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ya»; 29, 1938. 2,112,242 B. KRAMER ET AL. PROCESS FOR ACTIVATING PROVITAMINS Filed March 19, 1936 VARIABLE 9-1 VOLTAGE sou RCE / 3 CURRENT 33 32 50o’ '19s’:v CYCLES PER SECONU I000 INVENTCRS BENJAMIN KEAMEE ' ALEEWA'SOEKL SAMUEL NATEZLSO/V m ATTORNEY g .1 “ Patented Mar. 29, 1938 . ‘ g . UNITED STATES PATENT OFFICE I PROCESS Fort ACTIVATING 'PiiovITAMINs, Benjamin Kramer, Samuel Natelson, and'Albei-t‘ ‘ E° Sobel, Brooklyn, N. Y. I - Application March 19, 1936, Serial No. 69,736 9Ciaims. (01104-31) ' This invention relates to antirachitic vitamins \ antirachitic vitamin yield will be materially di and, more particularly, relates to novel apparatus for and methods of converting provitamins into 'minished. On the other hand, improper applica- , ,tion of too high a potential for that frequency antirachitic vitamins. » etc. may result. in a. spark discharge .which will ‘ Heretofore, several methods have been proposed and used to antirachitically. activate foods and sterols having no antirachitic potency. The most destroy» the provita'mins. Application of fre- 5 quencies below or above the critical range also reduces the ‘e?iciency of antirachitic conversion of \ Y widely accepted process for antirachitically' acti- the provitamins. vating substances comprises exposure to a source w . , ‘ ‘\ We have found that the most economical pro 10 of ultra-violetJlight.’ Commercial production by such a process‘ requires an expensive investment in materials, particularly quartz. A quartz duction of substances containing antirachitic vita- 10 mins is to activate ergosterol ‘or crudev cholesterol and subsequently introduce a small percentage of mercury arc lamp is used to generate ultra-violet rays which are directed upon the substance in a 15 solid state or, more generally, in a suitable liquid the activated sterols to foods and medicines, for example yeast, olive oil, milk, cod liver oil and the‘ ' I like. \The ergosterol or crude cholesterol is ap- 15 plied between the electrodes of the apparatus ac cording to our present invention, preferably in- a solid,loosely powdered state. In‘a‘nother form of our invention, the sterols or provitamin is dis ' solved in a suitablesolvent as, for example, ether 00 solution contained in quartz ?asks or the like. . Production of ultra-violet light by sources other than a mercury arc lamp, such as the glow dis‘ charge, open arc discharges or thecorona dison charge are relatively inefficient. Exposure of provitamins to open are or corona discharges results in the destruction of the vitamin almost as rapidly. as it is formed.v The other‘ proposed" methods for antirachitically activating :provitamins are of ‘ 2;, mere laboratory. signi?cance on account of the i very low e?icienoies of conversion together with the expensive apparatus and the skilled manipulation required. These methods include: cxposure of the material .to Xrays; bombardment 30 ‘of the material by electrons in ajcathode ray tube‘; subjection of the material to a high frequency alternating current greater than a thousand cycles. . and introduced between the discharge electrodes “ in a fine spray; a ‘ i . We_have found that the process according to our presentinvention also, has a sterilizing effect uponthefoodsor Substances subjected to it in that 2;, bacteria, PrOtOZOa'aIId other micro-Organisms are‘ destroyed. Foods which possess antirachitic properties in a greater 01‘ less degree. such as milk, olive oil, yeast, cod liver oil and the like, may be directly activated‘ by the brushdischarge ap- 30 paratus of our present invention. yAccordingly, an object of our invention is to provide novel methods of converting provitamins We have discovered a simple, inexpensive and‘ into antiratchitic vitamins. . 3;; very ef?cient method of'antiratchitically activat- . Another object of our invention is to convert 35 ing provitamins by an electric discharge- By an provitamins into antirachitic vitamins by a brush extended investigation of the action of the-difdischarge, ‘ ferent types of electrical discharges through gases uponprovitamins, We have" discovered that by 4o carefully Controlling the Various parameters. a critical condition exists whereby the conversion of ‘ provitamins to antiratchitic vitaminsis extremely ‘ favorable. The Critical electri?al discharge, generally referred to as the brush discharge, performs 45 the efficient, antiratchitic conversion. We ‘have found that for a partlcular physlcal apparatus’ a most favorable voltageexists, dependent upon the ‘A further object of our invention is to provide simple, inexpensive and ef?cient apparatus for and methods of converting provitamins such as sterols into antirachitjc vitamins‘ ‘ _ 0 still a further Object of our invention is to pro_ vide novel apparatus for andmethods of steriliz mg food Substances_ . ‘ These and other objects of Our'invention Wm 45 be evident in the following description in conne‘ci “on with the drawin in which . . hg' . . ‘ . spacing of the electrodes between which the ma terial is placed and thata most suitable frequency , 13”‘? 