US2549593A

US2549593A - Method and apparatus for vaporizing anesthetizing liquids

Info

Publication number: US2549593A
Application number: US645783A
Authority: US
Inventors: Clyde B Gardenier
Original assignee: Thomas A Edison Inc
Current assignee: Thomas A Edison Inc
Priority date: 1946-02-06
Filing date: 1946-02-06
Publication date: 1951-04-17
Anticipated expiration: 1968-04-17

Description

C. B. GARDENIER METHOD AND APPARATUS FOR VAPORIZING ANESTHETIZING LIQUIDS Filed Feb. 6, 1946 pril 17, 1951 INV ENTOR Clyde BG-ardenel" ATTORN EY Patented Apr. 17, 1,951

METHOD AND APPARATUS FOR VAPORZIN G AN ESTHETIZIN G LIQUIDS Clyde B. Gardenier, Belleville, N. J., assigner to Thomas A. Edison, Incorporated, West Orange, N. 1.,' a corporation of New Jersey Application February c, i946,V serial No. 645,783

My invention relates particularly to a novel method of and apparatus for vaporizing ether for anaesthetic purposes, and it has for an object to provide an ether vaporizer for an anaesthetizing apparatus, which is adapted'to enable the ether to be administered 'evenly under controlled conditions at nearly room temperature.

In the anaesthetizing apparatus now commonly used, the anaesthetic is produced by bubbling air through a body of liquidrether. This air carries away theV ether as it vaporizes, but it also carries heat from the liquid ether, which is the heat of vaporization absorbed by the vapor molecules, and causes the liquid ether to become intensely c old. As the liquid ether becomes colder, it chills more and more the airstream and reduces the rateof ether vaporization, causing the anaesthetic to become progressively colder and weaker. To counteract the chilling eifect, the vessel containing the ether is sometimes placed on a hot-plate. This heating is however ineffective -to` prevent the anaesthetic from yet becoming dangerously cold, and moreover it is dangerous in that it introduces a re and explosive hazard becauseof the high" inflammability of the ether.- To compensate for the gradual weakening of the anaesthetic, it is customary to increase the rate of airflow through the liquid ether,r but this has been unsatisfactory because it tends to cause the airstream to pick up particles of raw ether-i. e unvaporized ether. When these particles come in contact with the patient they sometimes induce spasms.

Because of these disadvantages in the-method of administering ether'as an anaesthetic not'only is the patient disquieted during the anaesthesia andv the length of timeprolonged for treatingthe patient, but'invariably the patient suffers from nausea as an after-eife'ct. Also, respiratory disturbances are oftentimes induced and sometimes even pneumonia isbelieved to be caused by the improper conditionof Lthe anaesthetic.

It is an object of my invention to provide a vaporizer for anaesthetizing apparatus which overcomes the aforementioned disadvantages.

It has been shown by the use of my invention in hospitals that an anaesthesia can be produced quickly, safely and to any desired depth without disquieting the Vpatient during the administering of the anaesthetic and without causing ordinarily any after-effects such as nausea or respiratory disturbances. It has` Abeen moreover shown that approximately only one-third as much ether is4 required to produce a given depth of anaesthesia by the use of my invention as has been heretofore 10` claims. (c1. zel- 12) 2 required. This more effective use of the ether is believed to be due to the fact that the ether is administered at nearly room` temperature and in a-thoroughly vaporized state. prime benets o my invention are that the patient can be diagnosedand attended to more' skillfully and in less time, and the response of the'patient to the remedial measures taken is ordinarily retarded but little by the undergoing of the anaesthesia. Moreover, by my invention little ether is discharged into the surrounding atmosphere during the administering of vthe anaesthetic with the result that the working conditions are -more comfortable for those who attend the patient.

It is accordingly a further object of my invention to provide an improved apparatus for administering ether more electively as an anaesthetic.

