A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c18.s8: The Jamakwala
A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c18.s8
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The Jamakwala
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We will now turn our attention to the methods of the *jamakwala*. He periodically visits the workshops of his patron, the *rungwala* from whom he obtains the necessary amount of *jamak* on the payment of a price which depends on the quality and the quantity of gold that has been coloured, as well as the loss of weight that has taken place in the articles during their make. To give an approximate idea of the commercial value of *jamak* it may suffice to state that we once purchased a *jamak* of 20 tolas of sovereign gold (which is 22 carats or 916.66 per mille fine) for one rupee only. We may also observe that the demand of *jamak* is not at present at par with the amount of its supply; and at some of the bigger *rungwala's* working-rooms, one may see big earthen jars full of this substance, collected and stored up for want of purchasers. It may be interesting to add that even in this obscure department of business, the evil genius of man has set to work, and one has to be careful in dealing with a *jamakwala*, if one is a new hand in these affairs.¹ On one occasion we happened to be defrauded and were given a substance as a *jamak* of 35 tolas of gold for what we considered the modest price of Rs. 2. But the thing turned out to be an imitation *jamak* only and all our best efforts could not discover in it the slightest trace of gold.
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¹ It may be observed, however, that a *rungwala* would never deceive a *jamakwala* in the same way as he would deceive a stranger for fear of losing credit and custom in the department of *jamak*-selling.
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Having obtained a sufficient amount of this fluid the *jamakwala* returns home. His first step is to get rid of the fluid part of the *jamak* by boiling it. For this purpose he has got large earthen vessels with wide mouths which can be placed over a fire. When almost the whole amount of water has been evaporated off, he pours out the viscous mass into an open eathern vessel and porceeds to what we shall call the second process of the *jamakwala*.
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With the solid matter of the *jamak* obtained by the first operation, the *jamakwala* mixes a small quantity of borax as well as a large amount of a substance known as *poonoor*. The weight of powdered *poonoor* that is thus added is about four times the weight of the *jamak* matter. Having thoroughly mixed these substances with such an amount of cow-dung as is required to give consistency to the material, he forms them into balls of about two or three inches in diameter. He then dries these balls and when perfectly dried they are ready for the third process.
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The *poonoor* employed in the above process is a hard quasimetallic substance that can be purchased from certain grocers at the rate of three or four seers per rupee. It is, they say, nothing but a bye-product in the operation of *rupā-pākāno* by which is meant the operation of chemically purifying silver which has been alloyed with a large amount of copper and other metals. The usual method of conducting this operation in our country is to mix up the alloy with a large amount of lead and after melting the whole mass to blow air from above. [This operation, as also the next one, is practically that of cupellation]. The pure silver, it is found, separates in the course of the operation and collects at the bottom, while the partially oxidised lead, together with the impurities which existed originally in the silver constitutes the *poonoor* of trade. We analysed qualitatively a sample of ordinary bazar *poonoor* by the wet way after dissolving it in nitric acid and found it to contain lead, copper and zinc with traces of silver and iron.
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The third process of the *jamakwala* is the main step in the reduction of gold. He scoops out on the earth in an open place a hollow of the shape of a hemisphere about a foot in diameter, and having thoroughly smoothed the interior of this hollow, he covers it with a layer of slaked lime about half an inch thick. After the lime has dried, it presents the appearance of a course white china vessel, imbedded in the earth. In this the balls prepared by the second process are placed. The *jamakwala* then forms a powerful charcoal fire over it and with two or three large pairs of bellows causes the flame to play on the mass below. The lead of the *poonoor* is soon reduced and dissolves, as it were, the reduced gold, silver and copper. A large metallic mass thus collects at the bottom of the hollow, consisting mainly of lead. The blowing is now continued as hard as possible from above and the metal being oxidised to litharge begins to be blown off. The process must be continued till the whole of the lead has passed off and a mixture of gold, silver and copper remains behind. Care should always be taken in this operation to see that the last trace of lead is thoroughly got rid of; for nothing affects so much the ductility and malleability—virtues most important for the purposes of the goldsmith—of gold as a mixture ever so little of lead. Thus "one two-thousandth part renders the metal too brittle for rolling and its very fumes produce a serious effect upon it."'¹
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¹ Maunder's Treasury of Science, Article : Gold.
