VI.-PEROXIDE OF IIYDROGEN ASD OZOSE:. [First Pnprr.]
BY ALIIEHT13. IJ:EDP. PII.D A n n o u n r d Y a n u n r y 20fh, ,J;5‘oo.
I n the Chemical N e w s (38, 224, 2 ; $ ~ 243, , 249 aiid 2 5 i ) I pnblished a series of articles, the chief otjjecbt of which was t,o prove that when the so-called atmospheric ozonoswpes were prepared with the utmost precautions, i ~ n t lsuljjectccl in the laboratory, rintler known conditions, to the operation of v n p u r s ; i i i ( l p e s otlier t l i n i i ozone', such as nitrous acid, Iiydrogcn i)t>roxicle,etc. ( h d i e s existent to a greater or less extent i i i the e:n.th’s ;~tniosphere),they ;ill unilerwent chaiige. 1Iydi.ogeii peroxide ;iffcc*tcfitl;ill tlrc ozontiscopes, thallous hydrate exccptccl. l‘he results ol,t:tiiicil w i t 1 1 this w t w eritcretl as doubtfill. In onc series ( i f trial$, o1,chr;itiiig wit11 :t v e r y dilute solution of peroxide, the thal!iiini palwr w;is yellowc~d: i i i x secoltd wries, t h e yelloiv stain was upon tht. edgc ~ n l yof the plw, the uentr~cremaining white. These resiilts were tlicrc explained tht: wppocition of tlie “ thallium peroxitlc untlergoin!,r rctluc~tioiii n cwntact witli hydrogel] peroxide, water iind oxygen being lil)eratcd.” I n other ~ o r d s while , the effects of hytirogen Iwroxitle i n ctiiinging t lie tlixlliuin ozonosc~q)ervere visil~lt~, yet, acwl)tirig :is true the generally receivc(l statement of Schoenl)ein, cunc-erning the niut uxl c1ecv)iuliosition of hydrogen and thalliiirn peroxitles, I attri1tntt.d tlie final slight result t o the reclucntion of any thallium pcroxicle first formed. ‘l’his inasnir~ch:is explanation was very uiisatisfactory t o r i i c tit the tiri~c>. it necessitated the supposition of an initisil oxidation, followed 1)y :I reduction cfTected by the cont,iiiuetl operation of oiir : i d t h e sarnv reagent, ant1 I was engaged i n its f i u t h c r study, wlieii the publioution of the :idmiixblc paper b y E. Scliociic, on this subject, rlefiiiitely Ile there tlernoiistr:ites the fal1ac.y of Schocnsettled tlie quest!on.* bein’a staterrlent, and shows that hytlrogen peroxiile can convert thallous into thallic oxide, not orily \vhen t,he perosi(le exists in solution, but also when it is i n the forin of v : i 1 ~ ) 1 . . I t may bc regarded as cu!ahlishcd, therefoi-e, that l t u r i e of the SOcalled ozonoscopes riecessarily indicate the presence of o z w e i n the atmosphere. \VhiIo my paper, writtell with t!ie o1)ject of d(monstrating the proposition just enunciated, was in course of publication, Mr. C. J.
_____~______ * B n n . der Cliem., 196,58.
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PEROXIDE OF HYDROGEN B D OZONE.
