fig1 depicts in cross section an embodiment of a convection - driven dispenser according to this invention . the embodiment depicted in fig1 includes an air - activated heater , an iron oxide heater . dispenser 1 includes inner container 2 , a closed container having bottom ports 3 and top ports 4 , all of which are holes . in operation air enters bottom ports 3 and exits top ports 4 . as shown , the ports are vertically oriented , but they alternatively could be horizontally oriented at the bottom and top of the container sides , respectively . inner container 2 contains porous paper or plastic packs 5 , each containing heat - reaction ingredients capable of undergoing an exothermic chemical reaction . packs 5 confine the solid reactants . as stated earlier , we sometimes refer to the confined reaction zone as the “ heater .” packs 5 in this embodiment define an air passageway extending vertically through the center of the heater from bottom ports 3 to top ports 4 . placed between packs 5 , proximate the tops of the packs and projecting above the packs in the air passageway are solid volatile compounds , liquid volatile compounds held in a porous matrix . the volatile compounds are item 6 . surrounding inner container 2 is insulating outer container 7 , having holes 10 aligning with ports 3 and having holes 11 aligning with ports 4 . attached to the top of package 7 is an eyelet 8 suitable for attaching a hook , chain or string for suspending dispenser 1 upright , for example , from the neck of a person . outer container 7 is integral with inner container 2 and is optional , as a single container could provide all functions , with an insulation surround if needed . shipping and display package 9 is an air - tight package , such as a sealed plastic bag or bubble pack . package 9 prevents air from entering container 2 and activating the heater . alternatively , seals could be place over the top and bottom air ports . mechanical activation of the exothermic reaction in this case comprises compromising the package or seals , as the case may be . to use the dispensing system , a user removes shipping and display package 9 and disposes dispenser 1 in a vertical attitude . air enters the air passageway of inner container 2 through ports 3 , 10 and 4 , 11 . in the case of the iron oxidation system , air entering the passageway contacts the reactants in packs 5 initiating an exothermic reaction . a vertical convection current results . hot air rises , and the exothermic reaction causes air to be drawn into the heater through ports 3 , 10 , to pass upwardly in the air passageway through and around packs 5 , where it is heated , and past volatile components 6 , which are caused to evaporate , and then out of dispenser 1 through top ports 4 , 11 . volatile compound or compounds 6 are heated due to the exothermic reaction in packs 5 . the shape of dispenser 1 is not critical . it could , for example , be circular , oval or rectangular in horizontal cross section . the number , pattern and size or sizes of ports 3 , 10 and ports 4 , 11 are adjusted to achieve the desired air flow for a particular application . packs 5 contain particulate solids comprising or containing ingredients for the heating reaction . reactants could as well be added as loose particles and kept in place by placing a fine screen atop them . eyelet 8 could be replaced with a hook for hanging the dispensing system , or one portion of a hooks - and - loops fabric fastener commonly known as velcro ® ( velcro usa , inc ., manchester , n . h ., u . s . a .) or magnet or releasable glue patch or other means suitable for attaching the dispensing system to a vertical surface . alternatively or in addition , outer package 7 could include a base ( see fig2 ) for standing the dispensing system upright on a horizontal surface such as , for example , a table top . fig2 shows in cross section a dispenser 21 comprising a decorative outer container 25 suitable for refilling with new inner containers . inner container 22 is similar to inner container 2 ( fig1 ) except that it is removably inserted into the outer packaging . it includes bottom openings , ports 23 , and top openings , ports 24 for air flow . it contains porous packs 5 and volatile compounds 6 as described above . inner container 22 and its contents are supplied in an air - tight package , not shown ( see fig1 ), and the exothermic reaction is mechanically activated by removing the airtight package , at which time inner container 22 is placed in the outer container . insulated outer container 25 has a removable top 27 . top 27 could as well be a hinged openable top . container 25 includes a base with openings for air , circumferential holes 26 . top 27 includes openings for air , a pattern of holes 28 . because there is a space between holes 26 and ports 23 , alignment is not required . similarly , because there is space between holes 28 and ports 24 , alignment is not required . it will be appreciated that insulated outer container 25 could as well be adapted for hanging or attachment to a vertical surface . in another embodiment , reusable outer container 25 could contain supports allowing packs 5 and volatile material carrier 6 to be inserted individually . these disposable components would be packaged in sealed airtight bags from which they would be removed for activation and dispensing . fig3 shows an alternate construction providing a different type of mechanical activation that is suitable for use with air - activated heaters and for use with non - air - activated heaters , for example , oxidizer comprising solid inert pellets containing potassium permanganate particles and fuel comprising aqueous glycerin , or , alternatively , solid calcium oxide and water . for exothermic reactions utilizing a liquid reactant , such as the two last mentioned , we prefer that dispensing air not flow through the reaction zone so as to preclude leakage of liquid from the dispenser . fig3 shows a dispenser 30 , an insulated single - container dispenser with multiple chambers . a