Further objects and features of my invention are to provide an improved vaporizer for anaesthetizingV purposes which does not require any external source. of heator power, which is reasy to use and control, and which is dependable over long periods of service without need for servicing or replacing of parts; also, it is an object to provide such an improved vaporizer which has no invention will be apparent from'the following I description and the appended claims@ In the description `of my invention reference is had to the accompanying drawings, of which:

Figure 1 is a partially elevational and partiallyY axialsectional view of a vaporizer according to my invention;

Figure '2 is a sectional view taken substantially on the line 2-2 of Figure l;

Figure 3 is a fractionalaxial section of the upper portion of the vaporizer;

Figure 4 is abottom view ofthe air-inlet tubev for the vaporizing chamber;

Figure 5-is a bottom view of a spreader tray for distributing the ether in the vaporizing chamber;

Figure 6 is van enlarged fractional sectional view taken substantially on the line 6--6 o1' Figure 5; and l Figure 7 is a fractional section taken substantially on the line 1-1 of Figure 2. Y Y

In Figure -1 there is Showna'n improved vaporizer l0 according to my invention `which isi adapted especiaHyforuse in anaesthetizing apparatus. This vaporizer has a-'container atjthe` top for a supply I 2 of the liquid'to be vaporizedwhich is typically ether. At the right side of The resulting the vaporizer there is an air-inlet tube I3 which leads downwardly into a vaporizing chamber I4 and at the left side there is an outlet tube I5 for conducting the anaesthetic, Which is a mixture of air and ether vapor, to the patient.

The container I I has a glass side wall I6 so as to enable observation of the level of the ether supply. This is a cylindrical wall lclamped between anged base and cover elements II and I8 which are sealed thereto by gaskets I9 (Figure 3). By way of example, the clamping is .effected by a central integral stem 20 on 'the ibase .element which passes through a central aperture 2| in the cover element and iis secured to the cover by a nut 22 threaded ontov the `end portion thereof, there being a gasket 23 between the nut and cover for sealing purposes. In the cover element there is also a ller opening which is closed by a screw capA Isa.

The container II and vaporizing chamber I4 areioined mechanically rby :a `'heavy frameY 24 which .is made of -a 'heat-conductive metal, say brass. :This frame has a .circular Abase 24a and an integral opstanding .block-shaped portion -24fb (Figurev 2). The base element I'I seats on the block portion .24h and 'has a nipple 25 depending within an axial hole 26 provided in the frame. In this hole lat yapproximately :the ibase level of the frame lportion 24b there is an annular -wall 2"Ix`integral with vthe frame and having a :central opening 28 of reduced diameter, and vbelow this wall there `is an lenlarged-diameter opening 29 extending downwardly through the bottom of the frame to `the vaporizing chamber and which is graduated in diameter in 'three steps. Threaded onto "the nipple 25 is a I'cylindrical -tting 3.0 which has a reduced-diameter nipple l31 atthe bottom thereof that extends through the opening 28. Threaded on this nipple 34| against the wall 2T! is a nut 32 `for retaining the base lIII of the container II to the frame.

The Ystern 204 has an -axial holeu33 extending therethrough which communicates with the interior space of .the container I.I at the bottom of the container by way of .a sidegopening ,3.4 (Figure 3). has a restriction forming a conoidal seat 35, and extending through the length of the stem `is a needle valve S5V which cooperates with this 5seat. The hole 33 `is slightly-larger in diameter :than

v'Below 'the opening 34 the axial hole 3,3

the needie valve, but at 31 the noie .is :reduced 50 to provide a seat :for ajpacking ring 38, the hole above=this reduced portion -being suitably -en' larged to provide a suitable space for 'this ring. Seatedonthe needle Valve above the4 pack-ing ring is a washer 39 and interposed between 4'this washer and a cylindrical cap 40 that is held vby screws 4I to the cover element :I8 4is a .compresf sion :spring 42 Vwhich :urges the fneedle v,valve downwardly against :the seat `35 into :closed position. A

The cap 4U has a ineck 43 which :receives the needle valve and provides a bear-ing therefor.