35
Kingzett made t h e unwarranted charge (Chem. News, 38, 243), that I seemed “ t o have fallen into a n error committed by many other observers, namely, that of estimating as ozone everything in t h e atmosphere capable of coloring so-called ozonoscope papers.’’ Moreover, he hmed this charge on a miaquotation, f o r in t h e paragraph h e quotes, I speak, not of t h e ozonic reaction, b u t of t h e “ so-called ” ozonic reaction, an epithet which he borrows in his own article. I n a later communication (Chem. News, 40, 96), Mr. Kingzett says, “‘l’here is no known process of slow oxidation which has been established t o produce ozone.” Couched, 3s it is, in such positive terms, this assertion caontravenes the statements of those who have experinlentally investigated t h e subject during t h e past forty years. It might, therefore, not unreasonably be anticipated that Mr. Kingzett should bring forward some new and crucial experiments of his own. H e adduces none. At t h e Yame time, he fails t o recognke certain distinguishing properties of ozone and hydrogen peroxide, and apparently is not conversant with many phenomena exhibited in the oxidation of phosphorus in moist air. Now, t h e property of ozone most strikingly characteristic, is i t s smell. This smell, YO f a r as long-continued familiarity with i t enables me t o judge, and whether the ozone is derived from the oxidation of phosphorus, or results from t h e action of t h e silent discharge on pure and d r y oxygen, o r accompanies the electrolysis of acidulated water (and t h e smell in t h e three cases is identical), is posesssed b y ozone only. It is not the odor of phosphorus, nor of chlorine, nor of t h e oxides of nitrogen, although it is sometimes compared with these very dissimilar bodies. Concerning the odor of hydrogen peroxide, there appears t o he wide diversity of opinion. Most of t h e works on v h m i s t r y , to which I have referred, state t h a t i t is odorless ; one authority mentions that its odor is peculiar, another that it resembles chlorine. T h e solutions which I have prepared a t different times myself, carbonic acid being employed to decompose t h e barium peroxide, have not evolved any odor t h t I was able t o recognise or perceive. B u t when air is forced for a few minutes through a phosphorus ozonator, such as is described in Chem. News, 40, 246, t h e atmosphere of a large lecture room becomes insupportable from the diffusion throughout i t of an invisible gas (not a white smoke like t h e so-called antozone), and there is everywhere present t h e penetrating and irritating smell of ozone. I n t h e next place, ozone is very slightly soluble, and water through which ozone has been pawed at, or below, t h e common temperature,
36
PEROXIDE O F HYDROGEN AND OZONE.
may be made to indicate the existence of dissolved ozone by appropria t e tests.* I t is certainly not too much to asmme, that when water through which ozone has been passed, is e l aporated to one-tenth of its natural bulk, its dissolved ozone is expelled. B u t under these circumstances, 30 c.c. of a solution which originally contained 2 . i mgrms of hydrogen peroxide, when evaporated down to 3 c.c., yielded, on titration, a result equivalent t o 3.4 mgrrns of the peroxide. T h e loss was due either to the decomposition of 0.9 mgrm of hydrogen peroxide, or to the expulsion of 0.44 nigrm of dissolved ozone. T h e former is by f a r the inore probable supposition, and i n either case, the body principally contained in the water was hydrogen peroxide. This water was contained in t h e first wash-bottle used in washing the ozone, generated by the action of phosphorus partly immersed in wquwpurissima, upon air which had been previously purified from all pre-existent nitrogen compounds (ammonia, nitroris and nitric acids), organic. particles, etc.t KO ,litmus acid was present in the water, as was *howti by examination with Griess’ test (inetadiamidobenzole), but it contained 0.49 mgrm of nitric acid, and 0.066 mgrni of ammonia. This determination waA made upon 481 liters of air, the amount of ozone found being 0.924 grm. The percentage of hydrogen peroxide in the first bottle of wash-water, as compared with the tot:rl weight of the air ozonised, was 0.00038 per cent. I n another trial, in which 420 liters of air were drawn over, and 0.805 g r m ozone produced, the amount of hydrogen peroxide contained in the first bottle of wash-water, was 2.01 mgrms or 0.00037 per cent of the total weight of the air aspirated. I t contained also 0.075 mgrm ammonia and 0.88 rugrni nitric acid, but of nitrous acid yielded not a trace t o metadiamidobenzole. I n a third experiment, in which 396.4 mgrms of ozone were produced, the wash-water contained 0.37 mgrm of nitric acid, no nitrous acid, and 1.3 mgrm of hydrogen peroxide, corresponding t o 0.00039 per cent. of t h e total weight of t h e air ozonised. One word as t o the close agreement in t h e percentages of hydrogen peroxide, found in the wash-water employed in t h e various trials. It was an agreement not anticipated a t the outset, and became evident only when the autual amounts of hydrogen peroxide, found in the course of experiments continued during more than 3 months, came, at their conclusion, to be calculated up as percentages __ - - . __ *Der. der deutsch. chem. Gesell., 12, 1831. +Upon Ammonium Nitrite, and Upon the By-products Obtained in the Ozonation of Air by Moist Phosphorus. JOURN,h f E R . CKEM. SOC., I , 145. By the Author.
PEROXIDE OF HYDROGEN AND OZONE.
