of resin, however, isa difficult task because of the changes 
which resins undergo in the process of fossilization. 
Resins polymerize with age, presumably by a free-radical 
mechanism. As a result, the fossil product is a macro- 
molecule of high molecular weight, largely insoluble, and 
not amenable to most of the usual methods of attack 
used in elucidating the structures of organic compounds. 
We have found infrared spectroscopy a useful technique 
in botanical investigations of both fossil and modern resins 
at Harvard University and in the classification of fossil 
resins for archaeological ends at Vassar College. We now 
hope to use our diverse interests and competences to 
undertake the large task of a systematic study of fossil 
resins. The goal is to classify them first relatively, 1.e. 
sorting them into groups of resins which share the same 
gross composition as revealed by their infrared spectra. 
Weeventually expect to determine their botanical source 
by comparison of the infrared spectra of recent and fossil 
resins corroborated wherever possible by paleobotanical 
data. Some results of this collaboration have been pub- 
lished previously (Langenheim and Beck, 1965). 
Infrared spectroscopy is useful particularly in com- 
paring fossil and recent resins because polymerization 
preserves all simple functional groups of the recent resin 
with the exception of carbon-carbon double bonds. Also 
skeletal frequencies are damped but not usually extin- 
guished completely. Thus, a similarity remains between 
the spectra of recent and fossil resins in that certain ab- 
sorption peaks can be matched one-to-one, although the 
intensity of these peaks is usually much weaker in the 
fossil resins than it is in the recent ones, especially at 
longer wave lengths. 
Over the past few years, we have prepared infrared 
spectra of well over a thousand fossil resins and several 
hundred present-day resins. It now seems appropriate 
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