1 is 3‘ Sc emanc dlagram usedtm the so of application of the alternating current exists of descnptlon of elem-1? discharge phenomena‘ 50 the order of 250-350 cycles. As will be explained in ‘more detail hereinafter, a voltage below the . critical ‘for a particular frequency, area and spacing of the plates and dielectric will produce a glow 5r, discharge instead of a brush discharge and the ‘through gases‘ ’ - ' Figure 2 is a qualitative graphical representa tion of the Several gaseous electric discharge phenomena. Figure 3 is a modi?cation of Figure'l. 55 ‘1 2,112,242 Figure 4 is a partial perspective illustration of a preferred embodiment of our present invention. Figure 5 is a qualitiative curve representing the e?iciency of conversion ‘of provitamins to anti rachitic vitamins withwrespect to the frequency of the applied alternating current potential. When a voltage is applied between two spaced conductors having a gaseous atmosphere between, a number of distinct types ‘of electrical discharges 10 may take place between the plates through the gas dependent upon the nature and magnitude of the potential applied to these plates. A variety of phenomena accompanies gaseous electrical dis charges including luminous, thermal, magnetic, 15 mechanical and chemical effects in varying de - by a voltage gradient which corresponds to sub stantially the maximum voltage which can be supported between the electrodes bounding the region, other conditions remaining the same. We further distinguish the “brush discharge” as the electrical discharge occurring after the glow dis charge, on increasing the voltage, and corre sponds to the region characterized by the curve portion 20 of Figure 2. The brush discharge cor responds in Figure 2 to the discharge produced in the vicinity of the peak voltage ea. Other con ditions which aifect the particular “brush dis charge voltage” for carrying out our process are the frequency of the applied voltage, the spacing of the bounding electrodes, the character of di grees. In accordance with our present invention‘, the chemical action of the electrical discharge is electric material used and the gaseous condition utilized and the conditions of operation are ad within the discharge region. of the other physical actions. This type of elec The brush discharge is maintained‘ by careful adjustment of the voltage for a given structure. Increasing the electrical energy or current supply to the electrodes causes the production of the ' trical discharge is known as the brush discharge. spark discharge represented by region 1|. Region In order to clearly set forth the critical param eters for optimum antirachitic conversion ‘of the 25 materials, the following discussion as to the 22 represents the electric ?ame which results from further increasing the current supply. Curve 23 justed so as to produce the type of discharge hav 20 ing a maximum chemical action and a minimum several types of electrical discharge is presented. Referring to Figure 1, two metallic plates l0 and represents the negative voltage-current charac- : teristic of the high tension arc and region 24 represents the low tension are as is well known by II are spaced from each other by a ?xed amount, for example, one centimeter. The space I! be 30 tween electrodes lil and II contains a gaseous those skilled in the art. It is to be understood that the graph plotted in Figure 2 is merely a qualitative representation of the several types of electrical discharge phenomena and that the ac atmosphere for example ordinary air at atmos pheric pressure. A variable high potential or tual voltage and current depend upon the type, voltage source I3 is connected to plates l0 and Ii surface area and shape of the oppositely disposed by corresponding conductors I4 and it. electrodes, the spacing between said electrodes, An ammeter “5 may be inserted in series with the type of gas and its temperature and pressure 35 as contained between the electrodes. ‘The type conductor ii for observation of the current ?ow ing during an electrical discharge between plates of voltage which produces the electrical discharge characteristics represented in Figure 2 may be an in and ii. Figure 2 is a graph representing the variation in » interrupted direct current or an alternating cur rent voltage. The frequency of the interruptions 40 the current of the discharge as indicated on am meter l6 as plotted with respect to the variable or alternations of the voltage source should be voltage applied between"-electrodes HI and II ‘ ‘Y with a ?xed spacing. At low voltages, for example below one‘ thousand volts, practically no current As the voltage between the plates i0 and II is slowly increased, 45 will ?ow between the electrodes. minute current will ilow between them as repre sented by curve ii. The discharge I1 is charac teristically non-luminous or invisible and is ac