T H E J O L 7 R S A L OF I * Y D C S T R I A L AlVD EiYGIA’EERISG C H E M I S T R Y
466
leums and their products can be differentiated in the manner there described. This was suggested as long ago as 1898 in a paper published by the writer in the Joztrual of the .Cociety of Chemical Indatstry for January, 1898,where data in regard to the differences in the amount of saturated hydrocarbons in various forms of bitumen were given, and the statement made t h a t asphalts are distinguished b y the large amount of sulfur they contain, the softer asphalts containing much less than the harder ones, and t h a t it is to the presence of this material t h a t many of the characteristics of the native bitumens are due. The relation of sulfur t o the solid native bitumens has also been commented on by Holde in his book entitled “ Investigations on Mineral Oils and Fats, ” where he has stated: “ A bitumen would be called a native asphalt when it contains considerable amounts (2 t o I O per cent, usually over 4 per cent) of sulfur not removable b y steam, when the amount of the latter in the chloroform extract which is insoluble in benzol is a t least 7 . 5 per cent and the asphalt, separated according t o the method of Marcusson and Eickman, contains 1.4 t o 31 per cent of oil. with a t the most 0.6 per cent of paraffine.“ “ A bitumen would be called a petroleum residual pitch if i t contains a t most I.; per cent of sulfur, even in the chloroform extract prepared as previously described, and further 26 to j9 per cent of oil, in which the paraffine amounted to 3.3 to 16.6 per cent.” The conclusion of Holde might well have been drawn from the data given in the writer’s paper in 1898. With the knowledge which we now have in regard to the products obtained from Mexican oil and their preparation, his statements may, however, be modified and amplified a t the present time. The relation of saturated t o unsaturated hydrocarbons in the native bitumens was followed up b y the writer in his book, “ T h e Modern Asphalt Pavement.” I n the first edition in 1905 the statement was made: “ T h e saturated can be separated from the unsaturated hydrocarbons b y strong sulfuric acid, and this will be found t o be a very important means of differentiating the oils and the solid bitumens among themselves, by determining the relative proportions of these two classes of hydrocarbons which they contain.” The relative proportion of unsaturated and saturated hydrocarbons in various bitumens has also been considered very recently by Marcusson in “ Communications from the Royal Material Testing Laboratory near Berlin,” Volume 30, 1912,page 7 7 . This writer has also remarked upon the peculiar nature of the Mexican material, but as he has had no knowledge of its behavior on attempting t o handle i t on a n industrial scale or with the industrial products as they are marketed he has not been able t o draw some of the concIusions which the data available t o the writer have made possible. ~VOOLWOKTH BUILDING S E W YORK
Vol. 5 , KO. 6
DISTILLATION OF TAR B Y P. P. SHARPLES
METHODS AND VALUES I K SPECIFICATIONS
The wide adoption of refined t a r in road work has led t o much study of the material both from a manufacturer’s and a consumer’s standpoint. The manufacturer is interested in the manufacture of the best possible product from the raw materials available, while the consumer is interested both in getting the best material and in holding the manufacturer up to his highest level. Many different tests have been proposed to define refined tar, but the only essential points to be defined in order to secure uniformity are the specific gravity, viscosity or melting point, free carbon, and a distillation test. Of these tests, the specific gravity, viscosity or melting point, and free carbon have been very well understood through the discussion which has raged around them, and the tests themselves are comparatively simple, using simple apparatus. On the other hand, with the distillation test so many variations are possible, each of them having a direct and important bearing on the result, that the standardization of a method of testing has been fraught with great difficulty. Each laboratory which has attacked the problem has chosen a form of apparatus of its own, or even where the apparatus was the same, i t was used in such different ways that radically different results have been obtained with the same apparatus. I t is hardly t o be wondered t h a t the manufacturer who came in contact with all these different methods had difficulties of his own in a t tempting to fill even a specification based on the analysis of his own material. The sources of variation in the methods of distilling may be enumerated as follows: I . Shape of still. 2. Size of still. 3. Position of outlet. 4. Material of still and weight. 5 . Method of heating. 6. Method of protecting still and outlets from drafts. 7 . Size of charge. 8. Rate of distillation. 9. Position of thermometer. I O . Accuracy of thermometer. I I . Size and shape of thermometer. 1 2 . Cutting points on fractions. 13. Personal equation. 14. Method of reporting results (by volume or b y weight). It is not necessary to go into detail in regard to the causes of variation in the different cases enumerated, but that they are serious is shown by Tables I , 11, and 111. Table I shows results obtained by Messrs. Arthur R . Warnes and W. B. Southerton, of the Midland Junior Gas Association, February, I 9 I 2. 1 Paper presented at the Cleveland meeting of the American Associa. tion for the Advancement of Science, Dec. 30, 1912-Jan. 4, 1913.
