US1557825A - Apparatus for treating shoe materials - Google Patents

Description

Oct. 20,1925.

F. M. FURBER APAnuus Fon 'mamme SHOE uATsRIALs Filed Sept. 20, 1924 2 Sheets-Sheet l 0t.120,lv 1925.1'

F. M. FURBER APPARATUS FOR TREATING SHOE IATERIALS 2 Sheets-Shed Filed Sept. 2o. 1924 Patented Oct. 20, 1925.

uma@ Enne smi/'sir 'oF-1?lfi'cai;J- f

, Missie-Hams;:restatefait A'ppiieatiqn Ifiled' septembateo;1924;--'Y sei-rauw; fissata: f y

lowing description,l infconnection with the accompanying fdrawvrn'gs isf a-v spec1{icat1on,'

like .reference characters on thedrawings-indica ti-ngilike` parts #1n-the several heures.

This yinvention xrelates to apparatus for heating shoe materials .Withor without moistv vapori Forexample; inthe manufaetv-.reot` boots and shoes it is common to heat the toes'V with hot,V moistvapor( at tivo stagesto renderthe niaterialssoft andpliant, first for the pullingeoverioperation, and seco1icl,^tor

i thelasting operati-0n'. Y The treatment is suby 2o stantiallyfthe same atboth of these stages but the .apparatus for=the first 'treatment is usually designed totreat .the materials-in Ia flat condition, whereas th at ffor the' second usuallyhas afhousinginto which. the toe end scrted tortueatnient..4 p.

A difficulty experienced 1n such treating with many ofthe-apparatusheretofore 1n use is that lit thesoftening effect `is rapid' enough to keep. pace with the'l subsequent` operations the upper leather isV tooyoften. scorched-.orstained, particularly when theV period of, treatment is Aprt'ilonged beyond the allotted tiine.- Inany event'7 the quantitv ot Waste .vapor discharged in to the atmosphere is usuallyI so great as to be a serious menace to health and machinery.

In view ot the 'above-mentioned conditions anobject of thepresent invention is toy pro-V` vide anniinproved @apparatus adapted to treat shoe-materials Withfheat Aand moistY vapor so that the desired softening .will beeffected at the. required rate Without danger ot scorching .or-l otherwise harming the tra the atmosphere 'of the Work-room,

In itsbroader aspects lthe-'imention is-ap'- plicable to various'torrns of apparatus including zthosef usedo'r pulling-over and .those used *for lasting.- Nevertheiessi cer tain' Afeatures ot the illustrated apparatus 'are more particularly suited to ltherequirenients ot one Aorinore pulled-,over shoes may bein#- leather, andnithout' a-ppreciably meisten-ing ofconditioning'V the materials.; for lastingy andthe invention Willbe described with sp-f cial reference/t0 such'use.

.It has been demonstrated Iinzpra'ctice. Ath atr the most satisfactory-type `'off apparatus* foi thefpurposesabove indicated lis' one in which,y thenioistfvapor is generated'at or close to'- the treating' station or:stations-butfwlientheapparatus is designed 'toftreat-Yaplurality of some cases impossible, to` maintain uni-Y torinityin the Vquantity ot -va'pbr supplied to the 'several stationsw Any considerable Y'in-f equality `'in -thisreSpect militates against uni torni-pulling-pover' or lasting astlievcasenay if be, and'tends toprodueesurplusvapor.v A'ccordinely,- an object-fofythis :invention V'is toprovide- 1na-trleating i-apparat'us for ythe pur poses stated, nnprovedmeans t'oinsure' unitornrquantities, 'as Well as uniforingtemf pe-rature',` of vapor at *each-'oli -a plurality fof' treat'inlfrfstations;` t e. I

To --tliis end 'the `illustratec'l apparatus' prof vides for generatingI an individual supply ot vaporj at each of ra *plurality fof tieati-ngstations by ,heating sinall quantitieso'fiva-f ter only as vaporisfneeded, ift-hereby Aavoid'- ing"l lossesL and the humidiffying"'resultvof maintaining' arelativejly large-body' ot water at Athe boiling temli'erature.l In relation to this aspect of the invention an object isto" insure lthe delivery of f equa-l lbut restricted quantities -of- Water attach-ofthe stations Where-ity isgto beconverted^into vapor.` A;

