January, 1926
I N D U S T R I A L A N D ENGINEERING C H E M I X T R Y
soy bean oils. A few typical experimental results are shown in Table XI. Increasing quantity of catalyst has been found rather consistently to favor selective hydrogenation. I n a large majority of experiments, although not invariably, increasing temperature has been found to favor selective hydrogenation of marine oils up to about 200" C., above which results are conflicting. T A B LXI-WHALE ~
OIL HYDROGENATED TO 75 IODINE VALUE UNDER VARYING CONDITIONS Temperature Nickel Solid acids C. Per cent Per cent
22.6 21.7 23.3 23.4 23.0 22.2 22.0 23.0 21.7 19.8 22.3 21.2
Conclusion
In view of all the experimental results set forth above, it appears that the hydrogenation of whale oil in the presence
83
of catalytic nickel results initially in the preferential conversion of the highly unsaturated Cza and CB acids to acids of either one or two double bonds without the formation of substantial quantities of saturated acids. At an iodine value of approximately 84, the character of the hydrogenation changes abruptly. Immediately below this critical point, hydrogenation results in the formation of substantial amounts of palmitic and stearic acids, while the Cm and CZZacids containing two double bonds are simultaneously converted to corresponding acids of one double bond, possibly with the formation also of very small amounts of saturated acids of 20 and 22 carbon content. Even a t an iodine value of 57, substantial quantities of unsaturated acids containing two double bonds are present in the hydrogenated oil. Menhaden oil behaves in a similar manner on hydrogenation, and on account of similarity in composition it is probable that the same will be found true of other marine oils. It must, however, be regarded as mere coincidence that the critical points in the hydrogenation of the particular samples of whale oils and of menhaden oil used in the present investigation were reached a t practically identical iodine values.
Perfection of Chromic Acid Method for Determining Organic Carbon' By J. W. White and F. J. Holben THE PENNSYLVANIA STATE COLLEGE, STATECOLLEGE, PA.
the procedure of Ames and H E need of a method Results of the present study show conclusively that Gaither, suggests the partial for organic combusorganic materials are capable of complete oxidation in a substitution of phosphoric boiling mixture of sulfuric and chromic acids. tion adaptable to the The sulfur trioxide absorption tube, used for the first for sulfuric acid, which estimation of organic carbon, both in solution and in time in this study, greatly simplifies the usual analytical was observed to reduce procedure and eliminates the need of a combustion tube. the volume of acid fumes. dry substances, is emphaThe data reported as the sized by the many attempts The proposed method has the advantage over dry comresult of the present study to perfect the chromic acid . bustion in that it eliminates the possibility of leaving were secured by boiling the method proposed in 1848 by behind the residue of undecomposed carbonates; moresulfuric-chromic acid mixRogers and Rogers.2 The over it may be used for the estimation of carbon both in early studies of the method solution and in dry substances. ture for 30 minutes. The sulfuric acid fumes given off by Warrington and PeakeJ3 The Knorr apparatus is suggested for chromic acid digestion as carried out in this work. were intercepted by solution together with the investigations of Cameron and Breain a U tube containing sulfuric acid of constant boilzealeJ4furnished data which led to the conclusion that oxidation of carbon in soils by means ing point (98.33 per cent) in contact with coarse glass of a mixture of chromic and sulfuric acids gave results lower wool prepared and arranged as described below. The rethan those obtained by furnace combustion in a current of sults secured by this method will be seen to agree with the oxygen. dry combustion results. Various substances were tested, As suggested by Ames and Grtither,6 the failure of chromic including such resistant materials as peat, alfalfa meal, acid to bring about complete oxidation, resulting in the libera- charcoal, barnyard manure, soils, etc. The use of the protion of carbon compounds other than carbon dioxide, is due to posed sulfur trioxide absorption tube eliminates the necessity the fact that the mixture of acids has been kept considerably of secondary combustion and greatly reduces the time rebelow the boiling point. quired to complete a determination. Results are reported Those who have previously studied the chromic acid method including digestion in concentrated acid mixture and also have made no attempt to determine the effects of boiling the with 25-cc. dilutions of 4 per cent ammonium hydroxide acid mixture and of intercepting the sulfuric acid fumes evolved and 3 per cent sodium hydroxide. incident to boiling. Ames and Gaither5 report results sePreparation of Materials cured by boiling the acid mixture, but made no attempt to prevent the acid fumes from passing into the carbon dioxide absorption tower. Schollenberger,e in his modifications of SULFURIC ACID OF CONSTANT BOILINQPOINT (338 C.) 1 Received August 6. 1924. -The acid used in the sulfur trioxide absorption tube 2 A m . J . Sci., [21 5, 352 (1848). is prepared by boiling sulfuric acid (specific gravity 1.83 to 8 J . Chem. SOC.(London), 37, 617 (1880). 1.84) for 2 hours in a Kjeldahl flask. The flask is allowed to 4 J . A m . Chcm. SOC., 26, 29 (1904). 'cool for a few minutes and then closed with a rubber stopper 8 THIS JOURNAL, 6, 561 (1914). to which is attached a sulfuric acid-pumice drying tube. 8 I b i d . , 8, 1126 (1916).
