34 THE .JOlTRNAL OF THE SOCIETY OF DYERS AND COLOURLSTS. [March 25.1891.

I’ROY. WATSON SMITH IN THE CI1All l .

THE CHAIRMAN briefly introduced the Lecturer explaining that owing to a severe cold Mr. Sharr was unable t o read the paper personally.

Mr. Sharp’s paper was then read as follows by JIr TIfonr WIIITAKER and Mr. C. RATWON :-

SOME NOTES ON CAUSES WHICH GOVERh THE FORMATION OF PERMANENT ANT OTHER DYES.

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BY JAMES SHARP, F.C.S., ETC.

SINCE my last lecture on Permanent Dyes, several of our members have requested me to pursue the sub ject further in support of the views I put before you and regret was expressed that the discussion was not adjourned. I n again bringing the subject beforc you, I do so in compliance with such request, and with the full knowledge that I must prove to you1 satisfaction that my conclusions as previously put before you are correct, or I expose myself to your criticism on both the practical and theoretical aspect: of these important questions, which are exercising the minds of many chemists and others engaged in the trade. The chief interest, as shown in the discus sion on my last paper, was directed to the propertier and uses of logwood and the various hydrocarbons Having Professor Smith in the chair, with hir great experience as editor and as cheniical lecturer a t University College, London, to the City Guilds and late of Victoria University, he will no doubt traverse my remarks, and if necessary correct me with judgment I now propose to bring before you some causes which govern the formation of perma- nent and other dyes produced from logwood and hydrocarbons generally, and which were of necessity excluded from my last paper. I n again speaking to you on logwood, no historical account is necessary. You all know that the wood known to dyers as log- wood was discovered in America, and that botan- ists have named the tree hmmatoxylon, whilst chemi- cal authorities are agreed that its colouring princi le is correctly represented by the formula C l , ;H l~6 , ; , and that practical dyers look upon the wood as consist- ing of about 90 per oent of cellular fibrous matter, in- soluble in water, and which has no value as a dye, and about 10 per cent. of colourless soluble sap or so-called glucosides, which is the colour-giving constituent of the so-called logwood. This dyestuff’ is put upon the market as prepared wood, hEmatein, and as extract, principally hrematoxylin, ready for the use of the dyer and printer. Both those conditions have special advantages, of which I shall speak later on ; but I may say that both these bodies were examined by Chevreul, Erdmann, Schutzenberger, and others, and a comparison of their dyeing power showed that 6 of the prepared wood (hzmatein) were equal to 10 of the fresh ground unprepared wood, as hzma- toxylin. But since those days new modes of applica- tion have been discovered, and for commercial pur- poses new mechanical appliances have been intro- duced for extracting the hzmatoxylin. Still these conclusions are practically correct. Now, to nianu- facture ure logwood extract, mostly hxmatoxylin, the woox is chipped in the ordinary way, not ground or oxidised, and the fresh chipped wood is extracted with pure or distilled water in copper extractors under pressure, and in consequence of the glucosides

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not being very soluble in boiling water, even under prcssure, after boiling about one lionr, the licluors are N ithdrawn and fresh water applied again and again until all the colour is extracted. Theae liquors are concentrated in vacuum pans to form extract of any roqnired strength, and no chemicals, drugs, or other ingredients should be present in best qualities of extract. The low qualities often have molasses present, and some commercial extracts are often manufactured from various colour-yielding products. Before speaking of the special uses and properties of hmnatoxylin, I will briefly describe the nzotlus opwandi of transforming the hxmatoxylin to hmma- tein. The wood is rasped or chipped, according to the purpose for which it is intended to be applied. The woud is moistened with at least 30 per cent. of water, and laid up in heaps of 10 or 20 tons in each bin ; the water is a t once absorbed into the wood, and it is an advantage to be able to keep the temperature a t about 65” F., although natural condition and extended time often have to answer. The colourless glucosides in the wood combine with oxygen, thereby displacing two molecules of hydrogen, as shown in the formula for hzmatein, C,,H,,O,: ; thus chemical action generates heat and necessitates the wood being turned and exposed several times during the trans- formation, which both regulates the temperature and favours uniform oxidation. The time required for complete conversion to hmnatein is from three to eight weeks, according to conditions present and the quality of wood in process. Although alkali added to the water does, by acting as a solvent, promote rapid oxidation and i m p x t a richer tone to the colour of the wood, all such uses are liable to give rise to corresponding disadvantages, but when the process is properly performed the colourless hxniatoxylin is conveited into the rich purple red colour hxmatein. These products, as put upon the market, are often more or less mixtures of the two bodies, and before I 3peak of their respective properties and uses, I will deal with those important causes which prove destruc- tive to the colour of the wood, often termed over- Jxidising, over-ageing or heating On these the authorities have been silent, and ractical conclusions have been based upon fallacious fypotheses. I trust C shall show conclusively the causes which govern the Eormation and destruction of this dye.

