592
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C E E M I S T R Y
TABLE1'11-SHOWING
INDEPENDENCE OF CARBONIZATION VALUE A N D O N HEATINGTO 250° Oil No. 1 No. 2 No. 3 Evaporation in 3 hrs., per cent . . . . . . . . . . . . . 17.3 19.3 19.6 23.9 21.0 22.5 Corresponding carbonization. per cent . . . . . . 0.16 0.14 0.17 0.18 0.30 0.30 Evaporation in 5 hrs., per cent. ....... . . . . . 21.3 24.3 27.3 30.7 26.8 29.5 Corresponding carbcnization, per c e n t . . . . . . 0 . 5 1 0.51 0.56 0.S5 1.09 1.05
EVAPORATION Loss
It so happens t h a t these oils have carbonization values t h a t increase as t h e flash a n d fire points become lower. T h a t this is accidental can be seen from Table V I I I , which gives d a t a on a few oils recently tested, and shows t h a t t h e flash a n d fire points are also independent of t h e carbonization value: TABI,~: VIII-SNOWING INDEPENDENCE OF CARBONIZATION VALUEAND THE F L A 5 H AND FIREP O I N T S
.
Flash point. C ...... . 125' 165O 190' 195' 195O 200° 200' 20S0 225O Fire point, C .... . . . . . 205O 205O 220' 235' 235O 240' 250° 245' 2 6 5 O Carbonization per cent 0.42 0.41 0.06 0 . 2 9 0.16 1.05 0.22 0.39 0.06
SUiSMABY
I n order t o determine whether t h e r e is a n y close connection between t h e r a t e of oxidation of automobile oils when exposed t o sunlight a n d air, a n d their carbonization values when heated .to comparatively high temperatures, a s t u d y was m a d e of three brands of oil. T h e gains in weight a.nd i n acidity a n d t h e increase in t h e carbonization value were determined. a t frequent short intervals. I n t h e first t w o of these tests, t w o of t h e oils showed nearly identical gains, t h e third differing quite noticea.bly. I n t h e carbonization tes.t t h e values for t h e three oils were quite far a p a r t , Of minor importance were determinations of t h e demulsibility, t h e iodine number a n d t h e Maurnen6 number. T h e effect of oxidation was t o increase t h e tendency t o form eniulsions with mater. T h e iodine numbers were lower a n d Maurnen6 numbers higher for t h e oxidized t h a n for the original oils. T h e changes in the carbonization values caused b y heating t h e above three oils a n d eight others t o 2 5 0 ' for different lengths of t i m e were t h e n studied, a s well as t h e changes caused by heating t o different temperatures for three hours. It was found t h a t in both cases t h e greater t h e carbonization value at first, t h e more rapidly did i t increase as t h e temperat u r e was raised or t h e time of heating extended. I n other words, a n oil which has a low carbonization value if heated t o 2 5 0 ' for t w o or three hours a n d a n oil showing a somewhat higher value under ,the s a m e conditions will be farther a n d farther a p a r t as t h e conditions become more strenuous. T h e carbonization value of a n oil is coming t o be recognized as a valuable criterion in routine testing, a n d methods for its determination are finding their w a y into text-books, as re11 as into t h e journals. Most of these methods prescribe heating t h e oil for m a n y hours, b u t it seems, from t h e work described above, t h a t this is unnecess a r y . I n most cases heating for 2'/2 hrs. is sufficient a n d has t h e advantage of permitting t w o runs in a working d a y , with t h e necessary interval of a n hour or more for t h e b a t h t o cool. Of far greater a n d indeed, of vital importance, is t h e exercise of extreme care in taking a n d preserving samples, as well as i n testing them.
