Minerals and Metals in Ancient India v1.c11.s5: Furnaces and Crucibles
Minerals and Metals in Ancient India v1.c11.s5
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Furnaces and Crucibles
v1.c11.s5.1
Any discussion about the minerals and metals may not be complete without the mention of kilns, furnaces and crucibles which were found at Mohenjo-Daro. Actually both the excavators viz., Marshall and Mackay found a good number of kilns in their respective areas; but, both of them have expressed their doubt regarding their proper functions. These might have been used for the baking of potteries and sometimes may be for metallurgical works. Let us discuss about those kilns which were unearthed by excavation.
v1.c11.s5.2
While digging in the HR areas of Mohenjo-Daro, Marshall found few houses. In the House VII of this area a pottery kiln came to light. It has an oval plan and is surrounded by a thin wall of a single course of burnt bricks. The kiln is 7 ft long and has a narrow mouth. At the further end is a little wall curved at the top, the exact purpose of which is not clear. The inner surface of the structure was badly burnt and cracked owing to firing and its bottom was covered with a layer of cinders or slag. For the rest the structure was filled with brickbats, potsherds etc. Marshall found near the mouth of the furnace two or three half baked betel-leaf-shaped clay plaques, and so he thought that it is not impossible that the kiln was used for baking objects of this kind. Another kiln of about the same size but circular in shape was recognised by Marshall among the building exposed by Vats in the VS areas, but its function was not clear to the excavator.
v1.c11.s5.3
Another kiln in VS area was exposed by the same excavator in House VII area. It is circular in shape with a diameter of 6 ft. The surrounding wall consists of a single course of bricks and the function of it, according to Marshall, may be that of a pottery kiln. (MS II 226)
v1.c11.s5.4
We have mentioned earlier, that not only Marshall but Mackay also found a good number of kilns when he further excavated Mohenjo-Daro. Some of them have got great importance.
v1.c11.s5.5
In the G section of the DK mound, no less than six kilns, including one in the middle of the central street, were found and other have probably been destroyed by inundation. Mackay thinks that this portion of the mound was the artisans’ quarter, many of whose inhabitants were potters. The city authorities allowed these potters to practise their craft in the suburban area so that the smoke of their kilns did not come towards the city proper.
v1.c11.s5.6
∗ MS I, pp. 192, 226 and MCK, pp. 6, 41, 49, 62, 102-03, 172-79, 202.
v1.c11.s5.7
In this connection mention may be made about the G section of DK area, where excavation has revealed few houses which according to the excavator are interesting. The partially preserved block IA with its two very fine stairways and the small amount of copper and bronze unearthed in this block, lay well to the west of the main building. This provides no indication as to the use of what must have been an almost palatial structure. Mackay is of the opinion that the number of copper melts in House VI of Block 2 perhaps indicates that at least a part of this building was devoted to metallurgical work. That metal was sometimes smelted at Mohenjo-Daro seems however proved by the find of copper ore together with a small piece of lead in a brick-lined pit in the middle of room 51 of House VI, adjacent to the palace. The presence of the piece of lead is particularly interesting as it may have been used to assist in smelting the copper ore. (MCK, 41)
v1.c11.s5.8
Again, in the eastern side of the room 33 of S.W. wing, two curious kilns were found. Both were 4 ft 3 inch deep and paved with brick, round the inside of each was a 4 inch ledge, but not at the same height. The bricks used in their construction were wedge-shaped and laid with mud mortar, and their walls had been carefully plastered with mud. According to the excavator, it is evident from the vitrification of the mud-lined walls of these pits, that they were used to fire objects at a high temperature, the fuel used being either wood or charcoal, of which the white ashes still remained. The ledges mentioned were probably intended for the support of a crucible, or if we assume that the kilns were used for glazing, a grating may have rested on the circular ledge in each. Mackay was inclined to think that these kilns were used for smelting something more fusible than copper, since there was no draught or vent in their lower portions; most unfortunately no objects were found in their vicinity to aid us in determining their use with certainty. (MCK, 49-50)
v1.c11.s5.9
Again in Block 2 House III, two pottery kilns, very roughly built, were marked by their presence. For one, the floor had entirely disappeared, but there were indications that it lay 1 ft 7 inch below the top of the kiln. The second kiln was also elliptical and in much better condition. Around the edge of its floor at the level of 5.7 ft there were a number of flue holes with an average diameter of 3.75 inch. (MCK, 62)
v1.c11.s5.10
Two other kilns were found in the court 21, 26 which belonged to House II.
v1.c11.s5.11
The larger of the two kilns stands against the outer wall of House VII and is practically circular in shape with an inside diameter of 7 ft 1 inch. Its wall which is 1 ft 4 inch high in place was roughly built of old pieces of brick laid in mud mortar and plastered on the inside only. The floor of this kiln is at a level of 3.5 ft and it is perforated with a number of holes which allowed the heat of the fire below to penetrate to the pottery. These holes were arranged in a ring round the edge of the floor with one hole in the centre. The excavators did not find the hole beneath the pavement, through which the fuel was put in, nor any flues: but this is not surprising for, save for the column that supported the floor, no foundation was found. The fuel was evidently placed in a rough hole in the ground: and it is clearly wood, for ashes in plenty lay around the column supporting the floor. Although no direct evidence was found that this kiln was used for pottery, there were at a little distance dumps of broken pots. (MCK, 102)
v1.c11.s5.12
Another much smaller kiln was unearthed immediately to the west of it. It stood at a considerably higher level. The walls are heavily plastered on the inside with mud which clearly shows signs of burning. Mackay is of the opinion that this is really the lower part of a smaller kiln used perhaps for baking vessels of small size. (MCK, 103)
v1.c11.s5.13
Thus Mackay concludes that several kilns unearthed in the G section of DK mound were undoubtedly used for baking pottery, and those in the palace (of Intermediate II date) may have been used by an armourer in the making and repair of weapons and tools, which recall the armourer's shop in the palace at Kish. All other kilns which should probably be assigned to the late I Phase, probably served for baking pottery and that is why these were placed in the outskirts of the town. (MCK, 172)
v1.c11.s5.14
This hypothesis of Mackay was confirmed when he got a number of kilns, and judging from the masses of potsherds around them it may be said definitely that these were exclusively used for the baking of pottery. These were open furnaces of the type still being used by the Sindhi potters. The advantages of these ovens, originally derived from "the practice of enclosing a fire with clay to concentrate the heat and subsequently raising the surrounding wall to a dome" are that the heat can be graduated by flues according to requirements, with a corresponding saving in fuel and the avoidance of smoke strains. (MCK, 177)
v1.c11.s5.15
In course of excavation, several pieces of pottery were found which appear to have been used either in connection with a kiln or in one case, as a crucible. One such specimen was found, which is thickly coated with a mixture of sand and clay, and there can be no doubt that it was expressly constructed to withstand heat. Mackay thinks that it served either as a crucible or more likely as a muffle for firing glaze. Another thin pottery plate, 4.17 inch in diameter and 0.2 in thick has a thick cement of mud and straw round the edge which shows signs of burning. The plate was evidently used to seal up the flue of a furnace; similar plates with a similar cement have been used for the same purpose in India till recently. Within one small open vessel, which was recovered with two others of the same shape and size, was found a grey paste, that was heavily fired apparently more than once. This vessel which has a fairly smooth interior may have been used as a kind of muffle.