July 15, 1934
INDUSTRIAL AND ENGINEERING
oil which were precipitated by silver, but also those from butter fat. This is not serious when the percentage of butter fat is in the neighborhood of 10 per cent, but becomes serious when larger percentages are present. By means of the approximate value A - B, we may determine what the K. F. was and add it as a correction. Table I1 gives results obtained on several samples containing varying amounts of butter fat and coconut oil. Results b y the regular Kirschner method are given for comparison, also the percentages of butter fat indicated by dividing these results by the average factor 22.6. A very interesting set of curves showing the relation between the Reichert-Meissl, Kirschner-Flanders, and Kirsch-
CHEMISTRY
287
ner values may be secured by plotting all the values given in both tables on the same sheet of cross-section paper. A consideration of the curves obtained would indicate that the method should be most useful on mixtures containing u p to 30 per cent of butter fat and from 10 to 40 per cent of coconut oil. The lower range might be extended by the addition of just enough of the silver salt of the fatty acids to saturate the solution in which the precipitation is to be made. On the Kirschner-Flanders curve this would appear to be the equivalent of 5 per cent of coconut oil. This the authors have never tried, but offer the suggestion for what it is worth. RECEIVED March 5, 1934.
Columbium in Steel Determination in 18-8 Chromium-Nickel Steel and in Low-Titanium Steel LOUISSILVERMAN, Ofhe of Inspector of Naval Material, Munhall, Pa.
T
HE use of columbium in steel is increasing rapidly, and a simple gravimetric method for its determination in alloy steels is available. Weiss and Landecker ( g ) , in a summary of the properties of columbium and tan-
talum, stated t h a t they could be separated from solution by perchloric acid, quantitatively, and in an easily filterable form. It was found that fuming with perchloric acid also gave an easily filterable product.
PROCEDURE COLUMBIUM.Two grams of alloy steel (0.8 per cent columbium, 18 per cent chromium, 9 per cent nickel) were dissolved in about 25 cc. of dissolving solution (750 cc. hydrochloric acid, 250 cc. nitric acid, 1000 cc. water) in a 400-cc. beaker. After the steel had been completely disintegrated, 20 to 25 cc. of 70 per cent (technical) perchloric acid were added. the heating was continued until red chromic acid formed and then 5 minutes longer. The contents of the beaker were cooled and diluted to 100 cc. with water, the chlorine was boiled out, and the precipitate was filtered off on a No. 40 Whatman paper. The paper was washed six times with hydrochloric acid (1to 10) and once with water to remove excess acid. The paper was transferred to a tared platinum crucible, the paper charred, and the crucible ignited, cooled, and weighed. This gave columbium pentoxide plus silica. About 5 cc. of 1 to 5 sulfuric acid and 3 to 4 drops of hydrofluoric acid were added. The crucible was heated (150' to 200' C.) to fumes of sulfuric acid, and then till practically all acid had been evaporated. The upper edge of the crucible was heated in the flame OP a Meeker burner (because of danger of spitting), and increasing portions of the crucible were ignited to drive off more acid; finally the residue in the crucible was heated to about 900' C. to drive out the last traces of acid. Columbium pentoxide remained. Silica was obtained by difference. The residue on the filter paper was black, which might indicate lower oxides or the carbide of columbium, To determine carbon, a sample of steel was fumed in perchloric acid, filtered off on a small Gooch crucible, and washed with hydrochloric acid and then with water. The crucible was dried at 110' C. and placed in a carbon furnace apparatus; the carbon was determined and found to be 0.05 per cent. It is possible that lower oxides of columbium were present. Hydrofluoric acid changes the residue to the higher oxide of columbium. Redigestion of the black precipitate on the paper with a mixture of nitric and perchloric acids is of no help. However, if hydrofluoric acid is added to the original dissolving solution, the residue from the perchloric acid treatment will be light yellow but will contain some silica. Such treatment of the steel would have no advantages. In the removal of the silica by hydrofluoric acid, sulfuric r: nitric acids may be used, but in decided excess to prevent partial volatilization of columbium as the fluoride. The residue must
be ignited strongly to remove the last traces of the acid radical present. The oxide is yellow when hot and nearly white when cold. The oxide may easily be removed from the crucible by fusion with phosphate. If the steel is dissolved in hydrochloric acid (1to 2), cooled, and cupferron added, columbium, some iron, silica, and carbides are found on the filter paper. When the paper is returned to the beaker, treated with 10 cc. of nitric plus 10 cc. of perchloric acid, fumed, and then treated as in the usual procedure, all the columbium will be found in the residue. TITANIUM. It has been shown (1) that titanium originally present in a steel sample can be dissolved out with perchloric acid. Weiss and Landecker (g) found that titanium causes tantalum and columbium to react differently after fusion than if titanium were absent. A steel containing both columbium and titanium was not available. However, a 1-gram sample containing columbium and a 1-gram sample containing 0.30 per cent titanium were mixed and run for columbium. The residue indicated that the perchloric acid had taken up all the titanium, and left the columbium. It has been found that perchloric acid will hold at least 12 mg. of titanium in solution. TANTALUM. Tantalum is expected to react in the same manner as columbium but no samples of tantalum in steel have been received. The data obtained are as follows:
Crucible Si02 Cb oxide grams Same, after H'F treatmeht, grams Crucible, grams SiOrCbzO6, gram SiOz, gram CbzOs, gram Si % CL, %
1 G. STEELTREATED WITH HNOa-HF IN Pt CRUCIBLE 19.8545 19.8443 19.8441 19.8341 19.8318 19.8219
- 0.0227 0.0104 0.0123 0.49
0.0224 0.0102 0.0122 0.48
0.0243 (2 g.) 0.0122 (1 g.)
0.86
0.85
0.85
+
+
1 G. Cb 1 G. .Ti (0.30%) STEELSMIXED
oxides, Crucible grame Same, after HF treatment, grams Crucible, grams
16,0264 16.0143
Remainder gram (shows i o Ti)
*0.0123
16.0461
2 Q. STEEL TREATED WITH HF-HzSOa BY CUPF~RRON METHOD 25.0994 25.0958 25.0715
.
...
c I N A 2-G. RESIDUS
2 p COz, gram 1 9 . C O ~gram ,
Carbon, %
LITERATURECITED (1) Silverman, Louis, Chemist-Andust, 23 (July, 1934). (2) Weiss and Landeoker, Chem. News, 101,2, 1 3 , 2 5 (1910). RECErVED .-t?ril 12, 1934.
0.0038 0.0019 0.05