This neck has a Vtransverse :slit -44 extending downwardlyfrom 4the top thereof which is engaged Vslidably by across pin 45 in the needle valve. This pin and slit cooperate- .to hold the valve. .x ed .against :rotation but to afford it 1an axial freedom of movement... Seated -rotatably on tthe rciapr40,j and journaledpn the -neck 43 thereof, is a .manual adjusting member -46 which has a .circular cam face -41 .at -the top thereof.. This cam-.facelies in sa .plane which is oblique to Y.thenaxis of the-needleyalve asindicated in Figure 1. Locked to the needle. valve by. the pin 45 is a cylindrical member 48 having a circular cam face 49 at the bottom thereof. This cam face 49 is also in a plane oblique to the axis of the needle valve and rests slidably on the cam face 41. The manual member 46 has a knurled peripheral portion so that it can be readily gripped and adjusted, and has a depending annular ange 46a provided with graduations .56 which, `with respect .to va registering mark 5I on the base of the cap 40, provde a visual indication of the adjusted positions of .the needle valve. For example, when the member .46 is in the vzero position indicated in Figure `1, the needle valve is held closed by the .spring 42, 'but .as the .member 46 is turned progressively through .a range of the inclined cam -faces '41 and -49 coact to lift the valve pro- .gressively from theseat 35 and allow the ether to escape at a faster rate from the container II.

To permit observation of the rate at which the ether is escaping from the container II, the block-shaped ff-rame portion X24h and the tting 3 0 have respective windows A5,2 and 53. The vttingis however closed by 'a -glass tube 54 therewithin which is clamped at the 'lower end lthereof against the bottom wall of the fitting and at the upper end against the nipple `25 by a :tightening of the fitting onto v.the nipple. AFor seal' ing pur-poses there are gaskets l5.5 placed atthe ends of the glass -tube 54 as yshown `in Figure.

The vaporizing :chamber I4 is lformed by a vessel 56 which engages telescopically Awith a depending circular `flange -51 on the frame `24. This vessel has Yan interior fcollar '58 .secured thereto near the top ithereof which is lclamped.

by screws 59 (Figure '2) yto the frame. Between this-col1ar and the flange .51 `there'is -a gasket 60 for sealing purposes.

The ether is conducted downwardly from the observation'chamber in the tube 54 .bya -tube :6I that is threaded ii-nter-iorly into the .nipple 3| (Figure 3). This tube 6I -has the lower (portion thereof .laredfoutwardly at :a wide angle to provide ,a baiile 62 `as is hereinafter explained. Below this baiile 62 there is a circular ,spreader tray 1'63Which is fitted Iinto the :largest-diameter portion of the stepped opening 29 aforementioned. vE-Ihis tray :has -a series of spaced .apertures -6'4 (Figure 5) vwhich are .formed prefer ably by perforating the tray gat the 'bottom -side with apointed -instrumentso as to raise a burr or `flange 65 around each aperture having a jagged top-edge 66 4as vshown .in Figure '6. When the ether drops onto the tray and rises to kthe levelof Athe .-lowermost por-tions vof these edges A6.6, it overflows through the vapertures into the vaporizing chamber. When the "vaporizer is mounted so that the Atray is `substantially yon a level lwith the .horizonte-1, about equal amounts -ofV ether 'oW through fthe -respective apertures to cause the ether .to [be distributed across lthe top of the .vaporizing chamber.

Air vfrom any suitable .source not herein necessaryfto-show is .conducted to the vaporizer bythe tube I 3 fractionally shown 4'and :thence y.by -a -nipple 61 to a cylindrical chamber -68 in the block portion r24h-of the frame. ,Tn-one -end of lthis chamber there is a .safety release valve :.69 which is adapted to prevent the air `pressure to :the vaporizerexceeding a :set `value. In the other .end yof this .chamber .there is ,fa valve 10 having -a tubu-l lar housing .'I.I that Ais press-fitted linto .the chamber. This housing `has acircumferential slot y'l2 (Figure 7 r which communicates `with a .duct 13 leading A4down from the .chamber :.68 ,through the frame. Rotatably tting .the .housing `.II and extending therethrough is a valve member 'I4 which has an annular shoulder bearing rotatably against the outer end of the housing 'Il under pressureof a nut 18 threaded on the inner end of the valve member and acting through a spring washer 11 against the inner end of the housing, This valve member has an axial opening 'I8 communicating with the chamber 68 and branching out into a series of circumferentiallyspaced.radially-extending holes 'I9 to 82 inclusive, which holesare graduated in diameter as shown in Figure 7. .On the outer end of the valve member there is a knurled knob 83 by which the valve member can be turned to bring the holes 19-82 selectively into registration with the duct I3 and control thereby the rate of airflow to the vapor- 1zer.

