ties. Melting point, however, does not appear to be a 
useful property in defining categories, although the ex- 
tremes might be suggestive of plant source. Degree of 
fluorescence under ultraviolet light varies appreciably 
with surface as well as with kind of material. Solubility 
also varies from nearly insoluble to almost completely 
soluble in various hydrocarbons such as chloroform, ben- 
zol, ether, acetone and various alcohols. Comparative 
behavior in different solvents may be helpful in deter- 
mining plant sources, but this has not as yet been care- 
fully evaluated. Thus, the presence of relatively large 
amounts of succinic acid (8 to 8%), which so strikingly 
sets off most of the Baltic amber from most other fossil 
resins, has appeared to provide a good distinguishing 
character for classification of all fossil resins. Neverthe- 
less, as viewed now, not only succinic acid, but other 
resin acids typical of certain kinds of trees, should be 
taken into account if plant source is to be determined. 
As Barry (1982) emphasizes, most of the classic methods 
of chemical examination of resins are of limited applica- 
tion. In analysis of amber, consequently, further inves- 
tigation directed toward understanding the relevance of 
specific chemical and physical properties to the problem 
of plant source and related post-depositional conditions 
is urgently needed. 
SURVEY OF OUTSTANDING AMBER DEposITs 
Ambers have been reported from deposits of Carbon- 
iferous to Pleistocene age, but they appear to be best 
represented in Cretaceous and Tertiary strata (Plate 
XL). Some question has arisen regarding the nature of 
the so-called resin rodlets reported from Carboniferous 
coal. Since the prevailing opinion holds that these are 
transformation products either of pollen exines or of 
cuticle rather than true resins (Freund, 1952), this materi- 
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