I n pursuing this business every large firm of dye- wood grinders, has experienced mishaps in the iot summer weather, when consumption and stocks tre the heaviest. The elevated temperature favours t too active oxidation, which a t times becomes quite ingovernable, even by turning and exposure, and in mch cases the results are what are termed over-aged, wer-oxidked and heated, and as the result the solour in the wood is wholly or in part destroyed, ust in proportion as the process has been checked or tllowed to run its course. The valueless residue has lot, so far as I know, been examined and recorded )y any competent person, though results are often xought about by having the heap too large and $00 thick, and neglect in turning and exposure. h e a t heat is generated, breaking up the hydrogen Croup which governs the formation and destruction If this important dye. The elevated temperature hav- ng removed all the moisture, practically there is no )xidieing agent or medium, while the conditions are ,uch as to dehydrogenise the hmnatein ; .therefore, i t s of interest to have these reactions placed iefore you clearly and consecutively. The colourless ircniatoxylin C,,H,,.O., is converted into hzmatein >ll;H,zO.G, thus becoming a rich dye, which is de- itroyed by removing two further hydrogen atoms, hus : C, ,,HloOl,. By removing two hydrogen atoms ‘rom hcematein it ceases to be a dye. Hence, I say

March25,1891.1 THE JOURNAL 011’ THE SOCIETY OF DYERS AND COLOURISTS. 35 ~- ~ ~ - ~- ~

the hydrogen atoms govern both the formation and destruction of h:rmatein as a dye.

I’or my test I have taken a known weight of pre- pared logwood and estimated the h,wnatein present, and calculated the quantity of peroxide of, :ydrogen necessary to displace two hydrogen atoms. 1 he colou is first extracted in boiling distilled water, filtered, an( the peroxide added, when almost immediately the mix ture ceases to have any dyeing power. Hithert we have no proofs in support of the over-oxidatioi hypothesis ; on the contrary, we dehydrogenise botl in formation and destruction of the hamatein, pro ving the process is not one of simple oxidation.

I should like to say one word on over-oxidation o hrcmatein, which, I think, does not arise in the pro cesses just described. Cases of real over-oxidatioi have become obsolete as the result of increase( knowledge and im roved mechanical a pliances ir the manufacture o f dyewood extract. t h i r t y year, agodyewood extract manufacturing was in its infancy Makers had to be educated by experience. Thej extracted prepared logwood in the ordinary way, an( tried to concentrate i t into extract by evaporating in open vessels, heated with copper coils or stean pipes. When the liquors were concentrated to abou 100 Tw., the over-heated steam pipes decomposed th( hitimatein in immediate cont tct, which was throw1 out of solution as an insoluble pitch of a dark brow1 colour, and which had no value as a dye. This ir what I call over-oxidised hatmatein.

I must now briefly bring before you some of thc properties and special uses of these products Practice has, to a large extent, appropriated them products to uses in which they are most valuable The colourless hmmatoxylin is most valuable in print ing and in some special processes of dyeing cotton, i r both of which the colour or black is mostly developec upon the fibre, whilst hrcmatein or aged logwood,wher applied upon mordants, is a definite dye, largely usec for woollen goods, as well as for silk and cotton. A1 the conditions are too numerous to enter upon, bui each have distinct advantages, whilst the dyed samplec before you present some most interesting features. 1 shall have to explain the remarkable influence whic2 known conditions of the cloth exercise upon thc results. Samples No. 1 and 2 are the same cloth chromed together, after which No. 1 was dyed witk prepared logwood as. hrematein, and No. 2 was dyed with the same quantity and quality of fresh ground logwood as h:ematoxylin both being calculated as dry wood, and the goods in both cases boiled one hour No. 3 is the same cloth specially treated by immer- sion in a soap solution, then stoved in sulphur fumes in the ordinary way, as for stove white, after which it was chromed and dyed with fresh ground wood as hmmatoxylin, exactly the same as No. 2. You observe the remarkable difference in depth of dye arising from the different conditions-firstly, in the wood ; and secondly, in the condition of the cloth, which clearly accounts for the erroneous conclusions arrived at from some tests. Samples Nos. 4 and 5 are from stoved white flannel, for the purpose of bringing before you a severe test in support of my assertion that the colour of hiematein C,,,H,,.O,, is destroyed as a dye by the dis lacement of two hydrogen mole- cules-thus C,, -€flo -Oil, with peroxide of hydro- gen, combining to form water ; the two samples were chromed together, and both had the same quantity and quality of dyewood, only No. 4 dyebath had been dehydrogenised with peroxide of hydrogen, calculated to displace two atoms of hydrogen, with the result that it ceased to be a dye. Whilst test- ing either the hematein or hzematoxylin alone, the condition of the cloth need hardly be considered, but in making comparative tests the condition of the

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cloth governs the results, from causes I have placed before you. The repared colour hsmatein is very

hsmatoxylin requires long boiling under pressure. I now propose to deal with those products

derived from coal tar, in support of a statement made in my previous lecture, which, I fear, was insufficient or so incomplete that some doubt remained in the minds of some whose position and experience entitles them to great respect. I fltated it had long been observed that with the increase of carbon molecules the boiling point and specific gravit of the raw roducts increased, that JUSt aa the boigng oint of tlese products increased, the d y a produce$ increased in permanency, with some exceptions-namely, those colours and products in which the di- or the tri-sulphonic acid group has formed a constituent art, also those colours which are formed upon the figre from colourless basic bodies, of which I previous1 gave you some examples, and now bring others be&e you ; and if I have inadvert- ently omitted anything which bears directly upon the

soluble in both \ ot and cold water, whilst the

Benzole ............ Phenplendiamine .. Benzidine .......... Toluel .............. Toluidine diamine . , Phenol.. ............ Aniline ............ Sulphanilic acid.. .. Toluidine .......... Xplidine ............ Naphthalene ...... Naphthol .......... Naphthylamine .... Naphthionic acid.. , Anthracene ........ Arithrol ............ Antbramine ........ Alizarin ............

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the manufacture of bright green-violet, etc., which are fugitive dyes, and were even more so when made

alcohol. By the use of heavier and more fixed reagents the yield of colour has been trebled, and the prices reduced sevenfold.

