US2915069A - Smoking device - Google Patents

Description

M. O. SCHUR SMOKING DEVICE Dec. 1, 1959 4 Sheets-Sheet l Filed July 15, 1954 n if l/ IIIA' INVENTOR. MILTON O. SCHUR Dec. 1, 1959 M. o. scHuR SMOKING DEVICE 4 Sheets-Sheet 2 Filed July 13, 1954 FIG. 5

IN VENTUR.

MILTON O. SCHUR CMA w AGENT Dec. l, 1959 M. o. scHuR 2,915,059

SMOKING DEVICE Filed .my 13. 1954 4 sheets-sheet s SQ- mg 52m u nn IN VEN TOR.

MILTON 0. SCHUR AGENT M. O- SCHUR SMOKING DEVICE Dec. 1, 1959 4 Sheets-Sheet 4 Filed July l5, 1954 INVENTOIL MLTON O. SCHUR du@ 2d.

AGENT `sMoKiNc VDEVICE Milton 0. Schuif, Asheville, N.C.`, assignor, byfl'nesne` astsignments,V to Olin Mathieson Chemical Corporation, a

corporation of Virginia Application July 13; 1954, ySerial No. 443,007

1 Claim.. (ci. isn-10) t This invention relates generally to cigarettes and simiy lar V'tobacco 4smoking `devices and more particularly to an improved filter therefor `and to a novel method for preparing the same. l

It Vhas been the `practice heretofore 'to provide smoking devices with a filter to remove filterable Aconstituents from the tobacco smoke. Filters prepared -from crepe paper in which the ldirection of creping runs Iparallel to the longitudinal axis of the filter and filters composed of alternate layers of paper and fluffy asbestos or cotton have been among the more successful filters heretofore available. These filters have been found to be relatively ineffective, however, in removing appreciable quantities of the undesirable Vconstituents from tobacco smoke 'unless they are wound or otherwise compressed so tightly as to form a filter whichimpedes `the flow of smoke'therethrough to such an extent that the smoking lproperties of' the ldevice are greatly impaired. It also has been4 proposed to include charcoal and other adsorbent materials in the tobacco in fsuch devices to improve the taste ofthe smoke but charcoal has not been utilized in` filters Vforcigarettes and similar devices because of the difiiculty of retaining it in an active condition in `-the filten SuchV prior devices and methods of removing undesirables fromy the smoke and improving Vthe 'taste fthereof have had adi ditional disadvantages including yfailure to Jremove some" of the undesirable materials fromthe tobacco smoke. It is an object of lthis invention to overcome Is`i1c`lt`disadvantages and provide cigarettes andisimilar smoking devices with a filter-which will effectively remove undesirable constituents from tobacco smoke without' retard ing the flow off-smoke throughthe device Ito an objec` tionable extent. Another object lof 'thefinventionis to provide a filter for tobacco smoking devices V"having'itin proved Afiltration characteristics and also having .an advantageous appearance. A 'further object fof the invention is to provide an improved method -forpurifyin'g andl otherwise improving the qualitiesof tobacco -s'mo'lte without detracting from the appearance of a cigarette. `Astill further object of the inventionfisto provide a cigarette.

having a filter adapted '-to remove undersira'ble "gaseous well as particulate constituentsfromltobacco smoke.

Other objects will become `apparent from the yfollowing description with reference lto Vthe accompanying drawinginwhich v vFigure l is a diagrammatic' perspective view'of' one type of apparatus suitable forforming 'a'filter illustrating one embodiment of'thisinventioni 'Figure 2 is a `diagrammatic view of informing anotherembodiment 'of the invention;

Figure'3 is a perspective 'view of a cigarette, partly fin section, illustratingone embodiment of this invention; fFigure tris `a perspective view, partially :in'sectiomof a :cigarette illustrating `another embodiment of this "invention;

Figure `5"-illustrates :filter fpaper ofi-aatype -utilizedwin accordance `with this invention;

Figure i6 is a diagrammatic vlewillustrating a methody vapparatus suitable A 2,915,069 VPatented Dec. 1, 1952 of assembling tobacco .and filters 'to form a rod of tobacco 4andthejfilters to be` subsequently separated .into cigarettes; t Figure 7'is a Vdiagrammatic view illustrating apparatus suitable for forming still another embodiment ofthe in`v vention; Y Figure 8 illustrates diagrammatically a method lof as-y sembling segments of filter material to form a lter for smoking devices; `v Figure 9jillustrates diagrammatically, in another View, a portion 'of the apparatus `ofFigure 7, and

