That an approximately quantitative result can be obtained under the
above conditions was shown in several cases in which deposition of
0.001 grm. of metal was confirmed with considerable accuracy, the
spiral or foil being weighed before and after the experiment.
A comparison of the delicacy of these tests with the ordinary
qualitative tests for antimony, mercury, lead, and copper by means of
sulphureted hydrogen, showed that the two were equally delicate in the
case of antimony and of copper, but that in that of mercury and of
lead the electrolytic test was at least eight times the more delicate.
These comparisons were made in aqueous solutions. In testing urine the
value of the electrolytic method is still more evident, for here the
color of the liquid interferes materially with the reliability of the
ordinary qualitative tests when only very small quantities of the
metals referred to are present.
Beyond the detection of mineral poisons, qualitative electrolysis can
only offer attraction to analysts in special cases, and the data on
the subject are to be found in the many electrolytic methods already
published. Beyond testing for gold and silver in this manner, I have
not therefore examined the applicability of these methods further.
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