37
of the total weights of the air used. T h e same agreement was found t o exist between the aniounts of nitric acid present in the wash-water, when their percentages were calculated in like manner. I n the first trial, 2 7 liters of air being aspirated, the nitric acid was 0.000318 per cent. of the total weight of the air ; in the second trial, 108 liters of air aspirated, it was 0.000318 per cent.; in the fourth, 85 liters aspirated, it was 0.000308 per cent.; in the sixth, 262 liter8 aspirated, 0.000328 per cent. In these four experiments, water was used in the jars of the ozonator. In the third trial, 45 liters of air being drawn over, the nitric acid present in the wash-watcr was 0.00054 per cent; in the fifth trial, 90 liters aspirated, it was 0.00054 per cent. In these two trials, the bichromate mixture was used in the jars. In another place,* I have shown that the amount of ozone produced by the oxidation of phosphorus, under given circumstances, is constant for any particular temperature, and consequently, the generation of ozone may be graphically represented by a curve, the production a t 6" C. being nul, rising to a maximum at 24-25' C., and then rapidly diminishing as the temperature approaches 44", the melting point of the phosphorue. T h e results above given, warrant, it appears t o me, the formulation of another proposition, viz : In the oxidation of phosphorus in moist air, there is formed both ozone and hydrogen per0xide.t 'l'he amounts of the two bodies evolved under given circumstances, bear a constant relation t o one another and to the air passed over, the percentage of hydrogen peroxide being very small as compared with that of the ozone. I n the experiments quoted above, the temperature being 18-21' C., the percentage of ozone, as referred to the weight of air aspirated, was 0.15 per cent.; that of the hydrogen peroxide, waR 0.00038 per cent., or but one four-hundreth part of the ozone. T h e amount of phosphoric acid in the wash-water, in the experiment in which 420 liters of air were aspirated, was 0.252 g r m ; of phosphorous acid, 0.013 grm. It was determined, by trial, that the presence of phosphorous acid in the solution, did not affect the titration of hydrogen peroxide. I n this connection, it iR likewise important to formulate the three following propasitions:
I. No nitrous acid is present among the final products. presence of hydrogen peroxide is, in itself, a sufficient reason.
The
*Chem. News, 39, 157.
t This statement. is not new.
Hydrogen peroxide was recognised by Schoen-
bein among the by-products of the oxidation of phosphorus.
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PEROXIDE OF HTDROGEN ANI) OZOSF:.
11. Both ammonia and nitric acid are present in the final products, the amounts found, standing in a constant ratio to the qnantity of air aspirated. Tn one trial, the results agreed with those corresponding to the formula of ammoniunl nitratv. 111. The generation of aminoninin nitrate and hydrogen peroxide, is as invariable a feature of t h e phenonitJna observetl during t h e cmrse of tge oxidation, as iri the prodiiction of phosphoric and phosphorous acid$. For this reakon, any explanation of the phenomena which neglected the coiiteniporaneous geiierrttion of ammonium uitra te and hydrogen peroxide, woii Id be i i n 1w f wr. These resiilts and tht2 ; L ~ N ~ ~VwCw~ I i i c i o n s , were arrived at aiid p ~ b l i s h e di n the early part of List y c w . rxylanation hrought forwan1 at that, time, and which ;is yet I havc~seen n o reason t o modify. was as follons:*--" As to the r ~ w o nfor t,he formation of ozone itself under tlwse c*ircrimstancrn, it ruay be cvmjectureci along with Lamont t and others, that it is connected with tliv uneven quantivalences of the elements taking part i n ttw e;wtiorr, which may be represented Iiy the equation : P, + O,, P,O, + P,O,+ 2 0 s . If this Iiypottiesis he true, then we should anticipate the tlwc~lopnient of ozone whenever oxidatinn of a pe ad occurred at rcnilw,ttnres compatil,le with the stability of the omnc' nioleciile. KVC.IIat thv temperature of combustion of hydrogen, this is sripposeetl b y C. 'L'han f. to be the caw. He explains i n this manner t h e ~)i~eseric*c~ of the ozone, which lie states he h i s detected i n tliv coinbustion of hycliwgwioiis substances p i l e r a l l y , and its absence in thc w i r l l ) i i s t ion of c a r h i . " 111entering into n e w c.onil,inntioris, t h c , oxyg(8ii rnoleciilcs mrist iinrlergi) temporary resolution i n t o their c o ~ ~ s t ~ i t i i catonis. nt These, while e n route to take up ncaw 1)ositioris in other cornl)inations, and animated by their atomic: energy, 0 1 ' c'nt:rgy of the ~ i a s c w ~state, t may either oxidize the oxygt.11 molecule, o r t h e nitroqeri ruolrcule, or the inoleculc of water. In the first placc', ozone w0111d 1)e ~irodiiccd; in the second, regarding water K S the basic body ant1 S S O iis the nitrile, there might he formed, as IIunt has indicated,$ an1iiioniiim nitrate; in the third, hydrogen peroxide," Snbsequent t o t h e publication of these results, Prof. NcLeod took rip the subject, and arrived at the conclusion that 11 " t h e gas obtained 'I'h(2
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*JOUR~ AMER. .. CIiEM.
