INDUSTRIAL A N D ENGINEERING CHEMISTRY
May, 1926
Isomer of Chloramine Yellow NN, Columbia Yellow, or Direct Fast Yellow (Color Index No. 814)
The sulfo acid was dissolved in sodium carbonate solution and subjected to the action of a freshly prepared sodium hypochlorite solution for 24 hours at 10" to 15' C. The original colorless solution slowly changed to a deep yellowish red.4ng The dye was salted out, washed thoroughly with salt solution, and dried. As so prepared, it formed a brown powder, easily soluble in water, and dyed cotton directly a yellow shade scarcely distinguishable from that obtained with chloramine yellow NN in solutions of similar strength. When subjected to the usual tests4 for fastness to acids, alkalies, light, etc., its behavior was practically identical with 9 Compare Farbenfabr. vorm. F. Bayer, German Patent 65,402; Fried. l a c n d n , 8 , 752; Winlher, 8 , 1922.
533
that of chloramine yellow NN. Tinctorially, therefore, it seems to make little difference in these dyes whether the methyl group is in position 5 or 6. Summary
1-By starting with m-nitro-p-toluidine, an isomer of dehydrothio-p-toluidine has been prepared carrying the methyl group in position 5. 2-From this new base a dyestuff has been obtained isomeric with chloramine yellow NN (Color Index No. 814), of similar properties and dyeing similar shades. 3-Other new compounds prepared in the course of the investigation were the 2-nitro4methylphenyI disulfide, 2amino-4-methylphenyl mercaptan (zinc salt), and 2-(pnitrophenyl)-5-methylbenzothiazole.
Corrosion of Steels in the Atmosphere' By W. G. Whitman and E. L. Chappell DEPARTMENT OF CHEMICAL ENGINEERING, MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE, MASS,
M
ETHODS of estimating the resistance of steels to at-
mospheric corrosion are of practical interest to both the user and manufacturer of the material. The most conclusive tests yet devised are those of long-time exposure to service conditions, but the time and expense required by such tests seriously limit their general application and emphasize the necessity for an atmospheric test which will give a reliable index of corrosion resistance within a short time. Many mistakes in rapid testing for atmospheric corrosion have been recorded because some accelerating factor was introduced into the test which was not present under normal conditions. In the simple method described in this paper the primary accelerating influence is m o i s t u r e 4 e., the steel is kept wet during a larger fraction of the time than obtains in service. The validity of this method of hastening corrosion is evidenced by the fact that the results compare satisfactorily with the results of long-time service tests on the same steel specimens.
almost entirely on the volume of the cylinder H and the water rate of the spray. The spray period in the tests described here was 15 minutes, while the drying period was varied from 30 minutes to 23 hours and 45 minutes. Samples
Most of the tests were run with specimens of steel supplied by the Bureau of Standards from a reserve stock of American Society for Testing Materials test steels. Other samples of these same materials had been exposed in long-time tests in the atmosphere at Pittsburgh, Annapolis, and Fort Sheridan, Ill., and their relative resistances to corrosion under service conditions were therefore well established. 2
Testing Equipment
The testing equipment is shown diagrammatically in Figure 1. T is a galvanized box, coated inside with metalin-oil paint. The steel test specimens, 2 X 6 inches, are held a t an angle of 30 degrees from the horizontal by paraffined wooden clothespins attached to horizontal supporting rods. A spray nozzle operates intermittently for 15-minute intervals, the cycle of operation being automatically regulated by the system shown at the right of the figure. Water drained from the spray in the test box flows through pipe A , going partly into the cylinder H , and partly into the waste line through valve B. The rate of inflow through the spray nozzle is greater than the rate of draining a t B, so that after 15 minutes the float, F , moves the lever system from position 2 to 1, closing valve C on the water line. The shutting o f f of the spray stops the flow through pipe A so that the cylinder H slowly drains through valve B. When the float reaches the lower check, L1,the water valve C is reopened, starting another period of spraying. The length of the drying time may be varied greatly by changing the rate of drainage at B. The length of the spray period, although slightly influenced by the rate of flow a t B, depends I
Received January 7, 1926.