T
I N D U S T R I A L A N D ENGINEERING C H E i W S T R Y
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SULFURTRIOXIDE ABSORPTIOS TUBE-A U tube 15 cm. long and 2 cm. in diameter (56 cc. capacity) is uniformly packed with approximately 2.5 grams of coarse glass wool in the manner illustrated (D). Before inserting the upper right-hand plug, the constant boiling point acid (98.33 per cent) is run from a buret (drop by drop) into each arm of the tube until the glass wool is thoroughly drenched. The excess of acid is allowed to drain into the bottom of the tube between the two plugs of glass wool. Sufficient acid should be added to fill the space at the bottom of the tube one-third full (12 to 15 cc. of acid are sufficient to saturate the glass wool and provide for the excess indicated). The lower right-hand plug is then pushed downward until it comes in contact with the excess of acid. The upper right-hand plug of untreated glass wool is then inserted, taking care to leave a space of 2.5 cm. between the two plugs. This precaution is necessary to prevent the acid from being carried over into the second tube during the passage of air through the train of tubes. The tube thus prepared may be used continuously until the volume of acid condensed is sufficient to fill the space at the bottom of the tube. CHROMIC ANHYDRIDE SOLUTION-A stock solution is prepared by dissolving 400 grams of chromic anhydride in a liter of distilled water. Ten cubic centimeters of the solution contain 3.39 grams Cr08. TABLE I-PER
CENT TOTAL CARBONDETERMINED ON SOILSBY WET COMCOMPARED WITH COMBUSTION IN FURNACE WITH COPPER OXIDEIN OXYGEN WET COMBUSTION 3.39 grams 3.39 grams CrOs. CrOs. 50 cc. 50 cc. Furnace 3.39 grams HzS04 combus- CrOa plus plus plus Differtion with 50 cc. 25 cc. 3% 2 5 c c . 4 % ence beCuO HzS04 NaOH NHiOH tween(2) SOIL (1) (2) (3) (41 and (1) 1,4678 $-0.0095 1.4692 1.4787 1.4630 DeKalb 2,5873 1-0.0238 2,5907 2.6145 2.5784 Berks 4-0.0314 2.8750 2,8640 2,8954 2,8784 Volusia 1.1917 +0.0178 1,1692 1.1556 1.1870 Huntingdon -0.0096 1.3192 1,3376 1.3083 1.3281 Westmoreland 4-0.0027 1.0949 1.0867 1,0894 1,0807 Upshur + O . 0128 1.5067 1.4816 1.4944 1.4808 Hagerstowna +O. 0232 2.0923 2.0725 2,0957 2.0739 Hagerstowna +0.0155 1.9948 2,0303 1.9997 2.0152 Hagerstowna +0.0020 2.2021 2.1734 2.1816 2.1836 Hagerstowno $0,021 1 1.6866 1.7065 1.6853 1.7064 Hagerstowv 1.8125 1.8249 1.8067 $0.0137 1.8262 Average a Soil from differently treated plots from old field plot experiment, Pennsylvania Station. BUSTION
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Determination of Carbon in Presence of Ammonia
Gortner,’ in connection with his studies of soil organic matter, found that it was impossible accurately to determine humus carbon in a solution of 4 per cent ammonium hydroxide by digestion with chromic acid. He suggests that such oxidation may result in the formation of ammonium cyanide or some of the aliphatic amines as well as nitric acid and oxides of nitrogen. Reference to Table I, Column 4, will show that the total carbon recovered in soils to which 25 cc. of ammonium hydroxide were added agrees with that found by dry combustion and also by digestion with concentrated acids. Preliminary studies showed that the boiling chromic acid mixture had no effect upon sulfate of ammonia as measured by the ammonia recovered in the residue after digestion by distillation with an excess of sodium hydroxide. The data reported as the result of the present study were secured by boiling the chromic acid mixture for 30 minutes, whereas Gortner kept the digestion mixture below the boiling point for 2.5 hours and passed the products of combustion through a heated combustion tube. Apparatus
To Knorr’s carbon dioxide apparatus, C, is attached the usual train of absorption tubes, including the 803 absorptidn 7
Soil Science, 2, 395 (1916).