central cylindrical chamber containing volatile compounds 32 , shown as a porous bag of mothball particles , is the air passageway . the air passageway is defined by inner cylindrical wall 33 , inner bottom 34 , and top 35 . inner bottom 34 and top 35 are provided with inlet ports 36 and outlet ports 37 , respectively . fig3 also shows an alternate construction for a user - openable air passageway . bottom 34 and top 35 are provided with peel - off covers 38 and 40 , respectively , that block inlet ports 36 and outlet ports 37 prior to use and prevent evaporated volatile compound from exiting the dispenser through outlet ports 37 . covers 38 , 40 could be replaced , of course , by an airtight container such as container 9 shown in fig1 . cylindrical wall 33 is heat - conducting , for example , metal . dispenser 30 includes an annular heater surrounding the central chamber . the annular heater includes two vertically separated chambers , upper annular chamber 41 filled with liquid reactant ( not shown ) and lower annular chamber 42 containing solid reactant 43 . upper chamber 41 is defined by hollow ring 44 . lower annular chamber 42 is defined by inner cylindrical wall 33 , outer cylindrical wall 46 , annular top 47 , and bottom 34 . rotatable annular ring 44 is rotatably attached to top 35 and slidingly engaged with inner cylindrical wall 33 . lower annular chamber 42 and rotatable hollow ring 44 are in sliding relationship . fixed top 47 of lower annular chamber 42 is provided with inlet holes 48 , and rotatable hollow ring 44 is provided with holes 49 , which can be rotated into and out of alignment with holes 48 by turning rotatable ring 44 so as to enable or prevent the flow of liquid reactant into bottom chamber 42 , respectively . outer cylindrical wall 46 is insulative to protect users and reduce heat loss . if wall 46 is not sufficiently insulating from its composition and thickness , outer insulating cylinder 50 , for example a polystyrene foam sleeve , may be provided mechanical activation of the heater comprises rotating ring 44 to align holes 48 , 49 , thereby compromising the separation of chambers 41 , 42 and permitting liquid fuel to contact the oxidizer , in this case solid oxidizer 43 . cover patches 38 and 40 are removed , thereby completing the opening of the passageway for convective airflow . as an alternative to cover patches 38 and 40 dispenser 30 could be provided in an air - tight package , in which case opening the package would remove the blockage provided by the package and open the air passageway to inflow and discharge . in special cases in which the material to be dispensed has a very low evaporative rate at room temperature , ports 36 , 37 may not be blocked . air is permitted to enter the inner chamber and contact porous bag 32 of volatile compound . liquid reactant from chamber 41 flows by gravity into chamber 42 where it contacts solid reactant 43 and initiates an exothermic reaction . heat from the reaction increases the temperature of air in the inner chamber , the air passageway , thereby inducing convective flow of air into inlet ports 36 , around and through porous bag 32 , and out discharge ports 37 . the construction of dispenser 30 could be reversed , with heater chambers 41 , 42 on the inside and the volatile product 32 in an outer annular air passageway chamber . such a construction would have the advantage that the exothermic reaction would be on the inside of cylindrical wall 33 , and outer walls 44 , 46 would not need to be as insulative . central reactant chambers 41 , 42 could be separated by rotatable top and bottom walls with alignable holes , similarly to the design shown in fig3 . alternatively , a central upper chamber could be a liquid - filled balloon placed above solid reactant 43 , in which case mechanical activation would be compromising the balloon wall separator , as by releasing a spring loaded dart by engaging a trigger located on top 35 or bottom 34 . fig3 illustrates a construction technique that can also be applied to a user - openable air passageway , namely , slidingly engaged rotatable elements with alignable holes . for example , if the construction of dispenser 30 were reversed as described above , with a central heater and an annular air passageway , lower chamber 42 could hold volatile compounds 32 , and hollow ring 44 could be open - topped or top vented . holes 48 would be the air passageway outlet ports , openable by rotating holes 49 into alignment with holes 48 . the same approach could be employed for use with a central air passageway , as follows : if the top of hollow ring 44 were made circular rather than annular , the central portion could overlie and slidingly engage top 35 and be provided with holes that align with outlet ports 37 when holes 49 are rotated into alignment with holes 49 to initiate the exothermic reaction . analogous constructions could be used for annular or central air passageway air inlet ports to utilize rotation to align holes and open air inlet ports . rotatingly openable air inlet ports , air outlet ports , or both are alternatives to removable cover patches or openable airtight shipping and display packages . as will be appreciated , construction of dispenser 1 ( fig1 ) could similarly be reversed with heater ingredients in the middle and surrounded by volatile compound 6 . if a rotatable lower cover with alignable holes were used in an air - activated dispenser , rotation of the lower cover would simultaneously open the air passageway inlet ports and remove the separation between reactants , that is , initiate the exothermic reaction . construction of other activation mechanisms is within the skill of the art . the following examples illustrate heating and dispensing volatile compounds in a solid form and liquid form . a porous pack containing 22 g of a mixture of iron powder , carbon powder , water , non - reactive particulate absorbent ( vermiculite ), and sodium chloride , according to u . s . pat . no . 3 , 976 , 049 was placed inside a vertically disposed cardboard tube 10 cm tall having a cross section of 6 . 