t Chem. ?Jews, 28.
SOC., I,
_-
156.
$ Journ. Chem. SOC. CZ], 9, 483; Journ. pi-. Cliem. [2],
I,
415.
$Cliemical and Geological Essays, T. S. Hunt, 2d ed., 472. (1 Chem. News, 40, 307.
PEROXIDE O F HYDROGEN A N I ) OZONIC.
39
during the slow oxidation of phosphorus, possesses the properties of ozone, and not those of hydroxyl, the only known peroxide of hydrogen." H e likewise states that it is extremely improbable that ozone and hydrogen peroxide are both formed, as these substances destroy each other. The principal quantitative experiment mentioned, was that of passing the gas, first through a tube heated to varions temperatures, then into a weighed sulphuric acid tube, and finally into a solution of potamic iodide and starch, acidified with sulphuric acid. In connection with these experiments, it is to he noted in the first place, that Prof. McLeod regards the question in the light of an nlternative, the presence of ozone excluding that of hydrogen peroxide, and vice wwsn. ?'his iriew, though supported by the statements of Schoentwin," that the two bodies nlutually decompose one another, is much weakened hy the recent elaborate experiments of Schoene,t who shown that when strongly ozonised oxygen, containing 5.2 volume per cent. of ozone, is agitated with a hydrogen peroxide solution containing 0.4 per cent. of the peroxide, or three t o four time8 as much of the peroxide as is adequate t o destroy all the ozone, it is only after the lapse of half an hour that as much as half of the ozone is destroyed. W h y then, it' hydrogen peroxide and ozone were both present, d i d not a gradual increase in weight in the sulphuric acid dryer, as the gas was heated at varions temperatures up to zoo0, indicate the progressive decomposition of the former ? The failure to obtain such a serial progression, is not explained. Neither is there any explanation of how an increase in weight in the cases where heat was applied, is necessarily t o indicate the presence of hydrogen peroxide, when an increase (and that a much larger one) took place when no heat was iised. Moreover, ozone itself undergoes decomposition at a temperat u r e of 200'; but a t this temperature, Prof. McLeod obtains by titration a result corresponding t o 3.4 mgrms, which is relatively greater than the amount obtained when the ozone was not heated a t all. I shall be glad if Prof. McLeod will correct me of error, if I am mistaken in stating that the decomposition of his potassium iodide solution, under these circumstances, wa5 due not to ozone (remaining a f t e r the air had been heated to 200°), but t o the presence of free acid. In the early part qf my own studies upon the subject,I investigated a5 an essential question, whether a current of ozonised air could be accurately
* Journ.
f. prakt. Chem., 77, 130.
t Ann. der Chem., 196,240.
