note on the use of potassium permanganate in the determination of nitrogen by the kjeldahl method

8/19/2019 Note on the Use of Potassium Permanganate in the Determination of Nitrogen by the Kjeldahl Method

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358 T H E J O U R N A L O F I N D U S T R I L A N D E N G I N E E R I N G C H E M I S T R Y Vol 13, N

22-Whitney and Ober: J . A m Chcm. Soc . 28 1901), 856-863.Gives an excellent bibliography, with brief com ment, of colloid work pub-lished before 1901. Nearly 150 references.

23-A. Muller: “Bibliography of Colloid Chemistry,” Z. anorg.C h e m . 89 19041, 121. 356 references grouped by subjects, with out com-ment

24-Hober : “Physikalische Chemie der Zelle und Gewebe.” Wil-helm Engelmann, Leipzig, 1911.

25-Rideal and Taylor: “Catalysis in Theory and Practice.” T h ehfacmillan Co. New York, 1919. Not primarily a colloid book but con-tains material of value to colloid chemists.

Kollozd-Zeitschrifi and its Bcibefte have devoted their columns exclu-sively to colloid research.

A new edition is promised.

Very important.

The Journal of Physical Chemistry contains a vast amount ofinvaluable material an d no stu den t of colloid chemistry canafford to neglect this journal. Ma ny of the articles con tain ex-ceptionally full summaries of the work done in special fields,an d are really monographs. Th e results of colloid research,however, are found in most of the great journals.

Since many chemists waste time and become discouraged byreading th e wrong book first, we urge a ny one of th e first threein the above list as the proper introduction to the subject.

OBERLIN, OHIO

OBGRLIN COLLEGE

HARRY N. HOLMES, hairmanCommittee on Chemistry of Colloids

Calendar of MeetingsTechnical Association of the Pulp and Paper Industry-

Spring Meeting, Waldorf-Astoria and Hotel Astor, New York,N. Y., April 11 t o 14, 1921.

American Pap er and Pulp Association-Annual Meeting,Waldorf-Astoria and Hotel Astor, New York, N. Y., A11 to 15, 1921.

American Electrochemical Society4pring Meeting, HotelChalfonte, Atlantic City, N. J , , April 21 to 23, 1921.

American Chemical Society-Sixty-first Meeting, Rochester,N. Y., April 26 to 29, 1921.

American Oil Chemists’ Society-Twelfth Annual Meeting,Chicago, Ill., May 16 to 17, 1921.

American Institute of Chemical Engineers-Spring Meeting,Detroit, Mich., June 20 to 21, 1921.

Seventh National Exposition of Chemical Industries-EighthCoast Artillery Armory, New York, N. Y., September 12 to1921.

NOTES AND CO RRESPONDENCENote on the Use of Potassium Perma ngana te in

th e Determination of Nitrogen by theKjeldahl Metho d

Editor of the Journal of Industrial and Engineering Chemistry:It was for a long time the practice in this laboratory to add

potassium permanganate a t the end of digestion in th e deter-mina tion of nitrogen. Abou t a year ago it was decided to de-termine whether th e addition of t he permangana te was neces-sar y. After making determination s for several weeks in whichpermangan ate was added t o one of th e duplicates, we concludedthat i t had no effect and its use was discontinued. O n tha t ac-

count we were surprised a t th e results obtained by Cochrane[THIS OURNAL, 12 1920), 11951. Th e results of fu rth er ex-periments lead to t he conclusion th at t he addition of perman-gan ate is not necessary when sodium or potassium sulfate andmercury are used with the sulfuric acid in the digestion.

I t was noted that Cochrane did not use either potassium orsodium sulfate and it seemed possible that the more uniformresults obtained when he used potassium permangana te weredue to th e fact th at the digestions were not complete a t the endof 2 . 5 hrs. Several digestions were, therefore, mad e with sodiumsulfate in one duplicate and none in the other. The resultsshowed that the digestion is not complete within 2 . 5 hrs. ifthe sulfate is not added.

Our results are summarize

No. ofDqtermina-

S U B S TA N C E tionsCottonseed Meal A . . . . . . 2Cottonseed Meal B . ..... . 2Wheat Mixed Feed A . . . . . 2Wheat Mixed Feed L Sc A 2Comp. Feces A . . .... .. . 2Comp. Feces B . . .. . . 2Broom Corn Silage Refuse A 2Broom Corn Silage Refuse B 2

:d in the

KMnOiAdded

Average6 . 9 9 36 . 9 7 72 .7202 . 4 7 01 .3421 .3600 . 4 7 20 . 4 6 4

following-Per cent c

2

NoKMnOaAdded

Average6 .8226 .7892 .7122 . 4 4 4I . 3941 . 2 8 30 . 4 9 20 . 4 8 6

table:f Nitrogen-

3NazS04

andKMnOaAdded

Average7 . 0 4 37 .0442 , 7 8 41 .4881 .3441 .3000 .4590 .424

4NanSOiand noKMnOdAdded

Average7 . 0 4 37 . 0 4 32 . 7 3 02 .4611 .4001 .4000 , 4 9 90 . 4 8 3

C. T. OWELL ND W. G. FRIEDEMANNOKLAHOMA GRICULTURAL XPERIMENT TATION

STILLWATER, KLAHOMAJanuary 20, 1921. . . . . . . . . .

Editor of the Journal of Xndustrial and Engineering Chemistry:I would call attent ion to t he fact t ha t in five out of the eight

samples analyzed, the data presented in Columns 1 andthe table support the conclusions drawn in my article.

