370 XJNIVERSITy OF VIRGINIA PUBLICATIONS 



10. The addition of carbon dioxide was found to cause the precipitated 

 vanadium sulphide to settle out. For example: 10 cc. of oil was mixed 

 with 1 cc. of stock solution of sodium vanadate, and hydrogen sulphide 

 and carbon dioxide gases were passed into the mixtui'e at the same time. 

 The precipitate was filtered off through a Gooch crucible and the vanadium 

 content of the filtered oil was determined as follows: A paste was made 

 with sodium carbonate and heated to drive off the volatile matter. The 

 residue was mixed with potassium nitrate and burned. The product was 

 extracted with water and the extract evaporated to 10 cc. The vanadium 

 content of this solution was determined by the permanganate method 

 given by Hillebrand in Bulletin 176 of the U. S. Geological Survey. This 

 analysis showed that some of the vanadium still remained in the oil, 0.0017 

 gram V2OS per 10 cc. of oil. 



Solubility of vanadium, sulphide in sidphur heari)ig petroleum. 



11. A water solution of sodium vanadate was treated with hydrogen 

 sulphide and filtered through a Gooch filter. Ten cubic centimeters of 

 sulphur bearing petroleum was added and allowed to stand over the va- 

 nadium sulphide for two days. It was then drawn through the sulphide 

 on the filter and its vanadium content determined as in (10) above. The 

 results showed 0.0023 gram V2O5 per 10 cc. oil. 



12. Vanadium sulphide ore was ground so as to pass a hundred mesh 

 sieve. One-fourth gram of this was mixed with 10 cc. of sulphur bearing 

 petroleum and allowed to stand two days. The vanadium in the filtered 

 oil was determined. Ten cubic centimeters oil showed 0.0010 gram V2O5. 

 The relative rapidity of filtering of this oil may have modified its vanadium 

 content, as compared with (10) and (11) above. 



The change of petroleum into a mass that resembles asphalt. 



The difficulties presented by the filtering of the precipitated vanadium 

 sulphide from oil were so great that a number of experiments were carried 

 out in the effort to obtain results that could be certainly depended upon. 

 It was noticed that the paste left on the filter paper would change in a day 

 or two to a brittle asphalt-like mass. 



13. Precipitated vanadium sulphide and the sulphide ore was mixed 

 with petroleum in a number of experiments and the mixtures allowed to 

 stand. When these had access to the air there was a gradual thickening 

 of the oil. In one experiment which was watched closely the oil became 

 very viscous on standing four months. After six months this was brittle 