-
WASTE
Figure 1-Rapid
Atmospheric Corrosion Tester
A set of specimens of irons in which the chromium content had been varied was furnished by Mr. Speller, of the National Tube Company. Duplicate test pieces (2 X 6 inches) were cut from all these specimens and exposed in the spray box as described. The samples were prepared for testing by a preliminary corrosion in the test box, after which the rust was cleaned off with 0.1 N hydrochloric acid, steel wool, and a towel, and the steels were washed thoroughly with warm water, alcohol, and ether. The samples were then weighed with an accuracy of 0.0005 gram. After exposure in the test box the cleaning and weighing were repeated. The average 2
Proc. A m . SOC. Testing Materials, Comm. A-6, 1921-4.
IiVDUSTRIAL A N D ENG1NEERI.A-G CHEMISTRY
534
Vol. 18, No. 5
average rate based on wetted time alone as recorded in the last column of Table I. Table I shows that the test differentiates consistently Test Runs between different kinds of steel. The real index of its validity comes, however, when its results are compared Run I . 45-minute cycle, repeated 224 times. The samples with the results of the A. S. T. M. service tests on the same were completely wet during the whole test period. Run 11. 60-minute cycle, repeated 106 times. A few of metals. the samples of copper-bearing steels showed dry patches each The data on service tests as reported to the A. S. T. If. time just before the spray started again. give the total number of sheets exposed and the number Run III. 190-minute cycle, repeated 21 times. The samples were all dry when spraying was resumed. The copper-bearing which had failed by perforation a t the time of inspection. samples dried first in From these data a maximum corrosion rate can be calculated 009 most cases. by dividing half the thickness of the sheet by the average Run I V. 1440-min- time before failure. ute cycle, repeated 17 0 OB In Table I1 the available data on these steels from the times. All samples were dry within 3 hours Pittsburgh and Fort Sheridan tests have been summarized. 007 of the time when the At Pittsburgh the rate of corrosion was so rapid that most n! spray shut off. of the samples failed by the end of G years and the test Y 006 has been finished. At Fort Sheridan the conditions were Results t much less severe and only a few sheets have failed. At The results of the Annapolis the corrosion has been so slight that no results four runs on A. S. are available a t this time. T. M. test steels are Table 11-Atmospheric Corrosion: Comparison of Field a n d Laboratory Tests g i v e n i n T a b l e I. -A. S. T. M. FIELDTBST--LABORATORY The two figures given Months exposure Corrosion rates TESTS before failure Cm./year Av. for each material repDESCRIPTION of 22-gage sheet Ft. corrosion resent data on dupli- A. S. T . M . OR Percent Ft. PittsSheri- Pittsrates STEEL Cu Sheridan burgh dan burgh Cm./yr. cate samples exposed Sample 0-31 Openhearth 0.016 37 10 to 16 0 . 0 1 3 0.036 0.076 in different parts of AA-10 Bessemer 0.010 14' 0.033 0.068 Bessemer 0.008 48 16 0.0099 0 . 0 2 9 0.051 t h e t e s t b o x . I n A-37 00-5 Open hearth 0.022 26" 0.018 0.042 penetration of the samples in centimeters per gear was then calculated from the losses in weight.
~
DlLLL
checks- and the relative ratings of the steels from the four different tests are in good accord. Table I-Atmospheric -Corrosion
Sample 0-3i
Percent Cu 0.016
AA-10
0.010
A-37
0.008
00-5
0.022
ccc-3
0.082
BB-30
0.125
110-23
0,248
CC-13
0.214
B-29
0.08
Bc-1
0.181
HHc-36
0.22
c-20
0.140
Hc-47
0.21
Run1 45 min.