No comparison was made in my article between the straightKjeldahl method and the Gunning modification, nor were anydata presented bearing on the use or non-use of permanganain any method where sodium or potassium sulfate is useraise th e boiling point of the digestate.

PENNSYLVANIA TATE COLLEGE D. C. COCHRASTATE COLLEGE, A.

February 5, 1921

Th e Forma tion of Anthracene from Ethyle nean d B,enzene-Correction

In our paper on the above subject [THIS OURNAL, I3 192081 several self-evident errors escaped proof reading, and wewish to have them corrected though they do not in any way affectour results or conclusions.

On page 208, first column, the reaction should read:H..

HOn the same page, second column, the reaction should read:

C2H4 I~HIO 3H.2 - .2 Cal.On th e same page, second column, footnote,the change should be

2C6 2H6 CeH6 - 2.6 Cal.and CMHW nstead of CIOHI~.

COLUMBIA NIVERSITYNEW YORK, N . Y.

J . E. ZANETTI AND M. KANDE

Th e E stimat ion of Cellulose in WoodEditor of the Jourllal of Industrial and Engineering Chemist

With the exception of a few attemp ts to determine the cellu-lose cont ent of lignified materials by dissolving and repre cipitat-ing the cellulose, i t has been the object of all quanti tati ve cellu-lose determinations to isolate the cellulose by dissolving out thenoncellulose compounds. A complete removal of these cpounds from a highly lignified substance, such as wood, without



Apr. , 1921 T H E J O U R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y 3 5 9

attacking the cellulose proper has never been accomplished.But i t is possible by careful manipulation to remove completelysome of th e noncellulose substances, such as rosin, lignin, an dlower carbohydrates, from finely disintegrated wood; and to ob-tain a residue which does not contain decomposition productsof th e cellulose originally present as such in th e wood. Th isresidue, however, differs chemically from normal cellulose as

represented by purified cotton, in that it yields an appreciablequa nti ty of furfural on distillation with hydrochloric acid, proba-bly owing to th e presence of highly res ista nt pentosans.

Of the man y methods th at ha ve been suggested for the qua n-tit ati ve determinatio n of cellulose in wood, none hav e been morewidely accepted than Cross and Bevan’s’ method, which is basedupon the removal of t he lignin by chlorination. The methodwaq originally applied to ju te fiber and included boiling of t hefiber for one-half hour in a 1 per cent sodium hydroxide solution,treatment with chlorine gas for 30 to 60 min., and dissolving ofth e lignin chloride in a 2 per cent s olution of sodium sulfite a tboiling temp erat ure. After washing, th e fibers were finallybleached with potassium permanganate.

I n applying th e method to wood fibers, several investigatorsfound that it was not possible to remove the lignin completelywith one single chlorination, bu t t ha t if the fibers were subjectedto alternating treatments with chlorine gas and sodium sulfite,a complete removal of th e lignin compound could be effected.Ren kerZ obtained from wood a residue which did not give anyof the lignin reactions, by repeating the treat ment six timeswith a tot al t ime of exposure to th e gas of 2.75 hrs. He alsomodified the original method by omitting the treatment withsodium hydroxide previous to chlorination, stating t ha t he thereb yobtained a considerably higher cellulose valu e with equal purit yof residue. I t is of imp ortance for th e following discussion t opoint out a t this place th at Renker based this stat ement upon thefact th at the residue did not give the qu alitative lignin reactions,while he did no t analyze th e residue with regard t o furfural yield.

According to Renker t he ti me of exposure to th e chlorine gasshould be as sh ort a s possible, since the cellulose itself is atta ckedby prolonged exposure to t he gas, an d he was supported by Heuserand Sieber,a who found th at under th e action of chlorine gas alayer of lignin chloride is rapidly formed on th e surface of t hefiber, preventing fu rthe r penetration of t he gas. It is thereforenecessary to dissolve this layer before the chlorination is con-tinued, and in doing so it is possible to remove t he lignin com-pletely withou t injury t o the cellulose. Sieber and Walter4found th at four chlorinations with a tota l exposure to th e gas of1 hr. were sufficient for th e complete removal of th e lignin in wood.They also allowed the fibers to remain in the same Gooch cruciblewith a stationary calico pad throughout the entire process ofpurification, thereby eliminating mechanical losses, which mightoccur when using Renker’s method. Their method of manipula-tion has been adopted by recent investigators with th e exceptionof Schorger, who used practically th e sa me method a s Renker.

The chlorination method has the advantage above other

methods of cellulose determina tion of being a well-studied re-action, simple in operation and quick, and giving a residue freefrom lignin an d witho ut decomposition products of t he originalcellulose. But i t was severely criticized by Konig and H u h d onaccount of th e high furfural yield of th e residue. These investi-gators proved that the furfural-yielding substances could bepractically completely removed from the wood fiber by hydrol-ysis, bu t the ir method of accomplishing this, as well as the meth odproposed by Tollens and Dmochowsky,6 both O which methodsinclude a hydrolysis with inorganic acids and both of which yield

“Cellulose,” London, 1918, 94.“Bestimmungsmethoden der Cellulose,” Berlin, 1910Z angew C h e m 26 1913), 01.P a p i e r - F a b r , 11 1913), 179.

“ Bestimmung der Cellulose in Holzarten und Gespinnstfasern,”Berlin, 1813.

a product free from lignin and practically free from furfural-yielding substances, cannot be recommended for quantitativeestimation of cellulose, because, as I have shown, the celluloseitself is at tack ed an d par tly dissolved in th e process of purifica-tion. I t is a fact that the furfural-yielding compounds of thewood are subject to hydrolysis, but it is equally true that evenvery dilute inorganic acids attack normal cellulose.