- featureof the inventionconsists i-nr'avinani-l fold' VVtor-deliveringf-individu-al supplies of."i i

water from? a-coniinon source ofsupply -to 'the-several stations Where the' Water is to be converted into vapor, 'and means for supplying' Water-fv at- `negligible velocity and pres'- sure through the manifold, thedelivery nozzlesr of 'the manifold beingpreferably restricted 'tonapillary proportions to ii'isure' equality in the q the .nozzljesfv Another object isito obtain improved eiii` ciency in the production of vapor' Withfregard tothe 'saving -ot-tinieand heat; Inthi's uantity of Water emitted by' K ZOUi respect a feature consists-"in the arrangement y o1c the Waterfdelivery 'noz'zlesin thermal relation tothe heating means whereby thetemperature oft the Water may bel raised -tov the 1 boiling point while the water is in the nozzles, and further, in the arrangement of t-he nozzles to emit vapor directly against the toes of the shoes and thus to utilize the pressure developed by the expansive action of the vapor in the nozzles to precipitate the vapor to the shoes.

Still another object of the invention is to provide improved means vfor insuring` diffusion of the heat and vapor 'in cases where a direct and more rapid treatment is not so desirable. For this purpose a feature of the invention consists in a housing of absorbent, refractory material, earthenware for eXample, having a work-receiving chamber. As shown, the apparatus is designed to utilize this type of housing and a non-absorbenthousing interchangeably. The non-absorb-` ent housing affords a direct application of heat and moisture and more rapid treatment. The choice of housings may be determined according to the shoe materials or the preference of the user.

Again, an object of the invention is to provide improved heating means whereby uniform temperature may be maintained at relation to said ribs.

a plurality of treating stations at a minimum of cost. A novel feature relating to the heating means consists in a metallic tray having depending flanges or ribs on its under side forming grooves or channels, and electric heating units arranged in said grooves or channels and in heat-conducting As shown, this tray has a trough or channel shaped to conform to the water-nozzles, and the latter are arranged therein the better to utilize the heat to produce vapor.

Referring to the drawings:

Fig. 1 is a perspectiveview, partly broken away, of the metallic tray that forms the bottom of a series of enclosed treating stations. Y

Fig. 2 is a perspective view of a metallic bar constituting a duplex water-nozzle, said bar being one of a plurality arranged in heat-conducting relation to the element shown in Fig. 1 and having individual Water passageways to divide the water into separatestreams and to emit said streams at the treating stations respectively;

Fig. 3 is a vertical Isection through the assembled apparatus including a metallic hood or housing to enclose the toes of the shoes. The plane of this section is indicated by line. IIL-HI of Fig. 4.

Fig. 4 is a top plan view of the elements y shown by Figs. '1 and 2 in their 'assembled relation.

Fig. 5 is a perspective View of the type of hood or housing included in Fig.

Fig. 7 is a vertical section on a larger scale, through the structure intersected by line VII-VH of Fig. 4.

Fig. 8 is a fro-nt elevation of the assembled apparatus equipped with individual hoods or housings for the toes of the shoes insteadl of the type of housing shown by Figs. 3 andk 5. These individual housings are made of absorbent, refractory material.

Fig. 9 is a perspective view, partly in section, of a portion of the apparatus shown by Fig. 8. v

Fig. 10 is a vertical section through the structure intersected by line lX-X of Fig. 8.

Fig. 11 is a perspective View of portions of the electric heating units and a portion of the element shown by Fig. 1.

/Vith the exception of the two alternative types of housing for enclosingvthe toes of the shoes, the apparatus is'the same in all the figures, but since there are certain considerations peculiar to the structure and effect of the two types of housing the apparatus will be described first with regard to the type shown by Figs. 3 and 5 and afterward with regard to the type shown by Figs. 8, 9 and 10.

Referring to Figs. 3 and 5, the housing 12 is made of metal, preferably sheet metal, and forms one elongated chamber having a horizontal series of openings 14 in its front wall and being open at the lbot-tom throughout its length and width. The openings 14 are proportioned to receive the toes of the shoes individually with no more clearance than is necessary to facilitate the insertion of the toes. Each vopening 14 therefore marks an individual treating station.