companied by negligible chemical or other physi cal e?ects. At a certain region I! which is defi nite for given conditions of temperature, pressure and electrode spacing the glow discharge begins which represents a discontinuity in the graph. Curve l9 represents the voltage-current relation relatively low, for example, below a thousand cycles, otherwise diiferent electrical actions will occur. Asthe frequency of the voltage source is increased, ‘the peak voltage supported, corre- , sponding to so of Figure 2, will be ‘lowered. An increase in frequency will increase the current ?ow between the electrodes Ill-II due to a ca pacitative or reactive current ?ow due to the func tion of the plates |I|—_ll as an electrical con denser. The phenomena of the electrical discharge be comes more complicated than the relatively sim ple representation of Figure 2 when dielectric ma terial is interposed between the electrodes ill-4 I. . Referring to Figure 3, a glass plate 25 is placed adjacent to the inner surface of electrode ill and another glass plate 26 at the inner surface of of the glow discharge. The voltage may be in creased to a very high value and the glow dis charge will still be maintained and the current plate ii. A variable high potential alternating will correspondingly increase. The glow dis 60 charge is accompanied by a characteristic lumi current source 21 is applied to the conductors 60 i4--II. If the generator 21 is operated at two nosity which includes ultra-violet light. As the voltage is further increased, it will reach hundred cycles and the voltage applied to the a peak value 80 which is practically the\maximum electrodes Ill and II is increased until the brush voltage which the electrodes i0--Il can‘ support v‘discharge corresponding to curve 20 in Figure 2 65 for a particular gaseous atmosphere and spacing. “ occurs, it will be found that the brush discharge 65 The glow discharge disappears at the 'region 20 will occur when the electrodes l0 and I l arecloser and the characteristic brush discharge occurs. together than the corresponding case where no The brush discharge has sometimes also been dielectric plates 25-26 are used. If the plates l0 called the silent discharge or the dark discharge. and i l of Figure 3 are separated a distance equal to that described in connection with Figure 1, 0 70 These terms are misnomers since the brush dis charge is neither silent nor dark for it is attended namely one centimeter, then the maximum vol tage corresponding to an of Figure'2 will be greater by a peculiar sound and by some light. at the brush discharge. The higher voltage is By the term “brush discharge” as used herein after in the speci?cation and claims, we refer to due to the presence of the dielectric material, 75 the electrical discharge produced across a region namely the glass plates 25—26 interposed be 75 3 2,112,242 tween the electrodes i0 and II which act to re duce the. potential gradient through the atmos within the actual brush discharge for antiarchit I icl conversion. _ Experiments'have shown that if phere as is well known in the art. However, ‘it is evident that a brush discharge may be produced between two electrodes as long as ,a gaseous at mosphere exists between them,‘ and that it is theprovitamin ‘substance 35 be placed at‘ the outer ‘regions of‘ the annular space, namely the regions 36 and 3'! immediately outside of the di rect . electrostatic‘ ?eld; negligible antirachitic difficult to‘ express the value of the voltage to be vitamin conversion] results, demonstrating ab applied for all conditions. If the frequency of generator 21 is increased, the maximum voltage sence of" ultra violet light conversion. . An important feature‘ of our present invention ‘ ‘The critical spacing of the electrodes ‘maybe resides in the “use .of a critical frequency for the‘ most‘ e?icient antirachitic conversion of the pro vitamin substance‘; We" have ~discovered that for supply as follows: The electrodes l0 and II, with sterols, the optimum frequency range of conver which a given discharge structure can support will be lessened.» _ determined foraparticular voltage and frequency most _, provitamin substances,‘ particularly the s the dielectric materials 25 and 26 in place (Fig. 3) if required, are connected to the supply and are ognizable spark discharge begins. The electrodes below 250 cycles, as vwell as for frequencies above 350‘ cycles. Figure 5 is a qualitative curve rep are then slowly moved apart until the spark dis charge just disappears. The brush discharge will vitamin substances" to ' antira‘c‘hitic vitamins plot gradually brought together until the easily rec -20 sion occurs between ‘250 and, 350 cycles. The ‘effi ciency of"conversion" decreases with frequencies then be evident to those. skilled in the art. 7 > We have ‘discovered that provitamins placed in the electrostatic, ?eld within a brush discharge are efficiently converted into antirachitic vita- ‘ 25 mins. We have also found that the