68
INDUSTRIAL AND ENGINEERING CHEMISTRY
sampled, and quickly returned to the bottles which were reweighed and heated another week, when the operation was repeated. All bottles were heated 4 weeks. The maximal loss in weight noted after heating a week was 1.73 per cent lost by one sample at 85" C. during the first week. The average loss per week per sample was 0.51 per cent, which indicated that the tubes extending above the oven tops effectively reduced evaporation. Inorganic ammonia and urea plus inorganic ammonia were determined by the method of Yee and Davis (16)in the mixtures before heating and in all the weekly samples. Onehalf gram of material was weighed directly into the special distillation flasks, and 5 cc. of water were added before either distilling the ammonia off or digesting with urease. Because of the relatively large amounts of ammonia present, it was necessary to use a more concentrated alcoholic caustic solution than that specified by Yee and Davis. As a further check on any possible loss in weight of the mixtures, either during the heating or the mixing, total PZOs determinations were also made on the mixtures before heating and on all weekly samples. The results obtained for the urea content were then corrected to the basis of the original material, using the PzO,content as a reference figure. These corrections were small. The results are given in Table VII. Some decomposition of urea occurred even a t 45O, and in one sample a t 65" C. the urea was completely destroyed in 4 weeks. The decomposition was very rapid a t 85" C. These results are, in general, what would be expected from the data on urea-superphosphate mixtures and show that these data are applicable to complete mixtures.
VOL. 29, NO. 1
Acknowledgment Thanks are due to J. 0. Hardesty for preparation of the ammoniated samples.
Literature Cited (1) Balareff, D., Z. anorg. Chem., 67,234(1910). (2) Bidwell, G. L.,and Sterling, W. F., IXD.ENQ.CHEM.,17, 147 (1925). (3) Clark, N.A.,J . Phys. Chem., 35,1232 (1931). ENQ.CHEM.,15,743 (1923). (4) Fox, E.J., and Geldard, W. J., IXD. (5) Hardesty, J. 0.. and Ross, W. H., paper presented before Division of Physical and Inorganic Chemistry a t 85th Meeting of American Chemical Society, Washington, D. C., March 26 to 31,1933. (6) Hill, W. L., and Jacob, K. D., J . Assoc. Oficial Agr. Chem., 17, 487-505 (1934). (7) Keenan, F.G., IND. ENQ.CHEM.,22,1378 (1930); 24,44 (1932). (8) Matignon, Dode, and Langlade, Compt. rend., 194, 1289-94 (1932). (9) Parker,'F. W., and Keenan, F. G., Chem. & Met. Eng., 39, 540 (1932); Am. Fertilizer, 77, No.10, 11 (1932). (10) Richter, V., "Organic Chemistry," Vol. I , p. 397,3rd American ed. translated from 8th German ed. by Smith, 1913. (11) White, L. M., Hardesty, J. 0..and Ross. W. H.. IND.ENQ. CHEM.,27,562-7 (1935). (12) Whittaker, C. W.,Lundstrom, F. O., and Hendricks, 5. B., Ibid.. 25. 1280 (1933). (13) Whittaker,'C. W.; Lundstrom, F. O., and Hill, W. L., J. Assoc. Official Aor. Chem., 18,122-7 (1935). (14) Whittaker, C. W., Lundstrom, F. O., and Shimp, J. H., IND. ENQ.CHEM.,26,1307-11 (1934). (15) Yee, J. Y..and Davis, R.0. E., IND. ENQ.CHEM.,Anal. Ed.. 7. 259-61 (1935). R B C ~ I V EJuly D 18, 1936. Presented before the Division of Fertilirer Chemistry at the 92nd Meeting of the American Chemioal Soaiety, Pittsburgh, Pa., September 7 to 11, 1936.