V O ~8, . NO. 7
A s t u d y of all t h e d a t a obtained shows t h a t t h e r e is n o direct proportionality, b u t only a rough parallelism, between t h e results of t h e different tests described above. I n conclusion, i t is shown t h a t t h e carbonization value is independent of t h e flash and fire points, a n d of t h e evaporation loss on heating. B E R ~ A OF U STANDARDS, WASHIIIGION
K JELDAHL MODIFICATION FOR DETERMINATION OF NITROGEN IN NI?RO SUBSTITUTION COMPOUNDS~ By W. C. COPE Received March 21, 1916
T h e Bureau of Mines has received numerous requests for information in regard t o t h e determination of nitrogen i n nitro substitution compounds, a n d as m a n y requests have come from skilled chemists it a p pears t h a t t h e information usually a t h a n d lacks details which are necessary t o obtain trustworthy results. T h e following method h a s been evolved from t h e work of Kjeldahl,2 G ~ n n i n g ,J ~o d l b a ~ e r ,a~n d others, a n d has given good results on a variety of compounds over a period of a year a n d half, a n d since several members of t h e laboratory force h a v e obtained consistent results it is believed t h a t t h e method is suitable for general analytical work. 11E T H OD
Weigh accurately about 0 . jooo g. of t h e nitro substitution compound a n d place in a joo cc. longnecked Kjeldahl digestion flask. T h e n a d d 30 cc. sulfuric acid (96 per c e n t ) , containing 2 g. of salicylic acid, a n d dissolve t h e nitro compound b y rotating t h e flask, or by heating over a s t e a m b a t h if necessary. After cooling, a d d z g. ol' zinc dust i n small portions at a time, continually rotating t h e flask a n d cooling t o prevent heating above room temperature. After all t h e zinc has been added, rotate t h e flask a t I O or 1 5 min. intervals for a b o u t t o 2 hrs. a n d t h e n let s t a n d over night a t room temperature. H e a t t h e flask very gently over a small flame until evolution of fumes has ceased (requirigg usually t o 2 hrs.), t h e n bring t o boiling a n d continue boiling for I'/* t o 2 hrs.; cool slightly a n d a d d I g. of yellow mercuric oxide (HgO) a n d boil I t o 1'/2 hrs. longer. Now a d d , after cooIing, 7 . 5 g. potassium sulfate ( K 2 S 0 4 ) a n d I O cc. more sulfuric acid, a n d boil 1 1 / ~ t o 2 hrs. longer. If t h e solution is clear a n d practically colorless t h e digestion is complete; if n o t , a d d I g. more potassium sulfate a n d boil f o r t o I hr. longer. Cool t h e liquid in t h e flask a n d a d d 2 5 0 cc. distilled water t o dissolve cake formed; t h e n a d d 2 j cc. potassium sulfide solution (80 g. per liter of distilled w a t e r ) , I g. granulated zinc, a n d 8 5 t o go cc. sodium hydroxide solution ( 7 j o g. per liter of distilled water), completing t h e determination as is usual for all modifications of t h e method. 5 2 8
4
Published b y permission of the Director, U. S. Bureau of Mines J. Kjeldahl, Z. anal. Chem., Bd 22 (1883). 366 Gunning. Ibtd., Bd. 28 (1889). 188. M. Jodlbauer, Chem. Zentr. (3 F.), Ed. 17, 433.
J u l y , 1916
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
593
p o u n d s s u c h as m e t h a n e , e t h a n e , ethylene, and similar hydrocarbons. (4)-Aromatic hydrocarbons. .......... (5)-The influence sf hydrogen on t h e above reacLIQUIDD I - N I T R O T O L U E N E Sample (a). . . . . . . . . . . . . . . . 15.01 15.14 15.01 15.13 Sample ( b ) , . . . . . . . . . . . . . . . . 15.39 15.40 15.45 . . . . . tions. TRI-NITROTOLUENE (6)-The transfer of h e a t in gas machines. Sample 1859.. . . . . . . . . . . . . . 18.36 ..... Sample 1860. .............. 18.30 18.38 In the work bearing on the primary decomposition of paraffin Sample I,. . . . . . . . . . . . . . . . . 18.41 18.48 hydrocarbons of high molecular weight the greater portion SamDle D . . ............... 18.24 18.28 LIQUIDTRI-NITROTOLUENE. ..... 16.18 16.19 16.21 16.18 of the experimental evidence points to a splitting of the carbon DI-NITROBENZENE ' chain with formation of olefin and paraffin. Conditions de(0)....................... 16.18 16.23 16.29 ( p ) , ...................... 16.39 16.39 ..... termine where the rupture takes place-low temperature and (m)....................... 16.51 16.58 16.63 high pressure tending to favor the splitting near the middle of NITROPHEWOL (.0.) ....................... 9.90 9.84 9.92 10.12 ( p ) . ...................... 9.99 10.08 . . . . . . . . . . the chain while a t lower pressures and higher temperatures the breaking off of low molecular weight hydrocarbons, such META-NITROANILINE. ................................. 20.04 19.92 MO~-O-NITRONAPHTHALEWE ........................... 8.08 8.04 as methane, ethane, and ethylene, but particularly methane DT-NITROWAPHTHALENE (1 : 5 ) ........................ 11.89 12.09 22.73 22.78 and ethane, becomes the important reaction. The members 22.70 DI-NITROANILINE (1 : 2 : 4 ) . . . . 22.63 18.31 18.28 18.24 PICRICACID .................. 