It is possible to lower the inferior limit of spectrographic trace analysis
of Sn in iron and steel1 if the Sn is separated by coprecipitation from the
solution obtained by dissolving the sample in a mineral acid.
The coprecipitation of Sn2+ 2•3 was in these experiments tested with CdS
which is formed in the investigated solution. The amount of Cd2+ must be
known because the spectrographic lines of Cd were used as reference lines,
i. e. as an internal standard