June, 1 9 1 3
T H E JOC-R.Y-IL OF I S D C - S T R I A L A S D ESGI.YEERI.YG
Tables I1 and 111 are taken from “Proceedings of The American Society for Testing Materials,” Vol. XI, 191 I , the report of the sub-committee on Distillation of Committee D-4. The three series of tests. “ A , ” “ B . ” and “C,” were made by three different observers in three independent laboratories on the same sample, and are especially important, since they bring out not only variations due to the method, but also variations due to the personal equation. I n the case of creosote oil where a similar distillation is made, i t was early recognized that every detail of the method of distillation must be clearly stated, in order that the results might have any weight. As small variations in the distillate might lead to the rejection of thousands of gallons of oil, i t was important that the chemists of the buyer and of the seller should agree. In the United States. the specification of the Maintenance of Way Association has been generally adopted for creosote oil. This specification recognized and provided for all the points enumerated above, except the size and shape of the thermometer. Some recent work on thermometers has shown that manufacturers of the instruments vary widely in their method of calibration and in the size of the different parts of the thermometer. These differences are of small account in ordinary thermometric work, but in distillation, where the range is wide and where the temperature is not stationary but advancing, i t is import a n t to define the size of the thermometer, its amount of emersion and its sensitiveness to change in temperature. If this is not done, the cutting points recorded will not be the same, since a thermometer which is lacking in sensitiveness will not arrive a t the true temperature until long after that temperature has actually been reached in the distillation. Out of the general chaos of methods proposed for road work have emerged four which are nom in somewhat general use. These methods are its follows:
CHE3IISTRY
467
solidified in the stem of the retort is liquefied by the application of heat and caught in the last receiver. When the maximum temperature is reached for each fraction, the flame should be removed from under the retort until the thermometer shows a drop of about five degrees. The temperature is then changed for the next fraction. Fig. 49. Asbestos cover for retort. DI~TILLATION TEST,AMERICAN SOCIETY
OF
CIVIL
ENGIXEERS 700 grams of the compound are weighed into a retort (E. & A. $-pint iron retort No. 4521) whose top is fitted with a tee as close as possible to the retort, and a condenser pipe 24” to 36” long. The upper branch of the tee is used for the insertion of a thermometer, the top of whose bulb is placed immediately below the main outlet of the tec. The distillation shall procecd at the rate of two drops per second.