Corrosion: Laboratory Tests Rates, Cm. per YearAveraee based on Run I1 Run 111 Run IV wetted 62 min. 190 min. 1440 min. time 0.0076 0.107 0.0358 0.0368 0.0788 0.0452 0.068 0.0838 0.0493 0.0660 0.051 0.0264 0.0480 0.0279 0.0312 0.042 0.0188 0.0356 0.0213 0.0457 0.039 0.0165 0.0388 0.0162 0.0547 0.031 0.0135 0.0241 0.0142 0.0274 0,025 0.0112 0.0193 0.0103 0.0292 0.024 0.00965 0,0218 0.0178 0.0178 0.022 0.0115 0,0145 0.0119 0.0185 0.020 0.0104 0.0221 0.0140 0.0175 0.019 0.0115 0.0137 0,00965 0.0117 0.018 0.00915 0.0140 0.0132 0.0137 0.016 0.00864 0.0112 0.00864 0.0107
It is evident that the corrosion rates are less in those runs where the cycle of spray operation is longer. This indicates the possibility that, since corrosion ceases when the steel becomes dry, corrosion rates based only on the actual wetted time would be the same for the different runs. From inspection of samples during the test it is estimated that a time of 2 hours after the spray had shut off represents the average wetted period. Since this corresponds to a total wetted cycle of 135 minutes, the results of Runs I11 and IV may be corrected to a wetted time basis by multiplying the observed rates by 190/135 and 1440/135, respectively. This has been done, and the corrected figures are averaged with the results of Runs I and I1 to give the
0.082 32G Pure iron Open hearth 0 . 1 2 5 32' ... Bessemer 0.248 0.214 35 Pure iron 22 to 41 Open hearth 0.08 46 Open hearth 0.181 Basic open hearth 0.22 C-20 Pureiron 0.140 He47 Basic open hearth 0.21 52 a One-half of time before failure of 16-gage sheet,
0.015 0.015
CCO-3 BB-30 11~23 Co-13 B-29 Be-1 HHo 36
ii'
The "months before failure" recorded in Table I1 are based on the thin s h e e t s (22 gage, 0.079 cm. thick). Results with 1G-gage m a t e r i a l (0.159 cm. thick) have been divided by 2 to put them on the same basis. The maximum corrosion rates given in the next columns a r e c a l c u l a t e d as described above. Finally, the average rates from the laboratory tests given in Table I are tabulated
0.019 0.018
0,009
0.016
$
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p,wo
o:Oi2
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Ooo9-
o.wl
o:oi3 0.012 0.010
0.039 0.031 0.025 0.024 0.022 0.020
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1
INDUSTRIAL A N D ENGINEERING CHEMISTRY
May, 1926
Conclusions
T a b l e 111-Atmospheric Corrosion of Chromium Iron: L a b o r a t o r y
Tests Chromium Per cent 16.02 13.00 9.23 8.29
-Corrosion Run I 0.00005 0.00007 0 . 00007 0.00005 0.0032 0,0023 0.0117 0 0061
Rates, Cm,/Year-Run I11 0.00015 0.00005 0,00012 0.00013 0.0026 0,0022 0.0076 0.0076
Average 0.00008
0.00009 0.0026
0.0082
535
The rapid test of corrosion resistance on bare steel described in this paper has given results within a few days comparing favorably with the results of long-time service tests on the same steels by the A. S. T. M. It is believed that the essential features which make such close comparison possible are the proper preparation of the samples by previous corrosion and the use of moisture as the sole accelerating agent.
Influence of Rate of Stirring on Reaction Velocity',? By F. C. Huber and E. Emmet Reid THE J O H N S HOPKISSUNIVERSITY,
BALTIXORE,
LID.
