US2627148A - Process for cleaneng spark plugs - Google Patents
Process for cleaneng spark plugs Download PDFInfo
- Publication number
- US2627148A US2627148A US2627148DA US2627148A US 2627148 A US2627148 A US 2627148A US 2627148D A US2627148D A US 2627148DA US 2627148 A US2627148 A US 2627148A
- Authority
- US
- United States
- Prior art keywords
- cleaning
- spark plug
- deposit
- abrasive
- tool
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 title claims description 5
- 238000004140 cleaning Methods 0.000 claims description 29
- 239000000203 mixture Substances 0.000 claims description 27
- 239000010433 feldspar Substances 0.000 claims description 8
- 229910000278 bentonite Inorganic materials 0.000 claims description 7
- 239000000440 bentonite Substances 0.000 claims description 7
- 229940028356 diethylene glycol monobutyl ether Drugs 0.000 claims description 6
- JCGNDDUYTRNOFT-UHFFFAOYSA-N oxolane-2,4-dione Chemical compound O=C1COC(=O)C1 JCGNDDUYTRNOFT-UHFFFAOYSA-N 0.000 claims description 6
- XLYOFNOQVPJJNP-PWCQTSIFSA-N Tritiated water Chemical compound [3H]O[3H] XLYOFNOQVPJJNP-PWCQTSIFSA-N 0.000 claims 1
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 claims 1
- 239000012212 insulator Substances 0.000 description 14
- 238000005498 polishing Methods 0.000 description 9
- 239000002904 solvent Substances 0.000 description 9
- 239000000499 gel Substances 0.000 description 7
- 229940092782 bentonite Drugs 0.000 description 6
- 235000012216 bentonite Nutrition 0.000 description 6
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000003960 organic solvent Substances 0.000 description 5
- 239000002184 metal Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 239000003082 abrasive agent Substances 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 239000002966 varnish Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- 239000007900 aqueous suspension Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000375 suspending agent Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- 239000003021 water soluble solvent Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 150000008280 chlorinated hydrocarbons Chemical class 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000003349 gelling agent Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 235000015110 jellies Nutrition 0.000 description 1
- 239000008274 jelly Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 229920000151 polyglycol Polymers 0.000 description 1
- 239000010695 polyglycol Substances 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
- C11D1/66—Non-ionic compounds
- C11D1/72—Ethers of polyoxyalkylene glycols
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C11/00—Selection of abrasive materials or additives for abrasive blasts
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
- C11D3/02—Inorganic compounds ; Elemental compounds
- C11D3/12—Water-insoluble compounds
- C11D3/14—Fillers; Abrasives ; Abrasive compositions; Suspending or absorbing agents not provided for in one single group of C11D3/12; Specific features concerning abrasives, e.g. granulometry or mixtures
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
- C11D3/16—Organic compounds
- C11D3/18—Hydrocarbons
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
- C11D7/22—Organic compounds
- C11D7/26—Organic compounds containing oxygen
- C11D7/263—Ethers
-
- C11D2111/20—
Definitions
- This invention relates to cleaning and polishing compositions, and more particularly to cleaning and polishing compositions for removing deposits from the insulators of spark plugs.
- Spark plugs as normally used on internal combustion engines collect a deposit on the insulator surface which reduces the effectiveness of the insulator. Though aircraft spark plugs are completely shielded, they do collect a deposit which causes deterioration of the insulating properties of the spark plug insulator.
- the deposit consists of minute particles of metal which are sputtered off by corona discharge from the metal components both at the top and the bottom of the spark plug well, of ingredients of the cable insulation which may become volatilized, of the residue from the silicone jelly used to fill spaces between components in the barrel area, of particles of carbon, of gum and of metal from tools used to insert the spark plug. This collection of dirt and grime conducts electricity especially when it has absorbed some moisture and reduces the insulating properties of the spark plug insulator.
- This compound may be removed by employing a cleaning and polishing composition in conjunction with a polishing tool or wheel.
- a cleaning composition consisting of a powdered abrasive, an organic solvent, and a suspension or gelling agent.
- the composition is in the form of a gel which adheres to the surface deposit on the spark plug insulator and dissolves or softens the binder or gum portion of the deposit before the abrasive cleaning and polishing action commences.
- Another object of the invention is to provide a composition capable of cleaning the gum. deposits from spark plug insulators when used in conjunction with a polishing tool or wheel.
- Another object of the invention is to provide a gel of powdered feldspar, diethylene glycol monobutyl ether and a water suspension of ben tonite for use as a cleaning and polishing composition.
