Aueust. 1927
INDUSTRIAL AND ENGINEERING CHEMISTRY
931
Lubricating Oils as Insecticides in Dormant Spraying’ By E. L. Green AGRICULTURALEXPERIYENTSTATION,STATECOLLEGEOF WASHINGTON, PULLMAN, WASK.
ONSIDERIKG the impunity with which petroleum prod- the insects as oils that had been more carefully prepared. ucts are handled by men, it is remarkable that they Thus it seemed reasonable to neglect, a t least for the time, are quite harmful to insects. This makes them pe- the question of refining and to determine the fraction of the culiarly useful as insecticides because they involve a mini- lubricating oil that gave the best results. mum of danger to the men who may come into contact with Method of Preparing Sprays them. In all the work reported here the oils were emulsified by In killing insects oily substances do not enter by way of the mouth and digestive system, but pass into the body di- the formula developed for the work in 1924 and called for rectly from the outside either as vapor or liquid.’,* Where brevity W. S. C. No. 1.‘ The emulsifier is a solution of potash the effect of ihe vapor is desired, the “lighter,” low-boiling fish-oil soap in crude cresylic acid.4~~This method of emulfractions of petroleum are used, and the space in which they sion was adopted as a standard treatment in tests where other are applied should be closed. In orchards, where wind cur- factors were varied because it appeared to give more uniform rents prevent a vapor treatment, oils are applied directly as emulsions than t n y other methods. Deliberate variations in the time and manner of stirliquid: The oil is dispersed ring did not visibly affect the in a relatively large volume A series of lubricating oils, selected to represent the character of the emulsion, of water, which is used to range of available oils, was tested as sprays for San and so it seems reasonable carry it to the insects. The Josh scale and leaf rollers under set conditions in 1925 to assume that the diluted water eventually e v a p o and 1926. Their viscosities and boiling ranges were sprays were protected from r a t e s , l e a v i n g the oil in taken and compared with their performance as inthe effects of unintentional place. The same amount secticides. Specifications for oils that may be expected variations. The same thing of oil without a c a r r y i n g to be successful are indicated and the relation of these agent would be a tenuous was not found to hold for properties to the toxicity is pointed out. mist, difficult to direct, and o t h e r t y p e s of emulsion. larger amounts are expensive and harmful to the trees. have been used chieflv for the In Washington oil sprays ~~. control of insects such as the San Jose scale (Bspidiotus perniciosus Comstock) and fruit-tree leaf roller (Archips Collection of Field Data on Toxicity arwrospilu Walk). The studies reported here were a part The relative toxicity of the various oils was determined by of an investigation conducted cooperatively by the Divisions of Entomology and Chemistry of the Washington Agricul- spraying trials in orchards infested with San Josh scale and tural Experiment Station during the last three years. The orchard leaf roller. The writer was present a t all the field report includes only those uses of oil for sprays applied in experiments reported and made up the spray solutions. Mr. the early spring before any foliage is exposed, and is confined A. Spuler, of the Division of Entomology, applied the sprays to an attempt to discover an oil of maximum toxicity and, and made the insect studies, particularly the mortality deby determining its properties, to set up a specification for terminations (Table 11). The methods used to determine spray oils that can be expected to be effective in killing insects. the mortality of both insects have been p u b l i ~ h e d . ~ . ~ The earlier investigators did not make critical studies of The data obtained show a disappointingly small degree of the nature of the oils they used. Beginning about 1910 more contrast in many cases. This situation cannot be improved attention was paid to this part of the problem, and by 1922 it by departing from the optimum conditions and using others could be confidently stated that of all the fractions of petroleum less favorable to the oils, because, in the experience of the the lubricating oils possessed the greatest value in sprays of workers a t this station, this leads to erratic and unreproducthis kind.2.3 Crude oil as a whole, and the fractions kero- ible results. Therefore conditions for practically perfect consene, naphthas, burning oils, and gas oils had been tried and trol, such as spray strength, type of emulsion, and spray techrejected in favor of the lubricating oils. nic which had been worked out for the red engine oil in previous years, were maintained throughout these tests.
