Chemistry of tanning in ancient Mesopotamia - Journal of Chemical

Chemistry of tanning in ancient Mesopotamia. Martin Levey. J. Chem. Educ. , 1957, 34 (3), p 142. DOI: 10.1021/ed034p142. Publication Date: March 1957...
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MESOPOTAMIA' MARTIN LEVEY Temple University, Philadelphia, Pennsylvania

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of the most aucient arts in the technological history of mankind is the processing of skins and hides to produce furs and leather for shelter and clothing. By the time of the Sumerians, who were the possessors of the earliest literate civilization in Mesopotamia, leather no longer was the commonest material for clothing. Ur, in the third millennium B.c., already possessed a thriving textile industry. At the same time, leather was still in demand for other uses such as for harness of oxen and donkey teams, door hinges, pouches, shoes, belts, and other objects. Leather was important in an inflated form for the ancient small boats and rafts. Parchment was used in the first millennium B.C. although no evidence for the means of its preparation exists in the texts known. The ancient Mesopotamian tanners used a surprising variety of skins and hides. Sheep skins, both with and without the wool, were the most common. Other hides used were from the ox, goat, snake, hog, wildcat, elephant, deer, shark, lion, wolf, and many others. The hide was a very important economic part of the slaughtered animal. For example, in a ease of what was probably "hoof and mouth disease," a letter reads, "The sheep which have a disease of the mouth are not strong; let them slaughter and remove the hides from the bodie~."~ 'Presented before the Division of the History of Chemistry at the 128th Meeting of the American Chemical Society, Minneapolis, September, 1955. This study was aided by a. grant from the American Philosdpbieal Society. The author is indebted to the Oriental Institute, University of Chicago, for the use of its Assyrian Dietionmy materials. HARPER,R. F., "Assyrian and Babylonian Letters Belonging to the Kouyunjik Collection of the British Museum," Luaar, London, 1897, Text 75, rev. 1-4.

Immediately after flaying, the fresh skins were cured by soaking in a solution of water and the native saline earth. The skins were then scoured. They were pounded and most of the inner flesh and fat removed with a fleshing knife, then probably dried and stored for a short time for the tanner. For depilabion, the skin was left to' putrefy to a limited degree. In primitive cultures this is done by immersion in urine followed by scraping with a blunt knife to remove the epidermis and roots. In ancient Mesopotamia, there is no evidence that any particular material was used to assist in this operation of depilation. It was probably carried out simply as a natural bacterial process. The texts, however, do provide us with evidence as to the ill-smelling nature of the tanner's work. This may have been due to the bating process without which it is difficult to make fine leather. This is the treatment with a dung infusion. Without doubt, it was this stage of the tanning procedure which was the main reason for the leather workers' living in their own towns. Pounding and rubbing of the skin a t this stage assist,ed in preparing the skius for the next step of tanning. TANNING

The oldest methods of tanning skins and hides are oil tannage and tawing, i.e., with alum. The former is the older judging by evidence from contemporary primitive peoples. The cuneiform literature reveals also that, in addition to these, the ancient Mesopotamians were also well acquainted uvith the use of vegetable tannins in this work.

JOURNAL OF CHEMICAL EDUCATION

First, it might be well to examine briefly the method of steeping the hides in the tanning solution. A technique still employed in the Near East seems to have been practiced in ancient Mesopotamia. This is the method of filling the skin or hide in the form of a bag with the tanning solution and then putting the filled skin or hide into the tanning vat. One tablet reads, "400 sheep skins, containers, steeped in the solution and puffed up."s An examination of the texts for evidence as to the actual tanning materials in use reveals that a first millennium B.C. tablet lists alum, gall nut, myrrh, and fak4 The gall nut yields a rich extract of tannin and was widely used in ancient times for this purpose. From other tablets, a slightly different version of the tanning procedure is obtained. The fragment of a ritual text describes the sacrifice of bulls whose hides were destined to be stretched on the kettle drum which accompanied the official in chanting his lamentations. You take this hide and steep it in pulverized flour of pure wheat in aqueous mixture, fine wine, land then] rub it with fine f a t of a pure bullock, alum of the Hittite country and gall nuts. Then you will spread it aver the brass kettle drum.'

