ANALYTICAL EDITION
142
The numerous plateaus shown in the case of petroleum products are extremely interesting. Petroleum is definitely broken up into comparatively simple fractions with distinctive boiling points (and percentages in the case of similar products) which consistently recur for a wide variety of petroleum products. The further study of these fractions to determine whether they are pure hydrocarbons, constantboiling mixtures, or merely compounds of almost identical boiling point is highly interesting but not absolutely nebessary t o prove the extreme sharpness of separation secured; the latter is also evident from distillations of close-boiling synthetic mixtures and of more easily identified components such as the lacquer thinners (Figure 6) and from hundreds of distillation analyses of all types of samples made in this laboratory with this general type of apparatus in the last three years. Such efficient primary separation of the constant or practically constant-boiling components of petroleum or any other complex mixtures enormously simplifies the taPk of resolving these constant-boiling components into their individual compounds by the use of supplementary methods (3, 9). Results of detailed study of some of the more distinctive plateaus secured above decane will be presented in a later paper. APPLICATIONS OF APPARATUS The apparatus described in this paper is believed suitable for both research and routine industrial analytical work. Its high fractionating effectiveness and precision of reflux temperature and distillate measurement should make it extremely useful in the investigation of composition of complex mixtures, in accurate analysis, and in the preparation of fairly large quantities (up to several liters or more) of difficultly separable pure compounds, in reasonable time. It may also be used for the purification by fractionation of small quantities of compounds such as the individual isomers of heptane or octane or other organic compounds, which are required to be of a very high purity not obtainable by other purifying means, because of the presence of other chemically similar com-
Vol. 5, No. 2
ponents. Incidentally, the use of the micro 2.6-mm. packed tube permits the fractionation of liquid samples only a few cubic centimeters in size. However, the apparatus is also especially suitable, because of its reasonable time requirement, ease of operation, compactness, and other advantages, for the routine industrial analysis of a great variety of commercially important complex mixtures, such as motor fuels, commercial solvents, absorption oils, lubricating oils, petroleum crudes, liquid organic chemicals, etc. Such precise fractionation analyses have a unique field of usefulness, not possible with apparatus of lesser fractionating effectiveness, in testing manufacturing equipment and plants by the material balance method, or for the actual design of new equipments and plants from such fundamental analyses of the raw materials. This is especially true of the petroleum industry, where the lack of suitable analytical methods has been a serious handicap in developmental work. LITERATURECITED (1) Bruun, J. H., and Schicktanz, S. T., Bur. Standards, Research Paper 379,871-2 (1931). (2) Dean, Hill, Smith, and Jacobs, Bur. Mines, Bull. 207 (1922). (3) Fenske, Quiggle, and Tongberg, IND. ENQ. CIIEM.,’24, 408 (1932). (4) Leslie, “Motor Fuels,” Chap. XV, Chemical Catalog, 1923. (5) Podbielniak, IND. ENQ.CHEM.,Anal. Ed., 3, 181 (1931). (6) Ibid., 5, 119 (1933). (7) Podbielniak and C. N. G . A. Gas Analysis Committee, PetroZeum World (Los Angeles), 14, No. 102 (1929). (8) Reilly, “Physico-Chemical Methods,” p. 106, Van Nostrand, 1925. (9) Washburn, Bruun, et al,, A. P. I. Research Project 6, Bur. Standards, Research Papers 145, 215, 236, 239, 280, 282, 311, 360, 379, 383, 432, 438, 439, 458, and 469. ( I O ) Weaver and Ledig, J. Am. Chem. Sac., 42, 1117 (1920). (11) Young, “Distillation Principles and Processes,” Macmillan, 1922.
RECEIVED September 15, 1932. Presented before the Division of Petroleum Chemistry a t the 84th Meeting of the American Chemical Society, Denver, Colo., August 22 to 26, 1932.
Combustion Train for the Determination of Total Carbon in Soils T. H. HOPPER, Agricultural Experiment Station, North Dakota Agricultural College, Fargo, N. Dak.