C
Work in 1924
In 1924, fifteen oils obtained from three oil companies were tried in the field and studied in the laboratory. The type of emulsion was established that was used as a standard treatment on the various oils in all later work. It was also found that a history of the oils, including data from the refinery, was needed in making selections for study. In 1925 and 1926, samples were requested that would conform to certain speciiications in order to get definite answers to the questions in mind. In the 1924 studies lubricating oils having very little refining treatment6 gave as good control of 1 Received March 23, 1927. Published with the approval of the Director of the Washington Agricultural Experiment Station as Scientific Paper 138, College of Agriculture and Experiment Station. For numbers in text see bibliopraphy a t end of paper.
*
Studies on Oils
Petroleum and its commercial products are mixtures of the various members of several series of saturated and unsaturated hydrocarbons, together with varying amounts of other substances that, in addition to carbon and hydrogen, contain nitrogen, sulfur, or oxygen.8 Isomers are also usually present, making the difficulty of separating the individual components very great.QJOJ1 The most careful fractional distillation produces portions which not only do not show a fixed boiling point, but also overlap the boiling ranges of the adjacent fractions, even when only one series is present. In all the series, the hydrocarbons of higher molecular weight have the higher boiling points. Hence in any fractionation of petroleum, the later, higher boiling fractions show the higher
932
INDUSTRIAL AND ENGINEERING CHEMISTRY
mean molecular weights. The viscosity and specific gravity are also higher. The fractions of a single crude oil may perhaps be identified by one of these constants, but with oils prepared from different crude oils this is not true. The representatives of the various homologous series and isomers of the same homologous series of hydrocarbons may then be present in different proportions and where these have not been removed the accessory substances will vary greatly. Consequently two petroleum products from different crudes may have, for instance, similar viscosities and yet in other respects show decided differences. For this reason it may be possible to select commercial oils by tests for definite purposes, but to identify them is often impossible and always extremely difficult. In any homologous series of hydrocarbons the properties generally change by steps from one member to the next in the series. Crude oils, being made up of a mixture of the members of several homologous series of hydrocarbons besides other substances, are divided by fractional distillation into portions in which, as the boiling range of the fractions rises, the individual members having higher boiling ranges tend to predominate. Therefore, other properties besides boiling range, such as specific gravity, viscosity, and mean molecular weight are found to change gradually from fraction to fraction much as the same properties vary from one individual hydrocarbon to another. If it is assumed that toxicity to insects is a property of the hydrocarbons, it would be reasonable to suppose that this property might also go through gradual changes. It should then be possible to trace a relation between the other properties of an oil and its insecticidal effect and to discover a fraction or portion of a given lubricating oil in which this property is at a maximum. Such a product would be made up largely of the group of hydrocarbons which is the most effective in killing insects. Proof of its existence would in a general way furnish support for the assumptions. Accordingly, experiments were planned which should disclose this particularly effective fraction. A selected series of oils was tested for insecticidal power by using them as sprays in orchards, and certain constants for each were determined in the laboratory in order to be able to describe them as a basis for specifications. These constants were selected with the purpose of determining and using for a basis of identification such properties as would be likely to influence the killing power. The following considerations suggested this view: Lubricating oils are very inert chemically and it would appear reasonable to assume that they are not more reactive within the bodies of insects than in the test tube. If this is true and their action is due to their physical properties, perhaps some one of these is intimately concerned with the killing of insects. It was therefore intended to note carefully the variation of insecticidal effect accompanying variations in the properties measured to determine in what cases these were parallel and in what others not parallel. The physical state of the oil as it travels through the tissues of an insect to the walls of the cells it kills may be vapor, liquid, or emulsion.'* In the liquid condition the wetting power or oiliness and the viscosity determine the penetration and thus may possibly affect the toxicity. The wetting power measures the tendency of a liquid to spread over solid surfaces only partially in contact with it, displacing films of other fluids. Plane or convex surfaces have been used in studies and in such cases the viscosity should not interfere. But where the surface to be covered is the lining of fine pores the viscosity may be expected to have a decided influence. No suitable methods for determining wetting power18J4 have been developed, but the viscosity was observed.