Although the housing 12 is open at the bottom the treating stations are enclosed by the housing and the element by which it is supported. This supporting element is a metal tray 16 and is preferably provided withv an upstanding marginal flange 18 to maintain the housing in the desired position and to guard against overflow of water. A trough or channel 20 is formed in the upper side of the tray 16 to receive the bars or nozzles 22, as shown in Figs. 3, 4 and 7. The under side of the tray is formed with depending ribs or Vlianges 24 to provide grooves or channels for 'the reception of heating units of the type shown by Figs. 6, 9 and 10.

rThis type of heating unit is a well-known commercialarticle, and althoughy made up of a plurality of parts it has the appearance of a. straight bar or strip. The unit comprises a protective covering of sheet iron made in two parts including a strip 26 and a strip 28. The marginal portions 30 of the strip 26 are bent over the longitudinal margiii-.al portions of the strip 28 to enclose the latter and to enclose strips 32 of insulating run in a continuous stream.l The dripping will supply enoughv Water for four treating stations. The distributing bars or nozzles 22 are maintained atl a temperature above the boiling temperature, and since the waterducts formed in them are so small and the passage of water through them is so slow, most of the Water in the nozzles is converted into vapor before it reaches the discharge ports 68. Then the pressure developed by the expansive action of the vapor produces a 'spurting effect which causes the vapor to travel with considerable velocity from the ports to the shoes overhanging them. If

any water overflows the ports 68 it runs into the trough 20 and isalmost immediately converted into vapor, havingbeen raised nearly, if not quite, to the boiling temperature before it is emitted. p

To give the distributing bars or nozzles 22 the highest possible temperature said bars and the trough 2O are shaped to conform to each other. As shown, the bars and trough are rectangular in cross-section and the bottoms of the bars are heated by conduction while the two upright sides are further heated by radiation from the corresponding surfaces of the trough which are very close. Additional heat for treating the work is raidiated from the. tray 16 and in a lesser degree from the housing 12 which is in heatconducting relation to the tray.

Although the preferred m'ode of use is to restrict the supply of water to a point that L willcause the greater proportion, if not all of it, to be vconverted into vapor before it reaches the discharge ports 68, it is obvious that a greater quantity may be discharged by opening the valve 56 to a greater extent. In the latter case the rate of flow through the distributing bars22 may be sorapidthat little, if any, vapor will be generated in the bars. Then the water will overflow the bars and be converted into vapor by direct contact with the heated tray 16. The capacity of the tray to hold water and its heating capacity are suilicientto prevent overflowing the tray unless a deliberate attempt is made to do so.

If the. character of the work is suchv as to require it, yor if the user prefers, the treatment may b e tempered by substituting the type of housing shown in Figs. 8, 9 and 10 for that kshown in Figs. 3 and 5. As shown yby Fig'S, four individual housings 70, one

they absorb moisture from the vapor and subsequently eXude the vapor so absorbed.v

To develop the absorption of vapor to a high degree, each unit is formed with a hori.

zontal` partition 72 by which a vapor-receiving chamber is provided under the treating chamber. This partition is preferably provided Awith small` ducts 74 through which some-of the vapor may rise-without being absorbed. The moisture absorbed by the partition 72 and the portions below it is difn l fused by capillary action throughout the upper part of the unit, and since the latter is heated to a considerable temperature by' the tray 16 upon which it stands a soft and even exudation of vapor passes from the upper part or cowl portion ofthe vunit to humidify the treating chamber formed lines are used in FigsyS, 9 and 10'to repre-y sent the glazed surfaces, while light lines represent the unglazed surfaces. It will therefore be observed that allv the exterior surfaces are glazed while the interiorv surfaces forming` the treating chambers and vapor-receiving chambers are unglazed. By reason of this localization of glaze the exudation "of `vapor is confinedr to the interior surfaces forming the treating chambers and at the saine time the glazed surfaces tend to minimize the loss of heat by external radiation. Accordingly, the greater partfof heat radiated bythe units 70 is radiated by the internal surfaces forming the treating chambers.

In some cases the desired treatment may be effected by restricting the supply of water, as hereinbefore explained in connection with the use of theV metallic housing 12, but if a greater degree of-moisture is desired the valve 56 may be adjusted to maint-ain a y shallow body of water in the tray' 16. In

this case the bottoms of the porous units 70 will stand in water and the upper parts of theunits will be maintained in a condition of complete saturation.

The illustrated apparatus includes a stand by which the tray 16 and the shoes'may be supported. As shown by Figs. 8 and 10, the stand comprises uprights and a pan 82.