Increasing the Effective Life of Razor Blades R. H. FASH 2504 Oakland Boulevard, Fort Worth, Texas
H E N safety razor blades are used with a brushless type of shaving cream, they become dull much more quickly than with a brush type of cream. Examination of both types of cream showed that the pH value of the brushless type was 7.2, while that of the brush type was 9.4. Since oxygen corrosion of steel occurs readily at a p H of 7.2 but is appreciably retarded at a pH of 9.4, the theory was formulated that the dulling of razor blades was due to oxygen corrosion during the process of shaving. An accelerated corrosion test was made by placing a new razor blade, that could be stropped, free from its paraffin coating, between the folds of a piece of cloth wet with a mixture of 20 grams of the brushless shaving cream and 80 cc. of water. The cloth with the razor blade was supported on the bottom of a beaker inverted in a larger beaker containing the mixture of shaving cream and water, the ends of the cloth extending down into the liquid so that the cloth was continuously wet with the liquid. Thus the razor blade was kept wet with water from the mixture and a t the same time was in contact with air. The larger beaker was covered with a watch glass. Each day the blade was dried, stropped twentyfive double strokes, and replaced between the folds of the
- -
cloth. The condition c the cutting edge of L e llade a t the end of 7 days is shown by Figure 1. A similar test was carried out a t the same time using the brush type of shaving cream with a pH of 9.4. The condition of the edge of the razor blade in this test a t the end of 7 days is shown by Figure 2. Determinations were made of the pH of various brushless and brush-type shaving creams on the market. The results are as follows : Shaving Cream Burma-Shave Mennen's Barbasol Glider Col ate Wilfiany Palmolive
Type Brushless Brushless Brushless Brush Brush Brush
PH 7.2 8.2 8.1
7.5
9.2 9.4 9.2
A series of accelerated corrosion tests was made with these shaving creams, with results similar to those shown in Figures 1and 2.
Effect of Potassium Chromate With the idea of retarding the corrosion of razor blades during shaving, potassium chromate was added to a commercial brushless shaving cream with a pH of 7.2. The potassium chromate did not change the p H value. Figure 3 shows the condition of the cutting edge of the blade after shaving tests
JANUARY, 1937
INDUSTRIAL AND ENGINEERING CHEMISTRY
with the untreated cream, and Figure 4 shows the cutting edge used with the chromate-treated cream. A similar shaving test was made using a commercial brush type shaving cream with a pE of 9.2, first as sold on the market and then when chromate-treated. The potassium chromate did not change the pH value. The condition of the cutting edge of the blades is shown by Figure 5. Figures 3 and 5'4 show that corrosion of the cutting edge occurs when the blades are used with shaving creams of 9.2 pH as well as with creams of 7.2 pH. Figures 4 and 5B show that the addition of potassium chromate to shaving creams having a p F value of 9 2 as well as to creams with a pH ,of 7.2 materially retards the corrosion of razor blades used with them. Similar comparative shaving tests were made with two other brushless types and oue other brush type of shaving crcam on the market. The effecton the cutting edge of razor blades was sirnilar to the results shown in Figures 3,4, and 5, In making comparative shaving tests, new razor blades of the same brand were used and were cleaned and dried irnmediately after use. Figure 6 is typical of the cutting edge of the nen razor blniles tested. Each blade was used an equal num-
69
ber of times by the s a n e person. The number of times a blade was used with untreated shaving cream was carried beyond the point of comfortable shaving. Five men, using different makes of razor blades, were given a supply of a brushless type of shaving eream, as sold on the market, with a pH of 7.2, and another supply of the same cream to which potassium chromate had been added. These men, starting with new razor blades, noted the number of shaves they obtained with a blade before it became dull and had to be discarded. Ail reported that they obtained a greater number of shaves with the chromate-treated shaving cream than with the shaving cream as sold on the market. The increase in the number of shaves varied from 50 to 200 per cent. Razor blades used with chromate-treated shaving creams have been in service without cleaning or drying and withoot reducing the number of satisfactory shaves obtained with a blade, in comparison with the number obtained when the blade was cleaned and dried in the customary manner. Shaving creams containing a chromate salt in an amount SUBeient t o inhibit oxygen corrosion have been used by several hundred men vithout n ease of skin irritation.
INDUSTRIAL AYD ENGINEERING CHEMISTRY
70
Passivation The action of chromate salts in inhibiting the rusting of steel is termed "passivation." Other substances than chromates can produce passivation of steel. The generally accepted theory of the action is that a tightly adhering, invisible film of an iron oxide is formed on the steel which protects
it.' Shaving tests were made in which the razor blade was dipped in a solution of a chromate salt after each shave. The
* Speller, F. N., "Corrosion, C a u s e and Prevention," MoGraw-Hill Book Co.. 1926.