Figure 10 "s a diagrammatic view illustrating another method of assembling tobacco and filters to forma rod of tobacco and the filters to be subsequently separated into cigarettes. "In vaccordance with this invention the foregoing objects as well as others vare accomplished, generally speaking; by 'providing smoking devicesjhaving a filter composed of segments of fibrous material, with at least one of the seg-y ments of' the lfilter containing particles o-f activated char# coal. Ordinarily, for best appearance, the filter 'when attached to a cigarette will be composed of segments, one adjacent the tobacco having particles of activated char-A coal Vexposed to the passageways therein, and another segment being substantially free from charcoal or' other discoloration at the mouth end. The invention contem` plates ras -a preferred embodiment a cigarette having a paper filter containing particles of activated charcoalfin combination with absorbent paper filtering material. l Y For the purpose of this invention, in the one segment the activated charcoal must be retained in such a manner that it Vdoes'not become deactivated. The utilization of glue or thelike to secure the activated charcoal particles to Vpaper is entirely unsatisfactory for the purpose since. such materials tendto deactivate the charcoal and prel vent its vsubsequent utility. Such an undesirable condition vis; avoided in accordancewith this invention by utilizing -paper in which the activated charcoal is included with the pulp "before paper sheet formation.' The result# ing sheet has the `particles of charcoal secured to the individualfibers intermes'hedfthroughout the paper in suchl a `way that the combined exposed `s'i'ufaces `provide iniproved filtering efiiciency. 'This tis of considerable atl-f vantage Lsinc"e,` wln`le other adsorbent materials '-suchas silica 'Igel and the like are: `effective as filtering media," they -do 'lnot Nlend ythemselves 'to either :this method -of 'inf corporationiwithfthe fibrous 'mate-rial or to 4methods in`` volvi'ng the use of adhesivesor'thelike *because they becorneftoo easily Ideactivated in tthe processing; While the `filtermateri'al of thisfinvention Amay `be utilized with z any'ftype of-jsnfoking device, it `is` particularly well suited as 1'affilter `fortcigare'ttes'.

#Althoughltactivatedfcharcoal yis' particularly -advant t geous as an adsorbent for acrolein, hydrocyanic acid' and*A other gaseous compoundsfin tobaccosrnoke, filters propely 'formed from? suitably processed Iabsorbent Ipaper lnot` containing :activatedtcharcoalvhave `utility iin Lremoving particulate material.' "This invention Tthus provides a` filter? having* optimum `filtering 'characteristics by combining lini' one filter'unitf'a desirablesegment having adsorbent char? acteistics with fanfeifective fabs'orbent paper 'segment' v Moreover,inaccordance with this finvention it is ,possibleto ,'coinbine a 'segment .'containingiactivated charcoal #with one or more segments which contain other adsorbentirnaL-l l teri'als or reactants `which t fare' iparticularly `rwell suited for removing certain-specific undesirable: constituents from"- tobacco smoke. w fInrsome relnbodirnentart 'nis` :aiivar1ta'V geousdoiplace at ,fleast` on'e 'segment :of absorbentmate: rial :between -ithefrtobacco and 'the :segment containing I aufA tivated ioharcol in'iorderftoremovesomeof :the un'desir-r able? @particulate t constituents before the smoke `freaohesgthe. activated charcoal @Segment- @With suchten arrange:-A

ment, the activated charcoal is not saturated with constituents which can be otherwise absorbed and maximum 4 adsorbability of the charcoal segment is thus maintained.

It is preferred, for best results, that the granulation of theactivated charcoal besuch that substantially all the particles thereof will pass through a Tyler screen having about 100 meshes per lineal inch and substantially none of the particles will pass through a Tyler screen having about 300 meshes per lineal inch. The paper tends to shed particles coarser than 100 meshes while particles finer than 300 meshes are less effective and tend to impart disproportionately undesirable blac'k color to the segment. For best results, the sheet paper should contain from about 2.5 to about 50 percent by weightv activated charcoal with about 20 to about 25 percent being the optimum amount for most filters. y In the composite filter of this invention the component segments or plugs may, of course, be of varied length. For example, they may be of equal length or, for optimum effectiveness in the removal of undesirable materials from the smoke, the segment containing the activated charcoal may be in the neighborhood of about twice the length of the segments not containing activated charcoal.