4 cm wide by 2 . 5 cm deep . the top and bottom were open . the contents of the pack began to react with o 2 in the atmosphere and become heated . thermocouples were placed at the top and bottom openings , and inside the center of the tube , near the heat pack . after 15 minutes of operation the tube adjacent the porous pack , that is , in the heating zone or in the heater , was heated to 38 ° c . it continued rising to 45 ° c . after 400 minutes , when data recording was stopped . the inlet air at the bottom opening was at 23 ° c . exit air at the top increased to 25 ° c . over 1 hour . after 1 hour of operation the top and bottom openings were partially covered to reduce them to 1 . 3 cm by 2 . 5 cm . the exiting air temperature increased immediately to 34 ° c . this slowly declined to 30 ° c . at about 120 minutes , where it stayed until about 260 minutes , when the inlet air temperature dropped to 21 ° c . and the outlet air temperature correspondingly dropped to 28 ° c ., where it remained . data recording was stopped after 400 minutes , at which time the temperature in the heating zone was still 45 ° c . the prototype dispenser could operate for longer than 400 minutes . a second vaporizing dispenser was made with the same amount of heater ingredients divided into four porous packs . these were stacked and wrapped with foam to make a heating chamber 7 . 6 cm tall by 3 . 8 cm wide by 0 . 6 cm deep . the thermocouple was placed between the two middle porous packs . this simulated a dispensing system wherein the inner container 2 ( fig1 ) and the outer container 7 ( fig1 ) are combined into a single insulated container . this vaporizer heated rapidly to 57 ° c . and then slowly to 60 ° c . at 90 minutes , after which it began to drop , reaching 50 ° c . at 240 minutes . the temperature at the top of the tube spiked quickly to 52 ° c ., dropped to 35 ° c . at 30 minutes , and then slowly descended to room temperature at about 250 minutes . a 0 . 36 g piece of filter paper was wetted with 0 . 46 g of a volatile compound , a scented oil removed from a commercial electrically heated dispenser . it was hung from a balance beam of a scale in a 21 ° c . room . the weight was recorded at intervals . the weight was divided by the initial weight of the oil to give the % remaining weight . this is shown as curve 41 in fig4 . two porous packs containing 22 g of the mixture of iron powder , carbon powder , water , absorbent particulate , and salt described in example 1 were placed inside a plastic box 11 cm tall with a cross section of 7 cm by 4 cm . the contents of the packs began to react with o 2 in the atmosphere and became heated . the box had four holes in the top and eight holes around the bottom , all of 6 mm diameter . a 0 . 34 g filter paper wetted with 0 . 46 g of the commercial scented oil described in example 3 was hung inside the center of the box , between the two heat packs . the filter paper was removed from the heater and the weight was recorded at intervals . the weight was divided by the initial weight of the oil to give the % remaining weight . this is shown as curve 42 in fig4 . a thermocouple was placed inside the box against the filter paper . the recorded temperature varied between 43 ° c . and 58 ° c ., depending on exactly where the thermocouple was placed after each removal of the paper for weighing . fig4 shows that at room temperature 26 % of the oil had evaporated after two hours in example 3 , while 83 % of the oil had evaporated in the prototype dispenser during the same time in example 4 . this shows an approximate tripling of the evaporation rate by use of the invention . as the rate of evaporation may be adjusted by changing the temperature , any desired evaporation rate may be achieved by changing the design of the heater : adding insulation or more heating material to raise the temperature , or reducing insulation or heating material to lower the temperature or adjusting the port size of the intake and / or exit . a 2 . 81 g naphthalene ( melting point approximately 80 ° c .) moth ball was hung on a balance in a 21 ° c . room . the weight was recorded at intervals . the weight was divided by the initial weight of the moth ball to give the % remaining weight . this is shown as curve 51 in fig5 . two porous packs containing 22 g of the mixture of iron powder , carbon powder , water , particulate absorbent , and salt described in example 1 were placed inside a plastic box 11 cm tall with a cross section of 7 cm by 4 cm . the contents of the pack began to react with o 2 in the atmosphere and became heated . the box had four holes in the top and eight holes around the bottom , all of 6 mm diameter . a 2 . 78 - g naphthalene moth ball was hung inside the center of the box , between the two heat packs . the moth ball was removed from the heater and the weight was recorded at intervals . the weight was divided by the initial weight of the moth ball to give the % remaining weight . this is shown as curve 52 in fig5 . a thermocouple was placed inside the box against the moth ball . the recorded temperature varied between 43 ° c . and 54 ° c ., depending on exactly where the thermocouple was placed after each removal of the moth ball . fig5 shows that at room temperature 2 . 1 % of the moth ball had evaporated after 4½ hours in example 5 , while 9 . 4 % of the moth ball had evaporated in the heater during the same time in example 6 . this shows an approximate quadrupling of the evaporation rate by use of the invention . a number of embodiments of the invention have been described . nevertheless , it will be understood that various modifications may be made without departing from the spirit and scope of the invention described in the following claims
a vaporizing dispenser comprising a user - activatable chemical reaction heat source and a volatile compound inside a container such that convection currents from the activated heat source volatilize the volatile compound and carry it out of the container .