Apparently the cellulose is much more resistant towards theaction of organic acids. In fact Schwalbe and Johnsen‘ foundth at cellulose heated with a mixture of glycerol and acetic acida t 135’ C. for several hours did not show any sign of at ta ck asindicated by reducing power, and a method of estimating th ecellulose cont ent of commercial wood pulps which included t histrea tmen t was developed by them. Later, Johnsen and Hovey*suggested a metho d of cellulose determination i’n wood consistingof a 4-hr. hydrolysis with glycerol and ac etic acid at 135’ c.with a subsequent chlorination according to Sieber and Walterand found t ha t by employing this method a residue of higherpurity could be obtained from wood fibers.

The subject of cellulose determination was recently discussedby Dore,a who arrived a t th e conclusion th at “all processes in-volving preliminary hydrolysis result in a diminished yield ofcellulose as well as total cellulose and are therefore inacceptableas ac cura te cellulose processes.” Par tly on th e basis of thisstatement, partly on his own observations, Mahood4 in a morerecent contribution to the subject states th at “The modificationof the Cross and Bevan method proposed by Johnsen and Hoveyappears to be of doubtful value since the cellulose, as well as th ehemicelluloses and furfural-yielding constituents, ar e attac ked ”

In view of t he importance of the subject u nder discussion, itwould seem advisable to prove such statements by convincingexperimental dat a. But Dore, as well as Mahood, has failedto do SO, and I hope t o be able to show in this article th at th econclusions arrived a t by the two investigators are based uponinsufficient analytical data and upon statements which are mis-leading and partly incorrect.

In order to facilitate t he discussion of some of th e experimentalresults, two tables taken from Dore’s publication are copiedbelowTABLE 1-COMPARISON OF METHODS F PRELIMINARY YDROLYSIS S

APPLIED O W O O S

Results in percentages of air-dry wood 11.62 er cent moisture)Ratioa-Cel-

lulose:TOTAL ELLULOSE CELLULOSE Total

Individual Av. Individual Av. Cel-

Renker’s modification ofCross and Bevan’s method.No hydrolysis

Original Cross and Bevanmethod. 1 hr. with 1 percent sodium hydroxide atboiling temperature

Johnsen and Hovey method.4 hrs. with acetic acid andglycerol at 135‘ C.

47.9348.4648.9748.7748.9148.2748.2445.8646.2845.8545.0745.6446.29

44.0444.1144.3744.49

48.51

45.83

44.25

36.0436.0236.7136.8437.0936.7636.9935.3835.4935.2535.0335.7635.55

34.6034.7334.7034.53

lulose

36.64 0.75

3.5.41 0.77

34.64 0.78TABLE 111-FURFURAL Y I l L D O F PRODUCTS

In percentages of air-dried material 11.62 er cent moisture)FROM

IndividualELLULOSE v

FROM TOTAL

IndividualELLULOSE v.1) Renker’s process N o hydrol- 2.66 0.52

ysis 2.36 . . . .2.69 0.482.38 2.52

2) Cross and Bevan’ s process. Al- 2.67 0.310.51 0.50

kdtne hydrolysis 2.63 2 . 6 5 0.24 0.27

Acid hydrolysis 2.20 2 . 1 9 0 . 2 7 0 6

Pulg Pape r M a g . Can. 13 1915), 600.J SOC. hem I n d . 37 1918), 132.THIS OURNAL, 2 19201,264.I b i d . 18 19201, 73.

3) Johnsen and Hovey’s process. 2.18 0.25



360 T H E J O C R N L O F I N D U S T R I L

Th e determination of a-cellulose gives, of course, an excellentindication of the purit y of t he residues, provided th e a-celluloseis a well-defined substance . Tab le 11 however, shows that thisis not so, since the furfural yield of th e a-cellulose obtained fromRenker’s process is considerably higher than of that obtainedwith Johnsen and Hovey’s method. The a-cellulose from th elatter process yields 0.26 per cent furfural, which is very close

to the yield from purest cotton cellulose,l e. e . 0.24 per cent.Wit h regard to furfural yield and a-cellulose con tent of th e resi-dues, it will also be seen from the two tables th at the celluloseresulting from Johnsen and Hovey’s method is of a higher puritythan that from Renker’s method (no hydrolysis), which latteraccordingly must give a higher yield. Assuming th at t he fur-fural originates with highly resistant pentosans (which has neverbeen disproved), th e difference in yield of pentosan-free or-cellulosewith t he two processes was only 1.58 per cent, while the differencein total cellulose in t he two processes was 4.26 per cen t, whichshows that Dore’s statement that the total cellulose and theor-cellulose “ar e destroyed in th e sam e proportion” is incorrect.

The difference of 1.58 pe r cent in th e yield of a-cellulose doesnot necessarily mean th at the normal cellulose is attacked in thehydrolytic treatment. Th e possibility natural ly exists th at a

cellulose which has been exposed to acid hydrolysis is more easilyatta cked by strong alkali t ha n a cellulose which has not receivedthis treatment. But it is more probable that the difference inyield is caused by the removal of carbohydrates other thanpentosans and less resista nt tha n cellulose. Apparently Dore.as well as Mahood, is inclined to consider as cellulose all sub-stances in the cellulose residue which do not give furfural reac-tion. This can hardly be accepted as correct since we mus tassume th e presence of hexosans of less resistance t ha n cellulose,and which therefore can be separated from the cellulose properby hydrolysis, but by a more effective hydrolysis than that ob-tained with sodium sulfite at 100” C.

