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15
Qoldberg and Brown (195O) have shown that rhenium is about
130 times more abundant and that lead is at least 50 times less
abundant than was previously assumed. This has created some doubt
as to the validity of the data published for the cosmic abundances
of the minor constituents of the less abundant elements. Previous
to Brown's investigation the values for rhenium and lead were
based entirely on the work of I. and W. Noddack. A comparison of
their worlc with that of others shows that, in general, data compiled
by these authors should not be accepted uncritically. In many
cases no other data are available and Qoldschmidt has used their
values considering, however, possible sources of error in their
determinations.
As will be evident from the detailed discussion under
individual elements, there are serious sources of error In all
data available. The data published in the last twenty years
and particularly since the war seem to be generally much more
reliable than that published previously. Even certain data of
such a reliable Investigator as V. M. Qoldschmidt have been
shown to be seriously in error, as for example in the case of
lead. Generally, the amounts reported for the rarer elements,
particularly in the range of a few parts per million, have decreased
with time. Hence in our choice of data we have tended to select
lower values rather than higher ones. In some cases we have selected
values definitely outside the reported analytical values. It is
our expectation tliat many reported analytical data are in error