DISTILLATIONTEST, AMERICANR A I L W A Y ENGISEERISC& MAIXTENAXCE OF WAY ASSOCIATIOX (Bulletin No. 65, July, 1905) Apparatus: The apparatus for distilling the tar oil or creosote must consist of a stoppered glass retort similar to that shown in diagram, having a capacity, as nearly as can be obtained, of 8 oz. up to the bend of the neck, when the bottom of the retort and the mouth of the offtake are in the same plane. A nitrogen filled mercury thermometer of good standard make, divided into full degrees Centigrade, must be used in connection therewith. The bulb of the retort and a t least 2 inches of the neck must be and remain covered with a shield of heavy asbestos paper, shaped as shown in diagram, during the entire process of distillation, so as to prevent heat radiation, and between the bottom of the retort and the flame of the lamp or burner two sheets of wire gauze, each no-mesh fine and a t least 6 inches square, must be placed. I t is also recommended that the flame be protected against air currents. An ordinary tin can, from which a portion of the bottom and all of the top have been removed, placed on a support attached to the burner, as shown on diagram, has been found to answer the purpose. Dzstzllatzort.-Before beginning the distillation the retort should be carefully weighed, and exactly IOO grams of the oil placed therein, the same being weighed in the retort. The thermometer should be inserted in the retort with the lower end of DISTILLATIOS TEST, OFFICE OF PLBLICROADS,~I’ASHIXGTON, the bulb 1/2’’ from the surface of the oil, and the condensing tube D. C. attached to the retort by a tight cork joint. The distance beThis test is made upon tars and tar products as follows: tween the bulb of the thermometer and the end of the condensing From the specific gravity of the tar, taken a t 2 j o C., the weight tube should not be less than 20” nor more than 24” and during of 2 j O cc. is calculated, and this amount poured into a tared the progress of the distillation the thermometer must rcmain glass retort of 7 j o cc. capacity. A cork stopper carrying a ther- in the position originally placed. mometer is then inserted into the tubulature so that the bulb The distillate should be collected in weighed bottles and all is on a level with the bottom of the juncture of stem and body fractions determined by weight. of the retort, as shown in Fig. 48. The distillation should be a continuous one and should take The tar should be heated gradually by means of a Bunsen about 4 j minutes. burner and the first fraction to 100’ C. caught in a graduated PROPOSED TENTATIVEMETHOD OF DISTILLATION 01:AXERICAK glass cylinder. A cold wet towel wrapped about the stem of SOCIETY FOR TESTINGMATERIALS(Page 241, Vol. XI, the retort serves to condense the distillate. If the tar is a crude one, containing much water, great care must be taken to pre1911, “Proceedings of the American Society for Testing Materials”) vent it from boiling over. After the first fraction is collected, however, distillation proceeds without trouble. Apparatus.-The apparatus shall consist of the following standard parts: ( a ) Flask-the distillation flask shall be At this point the receiver is changed for another graduated a 2 j o cc. Engler distilling flask, having the following dimensions: glass cylinder, and an asbestos paper cover (see Fig. 49) placed over the retort for the purpose of obtaining a uniform tempera- Diameter of bulb, 8.0 cm.; length of neck, 1j.o cm.; diameter of neck, 1 . 7 cm.; surface of material to lower side of tubulature, ture. The flame of the burner should be so regulated that not I I .o cm.; length of tubulature, I j.0cm. ; diameter of tubulature, over two drops of distillate per second are collected. At 1 7 0 O C. the receiver is again changed and a third fraction to 270’ C. 0.9 cm.; angle of tubulature, 7 j 0 . A variation of 3 per cent. collected. from the above measurements will be allowed. ( b ) Thermometer.-The thermometer shall be of hardened Distillation is then stopped, and any material which may have
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
468
glass, filled with carbon dioxide under pressure and provided with an expansion chamber a t the top: it shall read to 450° C., and shall be graduated in single degrees Centigrade, and shall TABLEI-DISTILLATION
OF
....
Below 14OoC 0.85 140-27OoC 41.00 27O-30O0C 21.00 Totaldistillate ... 62.85
...... ......
CREOSOTE, SP. GR. 1.057 8 oz. Retort
1.20 63.00 12.00 76.20
0.20 45.00 22.00 67.20
TABLE11-COMPARISONS
0.80 58.00 15.00 73.80
OF FRACTIONS OF
Time, minutes., . Per cent by weigh
0.20 0.85 16.21 8.36 16.22 58.16(b) 100.00
Residue .................... 57.13 Total 99.69 (a)Distillation carried to 270' C. only.
.......................