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Such is the tedious length and such the laborious and complicated nature of the processes by which the *neharwala* and the *jamakwala* extract precious metal from the large heaps of rejected sweepings and dirt and bye-products of the goldsmith's workshop. But their labours have only the empirical experience of years to guide them and not the acuteness of a well trained scientific mind; and accordingly we find that a large portion of their work is directed to achieve in a laborious and round-about way an object which a slight knowledge of chemistry enables us to secure in the simplest manner imaginable.
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With a view to shorten the labours of the *jamakwala* as far as possible, we began a series of experiments, investigating the properties of the *jamak* and trying to find out the easiest mode of extracting gold therefrom. As the results of our experiments we have found that, working on ordinary plans in the wet way, we can recover an amount of gold, which is equal to, if not in all cases greater than, the quantity which the *jamakwala* can obtain by his expensive and protracted methods.
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We need scarcely give the properties and the constituents of the various specimens of *jamak* which we obtained from the bazar from time to time for experimental purposes. The way in which a *jamak* is formed having been before described in full, the results of analyses will be nothing but tedious. It will be sufficient to observe that in all cases the *jamak* was a clear greenish-yellow liquid of rather thick consistency with a large mass of grey solid matter at the bottom consisting almost wholly of soluble saline matter.
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It may be also added that among bases, silver, copper, zinc, gold, aluminium, potassium and sodium were the principal ones that were found; while amongst the acids present, nitric, sulphuric and hydrochloric were recognised in large quantities. Traces of free chlorine could also be found in some of the solution, while perceptible amounts of iron were found in almost all.
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The microscopic appearance of *jamak* may be interesting as showing the exact state in which gold exists in the solution. With this view we examined under a miscroscope (magnfying 375 times) a drop of a clear solution of *jamak* as well as an amount of the solid saline matter lying at the bottom. The appearance, in both cases was the the same, only in the latter the crystals were more numerous and closer together. The octahedra of alum with occasional facets of cubes, the long furrowed and rhombic prisms of nitre and the cubes of common salt were very prominent. Between these, in numbers far less, could be discovered long, transparent needles. These were most probably crystals of double chloride of gold and sodium which is invariably formed when a solution of auric chloride is mixed with chloride of sodium. The constitution of this substance is AuCl₃. NaCl + 2H₂O, and it is the commercial "non-deliquescent chloride of gold" which is ordinarily sold in one gramme tubes.
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Besides the above crystals, we frequently found amorphous particles, wholly or partially opaque. Those that did not transmit light at all were probably particles of dust or other earthy matter which were present in the ingredients in the shape of impurities. But there were others which transmitted a beautiful green light and these were likely to be fine particles of gold. As these were rather few in number, it might be inferred that in the jamak, gold existed chiefly in combination. It is also probable that the greatest part exists as NaAuCl₄ + 2H₂O.
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From a liquid containing such a variety of substances in solution as the jamak does, it is no doubt a difficult task to precipitate the gold which is present perhaps in the minutest quantity of all.
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The reducing agents that are mentioned by chemists as suited for reducing gold from solutions are exceedingly numerous. Of those that are practically employed, the pricipal ones are ferrous sulphate, oxalic acid, sulphurous acid metallic iron. We tried each of these in a large number of cases and found that ferrous sulphate gives the best result of all. The reaction that takes place during reduction by ferrous sulphate is sometihng like the following :—
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2AuCl₃ + 6FeSO₄ = 2Au + 2Fe₂ (SO₄)₃ + Fe₂CL₆. The gold is precipitated as a fine, heavy, black powder and easily settles at the bottom.
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At first we used the pure material obtained from the chemists for precipitating jamak; but afterwards found that the crude article of the bazar, after being dissolved in water and filtered, yields a solution which serves equally well.
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This makes the process a matter of very little expense and with an anna worth of good crystals of hirakash (the Bengali name of ferrous sulphate), a jamak containing 8 annas weight (for about Rs. 14 worth) of gold can be satisfactorily extracted.
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We are far from thinking that in our experimental attempts to extract gold, we were able to catch the whole of the material that was present in the solution. It is very probable that in the fine state of division, in which the precipitation takes place, a considerable amount of the metal is washed away in the process of collection. But this loss is due to causes of a mere physical nature and can be prevented to a large extent by the use of better and more refined instruments.
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It has, however, been ascertained that even with rough instruments the easy and inexpensive mode of wet working gives as good results as the laborious and costly method of the *jamakwala*. The indigenous worker thinks himself fortunate if the amount of gold which he extracts is of twice the value of the *jamak* from which it is obtained, and we are convinced from the results of repeated experiments that the wet method promises in general no less than twice the amount of profit with the advantage of saving time, labour and expense.