Aniline salts are colourless bodies, and are included in my exceptions as capable of being transformed upon the fibre into a dark green salts. Take, for example, a solution of aniline hydrochloride and chlorate of potash, or soda, and impregnate the cotton fibre, then submit to a condition which decomposes the salts, when the aniline becomes highly charged with hydrochloric acid, forming an insoluble dark

een basic salt, which is not, in the true sense, a dye. the acid be abstracted by the use of alkalies, the

result is a black basic hydrate, which rapidly absorbs sulphurous acid from the atmosphere, and again becomes green ; the colourless aniline base simply becomes oxidised and insoluble upon the fibre, which does not amount to the manufacture of a dye. Sometimes goods so prepared are dyed on the top and

from rosaniline and iodide of ethyl and methyl

80 - - 87 -

180

184

- 192

215

220

285

290 -

320 - - - -

principle8 I sm advocating, be good enough to men- tion it in discussion, a t the same time bearing in mind that we are dealing with principles- only.

Now,if we take say pure benzole COHO, the boiling oint will be 80° U. By transforming one part to

genzidine, another part to phenylene diamine, and another part to aniline oil, we have three raw pro- ducts manufactured from one of the lightest coal- tar oils, all of which play an important part in the manufacture of fugitive dyes. For years the chryaoidine oran e and Bismarck brown were pro- duced from anfine and phenylene diamine, and these dyes were not so permanent or clean as they are to-da . And why 1 Simply because the .light benzole is no longer used, the heavier body toluidine having taken its place, with the result that stronger, cleaner, and more ermanent dyes are produced ; and as all other conchions remain unaltered, I ask you to say if the cause which overns such results is to be found in the heavier %ody toluidine C,H,N Further, if we take pure aniline and transform it into methyl and dimethyl aniline, we have the basic product for

- Chrysoidiaeand Bismarck brown : Fugitive.

- Satranine and Biemarck brown : Cleaaei

Picric acid : Not fast.

*An methyl and dimethy! yieldr greens and riolets: Fugitive.

Magenta : Fugitive.

Magenta : Fugitive.

and less fugitzve than above.

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Fast yellow : Fast.

Congo series : Fugitive.

Congo series: Fugitive. :Rode, etc. : Fast, -

$Violet, etc. : Fast.

tBrown. etc. : Faat.

passed a3 fast black, but of course they are not fast.

Then, again, in the production of magenta, it is necessary to have a mixture of say one part aniline and two parts toluidine. These colourless bodies are transformed into magenta dye by dehydration, thus following the reactions in forming hzematei'n, and the red dye produced is not very ermanent. Now, if we take toluidine alone, the teavier of those two bodies, and convert into safranine, a red dye, we have a much faster colour than magenta. Now if we continue to manufacture these red dyes from the still heavier bodies such as xylidine we find them too dear ; therefore they must be used in conjunction with still heavier bodies for producing azo dyes. For the moment we will pass to the yellow dyes ; although these acid dyes are excluded in my statement, the furnish a remarkable

roof in support of same. Plenol C,.H OH is the Ease for picric acid ; it distils at 182" C. gaphthol is used for producing a similar yellow dye, its formula CloH,OH, and the boiling point 285" C. If both

%tarch 2% 1891.1 THE JOURNAL OF THE SOCIETY OF DYERS AND COLOURISTS. 81 . _~ ~~

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bodies are treated alike to form yellow dye, the phenol yields picric acid, which is not a very fast dye, and the naphthol yields a similar colour, but much more permanent under some conditions. I ask you again to say if this comes from the use of the heavier body ; if Iiot, what does it come from 1

Now that we have arrived a t the naphthol series, we shall have proofs of the important lateral influences which the various snlphonic acid groups exercise in conjunction with the naphthols, actually governing the properties and uses of the dyes pro- duced, and even going further by prescribing the mode of application and the materials they will dye or will not dye. Hence you may find some reapon for my having some s ecial regard for those dyes in which the sulphonic acic! group occupies such an important position. Now the naphthols are almost colourless bodies, insoluble in water and hydrochloric acid, but soluble in caustic soda.

If we impregnate the cotton fibre with these colourless boiies in solution, by varying the mixture and diazotising, various colours of red, chocolate, brown, etc., are produced upon the fibre, and such colours are very fast, even against chemical reagents ; and if these bodies, the naphthol and naphthi- onic acid, be combined with the anthrol anthra- cene or alizarin series, whkh are the heaviest of till the coal-tar products, perfectly fast blacks and colours are produced. Whilst, on the contrary, if we introduce the benzidine group into the naphthol and na hthylamine or naphthionic acid series, we have refs as fugitive as the Congo reds, and more per- manent dyes of thin class are produced by the use of heavier bodies instead of benzidine, and the causes which govern the formation of direct dyes which require no mordants are clearly manifest in this important class of dyes. And again, if naphthols be used in which the di- or the tri-sulphonic acid group exists, the dyes produced have no affinity for cotton, either with or without a mordant. All the lightest bodies yield the most fugitive dyes, and just as the molecules increase the products yield dyes more and more permanent until they become abso- lutely fast. Perhaps the most remarkable illustra. tions are found in the naphthol, naphthylomine, and naphthionic acid series, which in themselves yield practically fast dyes, and when combined with the heavier bodies absolutely fast dyes. When united with the light benzidine grodp, however, the dyes are most fugitive, but have the special property of dyeing direct either silk, cotton, or wool, either separate or combined, whilst the presence of the acid group destroys the basic properties, and yields dyes which have no basic properties, and have no affinity for cotton. The primary causes which govern the per- manency of dyes produced from coal-tar products are to be found in such products, whilst other causes are to be found in the constitution of the dye itself, as produced by the various treatments to which i t is subjected in the process of manufacture, yielding properties of a special and extraordinary character.