- the insulator surface of spark plugs used on internal combustion engines becomes covered with a deposit of small particles of carbon metal, etc., bonded together by a gum or varnish. This deposit reduces the insulating capacity of the insulator. This fouling of the spark plugs is especially dangerous in aircraft engines. Thus proper aircraft maintenance requires that the spark plug insulators be maintained free of these deposits.
- the tool consists of a rotatably mounted cylindrical element having helical threads on its surface. This tool or any suitable polishing tool or wheel may be used to actuate this cleaning composition.
- the cleaning composition made in accordance with this invention consists essentially of a fine powdered abrasive material and an organic solvent for the organic binder or gum of the deposits together with a material to maintain the abrasive in suspension in the solvent constituent.
- the organic solvent used may be naphtha, a low boiling point hydrocarbon paraffin, or benzene, an aromatic, or carbon tetrachloride, a chlorinated carbon, or chloroform, a chlorinated hydrocarbon.
- the solvent acts t dissolve and soften the gum or varnish which holds. the deposited material on the insulator surface.
- the feldspar is a fine abrasive material which will scour or abrade the deposit and assist the cleaning action of the solvent.
- the bentonite when mixed with Water forms a gel which will hold the abrasive and solvent in suspension or distributed in the gel. In addition, the gel is a convenient and practical form, as compared to a liquid, for using the cleaning composition.
- a suitable cleaning composition may be made by compounding these ingredients within the range of percentages by weight specified in Table I.
- an improved cleaning composition may be formulated by employing a Water soluble organic solvent in the above composition.
- a water soluble organic solvent is employed in the cleaning composition, the compound is more stable and more active both as a solvent and as a cleaning abrasive. This improved action appears to be due at least in part to the improved homogeneous nature of the mixture when the water soluble solvent is used.
- Water soluble solvents such as the polyglycols and their mono or diethers, and especially diethylene glycol monobutyl ether, are particularly advantageous due to their non-toxic and non-inflammable properties.
- the preferred cleaning composition consists by weight of 57% powdered feldspar and 6% of a 9% water suspension of bentonite and 42% of diethylene glycol monobutyl ether.
- the cleaning composition or gel is swabbed on the cleaning tool or the Work.
- the solvent softens the gum or varnish binder in the deposit, while the abrasive as moved under the action of the tool abrades the deposit. This action continues throughout the cleaning operation with the solvent and abrasive continuously softening and removing by abrading the deposit.
- a spark plug cleaning composition consist- 4 ing of a mixture by Weight of 0.25 to 2.0% bentonite, 2.8 to 23% of water, which forms a gelatinous suspension agent and 40 to 65% of a powdered feldspar abrasive material and the balance diethylene glycol monobutyl ether.
- a cleaning composition consisting of a mixture by weight of from .25 to 2.0% bentonite, from 2.8 to 23% water, from 40 to 65% powdered feldspar abrasive and. the balance diethylene glycol monobutyl ether, between a tool and the spark plug and moving said tool and spark plug with respect to each other to clean said spark plug.
Description
Patented Feb. 3, 1953 PROCESS FOR CLEANiNG SPARK PLUGS AND COMPOSITION THEREFOR Taine G. Mcllongal and Earl W. Pierce, Flint, and Wilfred A. Bychinsky, Ann Arbor, Mich, assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware No Drawing. Application June 16, 1949, Serial No. 99,571
2 Claims. 1
This invention relates to cleaning and polishing compositions, and more particularly to cleaning and polishing compositions for removing deposits from the insulators of spark plugs.
Spark plugs as normally used on internal combustion engines collect a deposit on the insulator surface which reduces the effectiveness of the insulator. Though aircraft spark plugs are completely shielded, they do collect a deposit which causes deterioration of the insulating properties of the spark plug insulator. The deposit consists of minute particles of metal which are sputtered off by corona discharge from the metal components both at the top and the bottom of the spark plug well, of ingredients of the cable insulation which may become volatilized, of the residue from the silicone jelly used to fill spaces between components in the barrel area, of particles of carbon, of gum and of metal from tools used to insert the spark plug. This collection of dirt and grime conducts electricity especially when it has absorbed some moisture and reduces the insulating properties of the spark plug insulator.
This compound may be removed by employing a cleaning and polishing composition in conjunction with a polishing tool or wheel. Various cleaning compositions and procedures have been proposed for cleaning the deposits on spark plug insulators, but they are exceedingly slow and laborious. In accordance with this invention the applicants have provided a cleaning composition consisting of a powdered abrasive, an organic solvent, and a suspension or gelling agent. The composition is in the form of a gel which adheres to the surface deposit on the spark plug insulator and dissolves or softens the binder or gum portion of the deposit before the abrasive cleaning and polishing action commences.