The filter of this invention having two or more segments has the further advantage of making it possible to use combinations of various types of filters formed from fibrous material. The segment which contains the charcoal may be formed by any suitable method but it is preferred that it be formed in accordance with the invention disclosed in the application of Milton O. Schut and James C. Rickards, Serial Number 400,072, filed December 23, 1953 to form a filter. This segment may then be combined with at least one Segment formed from filaments of silk, cellulose butyrate acetate or other suitable fibrous filtering material. In another embodiment, preferred because of its exceptionally good filtering characteristics, both or all segments making up the composite filter are formed in accordance with lthe method disclosed in application Serial Number 400,072. In still another embodiment, a segment formed in accordance with the process disclosed by Edwards in U.S. Patent 2,160,201 and containing activated charcoal incorporated in the paper as described herein may be combined with any other suitable filter segment free from activated charcoal. Although high alpha paper is preferred for the absorbent medium other suitable'materials can be utilized. Plastic filaments such as cellulose ace tate, for example, can be utilized to advantage for forming the charcoal-free segment of this invention. Of the various combinations of segments possible, however, it is preferred that at least one be formed in accordance with the process disclosed in the co-pending application referred to above in order to insure optimum filtering characteristics. In fact, best results are usually achieved if each of the segments is formed in accordance with that process.

No care need be taken to align the passageways through one segment with those of an adjacent segment. Indeed, another advantageous feature obtainable in accordance with this invention is that such passageways will not be aligned and the passageways through the filter will thus be even more tortuous if the filter is divided into distinct segments than 'if in one piece. Such a divided filter is advantageous for some purposes even if no segment containing activated charcoal is included therein.

For optimum filtering characteristics paper weighing from about 7 to 30 grams per square meter before creping or before any other form of mechanical work such as crumpling or embossing has been performed should be utilized for forming the filter segments containing activatedcharcoal. A weight of about 7 to about 25 grams per square meter before' mechanical working should .be-utilized to form the other segments. -Sheets Y of greater weight can be utilized in the segment containing activated charcoal because such paper is softer and more pliant than paper of a comparable weight not containing activated charcoal. Greater pliancy and better filtering characteristics are obtained if only high grade pulps of the so-called high alpha pulps of alpha cellulose content of at least about 90% are utilized to prepare the ypaper containing the activated charcoal particles as well as for preparing the other segments of the filter.

In order to better clarify and further describe the invention the following are examples illustrating typical embodiments thereof:

About 25 parts activated charcoal within the granulation range of from about 100 to 300 mesh are added to about 75 parts by weight paper fiber furnish on a solids basis. The activated charcoal is intimately mixed with the solids in the furnish and the mixture is formed by conventional means into a sheet of paper weighing about 9 grams per square meter. The sheet during manufacture is creped by` conventional means.

After the formation of this sheet containing the activated charcoal, 38 plies thereof are piled one on the other to form a ribbon having 38 layers of paper, each about one-half inch wide.

Referring to Figure l, a sheet 1(a) of conventional cigarette Wrapper paper or other paper suitable for a filter Wrapper is pulled from roll 4 by any suitable means such as by an endless belt 23 through the forming cone 3 of a conventional cigarette making machine. Before sheet 1(a) enters the forming cone 3, the one-half inch ribbon of 38 plies of paper 2 containing activated charcoal are pulled from roll 5 and are laid on sheet '1(a). As sheet 1(a) is pulled through the forming cone 3 it carries the layers of paper 2 through the forming cone 3 where they become crumpled and compressed together as sheet 1(a) is convolutely wound thereabout to form Wrapper 1. Edge 7 of sheet 1(a) remains substantially perpendicular during the early stages of this.process. The width of wrapper 1 is about one and one-eighth inches and is sufficient to enwrap completely the cylinder of one-half inch width paper strips. Before wrapper 1 emerges from the forming cone, the plurality of plies of paper have been gathered together and compressed therein leaving a maze of tortuous passageways 39 as illustrated to best advantage in Figures 3 and 4. A suitable gum adhesive is applied to edge 7 by applicator wheel 9 and edge 7 is folded to overlap edge 11 by means of the final forming cone 6. The overlapped edges 7 and 11 are tightly bound together as heated roller 10 passes thereover and removes water and any other liquids from the adhesive. Rotary cutter 12 severs the resulting labyrinthal structure into rods such as 13. Rod 13 may be cut later to the desired length for use in making the filter. The density of the segments is about 0.1 to about 0.3 gram per cubic centimeter. The paper utilized is illustrated in Figure 5, the spots 41 indicating particles of activated charcoal.