Thi s would explain t he considerably lower yield of cellulose inthe commercial wood pulp processes tha n the yield indicated bythe cellulose determination, since the commercial processes in-clude hydrolysis a t high tempe rature an d pressure. It wouldalso explain why the yield obtained with Johnsen and Hovey’smethod is lower +an th a t of Renker’s method, because th e formerincludes an acid hydrolysis with acetic acid in glycerol at 135” c.Since this process removes the more resistant furfural-yieldingsubstances and hexosans to a larger exten t than Renker’s method,the residue is more identical with the pulps obtainable in thecommercial processes. Johnsen an d Hovey therefore consideredtheir method “very useful in the valuation of the various woods€or th e commercial paper pulp processes.”

Dore concludes that “the hydrolytic processes do not removean y appreciable a mount of the furfural-yielding complexes fromth e product.” Bu t there are no experimental dat a in Dore’sarticle to prove this conclusion, while Johnsen and Hovey’spublication shows tha t with their method over 10 per cent moreof t he tot al furfural-yielding substance is removed, or th a t be-tween 22 and 25 per ce nt of these su bstances still remaining inth e residue from Renker’s method are removed with their method.

In discussing th e removal of these substances by acetic acidhydrolysis, Mahood s tate s th at “approximately t he same resultcould be attained by a further chlorination of th e sample th anusual.” Bu t this is xtot so, since apparen tly the furfural-yieldingconstituents, while being comparatively easily hydrolyzed, arevery resistant t o chlorination o r oxidation. Furthermore, it

must be remembered that it is not permissible in a quantitativemethod to continue the chlorination after the total lignin hasbeen removed, since this would result in an oxidation of t hecellulose proper.

Mahood’s stron g criticism of th e Johnsen an d Hovey methodis based to a very great exten t upon Dore’s experiments, according

A N D E N G I N E E R I N G C H E M I S T R Y 1701. 13, NO

to which the normal cellulose is destroyed by hydrolysis withacetic acid in glycerol a t 135” C. For these experiments Doreselected as normal cellulose “a piece of c ott on sheeting which hadbeen repeatedly laundered and might therefore be consideredresidue consisting of highly re sis tan t cellulose, mostly oEnormal type.’’ This is fundamentally incorrect, since it is known th at t he resistance of cot ton cellulose is considerably

reduced by laundering. On the othe r hand, Schwalbe and John-sen have found that the hydrolysis with acetic acid in glyceroldoes not att ack t he cellulose. Purest c otton cellulose hydrolyzedwith this mixture and subsequently treated with nitrous gaseslos t only 0.12 per cent of its weight. Unfortunately thi s workhas not y et been published in detail, b ut i t has been referred t oin recent publications by Johnsenl and by Schwa1be.l

In conclusion, the writer wishes to refer to two statements inMahood’s article, because they are in disagreement with theresults obtained by other investigators, and should therefore bemore thoroughly investigated. Mahood found th at there wasan appreciable loss in weight of th e fibrous filter pad we d in t heGooch crucible, owing to t he actio n of chlorine. When usingpurified calico Sieber and Walter recorded a loss of 0.001 g.purified calico pad gained 0.0002 g. in the trea tmen t. Sieber

and Walter also found that cooling did not have any influenceupon the yield, while Mahood believes that the lower yield ofcellulose which he experiences with Sieber and Walter’s modi-fication of t he method as compared with th e original method isdue to the higher temperature.

Sieber and Walter’s modification of Renker’s meth od re pre-sents a decided improvement in th e process in mechanical manipulation, in t ha t i t eliminates mechanical losses of fiber, and themethod has therefore been adopted by most of the recent vestigators and by commercial laboratories. It should therefobe carefully investigated whether the lower yield with this pro-cess as recorded by Ma hood is du e to destruction of cellulosesubstance on account of excessive chlorine treat me nt, or whetherit is due to a less complete purification with Schorger’s equip-ment.

B JARNE JOHNSENAMMERMILL APER COMPANYERIE PSNNSYLVANIA

November 5, 1920. . . . . . . . . .

Editor of the Journal of Industrial and Enpaneering ChemistrJohnsen contends th at my conclusions “are based upon insuffi-

cient analytical data and upon statements that are misleadingand partly incorrect.” It is to be regretted that Johnsen offersno new experimental data in suppor t of th is rathe r sweepingstatement.

Th e first point a t issue concerns the definition of cellulose, andit is stated tha t I (in common with Dore) am “inclined to regardas cellulose all substances in the cellulose residue which do notgive furfural reaction.” This stat eme nt is indeed misleading,for, in regard to the cellulose obtained in t he investigation underdiscussion, I say t ha t “th e cellulose obtained in each case wastreated with chlorine and sodium sulfite to the point wherecolor was obtained.” Thi s defines wood cellulose as well aspresent knowledge of its chemistry will permit. Th e residuethus obtained is made up app are ntly of hexosans, pentosans, a ndpossibly furfural-yielding constituents other than pentosans.Johnsen’s original paper on the subject, a s well as his more recentdiscussion of it, is open t o th e criticism t ha t he does not definewha t he means by cellulose. Apparently he considers th at thereis bu t one, cellulose, and th at normal or c otton cellulose.pointed out by Schorger, it is no more reasonable to expect cot-ton to be the only cellulose in nature tha n glucose to be th e onlysugar. It is probable that wood celluloses should be looked uponas definite compounds of hexosans with varying amo unt s ofpentosans.

1 2 . ongew. Chcm. March 5 and 12 1918); ape r 28 19181, 2 7 7 . L O C . C i t



Apr., 1921 T H E J O U R N . 4 L O F I N D U S T R I A L

We are not obliged to assume, a s Johnsen contends, “th e pres-ence in wood of hexosans of less resistance4 ha n cellulose an dwhich Carl therefore be separated from cellulose by hydrolysis,but by a more effective hydrolysis tha n t ha t obtained by sodiumsulfite at 100” C.” This assumption is very convenient for th epurpose of corre latin g Johnsen and Hovey’s metho d of cellulosedetermination with th e wood pulping processes, bu t it ought to

have some experimental basis which as yet is entirely lacking.Commercial processes are a s a rule poor criteria by which to judgeanalytical methods. I t is generally considered that the differ-ence between th e yield of cellulose obtained from wood by t helaboratory method and that obtained by the pulping processesis due to the more drastic treatment in the latter which destroyssome of th e cellulose. Since Johnsen and Hovey’s method givesa “residue more identical with the pulps obtainable in the com-mercial processes” it may be assumed, i n the absence of experi-mental dat a to t he contrary, th at it, too, destroys some of thecellulose.

Johnsen objects to my statement that “approximately thesame result could be attained by a further chlorination of thesample than usual” in reference to the residues obtained by hismethod. Approximately 50 per cent of the furfural-yieldingconstituemts of woods are removed b y t he ch lorination process.It seems reasonable to suppose, therefore, that a further loss ofthese cons tituents would resu lt on continued chlorination (John-sen says “this is not so,” b ut gives nothing to show tha t i t is not).Since it i s not permissible, as Johnsen points out, to continuechlorination after the total lignin has been removed, as thiswould result in oxidation of t he cellulose, furth er chlorinationof t he sample th an usual would hav e the effect of reducing bot hthe pentosan a nd the pentosan-free cellulose content , and this isthe apparent effect of the digestion with glycerol and acetic acid.

Johnsen’s statement that my criticism oE his method is based“to a very considerable exte nt on Dore’s experiments” seems tobe an attem pt at subterfuge. My data show tha t the yield ofpentosan-free cellulose as well as t he pentosan content of the cellu-lose is reduced by preliminary tr eat me nt of th e wood sample withth e acetic acid-glycerol mixture. Johnsen explains this loweringof the pentosan-free cellulose b y assuming th at the loss i s due tohexosans less resistant than cellulose, but there is nothing inJohnsen’s paper to warrant this assumption. On th e other hand,Dore’s data corroborate mine, and although it is t rue t ha t laun-dering, beyond a certain point, reduces the resistance of cellulose,the data still hold for the comparative purpose for which theywere intended.

Johnsen’s observation that “two statements” in my article“are in disagreement with th e results of oth er investigators”should be modified to include only two other investigators, i e.Sieber and Walter working jointly, a nd i t should be noted t ha tmy state ment in regard to the effec t of temperature is supportedby Cross and Bevan and by the work of Re nker.

Th e fact th at my dat a are not i n accord with those of Siebesand Walter on th e loss in weight of t he fibrous pad emphasizesthi s poten tial source of error in t he procedure. I used the bestcalico obtainable an d subjected it to tre atme nt with chlorine andsodium sulfite prior to making the test runs. Th e loss entailedwill be determined largely by the previous history of the calico,an d since this can not usually be determined it c annot be assumedth at th e loss in weight will be negligible if accura te results aredesired. If other objections t o th e Sieber and W alter procedureare overcome this potential source of error can probably beeliminated by the use of a Willard crucible.1

Applying Johnsen’s tes t of pur ity of cellulose, i e. the amountof furfural i t yields, to th e cellulose residues obtained by me withSieber and Walter’s apparatus, they contain an average of 7.68

1 Described at the St. Louis Meeting of the American Chemical So-ciety, April 12 to 16, 1920. The bowl of this crucible is pyrex glass, whilethe bottom ronsists of a porous alundum disk which is fused to the glass.

A -VD E N G I N E E R I N G H E M I S T R 36 1

per cent pentosan, while those obtained wi th Schorger’s app ara tuscontain 7.85 per cent. Th e purity of the residues, which Johnsenthinks may be different, appears, therefore, to be of the sameorder.

Th e lower yield of cellulose using Sieber and Walter’s equip-ment does not a ppear to be due to “excessive chlorine trea tmen t,”as indicated by the following data from my paper:‘ “Five one-

half hour chlorinations were required for complete chlorinationfollowing Cross and Bevan’s procedure while periods of 20, 15,15, 10, and 10 min. were required with the modified procedure.”Taking int o consideration these experimental facts and also thework of Cross and Bevan an d of Renker, my stat emen t th at “thehigher yield (of cellulose) obtained using the original procedure,notwithstanding th e longer exposure to chlorine, is probably ac-counted for by a lower concentration oE chlorine and a lowerchlorination tempera ture” seems justified.

In th e hands of competent ana lys ts th e mechanical Iosses inmanipulation using the method of Renker an d of Schorger arenegligible. The only advanta ge of the Sieber and Walter methodis a shortening of the time required for the analysis. With th euse of the Willard crucible, a dilut ion of th e str eam of chlorineor th e use of a suitable cooling device or both of these, perhaps,it may be made t o give as good results a s the original Cross andBevan procedure.

The statement by Johnsen that the Sieber and Walter method“ha s been adopted by mos t of th e recent investigators an d bycommercial laboratories” is answered in part a t least by the fol-lowing from the article by Johnsen a nd H ovey ? “As in recentinvestigations use has no t been made of th is improvement, whichin our opinion is extremely valuable, th e preparat ion of th ecrucible as suggested by Sieber and Walter is described here.”Where it has been used it apparently has been adopted in theway that Johnsen and Hovey adopted it, i e . without determin-ing its accuracy in comparison with the original procedure.Johnsen’s suggestion that the controverted points should be“more thoroughly investigated” is therefore timely. I n thisinvestigation should be included ano ther of Sieber and Wal ter’ sconclusions as stated b y Johnsen “t ha t four chlorinations witha tot al exposure to the gas of 1 hr. was sufficient for th e completeremoval of the lignin from wood.” Schorgers found th e numberof chlorinations necessary to o btai n lignin-free cellulose to va rywith wood from the same species as well as with wood from dif-ferent species.