New York,
VOL. 29, NO. 1
results in lengthening the effective life of razor blades were not as satisfactory as when the chromate salt was incorporated in the shaving cream. The effectiveness of the treated shaving cream in increasing the life of razor blades is probably due to the breaking of the iron oxide film in the process of shaving and being immediately reformed by the passivating agent present. The use of passivating agents in shaving preparations has been protected by patent applications in a number of countries. So far patents have been granted in the United States, Canada, Great Britain, Italy, and France. RECEIVED .4pril
24, 1936.
Composition of a Yates Gasoline c. 0.TONGBERG,
M. R. FENSKE, AND J. E. NICKELS The Pennsylvania State Cofiege, State College, Pa.
T
HE constitution of Pennsylvania, West Virginia, and Michigan gasolines was discussed previously (1, 6, 7). It was found that a single batch fractional distillation of 45 gallons (170 liters) of a gasoline in a column with seventy to seventy-five theoretical plates a t a reflux ratio of approximately 40 to 1 will separate the constituents of the gasoline into narrow-boiling fractions. Such a fractionation enables us to classify different gasolines and to speculate with a reasonable degree of assurance as to the nature and amount of the hydrocarbons present. The Yates pool is located in Pecos County, West Texas, and in 1935 was the eighth largest pool in the United States (4). The gasoline has a relatively high octane number, 60 to 64 A. S. T. M., and is sometimes used as a base gasoline in making fuels of high octane number. The gasoline to be fractionated was caustic-washed and had the following properties :
nq
A. 6. T. M. Eneler Distillation. ~~
~
~
~~
Initial b. p. 108 42)
:!g lo
40
186 223 250 272
186) (106) 70 (121) 80 (133) 9 0 7
F 294 314 335 356 380
(' C ) ( i ~ ) (157) (168) (180) (193)
En$ point 410 (210)
A. P. I. gravity
Octane No. (procedure 345) Reid pressure at looovapor F. (38' C.), Sulfur content, % lb.
54.9 60 7 0.24
I
The fractionation was made in the column previously described (7), with the exception that, because of minor changes, the column had the equivalent of seventy to seventyfive theoretical plates when tested under total reflux with a mixture of n-heptane and methylcyclohexane. Forty-five gallons were charged into the still and fractionated a t an average reflux ratio of 35 to 1. The gasoline was accordingly divided into 180 fractions, each fraction consisting of 0.3 to 0.6 per cent of the charge. The average boiling spread (initial boiling point to 50 per cent point) as determined in a modified Cottrell boiling point apparatus was 0.2" C. (0.4' F.) although some fractions were obtained with a zero spread. A material balance follows: Noncondensable gaa Distillate Residue Hold-up and loss
gasolines fractionated in this laboratory under similar conditions. The difference between the peaks and valleys in the refractive index curve is small. The boiling points of the valleys of the refracthe index curve, unlike a paraffinic gasoline, do not correspond to the boiling points of the normal paraffins but correspond to the branched paraffins. I n fact, the rapid change of boiling point and refractive index a t the points in the distillation where the normal paraffins would normally be present lead to the conclusion that the normal paraffins are present in very small amounts, if a t all. The peaks in the refractive index curve are due, respectively, to cyclopentane, cyclohexane a t 80.4' C., methylcyclohexane a t 101.7', &hylcyclohexane a t 130.4', a nonanzphthene, cumene, and a naphthene a t 152.3', and tk methylbenzenes a t about 170" C. These conclusions were obtained from a study of the boiling point, refractive index before and after sulfuric acid extraction, refractionation data, octane number, and the experience gained in fractionating a large number of gasolines of various types. Since there are appreciable differences in refractive index among normal paraffins, branched paraffins, and naphthenes,
Vol. % . - of Charae
Total
2.5 66.0 24.7 6.8 __ 100.0
The results of the fractionation are given in Figure 1 and Tables I to IV. This gasoline differs markedly from other
A fractional distillation of 45 gallons (170 liters) of a Yates straight-run gasoline run in a standardized manner yielded considerable information regarding it 3 constitution. The gasoline was found to differ from other gasolines of paraffin type. A study of the fractions obtained showed that the gasoline consists mainly of naphthenes and branched paraffins. Methylcyclohexane and ethylcyclohexane were isolated and identified. No normal paraffins were found. Aromatic hydrocarbons are present in but negligible amounts below 157" C. (315" F.). However, certain fractions, with a lower refractive index and density than other fractions, have higher octane numbers.
