Structural changes in some ancient Indian timbers

Abstract

Ancient wood of four Indian tree species has been examined, largely by physical methods, in comparison with modern wood of the same species and with particular reference to the amounts and condition of the cellulose in the constituent cell walls. One of the specimens— Shorea robusta (2000 yr)— came from the wooden piles of the wall around the ancient city of Polibothra in Bihar, India; two— Lagerstroemia speciosa (7500 yr) and Mesus ferrea (47000 yr) -—came from the gem pits of Ceylon; and the fourth— Tectona grandis (2200 yr)— from the Karla Caves in the State of Maharashtra, India. The material was dated by the radiocarbon method. It is shown that in the first three specimens burial underground has led to a progressive reduction in the amount of cellulose present, both amorphous (rapidly degenerated) and crystalline (more slowly). With the oldest specimen (47000 yr) cellulose is still present but is non-crystalline. It appears that degeneration of cellulose under these conditions (in the apparent, though not certain, absence of micro-organisms) proceeds by a relatively rapid removal of amorphous or paracrystalline cellulose accompanied by a slower conversion of crystalline to non-crystalline cellulose. The specimen of Tectona held in an atmosphere, often warm and humid, for 2200 yr is superficially sound but the wood is nevertheless in part degenerated, the content of cellulose, including the crystalline component, having been considerably reduced.