Up to the present time the Johnsen and Hovey method hasnot proved to be4 “a standard method which could be recom-mended for future investigations.” I n fact, with the determina-tion of th e furfural-yielding constituents as the sole tes t of pu rityof t he resulting cellulose, th e trea tme nt with th e glycerol-aceticacid mixture, in addition to being objectionable for reasons al-ready pointed out , seems superfluous, since the percentage ofcellulose free from furfural-yielding constituents or “pure” cel-lulose can be obtained by d educting th e percentage of these“impurities” from the cellulose values obtained by chlorination.

Such a correction is recommended by Schwalbe6 and is madeby him and Beckere recently in t he analyses of some species ofGerman woods. It can be applied to the results of Schorgerand others who have recorded the pentosan content of the cel-lulose if one objects t o furfural-yielding co nsti tuen ts as impuritiesin the cellulose.

THE LABORATORY F ORGANIC CHEMISTRY S. A . MAHOODTULANR UNIVERSITY, EW O R L E A N S ,LA.

February 8 1921

. . . . . . . . . .THIS OURNAL, 12 1920), 875.J SOC. hem. I n d . . 87 19181, 1331.THIS OURNAL, 9 1917), 63.

’ SOC. hem . Ind . . 87 1918). 132r.6 2 ungew C hem. 8 2 1919), 125.

Zbid 82 19191, 229.



3 6 2 T H E J O U R N L O F I N D U S T R I L

ditor of the Journal of Industrial and Engineering Chemistry:Johnsen protests against my statement that “all processes

[for th e dete rmination of cellulose in woods] involving preliminaryhydrolysis result in a diminished yield of or-cellulose as well astota l cellulose and are therefore inacceptable as accurate celluloseprocesses.” This , he maintains, I have failed to prove “by con-vincing experimental data .”

The first part of th e above statement is nothing more tha nthe verbal expression of d at a which Johnsen has quoted in Table11 and may be regarded, therefore, as a fact beyond dispute ifth e da ta be accepted as reliable. Th e second part of my state-ment deals with th e significance and in terpretation of these factsand it is with this part that Johnsen’s criticisms are concerned.

Johnsen expresses a doub t as t o whether a-cellulose is a well-defined substance, inasmuch as that obtained from Renker’sprocess yields an average of 0.50 per cent furfu ral while tha tfrom the Johnsen and Hovey process yields only 0.26 per centfurfural. The differences in furfural yield do not necessarilyindicate that the a-cellulose is an ill-defined product. It is byno means certain that the furfural obtained from the a-celluloseresidues is due to pentosans; on the contrary, the fact that theyield is small increases the prob ability t ha t i t originated in other

substances, for it is well known that other carbohydrates thanpentosans a re capable of yielding furfural, usually, however,in but small amounts. Furthermore, the fact that th e amoun tof furfural obtained from an y one substance varies accordingto the conditions maintained during the analysis appears toindicate that the furfural is obtained, not altogether from pre-formed groups, but, a t least in p art, by rearrangements withinthe molecule. I n view of t he known labile character of the cellu-lose molecule, it is not unreasonable to regard th e furfural yieldof the a-cellulose as probably resulting from such rearrangement.The observed differences in furfural yield between the a-celluloseresidues by the two processes may be due to alterations in themolecular arrangement s during preliminary treatmen t. Suchchanges may be assumed to take place without necessarily im-plying that the two products are essentially different.

Since the furfural yield is subject t o th e influence of so many

possible factors, it would appear that the conclusion expressedin my original article is correct and that no significance is to beattached t o t he small furfural yield of the a-cellulose.

Johnsen claims th at t he a-cellulose by th e Johnsen and Hoveyprocess yields an amo unt of furfural approximating th at frompurified cotton. This claim is based upon the agreement of datawhich are not properly comparable. The figures quoted inTable I11 of Johnsen’s article show th at t he residue by th e John-sen and Hovey process yields 0.26 per cent of furfural expressedin percentage of the original air-dry wood. When recalculatedt o the basis of t he a-cellulose, which consti tutes 34.64 per centof the air-dry wood, the furfural yield by the Johnsen and Hoveyprocess becomes 0.75 per cent. When this figure is comparedwith th at given by Johnsen for the fur fural yield of purifiedcellulose (0.24 per cent), it is clear tha t the residue by the Johnsenand Hovey process yields considerably more furfural than puri-fied cotton.

Inasmuch as i t is generally recognized th at su bstances otherth an pentosans ar e capable of yielding furfural, we are not obligedeither to assume or disprove that the furfural yield of celluloseresidues is du e to pentosans. It appears probable t ha t th e sn-allyields of furfu ral from the a-cellulose residues are largely orwholly due to oth er sources; therefore Johnsen is not justified inassuming tha t the furfural originates in pentosans, or in applyinga pentosan correction to the residue. He has accordingly failedto disprove th at the tot al cellulose and or-cellulose are “destroyedin t he same proportion.”