Vol. 17, No. 1
tubes D and F. A is an Allihn gas-washing bottle containing 1: 1 potassium hydroxide. B is a sulfuric acid-pumice drying tube. D and F are the proposed sulfur trioxide absorption tubes. (Tube F serves the purpose of a drying tube and may be replaced by a sulfuric acid-pumice tube.)
APPARATUS FOR DETERMXNATION OB TOTALCARBON BY WET COMBUSTHIS APPARATUS ELIMINATES OBJECTIONABLE RUBBERSTOPPER CONNECTIONS
TION.
E contains glass beads and a saturated solution of silver sulfate in 5 per cent sulfuric acid. G is a weighed soda lime tube. H is a weighed sulfuric acid-pumice tube. I is a soda lime guard tube, and J is an aspirator. Air is brought from the outside atmosphere through tube attached to A . B, E, G, H , and I are McIntire tubes 12.5 cm. long and 2 cm. in diameter. CENT TOTAL CARBONDETERMINED ON MISCELLANEOUS MATERIALS B Y WET COMBUSTION COMPARED WITH COMBUSTION IN FURNACE AND BOMB WET COMBUSTION DRYCOMBUSTION 3 . 3 9 grams Per cent cars bon recovered Furnace Bomb CrOa ~ l u 50 cc. H&Oc compared MATERIALS (1) (2) (3) with (1) and (2 66.4404 66.4379 ... 99.9 Crude charcoal 33,8202 33.7215 100.3 ... Peat 45.5873 45.5786 99.9 Barnyard manure 41.9666 41.5543 100.9 Sucrose (43,3898)a 43.456 99.8 43.3348 Alfalfa meal (43.7360) 100.4 43.451 43.911 Alfalfa meal (43.5262) 43.4286 Mixed grain 43.487 99.9 (43.2379) 42,9160 Mixed grain 43.152 99.8 100.1 42: 303 42.296 42.3667 Cow duna a Figures shown in parentheses were secured by using 1 gram of material instead of 0.2 to 0.3 gram, in which case 20 cc. of “chromic acid” solution and 75 cc. sulfuric acid plus 25 cc. water were used. The last five samples were submitted by the Institute of Animal Nutrition, withholding their carbon figures until wet combustion results were completed.
TABLE11-PER
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Method
From 1 to 3 grams of soil or 0.2 to 0.3 gram of high-carbon material are placed in the generating flask, M . Ten cubic centimeters of chromic anhydride solution are run into a generating flask, followed by 50 cc. of sulfuric acid (specific gravity 1.83 to 1.84). Air is drawn through the apparatus and the solution brought to a boil. The solution is boiled for 30 minutes, during which time 1.5 liters of carbon dioxide-frec air are drawn through the apparatus. The flame is then removed and tubes G and H are closed. The combined weight of tubes G and H , corrected for blank, gives the total carbon as COz. (Inorganic carbon may be determined by means of the same apparatus.) WEIGHING SODALIMEAND ACID-DRYING TuBEs-The following procedure has been found necessary in order to secure accurate weights. The tubes, after being detached, are carefully wiped and weighed after an interval of 15 minutes. Both the soda lime and suIfuric acid tubes are weighed against a common counterpoise tube of the same size made up to a weight within 3 grams of the soda lime and acid-pumice tubes. Just before weighing each tube the valves are opened for an instant to equal-
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January, 1925
ize the inside and outside atmospheric pressures. In this manner the tubes can be weighed consistently within 0.3 mg., depending upon the accuracy of the balance used. Estimation in Alkali Humus
The results reported in Columns 3 and 4 of Table I show that the dilutions indicated did not interfere with the carbon determination. The method is therefore adapted to the estimation of carbon in alkali humus extracts, without the necessity of evaporation, which is attended under certain conditions by loss of carbon, as shown by the following experiment.
A 4 per cent ammonium hydroxide soil extract representing a composite solution from the extraction of several differently treated soils was equally divided. One portion was evaporated in copper boats on a steam bath and the second portion in a Hempel dessicator in vacuo at laboratory temperature. In a second case equal portions of humus solution were evaporated in like manner to constant weight in platinum dishes. The carbon was then estimated in the boats by combustion in a furnace. The platinum dishes were ignited over a free flame. The following results were secured: Steam bath Humus carbon, per cent 0.8045 Loss on ignition (humus), per cent 1.6033 Results represent average of four determinations.