In consecutive reactions we may have a slow reacThe influence of speed of stirring on the ratio of a tion followed by an exnumber of reactions has been studied. Three classes Historical tremely rapid one, or the have been found, those in which the rate is approxireverse. In either case the It is, of course, impossible mately a linear function of the speed of stirring, those to mention all In which over-all rate depends on stirring has been used t o acin which this relation becomes linear only after a certhat of the slow reaction. celerate chemical reactions, tain speed is attained, and those in which the rate is We may regard the reaction but a few are listed in which independent of the speed of stirring. To Class 1 of a gas with a liquid as the effect of s t i r r i n g w a s belong the ethylation of benzene by ethylene, the oxidastudied quantitatively. two consecutive reactions, Marc3 studied the rate of tion of sodium arsenite by oxygen, the oxidation of p of which the first is the crystallization. H e f o u n d nitrotoluene by chromate mixture, and the reduction of solution of the gas in the that at a c e r t a i n nitrobenzene by iron and dilute acid; to Class 2 the speed for any given temperaliquid and the second the turefurther increases in speed catalytic hydrogenation of cottonseed oil and of a hyreaction between the disdrocarbon; and to Class 3 the saponification of ethyl had no influence on the rate. solved gas and the liquid, H e also found salts whose benzoate at 60" C. and the reaction of benzyl chloride The rate of solution may be Of crysta11ization were with dilute aqueous solutions of sodium acetate and independent of the speed of slow and the reaction of the at 2oo c. stirring. Brunner4 s h o w e d dissolved gas rapid, in which t h a t the rate of solution was - case the observed rate of reDroDortional t o the 2/. Dower action must depend on the of {he stirring speed: Later, Van Name and Edgar6 showed that the rate of reaction of iodine rate of solution which is dependent on stirring. In case a gas with metals is proportional t o the 4/; power of the speed. Zeng- dissolves quickly but reacts slowly after it is in solution, heliss found t h a t if a gas is passed through a parchment capsule stirring may be expected to have little effect. the rate of reaction between the gas and the solution is increased. The reactions studied group themselves into three classes : Friend and Bennet' studied the rate of solution of pure iron in dilute sulfuric acid a t speeds ranging from 145 to 4000 r. p. m. (I) those in which the rate of reaction is approximately a They found t h a t the rate of solution is proportional t o the speed linear function of the speed of stirring, (2) those in which of stirring. Tzentnershvers found t h a t the rotation of a magnesium cylinder in dilute hydrochloric acid hastened its solution. the relation becomes linear only after a certain speed is reached, and (3) those that are but slightly affected by Danniensg noticed that the absorption of ethylene in sulfuric acid was increased 20 t o 27 times by stirring a t 200 r. p. m. Re- changes in the rate of stirring. cently, a n article from this laboratory, by Milligan and Reid,'o For Class 1 we have the relation described the influence of high-speed stirring on several systems. of stirring, from none up to 12,000 r. p. m.
1 Presented under the title "The Relation of-Reaction Velocity to Rate of Stirring in Various Systems" before the Division of Organic Chemistry at the 69th Meeting of the American Chemical Society, Baltimore, Md., April 6 to 10, 1925. Received November 7, 1925. From Ph.D. dissertation of B. C. Huber, 1925. Z . physik. C h e m . , 61, 385 (1908); 79, 71 (1912); Z. Lileklrochem., 15, 679 (1909). 4 Z . p h r s i k . Chem., 47, 56 (1904). 4 [bid., 73, 97 (1910). C o m p t . vend., 170, 583; 171, 167 (1920). 7 J . Chem. SOC.( L o n d o n ) , 121, 41 (1922). 8 Rec. lruu. chim., 42, 579 (1923). 0 Comfit. rend., 175, 585 (1922). loTHIS JOURNAL, 15, 1048 (1923).
*
a=a+br
in which v is the reaction velocity, r the rate of stirring in thousands r. p. m., a the velocity when there is no stirring, and b a constant. The curves all cut the axis above the origin. In the second class the reaction is very slow with no stirring, the rate increases a t first more rapidly than the speed of stirring, and later the relation becomes linear. The straight part of the curve is represented by 2,
= b(r
- r')
in which r' is the rate of stirring a t which the linear part of the curve would cut the axis if it were prolonged. It is