Vol. 19, No. 8
VIscosITY-The determination of viscosity is generally accepted in oil technology as a convenient method for distinguishing lubricating oils. The Saybolt Universal viscometer15 was used in this work because it is the common instrument of the oil trade. But because of the low temperatures in the field (0-15' C.) a t the time of spraying, it was evident that the internal friction of the oils as brought into play under field conditions must be very different from that a t the temperatures (37.8' C.) a t which the viscosity is usually determined. Therefore viscosity readings were taken at several temperatures from that of the room to 100' C., plotted, and extrapolated in the direction of low temperatures. SPECIFICGRAvITY-The specific gravity was taken because by comparing with other constants it is of value in showing the type of crude from which an oil was derived. A set of hydrometers was used and corrections applied to bring the readings to 15' C. (60' F.). ANALYTICAL DISTILLATION-TOstudy the possibility that the oils attack the tissues of the insects as vapor, the analytical distillation was selected as the third characteristic. It is useful in the detection of blending, closely defines the portion of the crude from which the oil was derived, and the results must have an intimate relation to the vapor tension. In their studies on toxicity ShaferI6J7used only gasoline, but Moore studied several hydrocarbons and repeatedly1*J9J0 called attention to a relation between vapor pressure and toxicity. It was expected that the present study would disclose such a relation in lubricating oils if it existed. From previous experience in the field and knowledge of the boiling ranges of those oils known to be successful, it did not seem reasonable to expect such a relation. Apparatus. The apparatus used in the analytical distillation requires some comment. The flasks and condenser were made according to the description in Dean, Hill, Smith, and Jacobs' method.21 The heating device they recommended could not be made, so this had t o be changed. Transite board ( l / ~inch or 3 mm.) with a 10-cm. hole was provided for the bottom of the flask. A conical cover of light sheet metal was made which would contain the flask up t o the level of the delivery tube. This had a separable seam, which was opened to admit the flask. After it was closed the flask was held inverted and steam-pipe insulating compound was rammed in around it. The transite plate was then attached to the sheet-metal jacket with three stove bolts. The top of the jacket was sealed with plaster of Paris. A small, carefully shielded gas flame was applied t o the portion of the flask exposed through the hole in the plate. During 1925 the vacuum was regulated by hand, a 15-gallon iron tank being placed in the line to prevent rapid fluctuations of pressure. In 1926, however, a regulator patterned after a recent description2* was made and used. For the sake of comparison with previous results, which had been based upon the recommendations of the Bureau of Mines,21a pressure of 40 mm. of mercury was always used. This brought such a stream of air through the regulator that spraying over of the mercury into the pump line became troublesome. This was met by sealing a bulb trap into the line coming out of the regulator, and by filling up the top of the containing tube with pieces of glass tubing to break up the bubbles. No visible fluctuation of the manometer occurred when the regulator was in use. At first a 200-cc. mixing cylinder was used as a receiver; later a device for cutting the 180 cc. of distillate into six 30-cc. portions was substituted, but no work was done upon the separate fractions. The distillate was measured as it collected and its volume plotted against the temperature.
There remains a possibility that the oil has entered the vital tissues of the insects while still a phase of a non-homogeneous system-i. e., an emulsion. Upon the basis of the information available it does not seem reasonable to dismiss this possibility, No studies upon it were found. It does not seem likely that the emulsion state continues through the cell walls, but it may persist to that point. Oils Studied
1925 Tmm-Lubricating oils (1, 2, 3, and 4) sent by the Standard Oil Company of California were of asphalt-base
INDUSTRIAL AND ENGINEERING CHEMISTRY
August, 1927
crude. Except oil 3, none had received more refining treatment than would entitle them to the grade of neutral oils, according to advices from the company. Thus they might be expected to have had the following p r e p a r a t i ~ n The :~ lubricating oil fraction remains in the crude stills after all the burning oils have come off. With paraffin-base oils or asphalt-base oils not containing much tar the entire contents of the crude stills are run to the lubricating-oil stills. Where the amount of asphalt is large, a preliminary run “to tar” may be made, either in the crude-oil stills or some other still, and only the distillate reaches the lubricating-oil division. Here the several fractions of lubricating oil are made by distillation, which is only for separation and not a refining process. This distillation is generally “dry;” several fractions are taken and these are prepared according to the requirements of the market. For the neutral grade the fraction is washed with sulfuric acid, allowed to settle, decanted, and similarly washed with caustic solution and water. The concentration and amount of sulfuric acid used are kept low, so that the result of the treatment is to reduce the acidity of the oil and improve its corrosion tests, but not to improve the color and other characteristics to any considerable extent. Thus the refining losses are kept small, but at the expense of the quality of the finished product. The unsulfonatable residue may be as low as 50 per cent, and is generally not more than 65 per cent. Oils 5 and 6 were sent by the Texas Company from Port Arthur to represent the lubricating-oil fraction of paraffinbase crude oil. F. TV. Hall, chief chemist of the Texas Company, also sent oils 7, 8, and 9. Oil 7 is a special light lubricating oil of asphalt base, oil 8 is a paraffin-base gas oil, the last “cut” below oil 5, and oil 9 is a mixture of red engine oil and enough kerosene (about 25 per cent) to bring its viscosity a t 37.8” C. (100” F.) to 70 seconds (Saybolt). This dilution was an attempt to secure greater penetration into the fine pores of the insects by reducing the internal friction of the oil. Similar attempts have been made for other purpose~.~~ 1926 TEsTs-For the third season’s work the Standard Oil Company of California was requested to send new supplies as nearly identical as possible with oils 1, 2, 3, and 4 of 1925. They were given the same numbers in 1926. In addition they were asked to send an asphalt-base gas oil (5), a heavy lubricating oil considerably higher in range than red engine oil (6), a typical automobile lubricant of about the middle of the range of those prepared for this purpose ( 7 ) , which goes by the name “Zerolene 5,” and a sample of their technical water-white lubricating oil (8). The Texas Company was asked to send duplicates of oils 5 , 6, 7 , and 8 of 1925. These were given the numbers 9, 10, 11, and 12 in 1926. In addition they were asked for a sample of water-white paraffin-base oil (13). The principal object sought in 1926 was verification of the data obtained in 1925, with reference particularly to the effects on scale. In addition, it was sought to establish the possible place of the water-white (decolorized) oils in dormant spraying and to learn more of the limitations of oils beyond the ranges previously tested. Results
STUDIESo x VIscosITY-Table I gives a description of the oils used, their specific gravities and viscosities. The plots of viscosity against temperature produced curves of similar appearance, differences between curves usually being in displacement along the temperature axis. They approximate a family of hyperbolas with asymptotes parallel to the coordinate axes. This has been noticed by others.24 From a study of the curves it appears that if the viscosities of lubricating oils are measured only a t 37.8’ C. (100” F.) or some
933
other t’emperature near that, this property will be defined as well as though a whole series of tests were made. It should be added that where differences exist a t this temperature, they are magnified rapidly below it,, while above it they gradually disappear. T a b l e I-Characteristics TRADE XAXE
NO.
of Lubricating Oils SP.Gr.
OIL COMPANY
(15’
c.)
VISCOSITY
SEASON O F 1925
1 2 3 4 5 6 7 8 9
Spray stock B Spray stock D Regular “E” pale paraffin Red engine oil stock 70 viscosity paraffin-base stock 100 viscosity paraffin-base stock 70 viscosity asphalt-base stock Paraffin-basegas oil 75 per cent red engine oil, 25 per cent kerosene Medium red engine oil
Standard Standard Standard Standard
0.9189 0.9226 0.9173 0.9253
95 97 102 260
Texas
0.8812
79
Texas
0.8880
110
Texas Texas
0.9216 0.8749
69 67
Texas Bought locally
0.8810 0.9280
76 248
0.9282 0.9238 0,9225 0.9310 0.8894 0.952 0.9373 0.8638 0.8750
105 100 105 237 4,1 460 52 73.
0.8848 0.9214 0.8712
106 69 65
0.8660 0,9255
142 230
S E A S O N O F 1926
1
2 3 4
5 6 7
8
9 10 11 12 13
Snrav stock Standard - - - - ~ -R Spray stock D Standard 100 pale oil Standard Red engine oil stock Standard Gas oil from asphalt base Standard W” gear-case oil Standard Zerolene 5 (automobile oil) Standard Mineral seal oil (water white) Standard 70 viscositv Daraffin-basestock Texas 100 visco&y paraffin-base stock Texas 70 viscosity paraffin-base stock Texas Paraffin-base gas oils Texas 150 viscosity water-white paraffin-base oil Texas Medium red engine oil Bought locally a Not comparable with other oils. - r - - 4
EFFECTS OF V A R I A T I O IN~VrscosITY-On comparing the results of spraying in Table I1 with Table I, it is apparent that variations of viscosity, other physical properties being constant, do not affect the insect mortality. For example, oils 3 and 5 of 1925, which occur again as 3 and 9 in 1926, have very similar boiling ranges but different viscosities. Their effects on insects are similar. The same is true of oils 4 and 6 of 1925, which are the same as 4 and 10 of 1926. Though differing in viscosity, they gave similar kills of insects.
OIL
Table 11-Field T e s t s of Oil Sprays SAX JOS$ SCALE A T LEAF-ROLLER EGGSA T 8 PER CENT 4 PER CENT” hTo t Per cent Per cent hatched Hatched hatched Dead Alive alive SEASON OF i9zQb
Check
10447 14857 12512 13894 12815 12135 10386 11293 18254 2866
50 129 22 13 15 4 1166 68 309 4763
0.47 0.9 0.17 0.137 0.117 0.03 I O . 00 0.6 1.66 63.3
5770 6200 6386 9280 6460 5370 6110 3566 5410 3390 362
0.017 0.064 0.031 0.0 0.0
0.037 0.065 0.0 0.0 9.69
SEASON OF 1926
4935 0.94 511 1 0.2 53 2.5 5 4602 110 991 0.6 5 0.08 5706 0 0.0 5923 0.00 0 0 814 0.0 4636 513 4256 456 9.67 10 1.9 6922 1450 526 7.6 23 1.6 0.96 0 0.0 4516 44 72 1 0.02 0 4711 777 1 0.0 0.11 0.0 0 4446 856 5 0 0.00 0 0.0 4978 685 4.22 0 657 172 0.0 3856 873 84 0 0.0 1.43 5788 0 836 0 0.00 0.0 4560 R. E. 0. 5004 0.24 0 1051 12 0.0 Check 3332 1072 24.2 53 636 77.0 a Because of unusually great winter mortality the field results on the San JosC scale are not so conclusive as desired, although thousands of insects were examined for each test. The experimental 01 .chard at Clarkston showed an average of 90 per cent of winter-kill among the unsprayed scale insects, with individual trees ranging between 8 3 and 100 per cent of scale mortality. The data on scales in tables or orchard spraying at Clarkston should be interpreted with the understanding that nine-tenths of the dead scales were winter-killed before spraying. This applies only t o 1925. b These data have already been published. See reference 6 in biblioaraphy.
1
2 3 4 5 6 7 S 9 10 11 12 13
Finally, in the case of oil 9 of 1925, which, as has been mentioned, was prepared by diluting an oil like 4 or 6 of 1925
INDUSTRIAL AND ENGINEERING CHEMISTRY
934
Figure 1
Figure 2
7
------------................. ........... I..
Figure 3
with kerosene, the mortality rate is reduced. If the added kerosene had been water, this spray would have been equivalent in concentration to a 6 per cent spray of red engine oil. In the same year a 6 per cent spray killed all but 7.7 per cent of the leaf-roller eggs and a 7 per cent spray all but 1.03 per cent, while oil 9 killed all but 1.66 per cent.6 From the tests of the unblended oils it appears that variations in viscosity do not of themselves affect the toxicity of oils, and from the
Vol. 19, No. 8
test of oil 9 it appears that the value of an oil as an insecticide is not materially improved by blending to reduce the viscosity. Furthermore, the viscosity of this oil before blending, and that of effective oils like 4 and 6 of 1925, is so very great a t the field temperatures that it is evident that viscosity has no important influence on the toxicity. EFFECTSWITH DIFFERENT BOILINGRANGES-Figure 1 is a plot of all the boiling ranges of oils used in 1925. They fall into several groups. Oil 7 stands alone, with a lower range than any of the others. 1, 2, and 8 are closely related, and so are 3 and 5, and 4 and 6. Oil 9 is blended. Reference to Table I1 shows that there are greater differences in effects on insects between the groups than between oils within the same group. Results in 1926 parallel those of 1925 throughout, although exact duplication is impossible. Because of their greater number, it was necessary to show the boiling range curves of the oils of 1926 in two figures (Figures 2 and 3). The curves of oils 3, 4,6, and 7 are given on both figures. Reference to these figures and to Table I1 shows that the duplicates of the oils of 1925 behaved in 1926 as they had in 1925. Therefore, for oils of this type it appears that the greater the fraction distilling between 240' and 300" C. at 40 mm. pressure, the greater will be the toxicity. Oil 7 of 1925 and its duplicate, oil 11 of 1926, contain practically none of this fraction and compared poorly in toxicity with other oils, while oil 6 of 1925 and its duplicate, oil 10 of 1926, contain almost nothing else and gave excellent results throughout. The other oils contain varying amounts of this fraction and their effects on insects varied in proportion. Other oils tried in 1926 but not in 1925 lead to still other conclusions. The two water-white oils, 8 and 13, both gave excellent controls of insects, yet one is below and the other above the range of the less refined oils found to be effective. The distillation curve of oil 8 of 1926 falls between those of oils 5 and 11, both of which gave poor controls. Oil 13 has a range closely related to that of oil 7, but is quite satisfactory, whereas 7 is not. Only a very small amount of the water-white oils will react with sulfuric acid, and it is believed that they consist almost exclusively of saturated Iubricating-oil hydrocarbons.*6 This is a t least an indication that it is these hydrocarbons that are effective in killing insect8 and that the sulfonatable materials may in some cases be detrimental. The refining losses in completely removing the color from lubricating oils are very large, and the identity of the substances so lost is unknown. ASPHALTVJGRSUS PARAFFIN-BASE OILs-One of the oils used in 1924 was a lubricating oil of paraffin base. Except for the fact that it deposited a slimy, waxlike material on standing for 3 months, it was very much like several others, but the kill of insects was decidedly poor.4 This raised the question whether asphalt- and paraffin-base oils could be regarded as interchangeable for spray purposes, It is well established that for a given range of boiling points paraffin-base oils show lower specific gravities and viscosities than asphaltbase oils.26 A change in the carbon-hydrogen ratio indicates that the proportions of the different series of polynaphthenes are not the same in both. The work done on oils 5,6, and 8 of 1925, and 9, 10, 12, and 14 of 1926 was intended to demonstrate differences in insecticidal powers of asphaltand paraffin-base oils. It will be seen that whatever other differences may exist, the effects of these oils upon insects are comparable with those of the oils of asphalt base, 1, 2, 3, and 4 of 1925, and 1, 2, 3, and 4 of 1926. Since none of the oils of 1925 and 1926 used showed any sediment, the burden for the failure mentioned above seems to fall upon the unknown deposit. TRADENoMENcLATvRE-Market conditions in general
INDUSTRIAL A N D ENGINEERING CHEMISTRY
August, 1927
have a controlling effect on refinery practice. This is well illustrated in the case of the two gas oils. Oil 5 of 1926 was described as an asphalt-base gas oil, and (Figure 2 ) contained practically nothing of the lubricating oil fraction. Oil 12 of 1926 was described as a paraffin-base gas oil, but it contained a large amount of material ordinarily considered lubricating oil. As a consequence, though similarly named, oil 12 made an effective spray and oil 5 did not. Conclusions
The property of killing insects under the conditions of this study resides in a considerable range of lubricating oils, but is greatest in the portion that distils over between 240’ and 300’ C. at 40 mm. pressure. Toxicity of the kind studied does not appear to be related to the viscosity of the oils. The presence of significant quantities of vapor or vapor pressure is doubtful, in view of the low field temperatures and the high boiling ranges of effective oils. Oils for this purpose may be from asphalt- or paraffin-base crude without prejudice to the effects. Oils that have been subjected to processes for completely removing the color are likely to be more effective than before the decolorizing treatment.
935
Bibliography I-Quaintaince and Siegler, U.S. Degt. Agr., Farmers’ Bull. 008 (1918). 2-Ackerman, U.S. Degt. Agu., Circ. 263 (1923). a-Melander, Wash. Agr. Expt. Sta., Bull. 174 (1923). 4-Melander, Spuler, and Green, Ibid., 184 (1924). 5-Lilley, “The Oil Industry,” D. Van Nostrand Co., 1925; see also other texts on oil technology for processes coming under “refining.” 6-Melander, Spuler, and Green, Wash. Agr. Expt. Sta., Bull. 197 (1925). 7-Spuler, Ibid., 172 (1922). 8-Brooks, “Chemistry of the Non-Benzenoid Hydrocarbons,” p. 23, Chemical Catalog Co., 1922. 9-Young and Thomas, J. Chem. Soc. (London),71, 440 (1897). l@-Young, Ibid., 73,906 (1898). 11-Jackson and Young, Ibid., 73, 926 (1898). 12-De Waele, J. A m . Chem. Soc., 48, 2760 (1926). 13-Brooks, loc. cit., p. 579. 14-Stanton, Archbutt, and Southcombe, Engineering, 108 (1919). 15-Federal Specifications Board, B U Y .Mines, Tech. Papev 323 (1922). 16-Shafer, Mich. State Agr. Coll., Tech. Bull. 11 (1911). 17-Shafer, Ibid., 22 (1916). 18-Moore, J. Agr. Research, 9, 11 (1917). 19-Moore, Ibid., 10,7 (1917). 20-Moore, Ibid., 13,11 (1918). 21-Dean, Hill, Smith, and Jacobs, BUY Mines, Bull. 207 (1922). 22-Peterkin and Ferris, Ind. Eng. Chem., 17, 1248 (1925). 23-Compare Wilson and Wilkin, Ibid., 18, 486 (1926). 24-Brooks, 206. c i t . , p. 577 (citations). 25-Mabery, J. A m . Chem. Soc., 48,2663 (1926). 26-Mabery and Mathews, Ibid., SO, 992 (1908).