The pan is formed with upstanding iianges v 811 to support the tray 16 Wit-h the least loss ofl heat, and for this purpose the tray is formed with lugs 86 formed to lhook over and rest upon said flanges. No other part of the tray touches the supporting means and the tray is therefore insulated thermally. If desired, thev tray may be securely bound to the pan 82 by a connecting screw 87, a single screw being suifici'ent for the the four treating stations. Y fastened to the bottonroit the board and is purpose and preventing any considerable loss` of heat by conduction 'from the trayto the pan. Y

A portion S8 projecting from the f front of the pan (Figs. 3 and `l0) affords anchorage for a verticallyV adjustable Work supportfSO. This Work support, as shown, is a board long enough to support teur shoes side by side Aat A bracket 92 is designed to be clamped against the front of the -portion 88.` For this 'purpose a vertical slot 94 is formed in the bracket to receive a lclamping screw 96, said sore7 extending through a hole in tlieportion. 8 8 and being 4provided with a nut 98 to produce the clamping ettect. l

vHaving thus described my invention,

what I claim as new and desire to secure by Letters'Patent'ot the United States is:

1 Anapp'aratus 'for treatingslioe materials comprising heat-'radiating means,

,means forming a series kof individual treat-- ing stations arranged inthe field of lheat adjacent to said heat-radiating means, nozzles arranged toeinit individual jetsof fluid at Isaidstations respectively, said nozzles be- 'ing in thermal' relation 'to said heat-radiating means, and means'to supply Water to said nozzles. y L

2. An apparatusfor treating shoe mate rials comprising means forming a treating station, a nozzle arranged to emit a jet vof VHuid tov'vard and adjacent to lan article of work'at said station, means'to supply Water to said nozzle, and heating means arranged to radiate heat 'to'tliework and to heat said 'nozzle to convert sorne or all otr the Water therein into vapor. Y

3. An apparatus :tor treating shoe materials comprising means forming 'a series of treating stations side by side, ai series of nozzles arranged t eniit individual jets of Huid adjacent to the articles of Work at said stations respectively. lmeans to supply Water to Ysaid nozzles, and heating A -I'neans arranged t0 heat said nozzles to convert some or all of the Water in, them into lvapor and to catch any Waterthat overflows them'- p l. An apparatus for treating 'shoe mate- 'rials comprising means forming la treating station, a. nozzle arranged, to einit a jetof 4Huid upwardly toward the undersideof an article of Worl; at said station,inean`sto Asuppl-y ivater to said nozzle, and heating means arranged to heat said nozzle toconvertsome or all of the ivatertherein into vapor and to catch and'ya'porize any Water that overflows said nozzle. p

' 5. An 'apparatusior 'treating shoe materials comprising means for supporting an article of Work for treatment', afnoz'zle arrangedtoemita jetpf fluid under and afdjacent to they ivork,f`1ne`ans to supply Water vto said 'ni-)zare by y-,f ra'vity from' level slightly vert'sonie louall ofthe Water therein-finto vapor. i i 6. apparatus for tr i ttin'g shoe materials comprising "alV hjeatradiating* tray, a t:plurality of nozzles arranged on said tray to be heatedthereby, means-to supply Water yto said.. nozzles tor be converted' intol vapor bythe heat, of saidi tray, 4and means to suppoitapluiality, rot articles of Work for treatnient adjacent to'biit out of Contact With said tray {and-nozzles. y7. 'An apparatus for treating shoe materials comprising a 4inetal tray: adapted to hold Water, elect-ric heating elementseni- Anegligible veloeity to said stations re'spec-,

tively, the delivery "po'rtionsgof Athe 'latter said means being Iinv lheat-condu'ctin'grelation to said trayto vaporize some or'allo'tV the Water before it isemitted. A9. apparatus for treating shoelmaterialsr*comprisingr a metal tray, chamberforming means yarrarf'ged"to standon said trayY and haviniglga vseries of openings to relceive the toes fof shoes ffindividually, said means being open `at-"th'e bottom-tg re'ceivle lheat and vapor from said tray, .means jt'o emit r,indifvidual stippli'es'nfWater Iin--said tray in register 'respectively with the stations to be oceupied bythe toesoth'e shoes,'and means to heat said tray ,for the purpose .,otl converting staidlindividual snpplies of Water into individual suppliesY of vapor;

Y' 10, shoestreating4 apparatus comprising `lfneans forming ahorizontfal 'series' of. en-

closed treating stations'liavingfopenings#to yreceive fthe toesy of slfoes individually,

'meat-S t9 iieatw-thstota1li er the fifaY said means, lmeans arrangedto supplyF Water "at negligible pressure-farete ,Siif1-botwae Vmeans heat-conducting relation Y't'osaid 'bottom to divide the vvater intoredual streams ande'mit saidh streams 'atpirijts in register vvitli said!4 openings respectively.