The duct 13 has a lower end portion of enlarged diameter (Figure 1) into which there is fitted a tube 84. This tube extends downwardly to the bottom of the vaporizing chamber I4 and terminates in a horizontal spiral th-atis closed at its inner end 85 and provided with a series of outlet openings 86 at the bottom` thereof as shown in Figure 4. v

The dispersed air from these spaced outlet openings passes upwardly through a channeled mass 8l in the vaporizing chamber, which is hereinafter described in detail, and passes out of the `vaporizing chamber through the apertures 64 of the spreader tray 63. Above the tray the air takes a circuitous path 88 defined by the baffle B2 aforementioned and a cooperating baile 89 which is concentric therewith as shown in Figure 1. This path 88 leads upwardly and radially inwardly to the uppermost part of the stepped opening 29 and then downwardly and radially outwardly above Vthe baille 89 toan outlet duct 90 in the frame 24. This bafiling is provided as a safety measure to prevent the outgoing airstream from carrying with it any particles of raw ether.

lIvhe duct 90 leads to the outgoing `tube l5 aforementioned to which it is connected by a nipple 9| that is threaded into the block-shaped portion 24bof the frame. Leading also from this outgoing duct, however, is an upwardly-extending duct 92 to which is connected a vertical tube 93 that opens at the top of the container ll. The purpose of this tube 93 is to equalizethe pressure above the ether supplywith that at the outlet of the container so that when theneedle valve 38 is opened the ether will escapeV from the vessel under the influence of gravity.

As an important feature of my invention, I select a porous material for the vmass 81 which has a high adsorptivity for the liquid to be vaporized. This is done so that a source of imme-V diate heat, a heat of adsorption, is provided to counteract the refrigerating effect produced by the ether as it vaporizes and to facilitate the vaporization of the ether. First, it may be noted that the term channeled is herein employed to mean that the mass has multitudinous interconnected channel spaces or interstices running therethrough such as may be formed in a solid integral mass or as occurs in a Vgraunlar mass of discrete particles. Preferably, materials in granular form are employed. Suitable examples of such materials are the activated porous solids such as of carbon, alumina, silica gel and clays, but carbon is preferred. VAs a typical example, the Vaporizing chamber may have 72 cubic inches of volume and may contain 14 ounces of porous granulated carbon.

The ether Vwhich drops into the vaporizing chamber contacts a vast surface area of the channeled carbon mass 81 and a portion thereof is adsorbed by this mass. Also, the ether has a large area of surface contact with the multitudinous air streams flowing upwardly through the channeled mass, which causes the ether to be readily vaporized. As portions of ythe ether are progressively adsorbed there is released av heat of adsorption in the vaporizing chamber, which is about 30 calories for each gram of ether adsorbed. This heat is immediately available for counteractn-g the heat loss caused by the heat of vaporization absorbed by the ether as it vaporizes. As beneficial results the vaporization of the ether is facilitated and the ether is delivered to the patient at a moderate temperature and with more eifective action so that less ether is required.

As a means of stabilizing further the temperature of the anaesthetic, I add a further source of immediately available heat to the vaporizer by placing the vaporizing chamber in close thermal contact with a body 94 of a crystallizable liquid having a 'temperature of crystallization at approximately room temperature, say 25 C. This .is done by providing a vessel 95 around the vaporizing chamber and filling the space between these vessels with the crystallizable liquid. This outer vessel may telescope with a dependingv annular flange 96 of the frame 24 and may have an interior collar 9? secured thereto which is clamped by screws 98 to the frame, the vessel being sealed to the frame by a gasket ring 99 placed between the collar 9'? and flange 9E. For filling purposes there is a screw plug 08 in the frame 2&1 leading to the space between the

vessels

95 and 96.