18.36 of the paraffin series down to butane in all probability follow some such mode ol' reaction as this. A blank determination should b e used t o correct The first problem to be considered in the study of the for nitrogen in reagents a n d i t is also advisable t o check secondary reactions, then, is the fate of the high molecular t h e m e t h o d with p u r e picric acid or s o m e o t h e r p u r e weight olefins which arise. It seems that the chief reaction nitro substitution compound. undergone by these high molecular weight olefins is a splitCooling during t h e addition of t h e zinc for reduc- ting into lower molecular weight olefins. A decomposition t i o n a n d t h e long s t a n d i n g before heating t h e acid into methane and compounds with two double bonds or one solution h a v e been f o u n d necessary i n order t o pre- triple bond also takes place. The intramolecular change of v e n t low results, a n d for t h e s a m e reason t h e h e a t i n g olefins into cycloparaffins is possible, but from the evidence available it is difficult to state what proportion of the should b e gradual. naphthene formation must be ascribed to this reaction.' T h e results given in t h e t a b l e indicate that the Hydrogenation of olefins takes place to some extent Polymm e t h o d is especially applicable for picric acid a n d t h e erization of olefins to naphthenes occurs, also polymerization nitrotoluenes b u t is n o t good for tetra-nitroaniline, of the high molecular weight unsaturated compounds to tarry tetra-nitromethylaniline, and di-nitronaphthalene. compounds. The reactions which form the lower molecular weight hydroBUREAUOF MINES, W A S H I N G T O N carbons are in general more rapid in their progress than the reactions of decomposition of these lower hydrocarbons. THE DECOMPOSITION OF HYDROCARBONS AND T H E Methane, in particular, is stable under the action of heat a t those temperatures which are used in the various apparatus INFLUENCE OF HYDROGEN IN CARBURETED used in the manufacture of gas. Thus those reactions which WATER GAS MANUFACTURE' result in the formation of methane and ethylene reach a conBy M. c. m'H1TAEER AND E. H. 1 , B S L I E dition nearly corresponding to equilibrium proportions on acReceived June 1, 1916 count of the slow decomposition of ethylene and methane; Although n u m e r o u s studies of h y d r o c a r b o n debut the system as a whole cannot be regarded as in equilibrium. composition h a v e been made, no one, nor all combined, I n considering the discussion of the reactions of the individual comprise a complete investigation. On account of hydrocarbons the effect of the presence of the end products t h e variety of t h e materials which h a v e been worked of a particular reaction must always be kept in mind. Also u p o n , t h e extreme complexity of t h e changes which the changing concentration conditions as the gas volume int a k e place i n a n y case, t h e differences in t h e t y p e s of creases with the progress of the changes involved must not be a p p a r a t u s used, a n d t h e a p p a r e n t inclination of m a n y forgotten. writers t o allow t h e reader t o do the greater p a r t of METHANE-The study of the influence of heat a t various t h e interpretation of t h e results, which i n m a n y cases temperatures on the hydrocarbon methane has usually been is well-nigh impossible, t h e presentation of t h i s ma- made with the idea in mind of finding the equilibrium proporterial i n condensed f o r m is obviously impossible i n tions of methane and hydrogen in the system carbon-hydrogena brief article, so t h a t only those points will b e men- methane. The equilibrium proportions are never even approximated in experiments made after the manner of those discussed tioned t h a t a r e necessary for t h e i n t e r p r e t a t i o n of in the latter part of this paper, nor under the conditions maint h e results reported herein. In t h i s connection t h e tained in the technical production of coal, oil, and water gas. work previously done m a y be classified as follows: The preservation of methane is desired in all these cases, for (I)-The p r i m a r y decomposition of high molecular its decomposition into carbon and hydrogen means loss of valuable carbon from the gas and the production of gases high weight paraffin a n d n a p h t h e n e hydrocarbons. (2)-The various ideas in regard t o t h e mode of in hydrogen which are unsuited for distribution. Hence the reaction of t h e products of t h e p r i m a r y decomposition. studies of the methane equilibrium are of interest only in so far as they indicate the tendency of methane to decompose under (3)-The t h e r m a l reactions of the simpler com- certain temperature conditions. 1 Authors' abstract of dissertation offered in part fulfillment of t h e In summing up the work on methane it can be said that the requirements for the Ph.D. degree a t Columbia University, 1916. T h e chief reaction is the decomposition into carbon and hydrogen, dissertation itself contains detailed information as t o the results of the vaC,y, CHI --+ C f K", and that the reaction, ? C H I --+rious researches bearing on the subject and discusses fully their relations to each other. 3H2, takes place to a small extent only. PERCENTAGE NITROGEN FOUND BY AUTIIOR'S METHOD
MONO-NITROTOLUENE
...............
10.06 Sample ( a ) , ( b ) Redistilled., . . . . . . . . . . . 10.16 (c) Crude.. . . . . . . . . . . . . . . . 9 . 6 2
10.11 10.19 9.61
10.20 10.14
10.06 10.20
~~
+
