A STUDY OF THE SOLUTION OBTAINED BY THE DECOMPOSITION OF THE DIAZO COMPOUND
The syrup which remained after distilling off the n-butyl alcohol was a thick brown viscous fluid in all cases. It has an acid reaction and is completely soluble in water. On testing it showed the presence of sulphur in quantity and the absence of nitrogen. Some was dissolved in water, filtered, and evaporated on the water bath. After its volume had been considerably reduced it turned a very dark brown, then blackish, and smelled very tarry. It did not crystallize at all, finally becoming very black. To a drop on a watch glass, a drop and then an excess of concentrated hydrochloric acid was added but with no apparent result.
Another portion of the syrup was dissolved in water, boiled with purified animal charcoal, and filtered. The filtrate was colorless. It was then evaporated on the water bath and solidified completely. Some of this solid was ignited and a white ash was left; had it been a sulphonic acid there would have been no residue. A qualitative analysis of the ash was made and much phosphate and calcium found present; therefore this solid was presumed to be a mixture of calcium phosphate from the animal charcoal and perhaps the calcium salt of the sulphonic acid. This showed that animal charcoal could not be used for purposes of purification.
“Activated charcoal” has been advocated for decolorizing solutions as well as for absorbing toxic gases; the author had become acquainted with this material while in the Chemical Warfare Service, and had obtained small samples of “Dorsite” and “Carbonite”. Some of this was powdered and the brown solution boiled with it until most of the color was removed. The solution was then filtered and evaporated on the water bath; a white crystalline solid was again left. Investigation of the activated charcoal showed that concentrated acids extracted some substance which was thrown down in a flocculent white precipitate on making alkaline with ammonia. Therefore another sample of the activated charcoal was boiled with concentrated nitric acid, filtered, and the charcoal washed free from acid; this sample did not decolorize well.
A sample of a specially prepared charcoal for decolorizing purposes manufactured by the Barneby-Cheney Co. was obtained and tried, but was unsuccessful; the color was not removed.
Infusorial earth, kiesel guhr, and “Sil-o-cel” were also tried unsuccessfully; Fullers Earth made a very clear solution but no color was removed.
Some of the brown viscous solution was dissolved in water, the solution filtered and evaporated to a constant volume (estimated when no more vapor could be seen to condense) under diminished pressure (water pump) until it became more brown. It was then allowed to cool, and dry hydrochloric acid gas passed in, first to expel all air or other vapor present, and then under pressure. The solution became slightly warm. A few fine crystals formed on the interior surface of the flask where some of the solution had spattered during distillation, which however were quite indistinct and seemed to be in the center of a drop of water or solution. On allowing the flask to stand over night the whole of the solution seemed to be filled with crystals. They were too indistinct to enable their crystalline form to be determined so an attempt was made to remove some for examination. As soon as they came into contact with the air they disappeared and left a very viscous solution, indicating that they are very hygroscopic. A small amount was removed and placed in a dish in a vacuum desiccator which was evacuated and left for a month, with periodical examinations. No solid appeared at any time.
This is as far as the investigation has been carried at the present time, April twenty-fifth, but its study is being continued.
CONCLUSION
The results of this investigation may be briefly summarized as follows: