US1863004A

US1863004A - Lubricant and process of making the same

Info

Publication number: US1863004A
Application number: US326901A
Authority: US
Inventors: Arthur W Burwell
Original assignee: ALOX CHEMICAL CORP
Current assignee: ALOX CHEMICAL Corp
Priority date: 1928-12-18
Filing date: 1928-12-18
Publication date: 1932-06-14
Anticipated expiration: 1949-06-14
Also published as: DE541268C; GB335152A; FR672813A

Description

Patented June 14, 1932 UNITED STATES PATENT OFFICE ARTHUR W. BURWELL, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO ALOX CHEMICAL OOBPORA'I'ION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK LUBItICANT AND PROCESS OF MAKING THE SAME No Drawing.

The presentinvention relates to a method of increasing the lubricity of oils,particularly, of oils of mineral origin,-and to lubricating compositions produced thereby.

It heretofore has been recognized that the lubricating powers of oils such as petroleum lubricating oils may be improved by incorporating therein or commingling therewith certain modifying agents. such, for example, as free fatty acids or their corresponding water-insoluble, or water-soluble soaps, or naturally occurring fatty oils such as lard oill, neats-foot oil, tallow, wool fat, and the li e.

I now have prepared'new and valuable lubricating oil compositions consisting essentially of mixtures of known lubricating oils of petroleum origin with addition materials (which will be described hereinafter with greater particularity) consisting of certain higl1-molecular-weight, oxygen-containing, saturated aliphatic compounds, resulting from the controlled oxidation of aliphatic hydrocarbons of mineral origin as described generally in my U. S. Patents Nos. 1,690,768

and 1,690,769. I have found that any one of such compositions possesses a markedly increased lubricity (i. e., greater capacityto lubricate) over that of an equal amount of the known lubricating oil which forms the major component of said composition. Furthermore, there is experienced no corrosion of metal surfaces wetted by the compositions; in fact, distinct anti-rusting properties obtain. 7

These addition materials exert no gumming effect either of themselves or in the compositions, nor do they oxidize upon continued exposure to air. The said materials not only are relatively inexpensive (as compared with agents heretofore proposed) but also are economical in that relatively smaller proportions thereof are used.

In my United States Patents Nos. 1,690,-

- 7 68 and 1,690,769. I have described generally a process of making aliphatic acidiccompounds by controlled oxidation of hydrocarbons or mixtures thereof such as the hydro-,

carbons occurring in or associated with petroleum oils, in liquid phase, at a tempera- 7 Application filed December 18, 1928. Serial No. 326,901.

ture above 100 C. but not substantially above 150 C., and at a pressure greater than atmospheric pressure but not substantially above about 320 pounds per square inch, in the presence of an exciter of oxidation, agitation and the necessaryoxygen supply being furnished by passing a stream of free oxygen containing gas (e. g. air) through the body of hydrocarbons undergoing treatment.

By the expression an exciter of oxidation I mean to include the known oxidation catalysts such as, for example, manganese stearate and other catalytically acting compounds of manganese or copper or iron, known oxygen carriers, and es ecially hereinafter-mentioned unsaponifia le, non-acidic, components of a previously oxidized body of hydrocarbons. In my co-pending application Serial No. 156,058, filed December 20, 1926, it has been noted that a petroleum hydrocarbon mixture comprising in part the material which has already been subjected to the treatment does not require the presence of an oxidizing catalyst or of added exciter of oxidation in order to effect normal oxidation.

During the course of such an oxidizing treatment, small amounts of volatile acids (typified by formic acid), volatile ketones ble in water but soluble in petroleum hydrocarbons and in the reaction mixture.

By protraction of the oxidation treatment it is possible to produce in the reaction mixture compounds which are insoluble in petroleum hydrocarbons and in the reaction mixture, which latter compounds have the nature of saturated, aliphatic, hydroxy-earboxylic acids and apparently result from an alternation of one or more groups of the aliphatic chain to groups.

According to the present invenion I operate in the above manner upon relatively high molecular-weight aliphatic hydrocarbons of mineral origin, including the petroleum-type waxes obtainable from oil shales and from other bituminous materials including brown coals, but preferably petroleum waxes (e. g. rod wax. scale wax, the so-called Sharples wax, and the like) and such petroleum distillates as consist chiefly of relatively high molecular weight hydrocarbons. Since the product forming the basis of the present invention is derived from the said acidic compounds which are insoluble in water but soluble, in petroleum hydrocarbons and in the reaction mixture, and since the yield of said petroleum-soluble acidic compounds may be depreciated by protracted oxidation, by the conversion of a portion thereof to petroleum-insoluble acidic compounds, I prefer. for economic reasons. not to protract the oxidation treatment beyond the point of incipient formation of the abovedescribed petroleum-insoluble compounds. Incipient formation of petroleum-insoluble compounds in the reaction mixture may be noted by simple observation of a test sam ple taken from the mixture, or by titration of such a sample. The time period is a handy, but not necessarily exact, indication of the stage of the oxidation. In those cases where the reaction mixtures does contain an appreciable or material amount of the said petroleum-insoluble acidic compounds. the latter may be separated from the reaction mix ture by the method. set out in lines 122 to 128, page 2 of my U. 3. Patent No. 1,690,769, consisting in treating said mixture with petroleum distillate.such. for example, as the oil whose lubricating properties it is intended to improve by the addition thereto of the acidic com.pound,and removing therefrom the resulting insoluble residue.

The resulting reaction mixture then is subjected to treatment with a hot aqueous solution of a caustic alkali whereby to saponify as completely as possible all the saponifiable compounds contained therein. l nsaponifiable components of the reaction mixture collect-by gravity separation-as a super natant oily layer above a subnatant layer of soap solution. Either of the two layers may be separately removed from their mutual container: e. g., the oil layer may be decanted, or the aqueous layer may be drawn off from below. The resulting soap solution is separated from the unsaponifiable constituents of the reaction mixture, the soap solution being further subjected to clearing by careful dilution with water until no more compounds are thrown out of solution and the main amount of soap solution becomes clear. It is from this soap solution that my addition materials are derived.

The soap solution, after separation from any compounds thrown out of solution by reason of the dilution. is acidified as for instance with a mineral acid, whereby to liberate those compounds which were united with the alkali. There will be found to be present in the mass precipitated by this reaction practically all, or at least the major portion, of the formed water-insoluble acidic compounds which are mono-carboxylic in their nature.

This precipitated mass then is transferred to a still where it is subjected to a very carcful steam distillation; i. e., brought to and maintained at a point somewhat above the boiling point of water, and treated by pass ing therethrough a vigorous current of steam until substantially no more volatile material passes over and until the odor of the mass has been so modified as to be no longer disagreeable. The resultin still residue, after careful drying, is my addition material, and is in a condition suitable for direct admixture with the lubricating oil.

The same practical result may be obtained by substituting an extraction procedure for the saponification and acidification procedure above described. As extractant there may be used ethyl alcohol, acetone or like ketone, or a higher alcohol. I have found ordinary 95% alcohol to be a desirable solvent for the saponifiable portion of the reaction mixture, and to have the effect of separating from the reaction mixture essentially the same mass or composition as is separated by practicing the saponification and acidification procedure above described. The extraction preferably (although not necessarily) is carried out at such a temperature as insures maintaining the components of the reaction mixture in liquid state. It is to be understood that by the expression separating the saponifiable components from at least the major portion of the unsaponifiable components appearing in certain of the appended claims I mean to refer to either of the two optional separation procedures just dcscribec.

The aforesaid mass,"upon examination is found to consist of from about 50% to about of the hereinbefore mentioned acidic compounds and from about 50% to about 25% of unsaponifiable ketonic, alcoholic, and

keto-alcoholic compounds,- all of relatively high molecular weight, which are miscible with the acidic compounds. Incidentally it is noted that these unsaponifiable oxygencontaining compounds persist in accompany-- ing the said soap solutions,even in clear solution in any dilution. It is 1possible to separate them substantially comp etely from the mass only by thorough extraction with ether or other equivalent organic solvent.

The said unsaponifiable compounds not only do not detract from the lubricity-increasing properties of the addition materials but exert a beneficial influence of the order of that of the acidic-compounds components of said addition materials. The addition materials vary somewhat as to the relative proportions of their components, depending in part upon the starting material selected, and in part upon the desired charaeteristics of the lubricating oil compositions to be produced. Typical analyses show the following compositions:

Free acids which will liberate carbon dioxide from cold aqueous The said addition materials, so prepared. are readily soluble in or miscible with lubrieating oils. and the preparation of admixtures requires no especial instruction. While they do no harm to the metals with which they come into contact. and therefore can be used in lubricating oil compositions in considcrablc amounts.-say, 2.5% to 10% by weight. or higher,I prefer. for reasons of economy. to use much smaller amounts since I find that additions of the order of from about 0.25 to about 0.75% by weight etl'ect astonishing results in breaking the surface tension of oils used on moving parts and in causing the oils to wet. and cling to. metal surfaces. Compositions containing my addition materials in the latter content range (i. e., 0.25%0.75%) appear to give an improvement in lubricity equivalent to that cfiected by from 3% to 5% by weight of certain previously used fatty oils. Larger add tions appear not to materially increase this cii'ect. Furthermore. my new addition materials appear to assist in breaking down the internal friction of lubricating oils.

As an instance of the above on the same bearing over a long period of time. the following results of tests are noted: A given lubricating oil oi petroleum origin. during the course of a protracted test. showed a given rise in temperature. Upon the addition of 0.50% by weight of my addition material to another portion of the same oil and the substitution of thcresulting composition 'tor the straight lubricating oil under exactly the same conditions of room temperature, load, speed of shafting, etc., the temperature did not rise to the same given point by as much as 35 C. As the result of a series of such investigations with various lubricating oils, it was found that the temperature decrease upon addition of my addition material ranged from 16 to 35 C., with an average decrease of about 22 C.

The invention has been described with particular reference to the use of my addition materials in lubricating oil compositions adapted for use between moving parts (i. e., as engine oil, bearing oil, and the like). It should be noted that the use of said addition materials is not restricted thereto, but includes admixture with known mold oils as excellent compositions for oiling the surfaces of metallic molds, such, for example, as those in which are cast objects of concrete, gypsum, basic magnesium chloride and the like, and that the hereinafter claims are intended to protect my novel addition materials per se, and as well lubricating oil compositions containing said addition materials irrespective of their particular applications. oil composition, notation should be made of a composition containing 90 to 98% of a reasonably good petroleum oil of say 40 viscosity, Saybolt, at 100 F., or of higher viscosity, and 10 to 2% of my. addition material, which, as stated previously, is soluble in pe troleum oil.

I have found that this composition is nongumming, does not oxidize in contact with air, and forms on the mold surface a tenaceous film which is not readily brushed, or washed, off by the flowing mix. Cutting oils may be improved by suitable additions,- up to say 50%, of the said addition materials.

In the foregoing description mention has been made of the fact that my addition material is in part saponifiable and in part unsaponifiable. The saponifiable portion has been described as being a mixture of acidic compounds of high molecular weight. While I have established definitely that said compounds have the nature and structure of saturated aliphatic hydroxycarboxylic acids, it is equally certain that said compounds in their normal state or when dissolved in petroleum or other non-aqueous solvent do not all react acid but are in part neutral in re action. They. however, readily saponify with caustic alkali or. alkali metal carbonate solutions,--especially upon heating slig1htly,to alkali metal salts of the simple acu s.

These facts were brought out by the attempt to determine the molecular weights of these so-called acids by the freezing-point depression method, when it was found that the average molecular weight of the acidic compounds is approximately three times that of the molecule of average simple acid as the latter is determined by titration, by

As a particularly advantageous mold analysis of its silver salt, or by the Karl'Rast method, using camphor as solvent. Berichte, 1922, vol. 2, B, page 1051. a

While I propose not to limit my invent-ion by any hypothesis'as to the actual chemical" constitution of these acidic compounds, the results of my investigations to date would appear to support the conception that they are rich in neutral-reacting esters, cyclic or ring esters, and inner-molecular anhydrides of simple aliphatic carboxylic acids of relatively high molecular weight, formed by the elimination of Water from one or more molecules of said simple acids.

This is indicated, for instance, when the simple acids (obtained by a careful acidification of their soap solution) are subjected to very careful drying at relatively low temperature; the molecular weights increase substantiallytfrom 2 to 4 or more times those of the simple acids.

If the analogy between the simple acids of high molecular weight hereinbefore described and other better known and lower molecular weight simple saturated aliphatic carboxylic acids, e. g. lactic acid, is controlling, it would appear altogether probable that there occur condensations similar to those occurring in the cases of said simpler aliphatic oxy-carboxylic acids, i. e., the formation of double esters (i. e., lactides),inner anhydrides (i. e., lactones) and/or simple or complex esters (as, for example, by the combination of acids and alcohols or "alcohol ketones present in the mixtures).

The following are suggestive representations of some of the reactions thought to'occur:

(I) onrooon nn-co on on, (ilHz 47H: i ("JH-OH A dHo (c am). (H2). JHa H:

The above lactone formation is known to occur in my addition materials, but whethcr it be or 8 lactone is not known.

Such ring esters as the above lactide may and robably do occur mem red rings.

The presence of such multi-membered rings has been demonstrated practically by substantially completely purifying the acidic compounds by separating them from the naturally associated ketones, alcohols, ketoalcohols and alcohol-ketones by extraction with ether, and determining their average molecular weight by the freezing-point depresslon method. The average molecular weight (less the water eliminated by slight heatmg) is approximately three times the average molecularweight of the acids themselves as found by the silver salt analysis or direct titration methods. From this findmg, and from the fact that lactones, of the above character occur in said mixtures, I deduce that said mixtures contain condensation products ranging from lactones up to say six-membered ring esters, with an average of three-membered ring esters.

I claim:

1. The method of increasing the lubricatmg properties of an oil ofpetroleum origin which consists in adding to said oil an oilsoluble addition material obtainable by oxias three', or fourdizing a mixture consisting essentially of relatively high molecular-weight, saturated, aliphatic hydrocarbons of mineral origin, in the liquid phase, at a temperature of from about to about 150 C. and at a superatmospheric pressure not greater than about 320 pounds per square inch, in the presence of an exciter of oxidation, until the point of incipient formation of compounds which are insoluble in petroleum and in the reaction mixture, which mixture comprises saponifiable and unsaponifiable components, separating the saponifiable components from at least the major portion of the vunsaponifiable components, treating the separated portion containing said saponifiable components with steam until substantially no more volatile material passes over, and drying the resulting residue.

2. The method of increasing the lubricating properties of an oil of petroleum origin which consists in adding to said oil an oilsoluble addition material obtainable by oxidizing a mixture consisting essentially of relatively high molecular-weight, saturated, aliphatic hydrocarbons of mineral origin, in the liquid phase, at a temperature of from about 100 to about 150 C. and at a super-atmospheric pressure not greater than about 320 pounds per square inch, in the presence of an exciter of oxidation, until the point of incipient formation of compounds which are insoluble in petroleum and in the reaction mixture, treating the resulting reaction mixture with hot aqueous solution of caustic alkali, separating the resulting soap solution from unsaponifiable components of the reaction mixture and diluting said soap solution with water until the solution becomes clear, acidifying the solution, so arating the resulting precipitate, treatin t e precipitatewith steam until substantial no more volatile material passes over," an drying the resulting residue.

3. The method of increasingthelubricating properties of an oil of petroleum origin which consists in adding to said oil an oil-soluble addition material obtainable by oxidizing a mixture consisting essentially of relatively high molecular-weight, saturated, aliphatic h drocarbons of mineral origin, in the liquid ase, at a temperature of from about 100 to about 150 C. and at a super-atmospheric pressure not greate; than about 320 pounds per square inch, in the presence of an exciter of oxidation, until the point of: incipient formation of compounds which are insoluble in petroleum and in the reaction mixture, which mixture comprises saponifiable and unsaponifiable components, extracting the said mixture with an organic solvent for the saponifiable components, separating the organic solvent from the so-separated portion of the reaction mixture, treating the said portion with steam until substantially no more volatile material passes over and drying the resulting residue.

4. The method of increasing the lubricating properties of an oil of petroleum orig 1n which consists in adding to said oil an 011- soluble addition material of mineral origin, said addition material being substantially free of hydrocarbons and consisting essentially of high-molecular-weight aliphatic oxygen-containing compounds including a substantial proportion of free saturated aliphatic carboxylic acids.

5. As a new product adapted for use in admixture with a lubricating oil of petroleum origin, an oil-soluble addition materlal obtainable by oxidizing a mixture consisting essentially of relatively high molecularweight, saturated, aliphatic hydrocarbons of mineral origin, in the liquid phase, at a temperature of from about 100 to about 150 C. and at a super-atmospheric pressure not greater than about 320 pounds per square inch, in the presence of an exciter of oxidation, until the point of incipient formatlon of compounds which are insoluble in petroleum and in the reaction mixture, which mixture comprises saponifiable and unsaponifiable components, separating the saponifiable components from at least the ma or portion of the unsaponifiable components, treating the separated portion containing said saponifiable components with steam until substantially no more volatile material passes over, and drying the resulting residue.

6. s a new product adapted for use in admixture with a lubricating oil of petroleum origin, an oil-soluble addition material obtainable by oxidizing a mixture consisting es sentially of relativel high molecular-weight, saturated, aliphatic ydrocarbons of mineral origin, in the liquid phase, at a temperature of from about 100 to about 150 C. and-at a super-atmospheric pressure not greater than about 320 pounds per square 111611, in the presence of anexciter of oxidation, until the point of incipient formation of compounds which are insoluble in petroleum and in the reaction mixture, treating the resulting reaction mixture with hot aqueous solution of caustic alkali, separatin the resulting soap solution from unsaponi able components of the reaction mixture and diluting said soap solution with water until the solution becomes clear, acidifying the solution, separating the resulting precipitate, treating the precipitate with steam until substantially no more volatile material passes over, and drying the resulting residue.

7. As a new product adapted for use in admixture with a lubricating oil of petroleum origin, an oil-soluble addition material obtainable by oxidizing a mixture consisting essentially of relatively high molecular-weight, saturated, aliphatic hydrocarbons of mineral origin, in of from about 100 to about 150 C. and at a super-atmospheric pressure not greater than about 320 pounds per square inch, in the presence of an exciter of oxidation, until the point of incipient formation of compounds which are insoluble in petroleum and in the reaction mixture, which mixture comprises saponifiable and unsaponifiable components, extractin the said mixture with an organic solvent %or the saponifiable components, separating the organic solvent from the soseparated portion of the reaction mixture, treating the said portion with steam until substantially no more volatile material passes over and drying the resulting residue.

8. As a new product adapted for use in admixture with a lubricating oil of petroleum origin, an oil-soluble addition material of mineral origin, said addition material being substantially free of hydrocarbons and consisting essentially of high-molecular-weight aliphatic oxygen-containing compounds in cluding a substantial proportion of free saturated aliphatic carboxylic acids.

- 9. The method of increasing the lubricating properties of an oil which consists in adding to said oil an oil-soluble addition material of mlneral origin consisting of free saturated aliphatic carboxylicv acids from about 23% to about 40% by weight, neutral lactones and esters derived from said acids from about 7% to about 50%, and unsaponifiable nonacidic, oxygen-containing aliphatic compounds from about 25% to about 40%.

10. A composition of matter consisting of lubricating oil of petroleum origin and an oil-soluble addition material obtainable by oxidizing a mixture consisting essentially of the liquid phase, at a temperature relatively high molecular-weight, saturated,

aliphatic hydrocarbons of mineral origin, in the liquid phase, at a temperature of from about 100 to about 150 C. and at a superatmospheric pressure not greater than about 320 pounds per square inch, in the presence of an exciter ofoxidation, until the point of inci ient formation of compounds which are insoluble in petroleum and in the reaction mixture,which mixture comprises saponifiable and unsaponifiable components, separating the saponifiable components from at least the major portion of the unsaponifiable components, treating the separated port on containing said saponifiable components with steam until substantially no more volatlle material passes over, and drying the resulting residue.

11. A composition of matter conslstlng of lubricating oil of petroleum origin and an oil-soluble addition material obtainable by oxidizing a mixture consisting essentially of relatively high molecular-weight, saturated, aliphatic hydrocarbons of mineral origin, in

- the liquid phase, at a temperature from about 100 to about 150 C. and at a super-atmospheric pressure not greater than about 320 pounds per square inch, in the presence of an exciter of oxidation, until the point of 1n- 'cipient formation of compounds which are insoluble in petroleum and in the reaction mixture, treating the resulting react-ion .II11X- ture with hot aqueous solution of caustic alkali, separating the resulting soap solution from unsaponifiable components of the reaction mixture and diluting said soap solution with water until the solution becomes clear, acidifying the solution, separating the resulting precipitate, treating the precipitate with steam until substantially no more volatile material passes over, and drying the resulting residue.

12. A. composition of matter consisting of lubricating oil of petroleum origin and an oil-soluble addition material obtainable by oxidizing a mixture consisting essentially of relatively high molecular-weight, saturated, aliphatic hydrocarbons of mineral origin, in the liquid phase, at a temperature of from about 100 to about 150 C. and at a superatmospheric pressure not greater than about 320 pounds per square inch, in the presence of an exciter of oxidation, until the point of incipient formation of compounds which are insoluble in petroleum and in the reaction mixture, which mixture comprises saponifiable and unsaponifiable components, extracting the said mixture with an organic solvent for the saponifiable components, separating the organic solvent from the so-separated portion of the reaction mixture, treating the said portion with steam until substantially no more Volatile material passes over and drying the resulting residue.

13. A composition of matter consisting of lubricating oil of petroleum origin and an oil-soluble addition material of mineral origin, said addition material being substantially free of hydrocarbons and consisting essentially of high-molecular-weight aliphatic oxygen-containing compounds including a substantial proportion of free saturated aliphatic carboxylic acids.

14. A composition of matter consisting of lubricating oil of petroleum and an oilsoluble addition material of mineral origin consisting of free saturated aliphatic carboxylic acids from about 23% to about 40% by weight, neutral lactones and esters derived from said acids from about 7% to about 50%, and unsaponifiable non-acidic, oxy encontaining aliphatic compounds from a out 25% to about 40%.

15. A composition of matter consistin of from about 90.0% to about 99.75% by weight of lubricating oil of petroleum origin and from about 10.0% to about 0.25% by wei ht of an oil-soluble addition material obtaina Is by oxidizing a mixture consisting essentially of relatively high molecular-weight, saturated, aliphatic hydrocarbons of mineral origin, in the liquid phase, at a temperature of from about 100 to about 150 C. and at a super-atmospheric pressure not greater than about 320 pounds per square inch, in the presence of an exciter of oxidation, until the point of incipient formation of compounds which are insoluble in petroleum and in the reaction mixture, which mixture comprises saponifiable and unsaponifiable components, separating the saponifiable components from at least the major portion of the unsaponifiable components, treating the separated portion containing said saponifiable components with steam until substantially no more volatile material passes over, and drying the resulting residue.

16. A composition of matter consistin of from about 90.0% to about 99.75% by weight of lubricating oil of petroleum origin and from about 10.0% to about 0.25% by weight of an oil-soluble addition material obtainable by oxidizing a mixture consisting essentially of relatively high molecular-weight, saturated, aliphatic h drocarbons of mineral origin, in the liqui phase, at a temperature of from about 100 to about 150 C. and at a super-atmospheric pressure not greater than about 320 pounds per square inch, in the presence of an exciter of oxidation, until the point of incipient formation of compounds Which are insoluble in petroleum and in the reaction mixture, treating the resulting reaction mixture with hot aqueous solution of caustic alkali, separating the resulting soap solution from unsaponifiable components of the reaction mixture and diluting said soap solution with water until the solution becomes clear, acidifying the solution, separating the resulting precipitate, treating the precipitate with steam until substantially no more volatile material residue.

17. A com osition of matter consistin of from about 9 .0% to about 99.75% by Weight of lubricating oil of petroleum origin and from about 10.0% to about 0.25% by weight of an oil-soluble addition material obtainable by oxidizing a mixture consisting essentially of relatively high molecular-Weight, saturated, aliphatic h drocarbons of mineral origin, in the liqui phase, at a temperature of from about 100 to about 150 C. and at a super-atmospheric pressure not greater than about 320 pounds per square inch, in the presence of an exciter of oxidation, until the point of incipient formation of compounds which are insoluble in petroleum and in the reaction mixture, whichmixture comprises saponifiable and unsaponifiable components, extracting the said mixture with an organic solvent for the saponifiable components, separating the organic solvent from the so-separated portion of the reaction mixture, treating the said portion with steam until substantially no more volatile material passes over and drying the resulting residue.

18. A composition of matter consisting of from about 90.0% to about 99.75% by welght of lubricating oil of petroleum origin and from about 10.0%'to about 0.25% by Weight of an oil-soluble material of mineral origin, said addition material being substantially free of hydrocarbons and consisting essentially of high-mol-ecular-weight aliphatic oxygen'containing compounds including a substantial proportion of free saturated aliphatic carboxylic acids.

In testimony whereof, I affix my signature.

ARTHUR WV. BURW'ELL.

passes over, and drying the resulting