I n order that you may follow these remarks more clearly I have placed on the sheet before you t h e combination of products and the results or pro- perties of the dye produced.

DISCUSSION.

The CITAIRMAN : I am surp, gentlenirn, we have all received this communication of Mr. Sharp’s with great pleasure and interest. Mr. Sharp was good enough to send me his paper for perusal, and having gone through it, 1 hare prepared it few remarks, and i f you will allow me, I will make use of them, and then call upon any gentleman present to enter into the dissussion. I was not present a t the reading of

the previous paper on this very interesting subject, but I have had the principal points of the communi- cation put before me by Mr. Sharp himself, and I have read i t also in the Journal. A? I understand, Mr. Sharp finds that logwood that has stood in heaps exposed to the air in a damp condition, under- goes, like a good deal of ligneous fibre under similar conditions, a kind of fermentation. I n such cases, the colouring matter in the logwood suffers certain changes considerably depreciative of the yield of colour, also that on evaporation of the hzematein solutions, I understand that there is a peculiar teu- dency to loss of colour by the separation of a kind of pitchy product, to the great detriment of those attempting to concentrate bythat means. Mr. Sharp finds, finally, that by treating hsmatein with hydrox 1 (peroxide of hydrogen) a very singular colourless sug- stance is produced in solution, or rather, a colourless solution is produced, which does not dye. Further- more, on attempting to oxidise that solution, colour is not restored. Mr. Sharp also, I understand, pointed out in his former paper that in certain cases oxidation may be regarded as a kind of reduction. I agree with him that it can be so regarded. Let us take an an exam le alcohol ; treat i t with an atom of oxy en and aldegyde is produced. Now, who can say t%at the oxygen enters into the com osition of the liquid in such case 1 The alcohol is refuced from C 2 H , 0 to C, H,O,two atoms of hydrogenhavin been abstracted by the oxygen added. If a further afdition of oxygen be made, however, true oxidation does take place, and the aldehyde is converted into acetic acid C2H,0,. That appears to me to be a different kind of process t o the first one, and i t would seem certainly advisable thatsome distinction should be made between the two. In the first case, certainly, looking from the aldehyde point of view, the molecules of the aldehyde cannot be said to be oxidised. I n other words, they have not absorbed oxygen, but hydro en has been removcdfrom them in the process. I n t f e second case, an oxygen atom has been taken up andabsorbed. There certainly should be some distinction of terms to differentiate between these two facts. Rut, from the point of view of the hydrogen in the alcohol, there has been oxida- tion. The oxygen atom has oxidised some hydrogen and transformed it into the form of water. There are two different kinds of action there, and one might cer- tainly regard the first one as a reducin process. Now if, by the action of his H,O,, f i r . Sharp can reduce a body like hamatein, which gives a powerful dye with bichrome, to a compound which gives little or no colour, and does this without separation of tarry or other coloured decomposition products, evolution of gas, etc., I think i t just probable he has traced the action to the formation of a kind of lezico compound. To say the very least of it, hlr. Sharp’s experiments in this direction are very suggestive, and I think they ought to be pushed further with the object of isolating the reduced com- pounds. However, if leuco compound, there is this difficulty, that l m c o compounds are oxidised back pretty readily to the original chromogene. Hence Mr. Sharp’s reaction with H,O, can scarcely have produced a true leuco compound. It must have pro- duced a more permanent compound destitute of colour, than a leuco compound. But there are many possible ways of doing that if we only regard the structural conditions necessary for the existence of chromogens and dyes. There is thus but one way in most cases of forming the leuco compound, whereas there may be numerous ways of so interfering with structure as to destroy a dye. We may either inter- fere wich the chromophor, when the colour will go, or we may interfere with the amido NH, or OH galt-forming groups, when it will also go. But

