A method of analysis of the total sulfur in crude viscose rayon was developed. This consisted of extraction of the sulfur with sodium hydroxide solution, oxidation to sulfates with bromine, and precipitation as barium sulfate. This method is accurate to one percent.

A more rapid method for the analysis of total sulfur consists of boiling the rayon in a dilute solution of sodium sulfite followed by titration of the sodium thiosulfate produced.

The total sulfur may also be roughly estimated by observation under the microscope. The presence of even a trace of sulfur may be observed by this method.

The form of the sulfur in the crude viscose rayon was shown to be entirely elementary sulfur. This was accomplished by extracting the sulfur with methyl alcohol and showing that the extract consisted of pure elementary sulfur. This result was supported by the series of experiments in Section V.

The reason for the incomplete removal of the sulfur from the rayon by organic solvents for sulfur was shown to be due to the inability of the solvent to penetrate into the cellulose structure. When the rayon was swelled by soaking in water, the solvents were able to penetrate into it and thus remove all the sulfur.

Extraction of rayon in a swollen condition for 20 minutes with acetone completely desulfurized it. This treatment did not appear to have any effect on the tensile strength or elongation. The use of acetone or methyl alcohol as a desulfurizing agent was shown to be feasible.

The low results in the case of sample number one may have been due to the reaction of the sulfur with sodium sulfite being incomplete, or, perhaps, due to the oxidation of some sodium thiosulfate by the air during the long time of boiling.

The method in general is not very accurate due to the difficulty of getting a good end point in the titration. The estimated accuracy is about five percent. However, this method is recommended as a method of analysis of the total sulfur in crude viscose rayon which may be used in the control laboratory of a rayon plant, since it was the simplest and most rapid encountered during this work.

In general the results indicate that the sulfur in the rayon reacted with sodium sulfite according to the reaction

S + Na₂SO₃ → Na₂S₂O₃