T
HE method of determining total carbon in soils by the direct combustion of the organic matter in a current of
’
carbon dioxide-free oxygen has been shown by Salter (2) to be not only satisfactory but rapid. This is especially true if ascarite is used as the absorbent for the carbon dioxide. Salter modified the procedure described by Fleming ( I ) , which is used in the iron and steel industry, Fleming points out that the principle is not new and that the rate of oxygen current and combustion for iron and steel is limited by the efficiency of the apparatus used to absorb the evolved carbon dioxide. Winters and Smith (3) have reported data showing advisability of the use of 0.25 gram of manganese dioxide per 2 grams of sample charge in order to obtain perfect combustion and results comparable to those obtained with the wet combustion method. The combustion train here described is a modification of those described by Salter (8) and Fleming (1). Special attention is called to several points in the assembly, The oxygen from the cylinder is let into the pressure system consisting of
a rubber basketball bladder A and two 5-pint (2.37-liter) bottles, B and C. The difference in the level of the two bottles, B and C, is adjusted to give an oxygen pressure of about 0.75 inch (1.9 cm.) of mercury in the pressure gage D during the combustion period. The scrubber F contains a 30 per cent solution of potassium hydroxide and the chloride tower G contains first ascarite and then granular calcium chloride, separated by a layer of glass wool. The mercury valve H serves as a check and as an oxygen-flow indicator. The silica tube I contains just within the exit end of the furnace J about 5 inches (12.7 cm.) of coarsely granular cupric oxide held in place by two plugs of asbestos fiber. The intake end of the combustion tube is fitted with a breech adapter which permits the introduction and removal of boats without disconnecting any rubber connections. The combustion may be observed through the cobalt glass window in the removable breech-block cap. The temperature of the furnace, which should be maintained a t about 950’ C. within the tube, is controlled by the rheostat
March 15, 1933
INDUSTRIAL AND ENGINEERING
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CHEMISTRY
recommend t h i s t y p e of absorption tube. Such t u b e s c a n easily b e made in the laboratory in quantity and their low cost hardly w a r r a n t s cleaning for recharging for use again. The scrubber R contains a 30 per cent solution of potassium hydroxide. Suction is applied t h r o u g h a l a r g e bottle, S , by an aspirator-type water pump T. The suction-equalizing bottle X a i d s i n g i v i n g a steady FIGURE1. COMBUSTION TRAIN suction, acting as a snubber or shock absorber. R and measured by means of a pyrometer having the thermoThe soil sample is mixed with 60-mesh carbon-free aluncouple placed in the position B indicated in Figure 2. A dum or 60-mesh carbon-free alundum and manganese dioxide groove was filed in the inner circumference of the clay insula- (S), using more alundum in proportion to the weight of the tion as indicated to accommodate the thermocouple. The charge in cases of soils containing high percentages of organic temperature difference measured by a thermocouple a t this matter. The combustion boats, preferably alundum, are point B outside the refractory and that inside the silica tube introduced directly into the hot tube, previously heated to the operating temperature of about A was determined and found to be 950" C. The flow of o x y g e n is constant after 90 minutes of heat100 to 200 cc. per minute, depending. The temperature curves for ing on the efficiency of the absorpthe two points in the p a r t i c u l a r tion tube, which in the case of the furnace used are given in Figure 3. one here described depends on the A constant difference of 40" C. was d i a m e t e r of the test tube from r e a c h e d and p e r s i s t e d after 90 which it is made. The rate of gas minutes of heating. flow can be regulated by placing a The purification section of the train consists of three Schwartz piece of c a p i l l a r y t u b i n g of selected i n t e r n a l d i a m e t e r and drying tubes, charged with amaladjusted length in the rubber tube gamated 20-mesh zinc, N , sulfuric c o n n e c t i n g the exit end of the acid and glass beads, 0, and phosFIGURE2. FURNACE, SHOWING posITIoN OF ahorus a e n t o x i d e or anhvdrone. COMBUSTION TUBE AND THERMOCOUPLE absorxltion tube. k. The use of the sulfur& a c i d Th;! usual details and p r e c a u tube lengthens the life of the charge in tube P and prevents tions necessary in making the determination of carbon by clogging as would eventually occur if phosphorus pentoxide use of this combustion train should be erident t o any one were used. familiar with dry c o m b u s t i o n work. The absorption tube Q is made of a test tube by sealing a Results obtained with this combustion bent glass tube of small diameter into the bottom, and after train have s h o w n satisfactory agreecharging with anhydrone and ascarite, as shown in Figure 4, ment w i t h t h e o r e t i c a l v a l u e s and the open end is closed with a stopper carrying a right-angle s a t is f a c t o r y agreement of duplicate bent tube. The stopper is made air-tight with sealing wax determinations. In the analysis of a E in which the tube number is impressed with a metal die just series of 222 s a m p l e s of soils which before the wax is set. When not in use or being weighed, the averaged 2.637 per cent of total caropen ends must be capped with rubber policemen. A tube bon, the average difference b e t w e e n made from a 1 X 6 inch (2.54 X 15.2 cm.) ordinary light- d u p l i c a t e s w a s 4.55 parts per 1000 weight test tube will weigh when filled about 80 grams. If parts of total carbon d e t e r m i n e d , a r, the quantities of carbon determined are small, a 0.625 X 6 difference which compares f a v o r a b l y with results o b t a i n e d by use of the procedures employed in general routine chemical analysis. FIGURE4. ABv,
3
SORPTION
TUBE
LITERATURE CITED (1) Fleming, Iron Age, 93, 64 (1914). ( 2 ) Salter, J. IXD. ENQ.CHEX.,8, 637 (1916). (3) Winters and Smith, IND.ENG. CHEW,Anal. Ed., 1,202 (1929). RECEIVED December 30, 1932.
GERMAUVEGETABLE OIL-MILLING INDUSTRY SHOWSGAINS.
FIGURE3. TEMPERATURE CURVESFOR FURNACE USED
inch (1.6 x 15.2 cm.) tube may be used, which, when filled, will weigh about 40 grams. Its low cost, light weight, and ease of wiping, and the fact that it can be hung on the hook of the balance stirrup for weighing are considerations which
Despite adverse conditions in world trade, the vegetable oilmilling industry of Hamburg is reported t o have increased its output during the last few years, according to a report from the Department of Commerce. Several large companies in and around Hamburg are said to be operating well toward capacity and oilseeds and fruits continue t o be imported in large quantities. Business has been so well maintained that one of the companies has expanded its plant by the erection of several new buildings, and has augmented its working force by 450 new men.