A second segment 42 is formed in accordance with the process described in the foregoing with the exception that 38 plies of paper substantially free from activated charcoal is substituted for the paper 2 shown in Figure 1. The segment 42 s twice the length that intended to be used in the cigarette. Segment 42 is then assembled with two segments 40 previously cut from rod 13, one on each end thereof and the three segments are fed into a cigarette making machine where they are placed in a cigarette wrapper containing tobacco 15 in the position illustrated in Figure 6. The resulting continuous rod of alternate areas of tobacco 15 and filters composed of segments 42 and 40 positioned as shown in Figure '6 is then cut into lengths suitable for cigarettes by severing the wrapper 14 and segment designated as a whole by numeral 42 along the line A--A, Figure 6, to form two segments y43. The resulting cigarette 16, illustrated in Figure 4, has two segments 40 and 43 of sub- `stantially-equal length and `tobacco 15 .enclosed within wrapper 14. AIf it is 'desired to iprovide they 'cigarette with a lter in which eitherv segment 43 or segment 40 is `less than one-halt of the length of the filter, the Alength is of course predetermined als -it is formed, as illustrated in Figure 6.

A particularly advantageous method for crumplingttheV web 19 is pulled through ra similar setof orifices 321, 32

and 33 and web l20 is likewise pulled through orices 34, 3S and 36. As shown yinthe-drawing theyoriiices are formed in plates 2S, 29 and 30 fof a suitable plastic material. The plates are spacedy apart .sufficientlyV to permit each of the webs to yexpand 4as shown, 211224,27, 37 and 38. The crumpled -webs 18, `19, and 20 are wound inthe web 1(a) to-form arod 13 such as `shown in Figure l. Such precrumpling -is `particularly desirable if the paper used for forming the ffilteringlmedium weighs more than about `16 grams per "square meter.

`In still another embodiment of ythis `invention, Vthe paper is embossed prior tocrumpling and a particularly advantageous embodiment in ywhich the paper is em bossed and precrumpled is illustrated in Figures 7 and 9. In the embodiment illustrated, paper web 45 Vis fed `from a roll 46 to a gang of rotary slitters 37 where it is cui into a plurality ofstrips :of desired widths. These strips, which may or `may not have fbeen previously creped,

`may then be passed "betweenembossing rolls. As y.illustrated `in Figure 7, two -pairs-of embossing rolls are rpreferred. If in the lfirst pair the ypositive roll 49 is the upper roll and the Vnegative roll 481is the lower roll then this arrangement is reversed in the second pair with the negative roll 5t) 'the upper and the positive roll 51 the lower roll. The pairs of rolls are separated from each other in order that the paper may expand after being embossed by the first pair before itis embossed by the second pair. The positive and negative surfaces'may be produced in `accordance `with Aany conventional means. For eXample, positive rolls 48 and 50 may be Toughened by surfacing the roll with very coarsesandpaper. :The surface of ythe negative rolls 49 and `51fshould -lbe of-`a soft material to permit the roughen'ed surface of the positive rolls to follow the paper wrapper into it. A layer of sponge rubberor similar` material is suitable for the surfaces of theserolls.

Ordinarily, in most embodiments, either the embossing rolls or the oriicedplates of Figure 2 will provide suf cient mechanical working of the paper for thepurposes of this invention, particularly if I'the paper has been .previ ously ereped. In one embodiment, however, .each strip of paper'cut by slitters 37 is passed through a `series of orificed plates 28,29 and Yll'after :having passed between the embossing rolls 48, A49, 50 and .51, as illustrated in Figures 7 and 9. This combination of embossing `rolls and yorificed plates Amay be desirable where the heavier absorbent materials are utilized. `In Figure 9, Lpa'per web 45 is slit into only three lwebs lof Anarrower .dimension but in some embodiments, lthis Web may be slit into a larger or smaller number .of webs.

In the embodiment of Figures 7 fand 9, the resulting crumpled Webs arewjuxtaposed yand `fed lwith 'a web 52 of Wrapper paper to-a forming cone 53. As illustrated, web 52 is delivered from roll 45 by endless belt 54. Fasting wheel 55, final cone 56 and heater 57 are similar to those described in connection with the apparatus of Figure 1. The resulting rod of filter material is subse- .6 y fquently cutntosuitable lengths for the formation of lter segments." t. g

One particularly desirable method for assembling iilter .tip segments lprior `'to -their =combination with tobacco to form acigarette is villustrated `in Figure .8. rIn. accordf ance with this method, lthe -rods produced by one of the embodiments hereinbefore [described are first cut into lengths twice that desired in the finished filter. Acomf posite rodhaving alength equal to an integral multiple of the `length fof thenal `filter tipris then prepared V.by assembling these segments together. These rods, in one embodiment offthis invention, are composed of alternate segments of two `different types of iilter material. yFor example, in Figure, segment 421 enclosed in wrapper 1 may contain particles4 of activated charcoal while segment 58 enclosedrin wrapper -1 .is formed from paper weighing about 20 grams per square meter but does not contain any adsorbent material. This lplurality of seg* ments is enclosed withina suitable wrapper 17 similar to that used for enclosing the .tobacco in a cigarette.

