Fluidez de las membranas

remaining regions of the spectrum are very sharp and there is

very little other evidence of adulteration.

A sample was taken with silicon carbide paper of an Egyptian

figurine which was thought to be made of wax (Boston Museum of

Fine Arts 72.4783). The sample was obtained on silicon carbide

paper in Boston and transported to England to be analysed. The

resulting spectrum is extremely similar to that of pure beeswax.

(Table 4.2). There is only a small shoulder on the C-H

stretching bands in the region of 3350 cm*1 and a slight shoulder

on the carbonyl absorption at 1715 cm- 1 . There is no strong

evidence of adulteration in the spectrum.

A sample was collected from a large block of wax at the probable

site of a metal casters workshop from the Maligawa excavations at

Kandy, Sri Lanka. (The site dates from around the 16th century.)

The sample had a sandy crust on the outside and the interior more

closely resembled fresh wax. A spectrum was recorded of both the

exterior crust and the interior. The spectra were found to be

very similar (Figure 4.2) in spite of the differences in

appearance of the samples. Both of the plots contain a rounded

absorption in the region of 3300 - 3360 cm*1 which is more

intense in relation to the other absorptions in the spectrum of

the weathered crust (Figure 4. 2 b ). The band in the region of

1050 cm*1 is also stronger in the spectrum of the crust. These

changes are probably due to hydrolysis of the material. Also,

they may be the result of natural impurities such as residual

carbohydrates which are visible in some of the reference spectra

collected from the combs. The spectrum of the exterior material

also contains weak bands at 1646 cm*1 (with a shoulder which ends

at 1520 cm*1 ) and at 1102 cm*1 which are not seen in the

spectrum of the material taken from the interior of the block.

These absorptions are more likely to be caused by the presence of

minor impurities than by ageing.

Beeswax mixtures

An ethnographic knife handle from central Australia was examined.

It was thought that the wax used to produce the handle was

obtained from Trigona bees whose wax has been reported (Dickson,

1981) to have superior working properties to that of Apis species

for the manufacture of experimental tools. It was also found

(Dickson, 1981) that the wax prepared by Aboriginals was loaded

with vegetable matter and ochre to an extent of 70% by weight.

It is necessary to adulterate the wax to prevent shrinkage and

add mechanical strength (Dickson, 1981). The spectrum obtained

of the handle material in this study contains absorptions which

are characteristic of beeswax with some unusual bands. The

spectrum exhibits the series of six absorptions in the region

1330 - 1190 cm*1 which have been observed in the spectra of the

wax of the Apis species, but not in the spectrum of the wax of

the Trigona species. It would seem that the handle was produced

from wax from an Apis species. However, not enough samples were

available of Trigona species wax to make a firm judgement on this

sample. The spectrum also contains bands at 1631, 1577, 1544

and 877 cm-1 which may be caused by additives and a broad band

centred at 3331 cm-1 which may caused by residual polysaccharide

material and pollen, but more likely to be caused by hydrolysis.

A sample from a Minbar at Shiraz, Iran was examined. The sample

was contaminated having been wrapped in adhesive tape for

transport. The sample was removed from the adhesive tape and an

attempt was made to find a fresh surface. A scraping of the

adhesive tape was taken with the silicon carbide paper and

included in the background spectrum in order to subtract any

contribution to the spectrum from the adhesive tape. The

resulting sample spectrum exhibits similarities to the beeswax

spectra, but there is an overall loss of relative intensity which

may be due to interferences from the adhesive tape or to the

presence of other additives. However, there are bands in the

region of 2900 cm*1 and one at 1736 cm-1 with a slight shoulder.

Absorptions are present at 1466, 1377, 1174 and 723 cm- 1 . There

are five weak absorptions visible in the region between 1330 -

1190 cm-1 .

A sample was obtained of the black resinous material (MFA1) found

outside the mummy Nesmin (Rhode Island School of Design). The

spectrum of the sample indicated beeswax with additives (Figure

4.3a). The bands in the region of 2900 cm'1 , at 1736 and 1713

cm*1 , at 1464, 1379, 1173 and 722 cm-1 are indicative of beeswax

and there are six very weak bands in the region 1330 - 1190 cm*1 .

However, the band centred at 3300 cm-1 merges with the C-H

stretching absorption which is widened at the base. The

absorptions in the carbonyl region are also widened and the band

at 1713 cm*1 is of equal intensity and indicative of the presence

of carboxylic acids (Mills and Plesters, 1963). The additional

carboxylic acids are evidence of a resin mixture. Also, the

bands at 1464 and 1379 cm*1 are not as distinct as in the pure

beeswax spectra and there is a shoulder to the right of the band

at 1464 cm-1 . The mixture was analysed by gas

chromatography/mass spectroscopy and found to be composed

principally of beeswax with additions of resin and bitumen

(White, personal communication).

Spectral subtraction with the interactive difference function was

utilized with the diffuse reflectance spectrum of the sample MFA1

(Figure 4.3a) and a spectrum of beeswax from Apis mellifera

(NHM19) (Figure 4.3b). The resulting spectrum (Figure 4.4)

contains features which are indicative of a resin.

Characteristic resin spectra are discussed in chapter 7.

A sample of wax from the surface of a burnt fragment of a Nimrud

ivory was analysed (See Chapter 14). The spectrum contains

evidence of beeswax and other additives. Bands are present in

the region of 2900, 1739, 1477, 1379, 1176, 958, 920 and 729

cm*1 . There are also bands evident at 1312, 1290, 1266, 1244,

1220 and 1197 cm*1 . However, the region near 1500 - 1350 cm*1 is

indistinct and not similar to the region in beeswax. The weak

absorptions near 1420 and 1340 cm*1 are not present. There is a

shoulder on the low wavenumber side of the band at 1477 cm*1 and

two absorptions at 1539 and 1504 cm-1 which have been assigned by

Kuhn to ionized carboxyl groups. There is also a shoulder on the