It is the object of this invention to provide a cleaning and polishing composition having both a solvent action and an abrasive action in the form of a gel which will adhere to the deposit on the spark plug insulator, so that it will simultaneously dissolve and abrade the deposit.
Another object of the invention is to provide a composition capable of cleaning the gum. deposits from spark plug insulators when used in conjunction with a polishing tool or wheel.
Another object of the invention is to provide a gel of powdered feldspar, diethylene glycol monobutyl ether and a water suspension of ben tonite for use as a cleaning and polishing composition.
The insulator surface of spark plugs used on internal combustion engines becomes covered with a deposit of small particles of carbon metal, etc., bonded together by a gum or varnish. This deposit reduces the insulating capacity of the insulator. This fouling of the spark plugs is especially dangerous in aircraft engines. Thus proper aircraft maintenance requires that the spark plug insulators be maintained free of these deposits.
On aircraft spark plugs this deposit forms particularly rapidly in the spark plug well. Thus a special tool has been devised to distribute and actuate or work the abrasive cleaning composition. The tool consists of a rotatably mounted cylindrical element having helical threads on its surface. This tool or any suitable polishing tool or wheel may be used to actuate this cleaning composition.
The cleaning composition made in accordance with this invention consists essentially of a fine powdered abrasive material and an organic solvent for the organic binder or gum of the deposits together with a material to maintain the abrasive in suspension in the solvent constituent. The organic solvent used may be naphtha, a low boiling point hydrocarbon paraffin, or benzene, an aromatic, or carbon tetrachloride, a chlorinated carbon, or chloroform, a chlorinated hydrocarbon. The solvent acts t dissolve and soften the gum or varnish which holds. the deposited material on the insulator surface. The feldspar is a fine abrasive material which will scour or abrade the deposit and assist the cleaning action of the solvent. The bentonite when mixed with Water forms a gel which will hold the abrasive and solvent in suspension or distributed in the gel. In addition, the gel is a convenient and practical form, as compared to a liquid, for using the cleaning composition.
A suitable cleaning composition may be made by compounding these ingredients within the range of percentages by weight specified in Table I.
Table 1 Percent Bentonite 0.25 to 2.0 Water 2.8 to 23 Feldspar 40.0 to 65.0 Solvent Balance A feldspar having the particle size as defined in Table II has been found particularly suitable for removing these deposits from spark plug insulators.
We have also found that an improved cleaning composition may be formulated by employing a Water soluble organic solvent in the above composition. When a water soluble organic solvent is employed in the cleaning composition, the compound is more stable and more active both as a solvent and as a cleaning abrasive. This improved action appears to be due at least in part to the improved homogeneous nature of the mixture when the water soluble solvent is used. Water soluble solvents, such as the polyglycols and their mono or diethers, and especially diethylene glycol monobutyl ether, are particularly advantageous due to their non-toxic and non-inflammable properties. The preferred cleaning composition consists by weight of 57% powdered feldspar and 6% of a 9% water suspension of bentonite and 42% of diethylene glycol monobutyl ether.
The cleaning composition or gel is swabbed on the cleaning tool or the Work. The solvent softens the gum or varnish binder in the deposit, while the abrasive as moved under the action of the tool abrades the deposit. This action continues throughout the cleaning operation with the solvent and abrasive continuously softening and removing by abrading the deposit.
Numerous modifications of the invention may be made without departing from the spirit and scope as defined in the appended claims.
We claim:
1. A spark plug cleaning composition consist- 4 ing of a mixture by Weight of 0.25 to 2.0% bentonite, 2.8 to 23% of water, which forms a gelatinous suspension agent and 40 to 65% of a powdered feldspar abrasive material and the balance diethylene glycol monobutyl ether.
2. In a process for cleaning spark plugs, the step of applying a cleaning composition consisting of a mixture by weight of from .25 to 2.0% bentonite, from 2.8 to 23% water, from 40 to 65% powdered feldspar abrasive and. the balance diethylene glycol monobutyl ether, between a tool and the spark plug and moving said tool and spark plug with respect to each other to clean said spark plug.
