A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c18.s7: The Neharwala
A History of Hindu Chemistry from the Earliest Times to the Middle of the Sixteenth Century A.D. v1.c18.s7
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The Neharwala
v1.c18.s7.1
Now and then the *neharwala* makes his appearance in the goldsmith's workshop, in order to obtain the collected sweepings and other refuse of the rooms, The interval of time varies from one to three months according to the nature of the work that carried on in the rooms as well as to the amount of gold that is manufactured into ornaments. It is useful to state here that every day before work is commenced, the room is swept very clean and the sweepings, instead of being thrown away, are carefully stored up in a corner.
v1.c18.s7.2
The heap of dust and rubbish thus accumulated from day to day is the chief object of the visit of the *neharwala*. Having inquired as to the amount of gold that has undergone manipulation since the last disposal of sweepings or *nehar* (from this the *neharwala* gets his name) as well as the nature of the articles that were manufactured, he proceeds to settle the price which depends chiefly on these conditions. The *nehar* of twenty tolas of good gold manufactured into articles, which required drawing, beating as well as soldering would generally be disposed of for a single rupee. It may be interesting to observe that a goldsmith, however dishonest in other respects, would never deceive a *neharwala* by selling to him a heap of ordinary rubbish for fear of losing credit and custom in the department of *nehar*-selling.
v1.c18.s7.3
The next thing that the *neharwala* wants to obtain is the heap of rejected crucibles.
v1.c18.s7.4
It has been stated before that indigenous crucibles cannot be employed more than once for melting purposes, and hence the number of waste crucibles is not small in our goldsmith's workshop. The nature of the crucibles and the amount of metal melted in each, together with the qualities of the gold, settle the price. We have seen a score of crucibles of average size selling for eight annas.
v1.c18.s7.5
If the goldsmith’s shop is large, the soot hanging from the ceiling and walls is also purchased.
v1.c18.s7.6
The last thing that the *neharwala* asks the shopkeeper is whether that day he would give a *taljhar*, by which is meant if he would allow the workmen’s mats to be removed and shaken and the space below the mats swept. This operation is ordinarily perfomed once a year. The sweepings thus obtained are again valued. And after paying the prices the *neharwala* returns home with his heavy load, which sometimes reaches the respectable weight of 50 or 60 pounds.
v1.c18.s7.7
The first thing that the *neharwala* does with his materials is to crush them fine. This is only necessary when earthen lumps of large size are formed and mixed up with the *nehar* in considerable numbers and is dispensed with in most cases where the large pieces are few in number and can be picked up and thrown away.
v1.c18.s7.8
The second process is to throw the curshed materials into a big earthen pot in which the *nehar* remains immersed in water for a certain number of days, depending on the quality and quantity of the *nehar*. The object of this is to reduce fragments of clay to a fine state of division by which particles of gold that might otherwise remain imbedded inside the mass of earthy lumps are at once exposed to view.
v1.c18.s7.9
The next and the main operation is that of working. The thoroughly soaked *nehar* is put in large earthen vessels and more water is added if necessary. The mass is then thoroughly stirred and the lighter earthy material which yet floats when the heavy metallic matter has settled in the bottom, is taken off. By the repetition of this process the solid matter is reduced to a very small bulk. It is then allowed to settle and the water is slowly poured off. The moisture that yet remains is dried up either on fire or in the sun.
v1.c18.s7.10
When several *nehars* have been separately washed in the preceding way, the remnants of all the washings are mixed together and the mixture in washed once again. This operation is exactly like the preceding but is carried on more carefully and in better vessels. When it has been completed, about one-quarter of the mixture may be perceived to consist of metallic substances.
v1.c18.s7.11
Among the metals present in this mixture, iron is often found and, as its presence is extremely undesirable when the meterials are placed on the crucible for melting, it is generally got rid of at this stage. Formerly this was done by picking up the separate bits of iron by fine pincers, but now-a-days the magnet is almost universally used for the purpose.
v1.c18.s7.12
The next process is that of melting. This is carried on in the ordinary way, care being taken to procure a crucible big enough for the purpose. The earthy matter sticks to the sides of the crucible, while the metallic portion melts and falls to the bottom. A mixture of gold, silver, copper and zinc is thus obtained.
v1.c18.s7.13
The old method of obtaining pure gold from such a mixture as this is said to have been as curious and interesting as certainly it was laborious and protracted. The alloy was first of all beaten into leaves of extreme thinness, about 5 inches square in size. Each leaf was then covered with a thin layer of a paste of brick dust and common salt. The leaves were finally arranged one above another and exposed to the heat of fire. After a certain number of days, depending on the nature of the alloy and the temperature of the fire, the gold was found to be very nearly pure.
v1.c18.s7.14
This method has now, however, been entirely superseded by the far easier and more economical process of treating the alloy with strong nitric acid.
v1.c18.s7.15
For this purpose, however, the metal must be obtained in a fine state of division. This is done rather ingeniously by melting the material and, while molten, by suddenly dropping it in water. By this means the metal is at once reduced to a fine powder without the expenditure of any manual labour in the way of hammering. Care, however, should always be taken to see that the vessel of water in which the molten metal is dropped has a wide mouth. On one occasion, at which we were present, the liquid metal was poured into a narrow-mouthed vessel, and the steam suddenly generated was so great and powerful as to very nearly cause an explosion.
v1.c18.s7.16
The extraction of gold from rejected crucibles is done much in the same fashion. These are pulverised and treated in the same way as ordinary *nehar*. Sometimes the powders of crucibles are mixed up with the common *nehar* to avoid the necessity of a separate series of operations, but more frequently the smallness of their bulk induces the *neharwala* to treat them separately.