CENTIGRADE
15
0.50 60.00 15.00 75.50
B 90
A
. S t a r t t o l l O ' C .............. 0.00 110Oto 170' C....... 17O0tO235'C ............... 21.50 235' to 270' C.. ............. 20.80 2 7 0 O t o 315'C ............... (a)
AT
C 75 0.29 1.44 14.61 24.06 15.73 43.31 99.24
1.10 56.00 14.00 71.10
4. Setting up the Apparatus.-The apparatus shall be set u p as shown in Fig. I , the thermometer being placed so that the top of the bulb is opposite the middle of the tubulature. All connections should be tight. 5. Method.-One hundred cubic centimeters of the dehydrated material to be tested shall be placed in a tared flask and weighed. After adjusting the thermometer, shield, condenser, etc., the distillation is commenced, the rate being so regulated that I cc. passes over every minute. The receiver is changed as the mercury column just passes the fractionating point. The following fractions should be reported: Start of distillation to I I O O C.; I I O to 170O C.: 170 to 235O C.; 235 to 270O C.; 270 to 300° C.;residue. To determine the amount of residue, the flask is weighed again when distillation is complete. During the distillation the condenser tube shall be warmed when necessary to prevent the deposition of any sublimate. The percentages of fractions should be reported both by weight and by volume.
SAMPLE MADEFROM WATER GAS TAR, Sp. gr. 1.1137. Free carbon 1.34 A B C A B C A 120
0.00 0.05 0.80 10.70 42.80 43.50 97.85
150
139
64
45
46
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.60 0.00 1.63 0.40 0.35 6.83 4.09 10.93 4.50 4.35 34.30 27.59 24.00 25.67 25.50 58.37(b) 67.35 61.80 71.10(b) 69.45 100.00 99.03 99.62 99.86 100.00 (b) Residue determined by difference.
B
C
64
45
42
0.00
0.00
0.00
0.00
0.00
0.00
0.07 11.90 26.97 60.87 99.81
TABLE111-COMPARISONSOF FRACTIONS OF SAMPLE MADE FROM COALTAR,Sp. gr. 1,2082, Free carbon 18.53 A B C A B C A B C A
............. 96 ... . . . 0.03 . . . 1.36 170' to 235' C.. ............. 17.54 235 to 270' C.. ............. 9 .SO 270Oto 315' C............... (a) Residue.. .................. 70.80 Total ....................... 99.42 Time, minutes.. Per cent by weight Start to l l O o C..
105
0.00 0.07 14.80 6.64 10.47 68.02 100.00 (a) Distillation carried to 270' C. only.
84 0.52 3.06 13.39 12.78 10.57 58.92 99.24
100 0.10
0.25 5.75 11.65 11.60 70.10 99.45
210
102
0.00 0.20 3.54 11.70 12.42 72.14(b) 100.00 (b)
93
50
............................
... ,~............. .............................
Specific gr. of distillate a t 15.5 C.. Melting pt. of residue..
5 seconds @ 40°
F.
1 .0345 7 2 . i a C.
have the following dimensions: Diameter of stem, 6.75 to 7.25 mm.; length of thermometer, 335 to 350 mm.; length from oo to 450° marks, 285 to 300 mm.; length of bulb, 20 to 22 mm.; diameter of bulb, 5.25 to 6.50 mm. It shall rise from 1 5 to~ g5O in not less than 3 seconds nor more than 5 seconds when plunged into boiling water. The thermometer shall be set up as for the distillation test, using water, naphthalene and dimethylamine as distilling liquids. The correctness of the thermometer shall be checked a t oo C. and I O O O C. after each third distillation until seasoned. (c) Condenser.-The condenser shall have the following dimensions: Length of tube, 500 mm.; width of tube, 12 to 15 mm.; width of adapter end of tube, 2 0 to 25 mm. (4 Stands.-Two iron stands shall be provided, one with a universal clamp for holding the condenser and one with a light grip arm with a cork-lined clamp for holding the flask. (e) Burner and Shield.-A Bunsen burner shall be provided, with a tin shield 20 cm. long by 9 cm. in diameter. The shield shall have a small hole for observing the flame. V, Cylinders.-The cylinders used in collecting the distillate shall have a capacity of 2 5 cc., and shall be graduated in tenths of a cubic centimeter.
35
0.00 0.00 0.00 0.00 0.15 0.18 0.00 0.00 2.84 5.90 3.40 2.84 11.41 10.33 9.40 9.16 12.66 10.37 9.60 11.40 72.00 73.07 77.60 76.45 99.06 99.85 100.00 99.85 Residue determined by difference.