TAINE G. MCDOUGAL. EARL W. PIERCE. WJLFRED A. BYCHINSKY.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,812,321 Davidson June 30, 1931 1,862,322 Soley June 7, 1932 2,006,162 Fuchs June 25, 1935 2,296,097 Emiley Sept. 15, 1942 2,356,792 Oakes et al Aug. 29, 1944 2,364,281 Ellinger Dec. 5, 1944 2,376,945 Stine May 29, 1945
Claims (1)
- 2. IN A PROCESS FOR CLEANING SPARK PLUGS, THE STEP OF APPLYING A CLEANING COMPOSITION CONSISTING OF A MIXTURE BY WEIGHT OF FROM .25 TO 2.0% BENTONITE, FROM 2.8 TO 23% WATER, FROM 40 TO 65% POWDERED FELDSPAR ABRASIVE AND THE BALANCE DIETHYLENE GLYCOL MONOBUTYL ETHER, BETEEEN A TOOL AND THE SPARK PLUG AND MOVING SAID TOOL AND SPARK PLUG WITH RESPECT TO EACH OTHER TO CLEAN SAID SPARK PLUG.
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2627148A true US2627148A (en) | 1953-02-03 |
Family
ID=3439450
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US2627148D Expired - Lifetime US2627148A (en) | Process for cleaneng spark plugs |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2627148A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2901383A (en) * | 1950-10-26 | 1959-08-25 | Wacker Chemie Gmbh | Process for cleaning objects |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1812321A (en) * | 1927-02-26 | 1931-06-30 | Carbide & Carbon Chem Corp | Finish remover |
| US1862322A (en) * | 1926-11-23 | 1932-06-07 | Carborundum Co | Saponaceous emulsion and product containing the same |
| US2006162A (en) * | 1934-07-25 | 1935-06-25 | Permatex Company Inc | Grinding composition |
| US2296097A (en) * | 1942-09-15 | Cleaning composition | ||
| US2356792A (en) * | 1938-11-05 | 1944-08-29 | Minnesota Mining & Mfg | Liquid composition for polishing and the like |
| US2364281A (en) * | 1941-04-25 | 1944-12-05 | William H Ellinger | Paraffin solvent |
| US2376945A (en) * | 1943-02-01 | 1945-05-29 | Turco Products Inc | Piston cleaning apparatus |
-
0
- US US2627148D patent/US2627148A/en not_active Expired - Lifetime
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2296097A (en) * | 1942-09-15 | Cleaning composition | ||
| US1862322A (en) * | 1926-11-23 | 1932-06-07 | Carborundum Co | Saponaceous emulsion and product containing the same |
| US1812321A (en) * | 1927-02-26 | 1931-06-30 | Carbide & Carbon Chem Corp | Finish remover |
| US2006162A (en) * | 1934-07-25 | 1935-06-25 | Permatex Company Inc | Grinding composition |
| US2356792A (en) * | 1938-11-05 | 1944-08-29 | Minnesota Mining & Mfg | Liquid composition for polishing and the like |
| US2364281A (en) * | 1941-04-25 | 1944-12-05 | William H Ellinger | Paraffin solvent |
| US2376945A (en) * | 1943-02-01 | 1945-05-29 | Turco Products Inc | Piston cleaning apparatus |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2901383A (en) * | 1950-10-26 | 1959-08-25 | Wacker Chemie Gmbh | Process for cleaning objects |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Jones et al. | Amorphous coatings on mineral surfaces | |
| DE3012332C2 (en) | Liquid fine polishing agent with non-drying properties | |
| DE1542633B2 (en) | METHOD OF PREPARING AN OLEOPHIL GRAPHITE AND ITS USE | |
| US2627148A (en) | Process for cleaneng spark plugs | |
| US3711428A (en) | Electrical resistor paste containing a small amount of charcoal | |
| US2705207A (en) | Method for removing paint and varnish | |
| US3819343A (en) | Medium for process of honing by extruding | |
| US3862026A (en) | Adsorption of n-paraffins with graphite-alumina pellets | |
| US1810660A (en) | Method of and composition for increasing the conductivity of | |
| US3265475A (en) | Buffing compositions | |
| US2356747A (en) | Cleaning composition and process | |
| US1324215A (en) | Abrasive and process of making the same | |
| US2838652A (en) | Method and apparatus for spark machining | |
| US2391376A (en) | Machinable insulating composition | |
| WO2002090478A1 (en) | Coating remover | |
| DE717710C (en) | Cleaning agent for spark plugs | |
| DE697963C (en) | Procedure for removing lamellar insulation from collectors | |
| US1620409A (en) | Paint and varnish remover | |
| US1750990A (en) | Commutator cleanser | |
| US1535953A (en) | Carbon remover | |
| DE897306C (en) | Process for the production of thickened mineral oils | |
| US2860076A (en) | Dynamoelectric brush | |
| US1360153A (en) | Transformer-grease | |
| DE478573C (en) | Liquid cleaning agent for cleaning collectors and slip rings of electrical machines from crust-like layers consisting of coal dust, fat and their combustion products | |
| Perkins et al. | Base Exchange in Soils |