The ritual texts, although written down in the first millennium B.c., probably stem from a very early date and perhaps reflect a technique dating back to the third millennium B.C. or earlier. The tanning materials in these texts were placed in one mixture in which the skin or hide was steeped. This procedure is still followed today in the region of Baghdad. Flour, as well as alcoholic liquids, was also used in these ritual texts. A magical text is interesting in that it makes full use of oil in the tanning process although it does not omit the use of alum and gall nuts.B It would therefore seem to be a combined series of operations making use of different techniques. Evidently, the magical text had its origin in very early times hut was later amended. TANNING MATERIALS

Fat of a bull, fine oil, and ordinary oil were known in the tanning of skins and hides. It is rather surprising that in the oil-rich Near East, tanning with oil was unknown in the Talmud. Oil tannage simply consists 8 JacossEN, T., "Cuneiform Texts in the National Museum, Copenhagen," E. J. Brill, Leiden, 1939, p. 69, Text 17:l-2. STRASSUIER,J. N., "Insehriften von Cambyses," Pfeiffer, Leipzig, 1890, Text 155. 6 EBELING, E., "Keilsohrifttexte aus Assur, religiiisen Inhalts," Wissensehaftliche VerBffentliohung der Deutsehen Orien&Gesellschaft, Vol. 34, Text 60, rev. 5-8. 8 T ~ u ~ ~ ~ n - D a aF., c m "Notes , Assyriologiques," Revue D'Assyriologie, 17, 29 (1920).

VOLUME 34, NO. 3, MARCH, 1957

of oiling or greasing the skin which is wet, then kneading and stretching it as it slowly loses moisture and absorbs the fat. The process is still in use today to make the finest furs by treating with oxidizable oils. Aromatic extracts were used probably as counteractants to the foul smells in the tanneries. Alum, a mordant in the dyeing of cloth and much used in pharmacy, was widely employed in the tanning of leather. It was obtained from the land of the Hittites, now Turkey, from Egypt and from an unknown country, Kashappu. Hides tanned with alum alone have no suppleness and are not very useful for most purposes. If salt or sodium sulfate is used with aluminum salt, a much better product is obtained. No evidence exists for this procedure in ancient times. However, alum was probably almost always contaminated with ferric salts which would, of course, tan. The quantity of ferric ion impurity would then determine the permanency of the tanning. I n the Talmud, however, alum was used with salt to make an excellent tanning agent. It was by empirical methods that the ancient Mesopotamians found that some form of tannin was necessary to make a more durable leather. The texts quoted show the use of the gall nut. I n addition, as tannin sources, the Mesopotamians used oak bark, sumac, and probably the rind of the pomegranate which contains much tannin. Flour of wheat and malt was used in the quoted Akkadian texts. I n the Talmud, skins and hides were often treated with flour and gall-nut powder. This produced the so-called sour hide. After tanning, leather was dyed or painted in various colors such as red, black, white, brown, green, and purple. TANNING TECHNOLOGY, AN ANCIENT ART

Tanning technology in ancient Mesopotamia showed progress until the Neo-Babylonian period. The use of leather products penetrated into every phase of Mesopotamian life. Although the evidence is not as yet available, it is likely that the techniques used were highly specialized for the various types of leather manufactured. Unfortunately, leather could not withstand the ravages of the Mesopotamian climate to allow proof of this point by chemical analyses of the artifacts. Few of the important modern phases of tanning technology have come into use because of scientific research as we know it today. Rather, the major tanning operations have come about as a slow empirical development from prehistoric times, through the ancient Mesopotamian period down through various stages to modern times as a connected and developing stream of knowledge. The evolutionary thread of this area of our technological development runs parallel to the blossoming of our cultural traditions in other fields.