After undergoing purification, it was shown to be
nearly pure silver. During the purification by washing it seemed to
change somewhat, and, consequently, some uncertainty existed as to
whether or not the purified substance was essentially the same as the
first product; it seemed possible that the extreme solubility of the
product in its first condition might be due to a combination in some
way with citric acid, the acid separating during the washing. Many
attempts were made to get a decisive indication, and two series of
analyses, one a long one, to determine the ratio between the silver
and the citric acid present, without obtaining a wholly satisfactory
result, inasmuch as even these determinations of mere ratio involved a
certain degree of previous purification which might have caused a
separation.
This question has since been settled in an extremely simple way, and
the fact established that the soluble blue substance contains not a
trace of combined citric acid.
The precipitated lilac blue substance (obtained by reducing silver
citrate by ferrous citrate) was thrown on a filter and cleared of
mother water as far as possible with a filter pump. Pure water was
then poured on in successive portions until more than half the
substance was dissolved. The residue, evidently quite unchanged, was,
of course, tolerably free from mother water.
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