antirachitic conversion is relatively insigni?cant for electri cal discharges occurring at the lower, voltages, namely the non-luminous discharge ‘represented by curve I‘! .in Figure 2 and the glow discharge resentation' 38 of the relativenconversion of pro 20 ted withv re’spectfto the frequency of the applied poteritialin cycles per second‘. ‘ ‘ It ishto be understood that a brush discharge occurs along the'points of curve 38 for the vari ous frequencies plotted. At zero frequency a rel atively'veiy small yield occurs’. As the frequency is increased to 250 cycles, the yield correspond ingly increases until the maximum. As the fre quency is. further increased to about 350 cycles, 30 30 represented by curve l9; and that the discharges ‘ the efficiency of vcon/version continues near the occurring beyond the brush discharge,v namely maximum. For particular substances, a peaked nature of curve 38; will be evident" at a single the spark ‘discharge and the electric are dis charges represented by curves 2|, 22, 23 and 24 ] critical frequency in ‘the order of 250-350 cycles. of Figure 2 actually destroy the provitamins. It ‘ However, inFigure ,5,’we have, not" attempted to accurately represent any’ particular case but is to be, understood thatthe brush discharge rep ' ‘rather tov give an approximate conception of the resents an electrochemical ‘conversion of thepro vitamin to the antirachitic vitamin. This elec “effect and range of thefrequency of the voltage trochemical action is analogous to the production generator 32' upon" the ef?ciency of conversion. of ozone-which has ‘also been found to be most For frequencies of the applied voltage to produce 40 the brush, discharge above 3.50'cycles, the effi 40 efficient in the brush discharge region. ciency of conversion diminishes until at 1000' cycles and above, the efficiency is relatively small. As seen by curve 38 of Figure 5 "approximately concentric electrodes as glass illustrated tubes provided in Figured. with metal .An outer, foil: 50% ofthe maximum efficiency or yield occurs with frequencies in the range'of 150 to 550 cycles cylindrical glass tube 28 is provided with a me In a preferred embodiment for carrying out the , process of our present invention, we utilize two per second. By choosing the intermediate fre_ quency range‘ of'250‘ to 350 cycles‘ per second 30 is coated with a metallic sheet or foil electrode _, the maximum efficiency or yield is approached. 30 upon its inner surface. The annular-distance ,For most provitamin substances a frequency of ~ between concentric tubes 28 and 30 is optional about 300 cyclesper secon'd'will produce best 50 tallic plate or foil electrode 29 attached to its‘ outer surface. The inner concentric glass tube and determines the volume capacity of the appa- . ratus. The metallic electrodes 29 and 3| are connected to a suitable alternating current volt age source 32 by conductors 33-34. 55 ‘ Ergosterol 35 or other suitable provitamin-ma terial is placed between the glass cylinders 28 and30. If a solid'state of the substance is used, it should be in a loosely powdered form. The , ‘value of the voltage from electric source 32 ap 60 plied between electrodes 29 and 3| is predeter mined, so as to produce a brush discharge there between. results. , . ‘ ' , ‘ It is, necessary for a gaseous atmosphere to prevail between ,thedischa'rge electrodes, there fore the solidprovitam'in 35 should be in a loose ly powdered state. When air is used, ,ozoneis formed during the activation process according to our invention. , Ozone 'orjtheaction of the oxygen itself acts 'to‘slowly decompose the vita ' mins and accordingly somewhat reduce the yield. We have found thatv if the'activation process be tween the concentricvtubes __28_ and 30 is carried One must be careful that the. voltage ' on in the presence of an inert gas such as nitro-, applied to the apparatus produces the true ‘brush discharge corresponding to curve 20 of Figure 2. If the current is too low, the inefficient glow dis charge represented by curve 19 will take place; if the current is too high, a. spark discharge rep resented by curve 2| will take placeand destroy any vitamins that might-be formed. In a par; ticular example, glass cylinders 28 andf30 of one millimeter thickness and with an annular space of two millimeters required a voltage of the order of 8000 volts to produce a brush discharge. __ We have found that it is necessary to place the provitamin substance 35 in the electrostatic ?eld I gen thev efficiencyof conversion is materially in creased.v Nitrogen may either be' continuously .passed'through the substance‘ "35 being activated in ‘the annular chamber or may be con?ned to . ‘the annular chamber if it is‘ made gas tight as will be understood by‘ythoseskilled' in the art. 1N0 activation is'obse'r'ved ‘ifv a solution ‘of pro vitamin' fills the annular space, since a brush discharge cannot be‘ established 'thru the solvent. A modi?cation for activating the ergosterol 01' other 'provitamin