hsmatoxylin and hsmatein contain no nitrogen. Hence the salt-forming group or groups must here be phenolic-hgd~oxyl or hydroxyls. Having got so far, I do not see that we can go further without an isolation of the pure substance, or an elucidation of (1) the bonstitution of hsmatein, and 2) of this new colourless body (if it be an indivi 6 ual) aa to constrtzltkn, and a comparison. It would be in- teiesting to know the action of zinc dust on this colourless body. As to the second part of Mr. Sharp’s paper: He proposes, a6 the result of his observations, what amounts to this, that if you take a representative or typical dye containing in its complex molecule the lowest aromatic homologue, a benzene group, and proceed to form other colours on that pattern, so as to rise in a homo- logous series, you will find that with increased rise, increment of CH,, etc., etc., and weight of molecule, ou will get deeper and more permanent colours. Jhus, if you proceed from aniline and get a colour like Fast yellow, you will get progressively deeper, finer, and more permanent colours as you substitute toluidine, xylidine, cumidine. This is a profound truth, it is a matter of observation ; but there is much more besides the mere swelling out of the moleculea and increased molecular weight to be taken into account, though as a general truth, I believe Mr, Sharp’s observations are perfectly correct. I am sure without the advantages and training of a theoretical and research chemist, Mr. Sharp has astonished me with the naturally powerful insight into the workings of law and order he ossesses, and is able to carry and to utilise in his laily practical work as a maker at$ user of dyestuffs. To return to Mr. Sharp’e point, increase of colour by increase of molecule”; there are one or two ways of increasing the molecular girth: (1) By doing so in the sense Mr. Sharp defines, and (2) by a multiplication of chromophors in the molecule-i.e., an increased com- plexity of the molecule, and here we have a very fine example in the caae of pimuline, which gives a good permanent yellow. Now no sooner was this ut into the market, but what did the. Germans do7 They showed their immediate a reciation of this rule Mr. Sharp brings before us. SPhey went straight to the Patent Office with specifications claiming the similar me of meta-xylidine and pseudo-cumidine. And if you just write into the prototype primuline, the elements of these amines, you have the colours derived. With increased weight of molecule they hoped to get a finer, richer colour than Mr. Green obtained. Now with such enormous increase of molecule as would be obtained by diazotisin such primuline bases, you may imagine, if Mr. Sfarp’s observation is correct, that the permanency for artificial dyes should be extra- ordinary, and so I believe my friends Messrs. A. G. Green, Crass, and Bevan find in their new photo- graphic methods based on this process and applied also to the treatment of textile fabrics. It is a some- what wonderful thing (to institute comparisons) that the far simpler structure with only one chromophoric group-viz, that in alizarin- should prove equal, in colours produced, to the far greater complexity of structure and chromo horic increase of such colours aa the primuline co~ours; but then we have to remember that in the alizarin chromogen we have that of an adjective colour, a colour working in con- junction with mordants, whereas in the primuline colours we have got more of a substantive colour, a different sort of dye. It would be a ver interesting thing in this connection, if some colour ctemist could string together into one molecule say a couple of alizarin chromogens, and note if greatly more perma- nent dyeing power were secured. If so, there would then be various ways of still further increaaing it, by

a multiplication of salt-formin groups-ie., OH groups. It is known that as the%ydroxyl groups in- crease from 2 to 3, we get stronger colours. Attempts might be made to increase the chromophoric capacity by doing somethinganalogous towhat is done by string- ing two primulines together. With regard to the function of the sulphonic acid y p in the colour referred to by Mr. Sharp, what think is generally regarded as the truththere,is thatthemultiplication of these groups in the coloiir tends merely to dilute the colour as a dyestuff in the colour-giving sense but to increase the solubilit . Probably the hold that the colour has upon fibre whch has been sulphonated would be after a certain de ree of sulphonation decreased rather than increase$, throu h being rendered ex- tremely soluble, These are &e ideas which have occurred to me in connection with Mr. Sharp’s paper. I daresay there is a great deal I have said which is open to correction but it wlll allow of greater scope for discussion if both the Chairman and the com- municant of the paper offer a field of attack together.

Mr. WILKINSON : Mr. Sharp speaks of dehydro- genising in his pa er, but I rather prefer the old term of oxidation. 1 t i ink we shall not differ very much, however, because the fact remains that after he has taken his atoms of hydrogen away, the molecule haa still more oxygen in proportion to its bulk than it had before, and consequently I think we may fairly say it is a more highly oxidised body than before he took his oxygen away. It seems to me that the old term could still apply, and that we might call it really a matter of oxidation. It comes to the same thing in the molecule a8 a whole. Then again, in getting the dye a little overdone, when he comes to treat it with peroxide of hydro en : If it was urely a matter of taking awa & e . hydrogen, ! think we should get it bac% again, because in the other case, when we get it from the ClfiHI4O6 to C1fiH1200, we can workit backwards or forwards- that is, we can get back the colour again from one to the other. If we take the leuco com ound,the colour- less compound oi lo wood, and oxixise that, we can deoxidise it again. %ow it seems to me that if Mr. Sharp is correct, the same thing should happen when he gets down to CloHloOfi, and he ought to be able to work it back again into the coloured compound. I am rather inclined to think that the colouring matter there is destroyed by some other means, and broken up rather more than is re resented by takin away two atoms of hydrogen. %th regard to the &men- tation of logwood or the “getting up,” there seems to me to be something more concerned than mere oxidation. If we take, for instance, a portion of some wood that has been treated and gone too quick!y, and put it into a large pile where the change is going on in the ordinar condition, we should soon find that it would act d e yeast, and the whole bin would go. That seems to me to show that there is some fermentative process involved apart from mere oxidation, which has never been t6oroughly explained. The reason of this action I cannot tell, and I have never beenable to find it in any book. It may be brought about undoubtedly without amthing bein put to the mass, but it is brought about mucf quicker if some wood that has gone bad has been put into the bin. Coming now to the difference in the logwoods as shown by the cloth Mr. Shar has exhibited, there is one little matter which strucg me in Mr. Sharp’s experiments, and that is in regard to the action of the dye where the cloth has been treated with sulphur or bleached. It occurred to me that the action of the sulphur there might very like1 muse a greater de osit of chromic acid ; that is, tiere would be a ikelihood of sulphurio acid

Idarch 2% 1891.1 TH$ JOURNAL OF THE SOCIETY OF DYERS A N b COLOURISTS. 30 - - ~ - ~ - ~-

being formed on the fibre and never washed oul thoroughly, and that that again has its effect upon the chrome. If a greater amount of chrome Waf deposited, then we have again a further action when it goes into the wood. To my mind that seems a likelier explanation than the fact of the fatty matte1 being present. Besides the sulphur compound itself, to my mind, may be likely to have some affinity fo1 the chrome compound, the same as it has in othei cases. It is quite possible the sulphur may form a kind of mordant for the chromium compound. U that is so, leaving out the action of the sulphuric acid on the chromic, it would have another tendency to take on itself a greater amount of logwood and form a deeper colour than before. There is one question there that I should like to ask Mr. Sharp’s opinion on. We find in the dyehouse occasionally that wood gets into that condition where it “ flushes’ - that is, the wood, the moment you get in the cloth, is on the fibre directly. You shall take two pieces and mordant them exactly the same, and give them two different woods and one wood will rush cn and the other be kept back to a considerable extent. I should like to know if Mr. Shar can explain this 1

