime), together with saltpetre (or other potash salt), in the proportion of 15 of ‘alum seed’ to 6 of the latter; when it has settled, the liquor is placed in small earthen vessels somewhat the shape of flower-pots, and crystallization takes place in three days. These crystals are again boiled one or more times to concentrate the solution, which is finally ladled into large thin bladder-shaped earthen *mutkās* or *gharās* with small mouth; these are sunk into the ground to prevent their breaking, and in five days the alum is found crystallized in masses. The vessels are then broken and the alum is stored.

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"Alum is also manufactured from the water of a hot spring north of Mhurr. The impure saltpetre, which is employed to supply the second base in the above-mentioned manner, is obtained by lixiviation of village refuse." (Ball's "Economic Geology", pp. 431-33).

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"IRON SULPHATE.—The green vitriol or copperas of commerce, which is known to the natives as *kahi* and *hara kāsis*, is produced principally from the so-called alum shales from which alum is prepared. As is the case also with alum, copperas is found sometimes as a natural exudation upon alum shales and other rocks which include iron pyrites.

Linked texts (3)

Rasaratnasamuccaya — Vāgbhaṭa (alchemist), Sanskrit
Suśrutasaṃhitā — Suśruta & Nāgārjuna (siddha/alchemist), Sanskrit
Tibetan translation ('Chi med mdzod) — Classical Tibetan