resides incontinuously spray ing it in the formof a ?nev d'us't between the an nular space’of‘a relatively vlong structure. The 75 4 2,112,242 ergosterol, crude cholesterol or other provitamin substance may be dissolved‘in a suitable solvent such as ether or alcoholand passed through the brush discharge in the annular space in the form feed this into a transformer designed to raise the voltage to the desired range. A condenser board is used in connection with the final transformer so as to keep the current and voltage in phase. / The ergosterol or crude cholesterol is a concen of a ?ne spray." Antirachitic conversion ‘of pro- ' vitamins to vitamins is evident with an exposure trated antirachitic vitamin source, It is too potent for direct consumption. Smallv amounts are administered or eaten, preferably in combina tion with a. food or medicine. A small percentage provitamin substance will increase the yield. Ex posure of a half hour will in most cases give a of the activated material is mixed with cod liver oilyyeast, milk or other edible substance. No maximum yield consistent with commercial pro duction. However, we do not restrict our process change in taste or odor of the food occurs. The to the time of exposure which depends upon the antirachiticpotency of the edible material treat shape and size of the ‘apparatus as well as the ed in this manner is equivalent to direct activa type and form of provitamin‘ substance being. tion thereof. It is much more economical to activated. produce edible or medicinal antirachitic sub Another important factor for increasing the stances by adding a small percentage of concen— as low as two minutes. Increasing the time of exposure to a predetermined maximum of the ii e?iciency of conversion'is the temperature at trated antirachitic vitamin content material to which’ the conversion takes place. the substances, as compared to direct activation thereof. It is to be understood that antirachiti 20 It is preferable to carry out the process at a temperature of about vcally potent substances may be directly activated inaccordance with our present invention. This application is a continuation in part of of the whole apparatus, and therefore of the sub- ‘ stance 35 being converted, may be maintainedcool our application Serial No. 723,314, filed May 1, 0° C. although good results will be obtained at ordinary room temperatures. The temperature by means of a fan directly blowing thereon or 1934. ' ‘i We claim: 1. The process for antirachitically activating provitamins which comprises introducing pro the apparatus. ' Other suitable forms of cooling will also be evident to thoseskilled in the art. - vitamin material into a gaseous region and apply The true nature of the electro-chemical action ing a voltage gradient across the gaseous region 30 containing the provitamin material for'producing during the brush‘ discharge has been in contro versy for some time in the art. However, in the a gaseous brush discharge about the provitamin present case, the activation appears to be due material, whereby the provitamins are converted preferably by the continuous circulation of cool ing water through the central circular tube 30 of to the impingement of ions or activated atoms or into antirachitic vitamins by the brush discharge moleculesproduced within the brush discharge acting on the provitamin material in the gaseous . from the gaseous dielectric, upon the provitamin atmosphere. substance which release their energy to the pro production of a brush discharge; ‘placing a pro vitamin substance such as ergosterol or crude containing the provitamin particles for producing a gaseous brush discharge about the provitamin cholesterol within the brush discharge preferably particles, whereby the provitamins are converted into' antirachitic vitamins by the interrupted brush discharge acting on the provitamin par 45 ticles in the gaseous region, and cooling the dis charge region to about 0“ centigrade to increase the efficiency of conversion. 3. The process for antirachitically activating ?ne dust spray, or a spray of a solution of pro vitamin substance through‘ the brush discharge; preferably maintaining an inert gaseous atmos phere such as nitrogen and keeping the substance coolpreferably at 0° C. The production of'the brush discharge should be determined for each particular structure designed. The necessary voltage is determined'by the shape of the elec trodes, their size and their spacing. Thefre quency of the applied voltage should preferably provitamins which comprises introducing pro- _ ‘vitamin material _in a powdered and loosely packed form into a gaseous region and applying a voltage gradient across the gaseous region con- ' taining the provitamin powder at substantially the maximum voltage which the region can sup~ , , be in a most efficient range for conversion. gen port for producing a, gaseous brush discharge about the provitamin material, whereby the pro erally within 250 and 350 cycles. A suitable source of the high voltage alternating current necessary for carrying out our process will be evident to those skilled in the art. An alternat ing current generator connected to a step-up vitamins are converted into antirachitic vitamins by the brush discharge acting on the provitamin material in the gaseous atmosphere. ‘4. The process for antirachitically activating provitamins which comprises continuously pass transformer will provide the necessary high volt ing a solution of provitamin material as a fine age. Li - vitamin particles into a gaseous region and apply ing a. voltage gradient across the gaseous region vitamin substance structure, or in the form of (H) .