Mr. SHARP : i n regard to Mr. bilkinson’s remarks upon logwood, you must, of course, understand that the two samples, 4 and 5, I have put before you havc been chromed together, and dyed with exactly the same quantity and quality of logwood. We have it as an accepted fact from the greatest authorities, which have never been disputed, that when hzematein is formed from hamatoxylin it is by the displacement of two hydrogen molecules reducing the hydrogen from 14 to 12. We mmmence with a colourless body, but by the displacement we have a rich purple dye. Subsequent oxidation is only a natural consequence. If you take a solution of logwood in the form of hzematein, extracting the colour with pure distilled water and filtering, and then add a calculated quan- tity of peroxide of hydrogen, in a moment we have a solution that will not dye. Now, my own views are- and I am very glad we have so able an authority in the chair to correct me if I am mistaken-that the oxygen in the peroxide unites with the hydrogen and forms water. It is not a dehydrogenising pro- cess directly, but the two molecules go together and form water. I think that is probably the correct interpretation of the action ; but if it is not, the object of these papers is to discuss errors and make them manifest, and to submit our views respectively to correction. I believe this action has not been pointed out by any authority before. If I am wrong, or may be proved to be wrong afterwards, all 1 can say is that I do not set myself to be an authority. I simply give you the result of practical, every-day experience. If that is not the reaction, tell me what IS. That is the point I want to know. With regard to the other reaction which takes place, since the days of Chevreul, who, in 1814 I think, made a careful and exhaustive examination in woods, and laid down a formula, afterwards verified by Schutzenberger, andin our own country by Stenhouse and Groves, and probably other chemists whom I might quote, the reaction in the formula has never been disputed. As to what Mr. Wilkinson suggests here with regard to dyeing on a cloth that is treated with fatty matter and then exposed to sulphur fumes, it may be to some extent correct ; if an excess of sulphur is left in the fibre it might lead to a little more chromic acid being upon the fibre, thus causing more oxida- tion of the wood because it is i n the state of hema- toxylin. If you were to add sulphuric acid to bichronie, and form chromic acid upon the fibre, you will have a more active agent in force, but I think you will find that that alone wiW not do. If that

_____ woulddo,you would not require fatty matter. A little acid with your bichrome would fix upon the fibre your chromic acid, and you could have a more active reagent working and might get results, but I do not think you would. You may get a difference to some extent, but you will not get the whole of the difference in m samples. I was personally very much struck wit% it, because we were testing these things, and we were seeking to verify a result, but we found that we were contradicting our own results. When we came to look into it, we found it arose simply through taking different cloths for different tests. We got the cloth here which we knew had not been treated with any soap or fatty matters whatever, and we found that the result practically is in entire har- mony with the pro ortions which were laid down by Chevreul and Erimann ; that is, that six parts of prepared wood or hzematein has the dyeing power of ten parts of thoroughly good wood in the form of hEmatoxylin. That, I have no doubt, is a fairly cor- rect statement. Now, when we had taken part of the same cloth impregnated with soap solution, and sulphured it, and put it into the hwmatoxylin bath, it dyed up equally as if it had been prepared. I quite think that the fatty acids of the baths are decom- posed in the sulphur stoving, and left insoluble upon the fibre. Exactly what action this has upon the hamatoxylin I am not repared to say, bacause that is another feature wkch, I believe, has not been brought forward by any scientiut, and is not t o be found in any work. My results, however, are based upon daily practice, and I think most of them will probably stand the test of experiment.

Mr. SLATYER : Mr. Watson Smith said it would be an interesting thing to treat with zinc the colourless body which Mr. Sharp has obtained. I may mention that I did so this evening, and I found on trying over Mr. Sharp’s experiment-treating hzmatein with hydroxyl--I got a colourless body, and one which gave very little colour to chromed wool. I then boiled some of the same substance with zinc powder, but did not get any reaction.

Mr. SHARP : We have failed to restore the colour up to the present.

Mr. SLATTER : The term dehydrogenising, used by Rlr. Sharp, is, I think, simply another name for what is understood by Mr. Wilkinson and myself, and also usually understood,as oxidation. It seems to me that the formation of the colourless body must be by oxida- tion or dehydrogenising, if you so prefer to call it, because, if the hwmatein is treated by a reducing agent, such as sulphurous acid, it is changed back to hEmatoxylin.