titrated by an acid solution of potassiiirri iodide, and determined that it could not.* ITnIess the presericca of oxygen be rigorously e x c l i i ( ~ from the solution, excessively tlilute acidified solutions of potassium iodide change even in t h e dirrk. In the light,, the strength of thu aolutiori remaining the sanie, the cliangv increases i n tlie smile ratio as t h e relative increase of t h e surface of cxposure of the solution t o the light’s influence. B u t wlicn oxygen is exclritlcd! stroiig sdutiuns containing excess of acid, may be exposed to die tlirwt Zh/?~t of’ the . s / o i f o r t l t r y s without uiide~~goiiig deconiposition. IIencc., when a current of air is allowed t o 1inss through an :tcitlitica(l solution of potassium iodide, it is placed uiitler c,imtliticliis most fnvoral)le t o its decwiipositioli, arid the arnouiits o f iotline lilieratcti will tleI)erid, tirst, upoii the relative arnouiits of ; k c i d ; t i i d iodide prestwt; and, ~ ~ ( ~ tupon i d , tlie intensit) of t h e light aiitl the relativcb tliriiensioiis of the surface of exposure. I have Iiceri rriost c~areful/ t o t t o :iuidify t h e potassium iodide solution dnriiig the c*uurse o f t h c c~xfjcriineiit,brit a t its close, and then, for the reasons above-itieritioiic(1, t o add oiily sufficient dilute acid t o decompose t h e iodate which lias Irecw fortned, and titrate at once. In coiicliision, I wish briefly t o summarize the argrirnents above stated. ‘ h e gaseous body giver1 off in the course (Jf the t’eactioii between moist phosphorus arid air, bas a very powerful a r i d Iwculiar odor, which is identical with that produced in the electrolysis of acidulated water. This is riot t h e case with hydrogen peroxide. Ozone is very slightly solubke i i i water, and is readily expelled from the solution uti h a t i n g . Hydrogen peiwxide is miscible i n :ill proportions with water, and solutions corit;titiing as much as une per cent. H,O,, may be concentrated by evaporation on the water bath, until a higher degree of coiicentratioii is reached, without great loss of peroxide ( w e also Schoene, Ann. der Cheni., 196, 60, and Davis, Chem. News, 39, 221). Wash-water, through which air ozunised by phosphorus has been passed, yields, after eonwritration, :L reaction due t o hydrogen peroxide. T h e absence of nitrous acid in sue11 wasli-water can be readily demonstrated. S o statement has been made as to tlie relative amounts of ozone and hydrogen peroxide geuertrted, but only as to the relative amounts e’uoluetl. T h e latter amounts are those which remain after t h e highly dilute atmospheres of hydrogen peroxide and ozone have operated up011 each other in the ozonising chamber. The absolute amounts depend upon the temperature, the period during which the ozone and hydrogen peroxide remain in con___________________ *Phil. Mag., April, 1879; Joum-. AMER.C ~ E MSoc., . I , 18.
PEROXIDE ( i F HYDROGEN AND OZONE.
41
tact with one another, t h e rate of flow of gas, etc.; b u t under giveii circumstances, the ratio of t h e hydrogen peroxide in the evolved gas to t h e ozone is a definite quantity. I n t h e experinients detailed, as c1c:termined upon the first portion of wash-water, i t was approximately the ab& part. It must be borne in mind, t h a t this number does not represent the total amount of hydrogen peroxide, b u t only t h a t dissolved in the tirst wash-bottle. This is t h e larger amount, b u t ciome is likewise present in t h e second wash-bottle, still less in the third, and so on. A portion escapes solution in t h e water even when a number of wash-bottles are employed, and finally passes into t h e potassium iodide ernployed to titrate the ozone. During the whole of this interval, the hydrogen peroxide and oznne are slowly decomposing one another; the results obtained, on titrating with potassium iodide solritiori, depending on the point in the series where the titration is effected. When the current of ozonised air issues again from t h e potassium iodide solution, it is laden with a white cloiid. Thio white cloud is the antozone of Schoenbein and other authors. It is, in fact Iiydrogeii peroxide, lield i n a state of aqueous suspension, and is the product yf' the actioii o$' the ozone upon the potassiurn iodide solutiou. As such, it is t o be discriminated from t h e white, cloud, which is to be seen in the first two o r three wash-bottles placed directly in conneetion with t h e ozonising chambers of t h e phosphorus ozonator. 'I'his latter white cloud is likewise suspended hydrogen peroxide, but its origin is t o be sought f o r in the same series of changes as that resulting in t h e production of t h e ozone itself. I t follows, from t h e above, t h a t the numbers obtained as t h e results of titrating the stream of ozone and hydrogen peroxide with potassium iodide, d o not represent ozone only. They represent also the relatively minute amounts of hydrogen peroxide, which, as I have shown in the paper piiblished in the early part of the preceding year, and previuusly alludetl to, always accompany the ozone generated b y the iretioil of moist air upon phosphorus. Filially, I desire to mention, in explanation of certain statements niade i n the latter part of the article, that they are founded upon experiments not as yet published, and t h a t I have, only been induced to ui:tke this preliminary notice of them, in order t o cotnplete an argument against what have appeared t o me t o be erroneous views.