' 11'. A shoe-treating apparatus'c'oniprising a substantially horizontal heat-#radiating plate, nieansto suppit asiies v(it articlsff a `work in overhang g relation --to -fs'aidplfata ami means'. u) "supply vaternegligible pressure to be converted into grapefruit, at

vide La 'stream' 'of @vater fin -equalsmallerfstreains, said manifold coinprising ldistributing nozzles arranged on the vupper surface of said plate to be heated by the latter.

ifold to divide a stream of Water into a plurality of equal smaller streams, said manifold having delivery nozzles arranged in said trough to be heated by contact with said plate. l

v18. A shoe-treating apparatus comprising a substantially ho-rizontal heat-radiating plate, meansto support a series of shoes side by side so that their toe portions overhang said plate, and means to supply Water at negligible velocity and pressure to be couupwardly.

verted into vapor under said toe portions, the latter said means including a plurality of discharge no-zzles lying on said plate to be heated thereby. v

14. A shoe-treating apparatus comprising va substantially horizont-alk heat-radiating plate, means to support a series of shoesside by side so that their toe portions overhang said plate, and-means' to supply` iyater at negligible velocity and pressure to be converted into vapor. under said toe portions, the latter said means including a plurality of discharge nozzles lying on said plate to be heated thereby, and the outlet ports of said nozzles being arranged to discharge 15. A shoe-treating apparatus comprising a metal tray, means arranged to heat it, means; arranged to supply individual and equal streams of Water by gravity through the bottom of said trayand thence horizontally through ducts of equal length in heatconducting relation to the bottomV of the tray, said ducts having emission ports, `and means ,forming a plurality of enclosed treating stations' above and adjacent to said ports. 16. Ay shoe-treating apparatus comprising means forming aseries of enclosed treating stations having openings to receive the toe portions of shoes, a metal tray supporting said means, means to supply Water bygravity through thevbottom ofsaid tray,.means to distribute the Water and discharge it in equal quantities atfpointsunder and in register with said stations' respectively, and meansto heatsaid` trayfor the purposeof converting the Water into hot moistV vapor.

.17. An apparatus for treating shoe materials comprising a metallic nozzle havingfa Water-'duct of capillary size, means to supply :water :at lnegligible pressure tossici duct,

18. An apparatus for treating shoe materials comprising a metallic nozzle having a Water-duct of capillary size, means to supply Water through said duct at negligible pressure, heat-ing means arranged to heat` said nozzle and vaporize any Water emitted therefrom, and means to support the Work vadjacent to the outlet of said nozzle and in the field of vapor.'

19. In an apparatus comprising means for supplying heat and moist vapor to treat shoe materials, an elementof absorbent, refractory vmaterial having a porous surface arranged to absorb heat and vapor supplied by said means, said element also having a.;

cowl portion to enclose the work andL to diffuse heat and e-Xude vaporto the Work,

20. Vln an apparatus.comprising means for supplying heat and moist vapor to treat shoe materials, an element of absorbent, refractory material having a porous `surface arranged to absorb heat and vapor supplied by saidmeans, a porous surface to diffuse heat and eXude vapor to the. Work, and a non-porous surface to localize the exudation of vapor at the latter said porous surface.

21. In an apparatus comprising means for supplying heat and moist vapor to treat shoe materials, an element of absorbent re fractory material having' a porous surface arranged to absorb heat and vapor supplied by said means, said element also having a coivl portion to enclose the Work and to diffuse heat and exude vapor to the Work, the external surface of said cowlI portion being non-porous. i

22. In an apparatus comprising means for supplying heat and moistvapor to treat shoe materials, an element of absorbent earthen- Ware having` a portion arranged tov absorb heat and vapor from said means, and a poi'- tion to enclose the Work and to eXude vvapor thereto. p

23. In an apparatus comprising means for supplying heat and moist vapor to treat shoe materials, an'element of absorbent earthen- Ware having a portion arranged to absorb heat and vapor from said means, and a poi.'- tioii to enclose the Work and to eXude vapor thereto,the exterior surface 'of the latter said portion being glazed.'