The composite rod 'of .Figure 8 maybe cut into any v desired length -for .feeding into a .cigarette making and tipping machine-,such `as is disclosed .in U.S. Patent 2,156,600. The segments adjacent to thetwo ends of the rod would have a-.predetermined length suitable for the final `filter on the .individual cigarettes; the othersegments would havea length twice `that suitable in the final filter. In :the Vcigarette making and tipping machine, the composite rods would be cut along lines B-'B through segment 58 as illustrated .in Figure Sinto composite rods of lesser length, each vrod being composed ofV two vsegments `59 `of theadesired length, Yand one segment4 421 twice as` long as desired in the 'finished product.

The resulting composite rod-of two segments 59 -and one .segment421 may then be fed into the tipping zone of a .cigarette lmaking .machine along with suitable chargesof tobaccoj1 fand wrapper y141 and there assembled into the continuous rod, shown in Figure .1.0, -of alternate tobacco sections .151 and .iilter sections .composedof :segment,s.`59\,and 4,21. Numeral 1 designates the wrapper about thei'iiltering material of each segment. In thismachine, the continuous rod of alternate sections of tobacco and'filteris .severed Atransversely alongv the line A-.A', through segment 421 toform Aa plurality of cigarettes v161 having .,a'ffilter composed `of segments 59 and 431 .enclosed within wrapper 17, .asshown in `Figure 3. The rod of `composite. lter `material Vof Figure 8 when cut lto theproperlength is alsosuitable forimaking filters-for other vsmokingdevicesas well as for cigarettes.

`If in forming the preferred segments of this invention, lightweight paperofdessthan about 16 grams per square meter is utilized,.good filtering "characteristics areyobtained if the Vonly crumpling of the .paper or other fibrous material is that .done -by the conci-of a conventional cigarette -formingfmachine while the paper is 4beinggplaced within the wrapper. With the .heavier weight papers of the vinvention and preferably even the lighter weight papers, however, the paper -is crumpled `by `a process in addition to the .one by which it is inserted inthe wrapper. Any .crumpling process which forms a multitude of irregularly extending and irregularly spaced .crumples maybe utilized to advantage, but best results are obtained if the paper is crumpled bya process kwherein the crumplesdare formed in a plurality of steps with a Atime' interval interspersed betweenY each step for the paperto spring bac or expand atleast partially. A vresult similar to that `desired is obtained by wedding orfcrushing aV sheet of paper `in the hand. In a preferred method for crumpling, the paper is drawn through a `series of orifices or dies .of graduated .,sizes, each orifice being smaller than the Vpreceding one, as will be fdescribed in-y offers no objectionable resistance partially pulled apart. 'Asimilarresult is also obtained if the paper is heavily embossedgbefore it is fed'to the forming machine. Indeed, embossing i'sone of the preferred methods of preconditioning the paper for use in the manufacture of cigarette filters. In general, the greater the Weight yof the paper utilized, the more extensive must be the crumpling or other softening means for optimum results.

,f The'filtering characteristics of a filter are further improved if substantially unfibrillated paper is utilized in forming the labyrinthal structure. As is well known in the paper making art, fibrillation is the first step in the conversion of pulp into paper. The more the cellulose fibers are fibrillated, that is, the longer they are subjected to the action of a beater, the greater the surface area of the fibrils and the tighter will be the interlock between the fibrils When'they are formed into a sheet. Paper which has beenformed from only moderately fbrillated or uniibrillated cellulose has an open structure which is substantially absorbent and the paper is relatively easily softened and crumpled. Paper containing activated charcoal may contain more highly fibrillated fibers than the paper utilized for forming the other segments of the filter because, as indicated hereinbefore, the charcoal tends to soften the sheet.

If crepe paper is utilized, vbest results are obtained if the direction of vcreping is transverse to the direction of fiow of smoke through the filter. Preferably, the percentage crepe in the paper should be Within the range of from about 8 percent to about 60 percent. In other words, a sheet about 10 inches long is reduced to a length in the range of from about 9.2 inches to about 4 inches when creped.