\ vitamin, converting it to the antirachitic vitamin. The important factors for the production of antirachitic vitamins from provitamins are the insulated from the metallic electrodes by glass plates or the like; using a loosely powdered pro Till . 2. The process for antirachitically activating provitamins which comprises introducing pro The alternator is adjusted to the proper ‘ spray through a gaseous region and applying a optimum frequency. For small quantity produc voltage gradient across the gaseous region con tion, an induction coil adjusted to, for example, 250 cycles of ‘interruption, may bepused to main taining the provitamin spray at substantially the maximum voltage which the region can support tain the brush discharge in an apparatus con for producing a gaseous brush discharge about structed to operate with the voltages, for example 8000 volts, presented at the output thereof. A convenient way of producing the desired fre quency and voltages is to generate the frequency the provitamin material, whereby the provitamins by one of the usual types of variable audio oscil- ., 5. The process for antirachitically activating provitamins which comprises introducing pro lators, to amplify this by means of the standard types of pie-‘ampli?ers and ampli?ers and to are converted into antirachitic vitamins by the brush discharge acting on the provitamin ma terial. . ' vitamin material into an inert gaseous'region'and 65 it 9,1 19,242 8. The process of antirachitically activating applying a voltage gradient across the gaseous region containing the provitamin material at substantially the maximum voltage which the vprovitamins which comprises introducing provi tamin material into a gaseous region and apply ing a voltage gradient across the gaseous region region can support for producing a gaseous brush containing the provitamin material at substan discharge about the provitamin material, whereby tially the maximum voltage which the region can support for producing a gaseous brush discharge about the provitamin material, and generating the brush discharge with an alternating ‘voltage having a frequency of. about 300vcycles per second, 10 whereby the provitamins are converted into anti rachitic vitamins by the brush discharge acting .the provitamins are converted into antirachitic vitamins by the brush discharge acting on the provitamin material in the inert gaseous atmos~ phere. 10 , 6. The process for antirachitically activating provitamins which comprises introducing provita min particles into a region of nitrogen gas and applying a voltage gradient across the gaseous on the provitamin material in the gaseous atmos region containing the provitamin particles at sub 15 phere. stantially the maximum voltage which the region charge about the individual provitamin particles,‘ phere. '7. The process of antirachitically activating provitamins which comprises introduci g provi tamin material into a gaseous region and applyihg 25 a voltage gradient across the gaseous region con- ‘ provitamins which comprises introducing provi tamin particles into a gaseous region and apply ing a voltage gradient across the gaseous region can support vfor producing a gaseous brush dis whereby the provitamins are con, erted into anti rachitic vitamins by the brush‘ discharge acting on 20 the provitamin particles in the hi ogen atmos-\ - ' 9. The process for antirachitically activating containing the provitamin particles at substan tially the maximum voltage which the region can 20 support for producing a gaseous brush discharge about the individual provitamin particles, and generating the brush discharge with an alternat ing voltage having a frequency in the range of ‘ 150 to 550 cycles per second, whereby the provi taining the provitamin material for producing a gaseous brush discharge about the provitamln material, and, generating the brush discharge with tamins are converted into antirachitic vitamins by the alternating brush discharge acting on the provltamin particles in the gaseous atmosphere,“ an interrupted current having about 300 inter 30 ruptions persecond, whereby the provitamins are ‘converted into antirachitic vitamins by the inter- - rupted brush discharge acting on the provitamin material in the gaseous atmosphere. BENJAMIN KRAMER. SAMUEL NATELSON. ALBERT E. SOBEL.