TABLE IV-COMPARISON OF REFINED TARS No. 5 No. 7 Penetration (Schiitte).. Distillation, 0 t o 170' C.. .....................
Vol. 5 , No. 6
77 seconds @ 40' 0% 21.7570 1 ,0433 73.8' C.
58
0.01 0.01 6.40
9.07 10.10 74.10 99.69
No. 9
F.
70 seconds a t 60' F. 07 0
15.9970 1.0481 72.2'C.
0.08 0.37 11.56 7.62 28.66 26.41 59.1l(b) 65.22 100.00 99.62
B
C
50
38
0.00 0.00 0.00 0.00 6.65 5.04 9.06 9.87 9.14 10.25 75.15(b) 74.62 100.00 99.78
No. 11 M. p. 113' F. 0% 9.12% Not determined 74.40 c.
The results of a long series of distillations made by members of the sub-committee on distillation, of the American Society for Testing Materials, given in Table I, show very clearly the marked difference in the results given by these methods, and also the differences that may be expected from different observers using the same methods. If these different specifications are examined, it will be noted t h a t the specification of the American Railway Engineering & Maintenance of Way Association provides for nearly all the possible sources of error noted on page 466. The personal equation, however, seems t o enter less into the results obtained by the Tentative Method of the American Society for Testing Materials. It would seem, therefore, that this method warrants a much wider acceptance than has been accorded it at the present time. The method, in addition t o its accuracy, has the distinct advantages over all the other methods (except that of the American Railway Engineering & Maintenance of
June, 1 9 1 3
T H E JOUR.\‘.4L
OF I : V D C S T R I . l L A N D E:‘\‘GI-\-EERISG
Way Association method) of requiring apparatus easily obtainable; of requiring a minimum amount of material for the distillation ; and of requiring a minimum amount of time. All of these are important considerations in a commercial laboratory. TABLEV-EXTTRACTS
O F VARIOUS
SPECIFICATIONS
AfASSACHUSETTS HIGHWAYCOMMISSION’S SPECIFICATIOK FOR REFINED TAR,1909: “It shall contain no body that distills a t a lower temperature than 223 degrees C. : not over 10 per cent by weight shall distill below 270 degrees C . ; and i t shall contain a t least 65 per cent, by weight, of pitch or bituminous material remaining after all bodies up to 360 degrees C. have been distilled.” ILLINOIS HIGHWAYCOMMISSION’S SPECIFICATION FOR TAR BINDER, 1912: “Disti[Zation.-Fractional distillation shall give results within the following limits, all measurements being by volume: “Up to 1 l o o C. the distillate shall not exceed 2 per cent, and shall be free from ammoniacal water. “From llOo C. to 1 7 0 ° C. there shall be not to exceed 5 per cent distillate, of which not more than one-fourth shall be naphthalene. “From 170° C. to 270’ C. there shall be not more than 30 per cent nor less than 20 per cent of distillate, of which not more than one-third shall be solids when cold.” NEW YORK HIGHWAY COMMISSIOS’S S P E C I F I C A T I O N FOR BITUMINOUS MATERIAL“T” (HIGH CARBONTAR), 1912: “ I t shall contain no body that distills a t a lower temperature than l i o n C.; not over 1 per cent shall distill below 235’ C.: not over 10 per cent shall distill below 270° C.; not over 20 per cent shall distill below 300 degrees C. “The specific gravity of the entire distillate shall not be less than 1.02. “The residue from the foregoing distillation shall have a melting point not greater than 7 5 degrees C.”
