159 
An Evouution MErHop FOR THE DETERMINATION OF SULFUR 
IN SULFIDES AND SULFATES. 
By FRANK C. MATHERS. 
The object of this research was to devise a rapid method for the 
estimation of sulfur in sulfates and sulfides, especially in the presence of 
such elements as molybdenum, which interfere with the precipitation of 
barium sulfate. The idea was to heat the material with some metal which 
would reduce all of the oxidized sulfur and then combine with it to form 
a sulfide. The rest of the method would coincide with the ordinary volu- 
metric evolution method for sulfur in iron and steel. 
Powdered potassium sulfate, containing 18.39 per cent. of sulfur, was 
used in these experiments. In each experiment, 0.2 gm. of the potassium 
sulfate was thoroughly mixed with the reducing metal and was placed in 
a crucible which was heated. Experiments with zinc dust as a reducing 
agent showed that it was impossible to reduce all of the sulfate at low tem- 
peratures and that at higher temperatures some sulfur was lost by volatili- 
zation along with the zine. 
Gms. of Zn Percent. of S Percent. of S in 
Used. Temperature. Evolved. the Residue. 
3.0 Bunsen burner, 5 minutes. 17.05 0.64 
3.0 Blast, 5 minutes. 17.20 0.11 
The use of a mixture of zinc and aluminum gave still poorer results. 
The addition of bases such as calcium oxide, calcium carbonate, sodium 
carbonate, or magnesium oxide were without beneficial effects. The use 
of some charcoal did not help. j 
Magnesium turnings gave the best results. To protect the porcelain 
crucibles, they were partly filled with 1.5 gms. of magnesium oxide and a 
cavity was made in this with the end of a test tube. The charge was placed 
in this cavity and was covered with 0.5 gm. of magnesium oxide. The por- 
celain crucibles, with well fitting lids, were heated for 5 minutes with a 