In order that there may be good heat conduction between the outside ambient and the vessel 95 as well as between the body of liquid 94 and the vaporizing chamber, the vessels 95 and 5t and the frame 24 are made of a heat-conductive 'material such as brass. Also, such material has a high heat capacity, which has a furtherY teme perature-stabilizing effect on the anaesthetic.

For exam-ple, the vessels and 56 and the frame 24 weigh typically approximately 5,000 grams and provide about 4,500 calories of sensible heat as the temperature thereof drops about 10 C.

The liquid 94 is chosen to have a high heat of crystallization and may be suitably any one or a mixtureV of the following: tertiary butyl alcohol, diphenyl methane, isoquinoline, phenyl ether, terpineol or methyl anthranilate. Considering tertiary butyl alcohol, for example, it may be noted that 1,000 gram-s of this liquid will release 21,900 calories of heat as the liquid crystallizes, The improved operation of my vaporizer over the method heretofore used may be strikingly noted by citing the results of the following tests: On vaporizing ether by the bubbling process with the use of a Sklar machine, with the air being initially at a temperature of 25 C. and passed at a rate of 10 liters per minute through 320 cc. of liquid ether initially at a temperature of 25 C., it is found that in ve minutes 82 cc. of ether are vaporized and the temperature of the anaesthetic has fallen to 6 C. below zero. In ten minutes 122 cc. of ether are vaporized and the temperature has fallen to 14 C. below zero, and in fteen minutes 147 cc. of ether are vaporized and the temperature has fallen to 17 C. below zero. Thus the anaesthetic has not only become intensely cold, so cold as to be dangerous to the patient, but the rate of vaporization has fallen off substantially, it being 82 cc., 40 cc., and 25 cc., respectively for the successive five-minute intervals,A

`By tcontrast, with :my invention `ether may be vaporized :at a :txed rate for periods Yof 4at lleast thirty :minutes or more `without any decrease :at all in the temperature of the resulting vanaes- 4thetic emitted :from the vaporizer throughout such period. `Purely lby way Aof example, it zmay lbe noted that for a given setting of the valve 13B, and ,on passing air through the vaporizer 'at a rate of liters per minute, with the air at .a temperature of 29 C., 300 icc. of ether may be vaporized Ain .flfteenmuutes and the temperature of the anaesthetic atthe end'of this period is yet 29 C. Forsmaller rates of vaporization the temperature of the anaesthetic may evenrise somewhat .during the initial part of a period `of use yof the 'vaporizen By actual use of this .vaporizer in hospitals it has been shown `that in view of this improved actioni. e., more 'thorough vaporization and stabilized temperature-the Aamountof ether required varied from 70 cc. :to .200 fcc. as against amounts of 300 cc. to 680 cc. by the bubbling method as now used. Also, 4it was found that anaesthesia was induced more quickly and smoothly, without coughing or gagging, and that the depth of the anaesthesia was more easily controlled. Also, the patient recovered more quickly from vanaesthesia without the 'usual after-effects -of .nausea and respiratory Vdisturbences.

It will be understood that the absorptive and crystallizing process Aabove described by which heat is liberated to the :anaesthetic will not go on continuously, should 'the apparatus be used without interruption over a long period, because in time the granular mass i8? would become saturated with ether and the liquid 96 would become wholly crystallized. It is found in actual use however that the vaporizer will operate continuously at near peak eiciency for at least a period of about eight hours. After such prolonged use the activated carbon seem-s dry to the ltouch but has a strong odor of ether. To free the carbon of this adsorbed ether, the air supply to the vaporizer is turned on -to circulate Vair through the vaporizing chamber at a fairly rapid rate fora short period, a period of 5 to 10 minutes being generally suiicient to recondition the carbon mass for another prolonged usage of the vaporizer. To recondition the liquid 94, heat may be added from any suitable source, If, however, the vaporizer may be let stand overnight in air at room temperature, the liquid 94 will absorb sufficient heat from the surrounding atmosphere to melt and become again a source of heat supply. It will be understood that these reconditioning operations may be repeated again and again without need for replacing the adsorbing mass 8l or the liquid S2. Because the heat is obtained without the use of any external source of intense heat, my vaporizer is utterly safe against any hazardof re or explosion. Also, my invention can be used Ain out-of-the-way places, if necessary, because it requires no source of electric power.