Mr. RAWSON : I should like to ask Mr. Sharp if he examined the exhausts in which that cloth was dyed, since a great deal depends upon what is left in the bath. Where the deeper shade was obtained,probably a smaller amount of colouring matter was left in the dyebath. My own experiments with fresh and matured logwood quite bear out the statement of Mr. Sharp that much depends upon the kind of cloth or material dyed. The view I take of the matter is that woollen cloth which has been milled and stoved is capable of fixing, under similar conditions, a larger amount of chromic acid than wool which has not been so treated. These conditions would certainly be in favour of the fresh wood, and for two reasons. In the first case a greater amount of the chromic acid on the fibre (up to a certain extent) would produce a deeper shade with the fresh wood ; and secondly, a portion of the colouring matter of the matured wood being fully oxidised, would be destroyed. I have made a number of experiments with fresh and matured logwood u on Botany yarn, and two students at the College (hfessrs. Burgess and King) have repeated

40 THE JOURNAL OF THE SOCIETY OF DYERS AND COLOuRIS‘I‘S. [March25,1Egl. - - ~~~~~~

them upon flannel. When the material WLLS mor- danted with 3 per cent. potassium bichromate, and 1 per cent. H,SO,, 10 per cent. of dry, fresh wood gave slightly better results on Jflanncl than 10 per cent. of dry matured wood. On the other hand, under identical conditions, matured wood gave better results on Botany yarn than fresh wood. I n this case, however, a second lot of mordanted yarn, dyed i n the partially exhausted liquors, showed that a much greater amount of colouring matter was left in thz “fresh logwood” bath than in the “matured logwood bath. This is, of course, what we would have expec- ted, and it is evident that in estimating the relative value of fresh and matured logwood, i t is important to take into consideration the amount of colouring matter left in the bath, after dyeing mordanted wool one hour, or even an hour and a half. I n our experi- ments where a large amount of logwood was usud (80 per cent.) the “matured” wood gave much better results than the “fresh” wood, both upon yarn and flannel, even when the material was mordauted with a great excm of chromic acid-viz, 6 per cent.

otassium bichromate, and 2 per cent. sulphuric acid. g u t the bath containing the “fresh” logwood invari- ably contained more colouring matter after dyeing than that containing the “matured” logwood. Muc; has been already said regarding the terms “oxidation and “ dehydrogenisation,” as applied to the production of hzmatein from hamatoxylin. I take the terms in such a case to be synonymous. Hydrogen is removed, and that hydrogen is oxidised to water. And again, although no oxygen is added, if hydrogen is taken away, and the other elements remain intact, it is per- fectly clear that the percentage of oxygen in the com-

I can scarcely agree with the 8hairman that the change may also be,fonsidTTed one of reduction. The terms “oxidation and reduc- tion ” convey quite an opposite meaning, as no doubt Mr. Watson Smith will admit.

Mr. SHARP : With regard to dehydrogenising and oxidation being synonymous terms, I do not quite agree with Mr. Rawson. I n converting hsmatoxylin into hzematein i t is unquestionable that you are displacing two hydrogen atoms and em- ploying an agent which simply makes them pass into water. No oxidation takes place there. That a t least is my view. Jus t the same as in the heaps of wood that become overheated, you have dehydro- genising going on there to a large extent to the destruction ot the dye, but you have no oxidising medium. I take it that the water that is employed in assisting the wood to ferment is simp!y carrying oxygen to the innermost part of the fibre. I do not take the extreme view that there is decomposition of the water itself, but that i t is a carrier of oxygen absorbed from the atmosphere. I make this distinc- tion between oxidation and dehydrogenising, that in the first instance from hiematoxylin to hzematein we dehydrogenise, and the 0,, group is not interfered with. There is no increase. Then, again, when by the addition of peroxide of hydrogen we form water with two of the atoms of hydrogen in the hsma- tein, no oxidation takes place. But, as I say, theee questions are in their infancy only, and probably require to be discussed fully before there is any resort to dogmatic assertion.

Mr. T. WIIITAICER : I am of the opinion, like most of our friend3 here, that maturing logwood is an oxidation process, though this depends un the posi tion from which you view the reaction. Whatever be the real action, and whether fnlly or partially matured wood is the best for a given purpose, is an important point, both in a scientific and pecuniary sense, and i t is one which with a little time will amply repay anyone who can follow the subject

ound is increased.

-~

further. There is one point which in small labora- tory tests is very important, and unless carefully watched is liable to give erroneous results-namely, the sampling of the woods. The wood when cut is not in the finest possible state of division, and it is only by careful sampling that a fair average can be obtained. If this is so with cut wood, i t is infinitely more difficult when selecting samples from the log. Two cuttings, presumably from the same ile of uncut wood differ very much in quality, a n 8 in a small sample you may easily get wood from a bad, a medium or good log with results varying in pro ortion. A large or bulk test is the best there. Conchons such as are mentioned by Mr. Rawson as to colouring matter left in the dyebath, as well as other seurces of error, are minimised to a great extent. I have tried along with Mr. Denison a few tests on the small scale, but as they are not complete I prefer to wait until I can speak confidently on this point. I n small experiments, where the smallest variation affects the accuracy of the results, the condition of the cloth t o be dyed is very important. I divided a piece of all- wool stuff containing 18 per cent. of grease into two portions. One I left as before,and the other I extracted with ether. The two pieces were chromed and dyed together, with a result in favour of the original piece containing grease. Regarding the iece of cloth which had been stoved before being usecfby Mr. Sharp, and which gave better results than when not stoved, Mr. Wilkinson suggests this may be due to deposition of chromic acid due to the action of the sulphuric acid on the bichrome. This may be so if the cloth has stood a long time since stoving, and what sulphurous acid i t contained has been oxidised to sulphuric. But in the case of a cloth fresh soaped and stoved, and which contains SOL, you would expect the action to be due not to the sulphuric acid but to the SOz reducing the bichrome from chromic acid to the st Ateof chromic oxide. This I tried and found to be the case, the wool when mordanted in the same bath with a piece of cloth unstoved being quite green b comparison *

and as is the case with this mordant, the h a c k obtained was deeper and bloomier than the unstoved pattern. Another source of error in blacks from logwood on the small scale is to be found in the slight yellow tint of some woollen goods used for experiments, which gives a corresponding density to the dyed fabric. Mr. Sharp in his paper mentioned the fact of wood being dry when overheated. This is quite correct so far, but wood may be at a high temperature and still be full of moisture. Spoilt or overheated wood is dry because of the constant turning to which it has been subjected while a t a high temperature, and the consequent loss of moisture.

