Chemical Analysis of Spelter

This analysis was undertaken with the view of determining the impurities in spelter and also to determine which of two methods would best give Antimony (Sb) and Arsinic (As).

There are three general methods used in the analysis of spelter.

1st. Is to disolve very slowly all but about 1/5 of a sample in dilute hydrochloric acid (HC1 plus H₂0). The remaining part of the sample is then filtered from the solution and disolved. In this determination, however, the Antimony (Sb) and Arsenic (As) are largely lost as Stibine ( SPH₃ ) and Arsine (AsH₃.) pass off as a gas. The other impurities are deposited on the remaining metallic zinc.

2nd. Is to make possible the determination of Antimony (Sb) and Arsenic (As). This consists in di solving a sample in dilute hydrochloric acid (HC1) and passing the off coming gasses through a solution of silver nitrate (AgNNO₃). This solution retains the Antimony (Sb) and the Arsenic (As). Antimony (Sb) as a precipitate and Arsenic (As) in solution.

3rd. Is to disolve the sample in aqua regia (HNO₃. 3HC1). This method has the advantage of the other two methods in that all the impurities are disolved and retained in the solution.