In practical use, the anaesthetist'predetermines the airflow rate for each patient and sets the airow through the vaporizer at that rate. Next, he meets the anaesthetic demands by adjusting the needle valve 36. Except for the ether which is adsorbed, substantially all of the ether which is released by the valve 36 is vaporized; as a result, the anaesthetist may control the degree of anaesthesia by adjusting merely the valve 3d Typically, `the valve kis rst opened sufficiently to supply the higher initial dem-ands for the -anaesthetic until the 'patient 'undergoes anaesthesia, :and then '.:the 'valve :is :closed `partially `to lsupply only enough ether -to maintain the desired `depth of anaesthesia. During the Yinitial .period when the liquid ether is fed to the porous mass Y8`i :at the :higher rate, progressive Aadsorption of the liquid occurs to provide Ya continuous supply of Ahieat'to the anaesthetic, as heat of adsorption, but'during thestand-by periods when only little or no vliquid 'ether is .fed to the porous mass 81, theair which is blown through the mixing .chamber to supply `the `oxygen demands of the patient does gradually icarry away vthe adsorbed liquid to desorb the porous mass r81. Typically, the stand-by period is sufficiently long vto cause the porous mass to be fully restored to its unsaturated condition. lThis restoration occurs without reducing .substantially the temperature of the air during the stand-.by .period since the desorption takes place gradually. Thus, in normal use, the porous mass 81 4provides a high rate of available heat during the temporary periods when the anaesthetic demands are greatest, 'to aid during those periods in thoroughly vaporizing the anaesthetizing liquid and in keeping the anaesthetic gas'at or near body temperature, and during the stand-'by periods this mass is restored to well nigh its full adsorptive capacity. As a'result, 'in the normal use o1" the apparatus no special deliberate reconditioning of the porous `mass Vis ever necessary.

While I Vhave herein particularly described an embodiment of my invention for anaesthetizing purposes with ether as an anaesthetic, it will ber understood that my invention has advantages as a vaporizer of other volatile anaesthetizng liquids and that I intend no unnecessary restric tion of my invention to the specific embodiment herein described. Also, it will be observed vthat changes and modications may be made in this embodiment without departing from the scope of my invention, which I endeavor to express according to the following claims.

I claim:

`1. In apparatus for vaporizing liquid for anaesthetic purposes, comprising a vaporizing chamber: the combination of a porous channeled mass of material in said chamber :capable of :adsorbing said liquid, means for introducing air into said chamber at a plurality of spaced points below said mass, an apertured means at the top of said chamber, means for dropping liquid onto said apertured means, said liquid passing through said apertured means under the inuence `of gravity and falling onto said mass at distributed points, and an outlet for conducting the air and vaporized liquid from said chamber, said outlet being 'in vcommunication with said chamber by way of said apertured means.

2. The method of producing an anaesthetizing gas at Imoderate temperature for a given period of time, which comprises feeding a volatile anaesthetizing 4liquid gradually to a massief porous material capable of adsorb'ing said liquid and producing a yheat of adsorption, and passing a stream of air through said porous mass to carry on vapor of said liquid at a lesser rate than that at which the liquid is lied thereto, whereby there is a progressive increase of adsorbed liquid in said material during said period, and also to carry oil the heat of adsorption, said porous material being of a suicient quantitythat it remains in subsaturated condition throughout said period.