24. In an apparatus comprising means .for

materials, a hollow element of absorbent, refiac-tory'material having a `porous surface arranged to absorb heat and vapor supplied by said means, and a porous internal surface to diffuse heat and exude vapor to treat the Work enveloped thereby. s.,

25. In lan apparatus comprising means for .illO

, supplying heat and moist vapor to treat-shoe supplying heat and moist vapor to treat shoe materials, a hollow element of absorbent, re fractory material having a chamber to receive the vapor, a work-receiving chamber, and a partition separating said chambers, the internal surface forming the first said chamber being porous to absorb vapor and the internal surface forming said workreceiving chamber being porous to exude vapor to the work enveloped thereby.

26. In an apparatus comprising means for supplying heat and moist vapor to treat shoe materials, a. hollow element of absorbent, refractory material having a chamber to receive the vapor, a work-receiving chamber, and a partition separating said.l chambers, the internal surface forming the first said chamber being porous to absorb vapor and the internal surface forming said workreceiving chamber being porous to eXude vapor to the work enveloped thereby, the eX- ternal surface of said element being nonporous.

27. In an apparatus comprising means for supplying heat and moist vapor to treat shoe materials, a hollowr element of absorbent, refractory material having a chamber to receive the vapor, a work-receiving chamber, and a partition separating said chambers, the internal surface forming the first said chamber being porous to absorb vapor and the internal surface forming said workreceiving chamber being porous to eXude vapor to the work enveloped thereby, said element having one or more vpassageways through which vapor ma7 flow from the first said chamber to said work-receiving chamber.

28. In an apparatus for treating shoe materials, comprising a metallic receptacle, means for supplying water thereto, and heating means arranged to vaporize the water so supplied, an element of refractory, absorbent material arranged to absorb heat and vapor generated by said heating means, said absorbent element having a cowl portion forming a work-receiving chamber.

29. In an apparatus for treating shoe ma terials, comprising heat-radiating .means, and means to supply water thereto to be vaporized, an element of refractory, absorbcnt material arranged to be supported by said heat-radiating means, said element forming a work-receiving chamber and having a poro-us surface arranged to absorb vapor and a porous surface to exude vapor to treat the work.

30. In an apparatus comprising means for supplying heat and moist vapor to treat shoe materials, an element of refractory, absorbent material arranged to be heated by said means and toabsorb vapor, said element having a portion formed to overhang the work, and the work-confronting surface of said overhanging portion being po-rous to exude vapor to treat the work.

31.111 an apparatus comprising heat? radiating means and regulatable means yto supply water at a constant but variable rate to said heat-radiating means to be vaporized thereby, an absorbent, refractory element ar- 'anged to be heated by the first said means and to absorb vapor generated thereby, said element having a cowl portion forming va work-receiving chamber the internal surface of which is porous to exude vapor to the work.

32. A treating device consisting of a housing of absorbent, refractory material having a work-receiving chamber, the internal surface forming said chamber being porous to exude vapor.

33. A treating device consisting of a h0using of absorbent, refractory material having a work-receiving chamber, the internal surface forming said chamber being porous to eXude vapor and the external surface being nonporous.

34. A treating device consisting of a housing of ab-sorbent, refractory material having a work-receiving chamber and a chamber to receive heat and moist vapor.

35. A treating device consisting of a housing of absorbent, refractory material. forming a work-receiving chamber and a chamber to receive heat and moist vapor, the surface forming the latter said chamber being porous to absorb heat and vapor, and the surface forming the first said chamber being porous to eXude vapor and diffuse heat tothe Work.

36. A treating device consisting cf a hollow element of earthenware forming a workreceiving chamber and a chamber to receive heat and vapor, the internal surfaces forming said chambers being porous and theeX- ternal surface of said element being glazed.

37. A tre-atincr device consisting of a hollow element ofp absorbent, refractory material forming two chambers, one above the other, and having a horizontal partition separating them, the internal surfaces forming said chambers being porous and the eX- ternal surface of said element having a coating of nonporous, vitreous substance.

In testimony whereof I have signed my

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