The data in the last column of Tab le 11 quoted by Johnsen,show t ha t the to tal cellulose by th e Renker process contains anaverage of 75 per cent of or-cellulose, while tha t by the Johnsen

A N D E N G I N E E R I N G C H E M I S T RY Vol 1 3 , No.

and Hovey method co ntai ns an average of 78 per cent of a -cellu-lose. In the case of co tton cellulose, the tot al cellulose by tRenk er process yielded 95 per cent of its weight of -cellulose,and th at by the Johnsen and Hovey process yielded 94cent of a-cellulose. This is ap pare nt from the following da taquoted from Table IV of my original article:’

R i t i o

,-cellLiosTotal Cellu-otalTREA TME NT Cellulose a-Cellulose lose

No hydrolysis Renker’s method) 89 .9 0 80 .32 0 . 9 5Acetic acid and glycerol 4 hrs. at 135” C

Johnsen nd Hovey’s method). . 85.91 80.63 0 9 4

My original contention, in so far as it applied t o the Johnsenand Hovey process, was that the differences between 75and 78 per cent in one instance, a nd between 95 and 94 per cein another, ar e not sufficient to indicate a material improvementin the purity of the product by the Johnsen a nd Kovey processover that by the Renker process. It therefore appears correctto ascribe th e diminished yields of to tal cellulose and a-celluloseto a destructio n of those substances in practically the sameproportion.

Johnsen has shown th at if the furfural of the a-cellulose becalculated t o pentosan and d educted, th e residue by th e Johnsen

and Hovey process still con tains 1.58 per cen t less of th e pentosan-free a-cellulose than th e residue by the Renker-process. Thisdifference, he maintains , is probably due, no t to a n attac knormal cellulose, bu t to a removal of less resistant carb ohydratesnot properly to be regarded a s cellulose. However, these car-bohydra tes, which Johnsen would exclude from the a-celluloseresidue as not being normal cellulose, are resistant to chlorina-tion and sulfite treatments and the subsequent treatment with17.5 per ce nt sodium hydroxide. It would seem, therefore, thatthere is little or no justification for designating them as “lowercarbohydrates,” or classifying them with the hemicelluloseswhen their properties are so much more closely related to thoseof th e true celluloses.

In my original article2 my conception of cellulose “as applieto material derived from woods,” was stated as the “residueremaining after alternate treatments with chlorine and sodium

sulfite solution” when th e process is “preceded with non-hydro-lyzing treat ments only. The residue so obtained should befree of lignin an d hemicelluloses. It may contain CY-, p - aycelluloses corresponding to the definitions of those substancesimplied by the conditions of the mercerization test also fmfural -yielding complexes, but should be free from easily hydrolyzablepentosans.” The quotation s should render unnecessary anyspeculation as to what I consider cellulose.

The defini tion of cellulose as a residue of processes is consis tentwith th e views of Cross and Bevan and those of Renker. Schor-ger, who confirmed some of Renker’s views, has g iven a formdefinition of cellulose as “the residue remaining after alternatetreatm ent with chlorine gas and sodium sulfite‘up to th e pointwhere the chlorine sulfite color reaction or the Maule reactiondisappears.”* All of these authors regard cellulose as a residuof processes. Unt il more complete information exis ts regardingits chemical nature, it appears desirable to regard wood celluloseas a group of substances with a similar degree of resistance toreagents. Repeated attempts to narrow it down to a singsubstance, similar to th e cellulose of cotton, h ave been uniformlyunsuccessful. because th e high resistance of t he residue requiresthe use of drasti c reagents, which invariably atta ck all membersof the group.

Johnsen claims th at my statement t ha t “t he hydrolytic pro-cesses do not remove any appreciable amount of the furfuralyielding complexes from the product” is not supported by ex-perimental dat a. The data quoted in Table I11 show that the

THIS OURNAL,, 2 1920), 68

LOC ., p. 269

8 T ~ r s OURNAL, 9 1917), 563.



Apr. , 1 9 2 1 T H E J O U R N A L O F I N D U S T R I A L

total cellulose by Johnsen and Hovey’s method yields only 0.33per cent less furfural tha n th at by Renker’s process. The sametab le shows a variation of 0.33 per cent between the highest an dlowest of four determinatio ns of furfura l yield on mat eria l pre-pared by Renker’s process. No significance can be attached,therefore, to a diminut ion of a few ten th s of 1 per cent in furfuralyield, and t he results indicate th at a t most only a trifling re-duction in furfural yield is accomplished by the Johnsen and

Hovey method.I t is claimed for the Johnsen and Hovey method that it gives

a residue corresponding closely to that obtained in manufacturingwood pulp, and tha t i t is therefore “very useful in the valuatio nof woods for th e commercial paper pulp processes .” I do notdispute the possible value of this method as a echnical methodin pulp mill practice. Th e residue, however, does no t conformto a ny recognized conception of cellulose and should no t be SO

designated. Johnsen does not claim tha t the residue by theJohnsen and Hovey process is “pure” in the same sense that heregards. the Renker residue as “impure.” He claims that th eformer is purer, but t he most favorable dat a show th at a t bestit can be regarded as only slightly purer. Furthermore, th ereduced yields of total and a-cellulose by th e process show th attru e cellulose is partly destroyed. (This statement rests uponthe experimental data which Johnsen has quoted. It has beenquestioned by him but not disproved.) It is my contention,therefore, that however useful the Johnsen and Hovey methodmay be for judging the paper-making qualities of woods, it isunsuitable for scientific investigations on the chemical nature ofwoods or other cellulosic materials.