SPECIFICATIONS FOR “BITUMINOUS CONCRETE PAVEMENT,“ ADOPTED ASSOCIATIONFOR STANDARDIZISG PAVXNG SPECIFICATIONS IN JAN., 1912: “ C o d T a r Cement.-So distillate shall be obtained lower than 338’ F., and up to 600 degrees not less than 5 per cent. and not more than 20 per cent of distillate shall be obtained. The distillate shall be of gravity of n o t less than 1.03 a t 60 degrees F. The residue shall have a melting point of not more than 165 degrees F . “In making this distillation an 8 02. glass retort shall be used, and the thermometer suspended so that before applying the heat the bulb of the thermometer is inch above the surface of the liquid.” ROADBOARDO F ENGLAND’S SPECIFICATIONNO. 5 ADOPTED I N APRIL, The t a r shall be free 191 1: “SBecification /or T a r No. ,?.--Fractionation: from water, and on distillation shall yield no distillate below 140” Centigrade, nor more than 5 per cent of distillate up to 220 degrees Centigrade, which distillate shall remain clear and free from solid matter (crystals of naphthalene, etc.) when maintained a t a temperature of 30 degrees Centigrade for half an hour. “Between 140 degrees and 300 degrees Centigrade it shall yield not less than 15 per cent. nor more than 2 1 per cent of the weight of the Tar.” BY
THE
V A L U E IN SPECIFICATIONS
A distillation clause in specifications for road t a r was originally introduced with the idea of governing the consistency. Methods for determining consistency have, however, been so well worked out in recent years that the distillation test is not required for this purpose, and the mistake has often been made of calling for a distillation test not in accordance with the viscosity test. The two are closely related, as is shown by Table IV, showing the total distillate of four refined road tars of differing viscosities, made from the same raw tars, as determined by the American Railway Engineering & Maintenance of Way Association method. The real value of the distillation test is that when properly worded i t defines t o a certain extent the tars from which the product may be produced and the method of distilling them. The results should always be interpreted with reference to the other constants determined. The distillation specifications may be made t o show: I . The detection of water. Water will be shown in
CHEMISTRY
469
the first fraction and may be determined quantitatively. 11. The kind of tar. For this purpose the specific gravity of the oils distilled is indispensable and should .be required. Interpreted with reference to the free carbon and the viscosity, coal t a r and water gas tar may be distinguished by the specific gravity of the oils. 111. The method of manufacture. The detection of a cut back t a r may be inferred from a n abnormal specific gravity of oil for the viscosity, and from a n abnormally high melting point of the residue of distillation. For this purpose the melting point of the residue should always be required. IV. The presence of abnormal amounts of naphthalene. An examination of the Iiquefying point of the oil will indicate abnormal naphthalene. An examination of some of the specifications in use would seem to show little uniformity in the requirements, and few indicate the method to be used, thus invalidating, to a certain extent, the objects aimed a t . I n Table V are shown a number of current specifications calling for approximately the same grade of refined tar. I t will be noted that no two use the same cutting points, that no two specify the same end point and t h a t only two call for the specific gravity of the distillate and the melting point of the residue. The great variety in the specifications takes away no small part of their value, as the direct comparison of the results of different observers is prevented. The importance of the test would seem to warrant its standardization. The important points to be observed in drawing specifications for distillation are: I . Absolute definition of method. 2. Designation of specific gravity of oil. 3. Designation of melting point of residue. 4. Conformance of distillation specification with other parts of the specification. 297 FRANKLIN ST. BOSTON,MASS.
THE DETERMINATION OF SULFATE IN AMMONIUM SULFATE SOLUTION WITH SPECIAL REFERENCE TO THE TESTING OF ILLUMINATING GAS‘ By R. S. MCBRIDEAND E. R . WEAVER
The following paper is a report of a short series of experiments undertaken t o determine the methods most suitable for sulfate determination in the testing of illuminating gas. I t is believed that some of the results obtained may be of general interest. I n the use of the various forms of apparatus for determination of sulfur in gas a solution of ammonium sulfate and ammonium carbonate is obtained, and it is necessary t o determine the sulfate present in such solutions. For official or commercial testing an accuracy of two or three per cent in this determination is ample; i t is, 1 Paper presented a t the Annual Meeting of the American Chemical Society, Milwaukee, March, 1913. This paper reports the same investigation that is given in the latter part of Technologic Paper, No. 20 of the Bureau of Standards. Published by permission of the Director, Bureau of Standards.
