T H E JOCR,VAL OF I n ; D C S T R I A L A S D E.VGIiYEERISG CHEJIISTRY.
202
prepared as follows: neutralize very carefully 400 cc. of eighty per cent. acetic acid in a liter flask with strong ammonium hydrate; add twenty grams of citric
Average samples of different car loads showed the following percentage, one gram of material being taken for analysis:
CaSOl CaFl Average plus obtained b y W-eighed decomposition equal 0.29 per as CaF2. cent. with H?SOa. to CaS04. 1
2
3
4
5
6
Keystone ground.
., . ..
A - l Ground
Gravel.. . . . . . . . .
I II :;::: I 99.07 99.01 99.06 96.81 96.77 96.86
89.38 86.76 Gravel.. . . . . . . . 86.87 86.85 82.14 Gravel. . . . . . . . , . 8 2 . 1 3 182.08 66.02
.
Unwashed s a n d . . 66.04
172.75 172.65 172.63 168.80 168.73 168 89 155.72 155.69 155.71 151 .OO 151.24 151.27 143.03 143.00 143.10 114.80 114.86 114.82
99.06 99.01 98.99 96.76 96.80
1
0.42 1.47 1.42 1 .45
86.72 66.75 82'03 82 .OO 82.06 65.83 65.87 65,84
I 1
1
3 . 3 31 3.29 4.93 0 4.95 82.32
66.14
acid and fill up t o the mark with strong ammonium hydrate). Digest on a boiling mater bath for thirty minutes ; filter and wash b y decantation with hot water containing a small amount of the ammonium acetate solution just described, then with pure, hot water; ignite in the same crucible and weigh. The residue should be perfectly white and should be pure calcium fluoride. T o test this, add 2 cc. of sulfuric acid, heat to decompose the calcium fluoride, and evaporate the excess of sulfuric acid ; repeat this operation, using I cc. of sulfuric acid. Now weigh the calcium sulfate, add five or six grams sodium carbonate, fuse and dissolve in hydrochloric acid in slight excess; should a white precipitate occur a t this point i t will indicate the presence of barium. To prove this method I selected clear crystals of fluorspar, pulverized the same and purified it by treating with acetic acid, hydrofluoric acid and ammonium acetate; the washed, dried and ignited powder was decomposed by sulfuric acid and the calcium sulfate weighed. By taking an average of six determinations 0.387j gram of this fluorspar formed 0.67jj5 gram of calcium sulfate equal to 9 9 . 9 7 per cent. calcium fluoride. One gram of this fluorspar treated as described showed the following results as a n average of twelve determinations: Gram. Loss in weight by treating with acetic acid. . . . , . . . . . . . . . . . Loss in weight by treating with HgO and H F . . , . . , . . . . . . . . Loss in weight by treating with ammonium acetate. . . , . . . . .
0.0015 0.0002 0.0012
The amount of calcium fluoride lost in these different manipulations was 0 . 0 0 2 9 gram, or 0 . 2 9 per cent., if we take one gram for analysis. I now analyzed mixtures of material of known percentage similar in composition to fluorspar and obtained the following results, using one gram for analysis:
.
Taken., , , , . . .
.
Taken., . . , . . . Taken., , . , , , , . Found .... , , . . .
CaF2.
SiOz.
CaC03.
PbS.
85.11 85.0i 80.05 80.03 78.45 78.41
6.66 6.61 7.71 7.70 8.32 8.29
5.59
1.50
1.14
ZnFeS.
2.50
1.82
1.40
1.43
5.57 7.92 7.87 10.40 10.34
0.45
99.31
96.85
1
So1ub 1e in acetic acid less 0.15 h\-erage. per cent. Average.
SiO?.
t
89.28 89.29
>Iar., 1912
f
{
I t 1 t
I
1.45
(I:;
0.88
(I:;:
1
1
1 1
6 .' 0 18 9 6.12
$
1 5 .' 5 2 7 15.65
5
t
8.6i
13.75 13.i6
1
13.77
I
)
I
1
CaC03 equal tocoz
0.24
0.116
0.26
0.88
0.35
0 80
4.23
1.75
3.98
4.68
1.95
4 43
6.13
2.61
5.98
15.58
6.83
15 52
1
4.93
I
13.80
0.20
4.27 4.17 4.25 4.72 4.69 4.63
3 31
8.71
8.5 70 9
{ i(
con.
I
1
The calcium sulfate obtained by decomposition of fluorspar was fused with sodium carbonate and the cake dissolved in hydrochloric acid. The solution was perfectly clear, showing a total decomposition of the fluorspar and the absence of barium. As our fluorspar does not contain any gypsum and heavy spar, I did not investigate its influence on the calcium fluoride determination, but it is evident that small amounts of calcium sulfate will be leached out, if present, together with the carbonates. Barium sulfate is easy to detect and can be determined as usual. The only constituent of injurious influence would be any silicate containing calcium. F. Julius Fohs, in Bulletin 9 of the Kentucky Geological Survey, states the following silicates occurring associated with Kentucky fluorspar: Apophyllite, Datolite. Desmine, Epidote, Laumontite and Natrolite. Apophyllite and Natrolite cannot be present in the fluorspar because there are no alkalies to detect. The same with Datolite. I could not find any trace of boron; Desmine and Laumontite cannot be present in any considerable amount, there being only veq- small amounts of aluminum in the spar. I have made a support of aluminum which enables me to handle six crucibles a t a time and I can .finish six analyses in ten hours. LABORATORY FAIRVIEW FLUORSPARASD LEADCo., GOLCONDA. ILL.