Johnsen has taken exception to my statement that “cottonsheeting which had been repeatedly laundered” might be con-sidered “a residue of highly res ist an t cellulose most ly of thenormal type.” The fact tha t the residue on chlorination yielded95 per cent of a-cellulose shows both a high degree of res istan ceand a high proportion of a r normal cellulose. No claim hasbeen made that it was in any sense a chemically pure cellulose,and it was not necessary that it should be such for the purposein mind, namely, to determine whether cellulose from an unlig-nified source showed the same behavior as wood cellulose. Th eda ta show t ha t this cellulose, as well as wood cellulose, gives lesstotal and less a-cellulose when treated by t he Johnsen and Hoveymethod. Th e reduced yields of a-cellulose indicate tha t thenormal cellulose is attack ed by this process.

Experiments with highly purified cellulose are undoubtedlycapable of contributing grea tly to o ur knowledge of fundam entalcellulose chemistry. I t is unfortunate that the valuable datato which Johnsen has referred have not been published in detail,and it is to be hoped that they soon will be made completelyavailable. WALTER H. DORE

’

UNIVERSXTY OF CALIFORNIA EXPERIM~NT TATION

BERKELEY, ALIFORNIAJanuary 31, 1921

A N D E N G I N E E R I N G C H E M I S T R Y 3 6 3

Anthraquinonea-Benzoylbenzoic acid

z angew. C h e m . 19 19061, 69; e y. 41 1908), 3631Quinizarin 1,4-Dihydroxy-anthraquinone)

B e r. 6 1873), 508; U. . Patent 708,142. This product is used in theproduction of two very important dyestuffs, namely, Alizarin and CyanineGreen, and Alizarin Direct Violet, also known as Alizarin Irisol

2-MethylauthraquinoneBer., 41 1908j, 632. This very important intermediate is used in the

manufacture of three well-known vat dyes, namely, Anthrdflavone G,Cibanone Orange R, and Cyananthrol R and G. This last-named inter-

mediate is used in the production of other intermediates, from which areproduced other vat dyes such as, for example, Indanthrene Gold Orange G

Hydron YellowD . R. P. 1,055,287

A very good reference on all the above-mentioned produc tsmay be found in “The Manufacture of Intermediate Productsfor Dyes,” by J. C. Cain, 2nd Ed., Macmillan Co., 1919.

You may see from the above list, which is by no means com-plete, t ha t there are some very importan t product s among them,from the standpoint that they are the starting points for themanufacture of dyestuffs , a great propo rtion of which have notas yet been produced in this country.

THE CHEMICAL OUNDATION, NC. ARTHURLINZ81 FULTOM T., NEW YORK, N. Y.

March 5, 19?1

A Memorial of Sir William RamsayIt has just been learned tha t the Dean and Chapte r of West-

minster Abbey hav e decided to place a bronze medallion in theAbbey as a memorial of Sir William Ramsay.

The news of this trib ute t o the genius of the brilliant Englishchemist will be received with th e deepest and most sympa-thet ic intere st among his many American friends, who regardedhim so highly a s a scientist and loved him so truly as a man.

Phthalic Anhydride DerivativesEditor of the Journal of Industrial and Engineering Chemistry.

I noted with inte rest the list of phthalic anh ydride derivativesappearing in THIS OURNAL, 3 1921), 274. I was surprisedto no te th at some of the commercially most important deriva-tives have been omitted. I am listing below certain of theseproducts and the li terature references for the same, and suggestthat these be added to the list already published.

Naphthoyl benzoic acidNaphthanthraquinone

Schultz’ “Dyestuff Tables,’’ 260. Also, under the dyestuffs shouldbe added the product known and sold as Sirius Yellow G, which is producedfrom the above -mentio ned intermediates, and is an important dyestuffin the lake pigment industry.

Federal Trade Commission RulingsThe Federal Trade Commission has denied the application

of th e M eadows Oil and Chemical Corporation for license underth e Trading-with-the-Enemy Act to use trade-ma rks coveringichthyol. A former application made in November 1920was denied, but t he company applied for a re-hearing, which tookplace on January 25. The Commission says “it is not to thepublic interest to grant th e desired license.” Last Decemberthe War Trade Board called the company’s attention to thefact th at a bulletin issued by the company regarding im-portations of ichthyol had been so worded as to mislead a num-ber of firms into thinking i t an official state men t of t he W arTrad e Board. The Meadows Company has issued a stat emen texplaining that this impression was not intentionally created.According t o a statement bv the Board. “Informationreceived Iby t he War Tra de Board would tend t o show th atAmerican ammonium-ichthyol-sulfonate and other substitutesfor German ichthyol-satisfactory physically, chemically, andtherapeutically-are obtainable from domestic sources on rea-sonable terms as to price, quality, and delivery. It is under-stood, of course, tha t th e American product is not derived fromthe bituminous shale found in Seefeld, Tyrol, but is derivedfrom a somewhat similar fossiliferous rock found in Texas. Anysta teme nts which we may make regarding t he issuance of licensesto import German ichthyol are subject to revision upon the re-ceipt of new information which may tend t o prove tha t th e Amer-ican product is or is not a satisfactory substitute in all respectsfor the German ichthyol.”

Th e Commission has cited the Winthrop Chemical Com-pany? Inc., New York Ci ty, in compla int of unfair com-petition in the drug trade. The company is charged withfalsely advertising that genuine veronal is sold exclusively byth at company. Prior to t he war veronal was sold in theUnited States under a German patent, and during the war threeAmerican manufacturers, not including the Winthrop ChemicalCo. were licensed by the Federal Trade Commission to makeand sell veronal. Subsequently the Winthrop Company boughtfrom the Alien Property Custodian the German trade-mark withthe right to make and sell veronal. April 12, 1921, or shortlythereafter has been set for the hearing of t he complaint.

‘

note on the use of potassium permanganate in the determination of nitrogen by the kjeldahl method

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