Hempel 0.8945 1.7130
The Surface Tension of Crude Oils’ By Ellery H. Harvey BUCKNELL UNIVERSITY, LEWISBURO, PA.
URING an investigation of the method of determining surface tension with the du Nouy tensiometer, a complete set of crude oil samples, representing all the important producing fields of the United States, became available for testing. Such data as are reported herein will be,of interest to the oil technologist and at the same time will indicate the tendency of the du Nouy readings to vary from the results obtained with the more widely known “capillary tube” and “drop weight” methods. Such a comparison is necessary, since there is no recognized standard method of determining this important constant. With over a dozen methods of varying degrees of complexity from which to choose, and the results obtained not being necessarily comparable, it is highly desirable that the technic employed be indicated in reporting any surface tension measurement.
D
TABLE I-SURFACE TENSION OF THE CRUDEOILS OF THE UNITED STATES (Temperature 24’ C.) STATE OIL FIELD Dynes Vew York Allegany County 30.18 ?ennsylvania Mercer County 32 92 Pennsylvania Allegheny County 28.81 Zennsylvania Composite of state 29.16 1,ima 30 87 -Ihio -.. -Corning Ohio 30.52 Lima Indiana 30.87 30.87 Lawrence, Crawford, and other counties Illinois Big Sinkinn Kentucky 30.87 32.92 Ragland Kentucky 29.49 Maryland West Virginia West Virginia 29.49 Eureka California 34.30 Eastside Coalings Kern California 37.72 Sunset California 32.92 Sunset California 35.67 Santa Maria California 31.55 Montebello California 35.67 Montana Winnett 27.44 Wyoming Big Muddy 32.24 Wyoming Salt Creek 34.30 Colorado Florence 32.92 Kansas Augusta 31.55 Kansas Florence, Peabody 31.21 Oklahoma Billings 29,83 Oklahoma Ponca 30.18 Oklahoma Cushing 29.83 Oklahoma Pershing 30.87 Oklahoma Hewitt 31.21 Oklahoma Madill 26.76 Texas Burkburnett 30.01 Texas Media 31.21 South Texas Somerset 29.15 South Texas Goose Creek 33.62 South Texas Humble 34.64 South Texas West Columbia 33.62 Arkansas El Dorado 30.18 Louisiana Caddo 30.52 Louisiana Pine Island 34.30 Louisiana Anse La Butte 34.64
The du Noiiy apparatus2 is essentially a torsion balance in which the ring method is utilized, but instead of measuring 1 Received 2
May 16, 1924. J . Gen. P h y s i ~ l . ,1, 521 (1919).
the tension by the time-consuming use of weights, the torsion of the wire is used to counteract the tension of the liquid film and break it. To determine the factor for converting from dial readings to dynes per centimeter, the instrument is standardized with distilled water a t a definite temperature and, since this reading is only about 72, it is assumed that the strain on the wire is proportional to the angle torsion. With pure liquids and in the absence of vibration and temperature fluctuations the instrument in quite satisfactory, no other apparatus being as simple, rapid, and requiring as little material with which to work. When working with solutions, in addition to the foregoing precautions, evaporation must be prevented and the surface renewed. Table I1 furnishes a comparison between the results obtained with the du Noiiy instrument and those obtained with the capillary tube and hanging drop methods. It is evident from the data that the du Noiiy method tends to give results slightly higher than either of the other methods, the results obtained with the stalagmometer being in closer agreement with the du Noiiy results than those obtained with the capillary tube. TABLE 11-COMPARISON
OF RESULTSB Y VARIOUS METHODS (Temperature, 24‘ C.) du Nouy Capillary tube Hanging drop Dynes Dynes Dynes 26.76 23.92 25.64 30.01 27.26 28.81 30.87 27.90 29.57 30.18 27.30 28.86 31.56 28.53 30.30 30.52 27.53 29.27
STATE Oklahoma Texas Kentucky New York Kansas Ohio
For the purpose of determining whether doser agreement could be obtained if pure liquids were compared, the C. P. chemicals listed in Table 111were examined. TABLE 111-RESULTS
LIQUID Aniline Carbon disulfide Chloroform Pyridine Toluene
WITIi PURE LIQUIDS (Temperature, 21’ C.) du Noiiy Capillary tube Hanging drop Dynes Dynes Dynes 46.21 44.89 45.78 36.23 33.11 34.00 31.25 27.63 29.07 40,56 38.27 39.41 32.25 28.80 29.94
While the same relative differences between the methods persist, without a more extensive investigation illustrating to the contrary, it does not seem possible to derive a conversion factor that will apply in all cases.