DETERMINATION O F MANGANESE I N STEEL. BY
JAMES
J. BOYLE.
Received December 15, 1911.
After successively trying for some time the color method, Johnson's lead peroxide-sodium arsenite titration method and the ammonium persulphate-sodium arsenite titration method for manganese in steel with varj-ing success, the writer has adopted a suggested
Mar.,
1912
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y .
modification of the latter method which gives better and more concordant results, closely approaching the bismuthate method in accuracy. Experience has shown that the color method cannot be used with all kinds of steel, as various shades of color are obtained, which do not compare well. Johnson’s method gives fairly good results. The chief objection is that some solution upon decanting is always left in the test tube, the error increasing as the manganese in th-e steel varies from the manganese content of the steel used in standardizing .the sodium arsenite solution. Furthermore, various shipments of lead peroxide did not have the same oxidizing power. Using Walter’s persulphate method, and titrating the permanganic acid obtained with sodium arsenite, gives gratifying results, providing the permanganic acid is kept ice-cold. In first trying this method in warm weather, difficulty was experienced b y the solution rapidly re-oxidizing, so that unless the arsenite was run in rapidly, the results obtained were poor. I t was found that if the solution was warmed a few minutes after the titration was made, re-oxidation would be so complete that if again titrated as before, a practical check could be obtained. By keeping the solution ice-cold, there is no oxidation and good results are obtained, providing the operator is familiar with the end point, which is a suggestion of yellow, free from pink tints. A modification of this method was worked out, which produced better results. Briefly, the method is : Weigh out one gram of steel, dissolve with I O O cc. of nitric acid (sp. gr. 1.20) in a zoo cc. beaker b y placing on a hot plate and heating till no more brown fumes appear. Remove from the hot plate, cool and dilute to 500 cc.. mixing thoroughly. Take I O O cc. of the well-mixed solution, corresponding to 0 . 2 gram of steel, place in a 300 cc. Erlenmeyer flask, and heat on the water bath till warm. Add 15 cc. of silver nitrate (1.33 grams per liter) and about a gram and a half of ammonium persulphate, warming about a minute or two after the color commences to develop: 8001, add a slight excess of sodium chloride (6 cc. of solution containing I .4 grams per liter) so as t o precipitate all the silver; titrate with a standard solution of sodium arsenite till all pink shades are gone, and the white of the precipitated silver chloride alone remains. This end point is very sharp and more easily determined than that of the other methods. The silver nitrate being all precipitated, no re-oxidation of the reduced permanganic acid can occur. The sodium arsenite was standardized against a Basic Open-Hearth steel of the Bureau of Standards, sample No. 13-u,the results obtained b y the various analysts on this steel being more concordant than on the other standard samples.
203
The accuracy of this method was noted by determining the manganese in four Bureau of Standards samples of steel, the results obtained being within one per cent. of the general averages for these steers. TESTINGLABORATORY, AMERICAN BRIDGECOMPANY, AMBRIDGE. PA.
CARBON DIOXIDE: ITS VOLUMETRIC DETERMINATION. B y LEON T. BOWSER.
Some time ago there appeared the description of a procedure devised b y J. C. MimsI for the volumetric determination of carbon dioxide, and from i t the writer has succeeded in evolving an accurate and reliable method. There are no new reactions involved, merely an adaptation of well-known principles to a suitable form of apparatus. Stripped of details, the procedure is essentially that of releasing carbon dioxide b y means of hydrochloric acid, absorbing it in a strong alkaline solution and measuring the absorbed gas by titration with a standard acid. Absorption is accomplished in a tower especially designed to meet the conditions. No preliminary guard tubes are necessary, and instead of rigidly excluding water from contact with the potash solution i t is the practice to distil over a small amount, thus insuring the mechanical carrying over of residual carbon dioxide along with the water vapors. The solution previous t o titration contains a mixture of potassium hydroxide and carbonate, since bicarbonates do not exist in the presence of alkaline hydroxides. In titrating with an acid, using phenolphthalein as indicator, disappearance of the pink color marks the point a t which all hydroxide has been neutralized and the normal carbonate has been converted to bicarbonate or, in other words, the normal carbonate has been half neutralized. The titratiori being continued, after adding a drop of methyl orange, appearance of the usual acid reaction denotes complete neutralization of the bicarbonate. The volume of acid used in the latter titration, then, is just one-half of that required t o release all the carbon dioxide from the condition of a normal carbonate. I t follows t h a t I cc. of normal acid used in the titration between the two end points is equivalent to 0.044 gram CO,. The form of apparatus used is shown in Fig. I. F is a flask in which the carbonate is decomposed by an acid, which is introduced through a small separatory funnel, S. That used b y the writer was originally part of a Geissler alkalimeter, but doubtless could be supplied alone by dealers in apparatus. In Fig. 2 is shown an easily made substitute; the entire arrangement should be as small as possible, the capacity of the funnel body being about I O cc. The necessity for the constriction at the top will be explained presently. The condenser C, of Fig. I, is specially constructed so that the inner tube may be quite short and of as small a bore as possible. All tubing used in the apparatus, except the body of the tower, is of 2 mm. internal diameter, which allows 1 Bull.
65, 156. U. S. Bureau of Chemistry.