3. In the operation of an anaesthetizing machine: the steps comprising gradually feeding a volatile anaesthetizing liquid to a porous mass of a material capable of adsorbing the liquid and producing a heat oi adsorption, simultaneously passing air through said mass to carry orf vapor of said liquid at a lesser rate than that at which the liquid is fed thereto and to carry ofi also said heat of adsorption to provide an anaesthetizing gas at moderate temperatures, and then reconditioning said porous mass for further adsorption of said liquid, only by blowing air through the mass.

4. In the administration of an anaesthetic: the method comprising feeding a volatile anaesthetizing liquid to a porous mass ci a rnaterial capable of adsorbing said liquid and producing a heat of adsorption, simultaneously passing a stream of air through said mass to carry off vapor of said liquid and said heat of adsorption to produce an anaesthetizing gas at moderate temperature, said porous mass b.ing of suflicient quantity that the same remains in a subsaturated condition during the period of administration of the anaesthetic, and conducting said anaesthetizing gas fromsaid porous mass through a circuitous path having free drainage to the porous mass.

5. An anaesthetizer adapted for producingr an anaesthetizing gas at moderate temperature at least throughout a normal period required to eieot an anaesthesia, comprising a container for a volatile anaesthetizing liquid; a chamber containing a porous mass of a material capable i' adsorbing said liquid and producing a heat of adsorption; means for feeding liquid from said container to said porous mass at a rate in excess of that at which the liquid is adsorbed by said porous mass to provide a normal supply of vapor of said liquid for anaesthetizing a patient; and means for passing air through said mass to carry oilE said vapor and heat of adsorption to provide an anaesthetizing gas for a patient at a normal rate, the quantity and porosity of said mass of adsorptive material being such that upon supplying said liquid and air thereto at said rates the material remains in a subsaturated condition during said period of use and the temperature of the anaesthetizing gas is held substantially constant during said period.

6. An anaesthetizer for producing an anaesthetizing gas at moderate temperature comprising a container for a volatile anaesthetizing liquid, a vaporizing chamber containing a granulated porous material capable of adsorbing said liquid and producing a heat of adsorption, a tray at the top of said chamber having apertures in the outer portion thereof, a tube leading from ber immediatelyv surrounding said vaporizing chamber and containing a crystallizable liquid which crystallizes substantially at room temperature to provide a heat of solidifioation to said vaporizing chamber as the temperature in the latter tends to fall below room temperature.

7. In the method of producing an anaesthetizing gas: the steps comprising gradually feeding a volatile anaesthetizing liquid to a porous material capable of adsorbing the liquid and producing a heat of adsorption, simultaneously passing a stream oi' air through said porous material to carry off vapor ci said liquid at a lesser rate than that at which the liquid is fed to said porous material and also to carry oil? heat of adsorption, and then. further passing air through said porous material suficiently to gradually desorb the same.

8. The method of producing an anaesthetic gas at moderate temperature which comprises Volatilizing an anaesthetizing liquid and simultaneously producing heat in intim-ate thermal relation with the gas so produced by gradually feeding said anaesthetizing liquid to a material having a high adsorptive aflinity for said liquid and being in an adsorptively unsaturated condition whereby a portion of the liquid so fed to said material is adsorbed to produce a heat of adsorption and passing air across said material to carry on" said heat of adsorption and Volatile gases of another portion of the liquid so fed to said material.

9. An anaesthetizing device comprising a vaporizing chamber, means for blowing a stream of air into said chamber, means for feeding a Volatile anaesthetizing liquid into the air stream within said chamber, and means in the air stream within said chamber responsive immediately to contact of said liquid therewith for producing heat in immediate transfer relation with said air stream.

10. An anaesthetizing device comprising a yaporizing chamber, means for blowing a stream of air through said chamber, means for feeding a volatile anaesthetizing liquid into said chamber including means for distributing liquid through said air stream, and a porous mass within said chamber and responsive to Contact of said liquid therewith for producing an immediate heat in said chamber throughout said air stream.

CLYDE B. GARDENIER.

REFERENCES CITED The following references are of record 'in the ile of this patent:

UNITED STATES PATENTS King Dec. 27, 1938