73001 S5003155

charged at the top with beech and plna charcoal ln the ratlo of 1:2 and with roasted and slfted Iron ora. The ratlo of the ora to the charcoal was 1:2. The weight of each charge of charcoal and ora was about 2 kg. Dnrine tbe flrst few hours the charge was fed lnto the furnace slx>sevan tlaei per hoar. then four times. dapendlng on the rata of consuaptlon of ore and charcoal ln the furnace.

As a rule the sweltIng took twelve hours to conplete. Durlng the sweltlng the tewperature Inslde the furnace was measured by means of Pt-PtRd thernocouples. The dlstrlbutlon of tewperature for a two-bellows furnace are lndlcated ln Fig. 4. It is evldent that the zonę of hlghest temperaturę ls on the level of the blast hole, and it is there that the iron sponge is forwed. The highest tewperature recorded in the Holy Cross furnace did not exceed 1400*C. Simultaneously the concentration of oxides of carboe was established by neans of an Orsat apparatus.

During tbe last two-three hours of the smelting no iron ore was charged but the furnace was fed with charcoal. Finally, the shaft was bro-ken to pieces and the iron sponge and slag were left to cool. Unfortunately we ba we not yet be en able to separate hot iron sponge from the slag, whicb jmst be separated by hanwering when cold.

At present two variations in smelting technique are under investigation. First there is swelting in the tali furnace using an induced natural blast; and second there is swelting in a slightly shorter furnace 80-100 cm high using single bellows. The experiments have investigated the optimum angle for the blast hole and have shown that the smelting is improved if the angle of the blast holes is about 30° downwards with respect to the shaft and if a smali hole with a diameter of about 2 cm is madę in the opposite side of the furnace wali just above the level of the blast hole (Fig. 5). This allowed sonie gases to escape when the blast was applled and resulted ln an increase in the size of the reduction zonę. Figs. 6 and 7 illustrate the sequence of operations, described above, for the ezperlmental sweltings.

No measurements of temperaturę and gas concentration have been madę with the latest experiments, as we did not wish to disturb the progress of tbe reduction by the presence of thermocouples and sampling tubes. However, laboratory investigation of the iron sponge and slag has been carried out. Platę 1 shows the cross section of three iron sponges madę during the experi-mental smeltings. The proportion of the cross section, which consists of wetallic iron, amounts to an estlmated 20%. The microstructure of the Iron Bponge ls shown in Platę 2. The metallic iron nodules were surrounded by the oxides-slag mass and sometimes by charcoal. The carburization of tbe iron was very sllght (about 0.15% of carbon). The microstructure of tbe iron was ferritlc with a smali amount of cementite III, and was independent of the type of bloomery furnace used. In our experimental smeltings we have never obtained highly carburized metallic iron, apart from the occaslonal smali nodule of iron containing up to 0.8% carbon.

One sponge was then forged into a smali bar (Fig. 8) from which a fcjtlfe blade was madę (Fig. 9). The blade of the knlfe was hardened by carburization and quenching. The following flgures illustrate the micro-structures of tbe bar. The carburization was hlgher because of the forgimg process and reacbed 0.4% carbon. In the microphotographs we can obserwe ferrlte, pearllte and non-metalllc lncluslons. Ali the metallic lwclusioos were identifled by means of microanalysls. Ue found many

complex incluslons containing iron oxides, lillute and ilaiAia oxlde*, Platę* 3 and 4 show the microstructuree of the blade af ter the cerberi-zation and quenching proces* (martensite and aastenite). A typical complex non-metalllc lncluaion is shown in Platę 5-

The result* of the smelting experimeat* bave lad te the cokImIm that the ancient iron smelting was carrled out using a satsrslly induced draught without the aid of bellows. This i* Independently sepported by the sltes of the furnaces themselves, which are always on sloplag or high ground, and also by the absence of clay tuyercs in the escarations, which would have been essential if bellows had been esed.

Pinally, I would like co add that for some years aow the experimemtal smeltings have been lncluded ln an entertalnmeat programme for tomrlsts. Every year in September the * show* is enacted on tbe slopes of the Soły Cross Mountains. The smelting is accoapanied by folk art fslrs sad by folk musie. The whole event lasts three days aad as many as 100.000 people gather around to witness it.

References

Bielenia, K 1965. Badania doświadczalne nad wytopem zelaza w kotlince Świętokrzyskiej. Wiadomości Archaeologiczne, XXXI, 417-421

Bielenin, K 1970. Komplexe technologiscker und archaologlschem Forscbunge* u ber die frugeschicht liche Eisenverhuttumg lm Gebiet won "Góry Świętokrzyskie". Act.es due VIIe Congies International des Sciences Prehistoriques et Protohistorigues, 34-37. Prague

Bielenin, K 1973. Schmelzversuche in Halbeingetieftes Rennofes la Polem. Die Versuchsschmel zen und ihre Bećeutung fur die Metallurgie des Ci sens und dessen Ceschichte, 62-70. Schaffhausen-Prag

Bielenin, K 1977. Fruhgeschichtliches Berg ba u und Eisenhutcenwesen in

Swietokrzyskie-Gebirge. Eisenverhuttung wor 2000 Jahzen Archaologiscbe Forschungen in der VR Polen, 11-26. Berlin, Dusseldorf

Bielenin, K 1977. Ubersicht der Typen von altertumliches Rema©fes au£ den Gebiet Polens. Wissenschaftliche Arbetien aus dem Buzgenland, 50. 127-146. Eisenstadt

Mazur, A & Nosek, E 1966. Od rudy do nora. Materiały Archeologiczne, VII, 19-50

Radwan, M 1961. Dalsze próbne wytopy w piecykach dymarskich typu świętokrzyskiego. Kwartalnik Historii Nauki i Techniki, IX. 366-376