It has been found that the filter of the instant invention not only removes all of the undesired constituents removed by the filters heretofore available but has the added advantage of removing substantial quantities, often the greater part of the acrolen and hydrocyanic acid and other undesirable gaseous materials from the smoke. Thesefilters are effective even though'the resistance to the ow of smoke is no greater than that equivalent to the loss of head of about 5 centimeters of water when the smoke is passing through the filter at a rate of about 18 cubic centimeters per second. It has been found that a cigarette provided with one composite filter embodiment of this invention composed of one segment adjacent the tobaccowhich contains about 25 percent activated charcoal incorporated in the filtering medium in the ber furnish and one segment containing no clinging particles of an absorbent material removed about 60 percent of the acrolen and about 30 percent ofthe tar from the tobacco smoke. The drag or loss was about 3.2 centimeters ata ow of about 18 cubic centimeters per minute. The charcoal containing segment was about l millimeters long and had a density of about 0.25 gram per cubic centimeter; the charcoal free segment of the filter was about millimeters long and had a density of about 0.21 gram per cubic centimeter. Each of the filter tips in this embodiment was prepared substantially in accordance with the process of the embodiment described hereinbefore except that three strips of paper weighing about 2O grams'per square meter-were utilized. The three strips forming the segment having 25 percent activated charcoal incorporated therein were each about five inches wide and those forming the charcoal free segment were about seven inches wide. The filter of this invention not only removes particulates from the smoke, but unlike even the more elective lters heretofore available, removes irritating gaseous components. It to the flow of smoke therethrough.

" The Iactivated charcoal segments containing various typesof activated charcoal which have been properly purified and which are of the desired characteristics, because of high adsorptive characteristics, particularly for substances in the gaseous form in the smoke, remove constituents from the smoke not removed by the heretoforeknown lters. The composite filter having adsorptive segments combined with absorptive segments removes a large proportion of the acrolen and hydrocyanic acid from the smoke and greatly reduces the concentration of other saturated and unsaturated aldehydes, ketones and saturated and unsaturated hydrocarbons, both aromatic and aliphatic as well as volatile acids.

Although various embodiments of this invention have been described in detail in the foregoing, such a description is only for the purpose of illustration and many modifications can be made by those skilled in the art without departing from the scope lof the invention except as limited by the appended claim.

What is claimed is:

A filter for tobacco smoke comprising a Wrapper, and enclosed within the wrapper a series of segments arranged in end to end abutting relationship, each of said segments `consisting essentially of a plurality of fibrous layers of mechanically worked paper sheet originally weighing not more than about 30 grams per square meter substantially filling a length of said wrapper but having tortuous passageways extending generally longitudinally through the filter between the layers of paper, a substantial number of the passageways of one segment being out of alignment with passageways of the adjacent segment, the paper sheet having been mechanically worked until fibers thereof have been pulled apart, at least one of the segments in the series having particles of activated charcoal bound to the paper solely by intermeshing fibers of the paper, said charcoal having a granulation preponderantly within the range of from about mesh to about 300 mesh, and at least one of the segments being free of charcoal particles.

References Cited in the file of this patent UNITED STATES PATENTS 328,947 Johnson Oct. 27, 1885 1,967,585 Minton July 24, 1934 2,033,867 Segal Mar. 10, 1936 2,145,528 Ruau Jan. 3l, 1939 42,156,600 Molins May 2, 1939 2,164,702 Davidson July 4, 1939 2,219,491 Podmore Oct. 29, 1940 2,258,823 Tarrant Oct. 14, 1941 2,342,924 Davidson Feb. 29, 1944 2,708,982 McGut May 24, 1955 FOREIGN PATENTS 189,399 Switzerland May 1, 1937 265,825 y Switzerland Mar. 16, 1950 266,602 Great Britain Mar. 3, 1927 287,549 Switzerland Apr. 1, 1953 406,401 Great Britain Mar. 1, 1934 518,331 Belgium Mar. 31, 1953 538,529 Great Britain Aug. 7, 1941 607,442 Germanyr Dec. 27, 1934 612,737 Germany May 3, 1935 653,666 Great Britain May 23, 1951 666,308 Great Britain Dec. 16, 1948 665,278 Great Britain Ian. 23, 1952 682,930 Great Britain Nov. 19, 1952 695,046 Great Britain Aug. 5, 1953 Great Britain May 5, 1954

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