Crystallization of Paraffin Wax‘ By F. H. Rhodes, C. W. Mason, and W. R. Sutton CORNBLL UNIVERSITY,ITHACA, N. Y.
A sample of slack was was sweated and the melting the funnel and its contents ITHIN recent years points and the average molecular weights of the indiwere placed in a large glass a n u m b e r of i n v e s t i g e t o r s have vidual fractions thus obtained were determined. The c y l i n d e r in a themostat. fractions were also examined microscopically- During The temperature was raised studied the crystallization of paraffin wax from petroleum the crystallization of Parafin wax two types of crystals very slowly and the oil that were obtained-needles and PlatesThe relative sweated from the wax was hydrocarbons and from sevamounts of these two type5 are determined by the collected in fractions. The era1 other solvents. It has been shown that the solid conditions under which the crystallization is effected. average molecular weight of paraffins m a y c r y s t a l l i z e Comparison of the optical properties shows that the the material in each fraction either in plates or in needles, needles obtained in this way are not true single crystals, was determined by the cryothe crystal habit depending but are composed of concentric aggregates. scopic method, using naphupon the exact conditions unthalene as a solvent. der which the crystallization is effected. Similar crystals are Fractionation Data obtained when melted paraffin is allowed to cool. The exact WEIGHT Av. relationship between the plates and the needles that may be OF MELTING MOL. WT . present in ordinary paraffin wax has not, however: been defic. F. FRACT1oN Grams C. F. nitely established, nor has evidence been presented to show 1 Below 49.9 Below120 41 43.3 110.0 416 49.9t053.9 120to129 120 47.2 117.0 403 that the two types of crystals in the solid wax are distinct 53.9to57.2 129to135 114 49.9 121.8 417 135 t o 137 132 61.7 126.0 432 crystal entities formed from different chemical compounds 4 57.2 t o 58.3 6 58.3 t o 6 0 . 0 137 t o 140 60 54.0 129.2 443 or from distinct solid modifications of paraffin. 6 (Res.) Above 60 Above 140 63 56.7 134.0 445
W
Preparation of Materials
Several samples of paraffin used were prepared from slack wax from Pennsylvania crude petroleum. The original slack wax was obtained from the Conewango Refining Company. It showed a melting point of 50-51’ C. (122-124’ F.). This slack wax was separated into several fractions by sweating. A circle of fine copper screen was fitted to a 15-cm. Buchner funnel, the outlet of the funnel was closed, and cold water was run in until the water level was about 1.25 cm. above the screen. About 550 grams of the melted wax were placed on top of the water, forming a layer about 5 cm. thick. When the paraffin had solidified the water was drained and 1
Received April 7, 1927.
‘
Am. SOC. Testing Materials, Standard Method D 87-22, Standards, p. 882 (1924).
Beginning with fraction 2, the average molecular weight increases with the melting point. This is to be expected, since the paraffins of lower molecular weight have lower melting points and should concentrate in the more readily fusible fractions. The b s t fraction, however, has a molecular weight somewhat higher than that of fraction 2. This may be explained by the assumption that the original slack wax contained a small amount of paraffins of higher molecular weights than those of the compounds which constituted the major portion of the crystals. When the wax was sweated these higher hydrocarbons dissolved in the first fraction of the melt, giving an oil of rather high average molecular weight. The