Mr. SHARP : 13ut when the process is completed, if you leave the wood alone i t will be as dry as tinder. It depends upon the point where you stop i t exactly as to the result. The experiment is too expensive, however, to try.

Mr. WHITAKEX : I t is indeed an expensive experi- ment, but the wood has usually been turned over time after time in the attempt to save it, and it is dry for this reason alone. I think the subject introduced to-night is one on which we ought to have, and shall no doubt have, further information before very long.

Mr. K A Y : I have been trying a few experiments with logwood recently. I had some ideas with regard t ) the constitiition of the dye, and thou-ht i t might be allied to the phthalein series-p g , 07 the phenol- phthalein type. Recently some papers have appeared showing the action of %n dust on h:t~matoxylin. I rcpeated the experiment, and obtained among the xoducts an oily substance, and a hydrocarbon, which f a d previously been obtained. I also tried the action of melted potash, which had previously been done.

March25.1691.1 THE JOURNAL OF THE SOCIETY OP DYERS AND COLOURISTS. 41

Pyrogallic acid is btated to be among the pro' ducts of decomposition. I was not able to confirm this, but ascribe failure to insufficient action of the potash. By the condensation of acetic anh dride pyrogallol, and resorcin, I obtaineda body Cl,,€!, 20,,. I thought,. according to theory, I might obtain hwmatoxylin, or a body of same composition. But this was not the case. These experiments are being continued.

The CHAIRMAN : Is that body colourless '? Mr. KAY : It is a coloured body -a reddish orange.

The further oxidation of hwmatein is an interesting fact ; but i t appears to me not possible that such a simple change-viz., that two atoms of hydrogen should have gone out to form water-should take place. I think hEmatoxylin may bs regarded ae an alcohol, and hematein the corresponding alde- hyde. This view is partly confirmed by the com- binations of the latter with two molecules of ammonia. This is characteristic of these bodies. This colourless body seems to me to be more likely to be a decomposition product, than to be formed in the simple method Mr. Sharp has suggested. It is certain1 a very novel and interesting point, and I should wisi to carry experiments further and study the action more closely. The experiments are yet in a rather crude state, but I hope to perfect them, and obtain a little more definite information. There are some very interesting and novel facts brought to light by Mr. Sharp's paper, and some of them offer a valuable field for investigation. I have taken very great interest in the paper, and was certainly struck with the experiments.

Mr. SHARP: I have no doubt it will be clear to the minds of most present that the results obtained in this, like many other processes where you initiate processes of manufacture, are governed by circum- stances. You may take hxmatein and start upon it for the production of a great many bodies. With regard to the discovery of an oily body, probably it is within the knowledge of many of you present that htematein contains fuse1 oil. That is a discovery that has long since been made. I am very glad to hear that so young a chemist as Mr. Kay has got so far upon the wa . I think it is very praiseworthy for him to have dbne so. With regard to different treat- ment, as I say, you may manufactlire 10, 20, or 100 bodies, according to the treatment you apply-if you want sugar, if you want 50 different things, you can get them. What I value most in all the experiments which come before us, is their practical bearing and their object of evolving something beneficial to the dyeing of the textile fibre. If they aim a t the pro- duction of some fine chemical that we have to go into the druggist's shop for, I do not feel interest in them at all. Something on,: wider basis is what I aim at.

Mr. WILKINSON: lhere is one other matter I think we must not lose sight of, and that is this : I n any trials that we may make we may reasonably expect to find a great deal of difference owing to the difference of conditions. I should not expect foi a moment to find, nor should we find, a trial on a large scale and a small scale toagree, nor should Iexpect two trials on a small scale to agree, unless carriedout under exactly similar conditions. I feel quite sure in my own mind that if I was to make two trials on a small scale, one in a porcelain dish and the other in a beaker, I should get results different, because there is so much greater surface exposed. The body itself is so sensitive to oxidation that the two trials would naturally come ont very differently. That is what T shonld expect, and that is where the ditticulty comes in in atteinlpt ing to coinparesmall trials with large trials. I think, however we may fairly reaeon that if we take new cut wood, and make an experiment, my, in a porce-

lain dish, and boil it for a long time, we shall ulti- mately get pretty near to the result where the whole of the colonring matter is converted from the colonr- less into the coloured body, and would act exactly similar to that from well-matured wood. We have, then, to take this into consideration, that on a large scale in practical work we cannot attain such rdsults. We cannot have that amount of action, because we have not the same amount of surfaces exposed corre- sponding to the depth of the vessels, If there was nothing else but that one fact, it is sufficient to account for the variations in trials of that descrip- tion. Again, supposing we were wanting to get a similar result on a large scale. I n making two trials we would get a different result if we boiled for a longer or a shorter time, all other conditions being exactly equal. Therefore, for anyone to set about to make trials to agree, it would be necessary that their vessels, their time, their quantities, and everything else should be exactly alike ; otherwise we should have just as many different results as we had persons trying, and then that multiplied by the number of times the persons tried.

The CKAIRMAN : With regard to the question of dehydrogenising or reduction, there is this way of looking a t it. It can be looked a t either in a logical or a chemical sense. We may take it in this way, that the hydrogen in the alcohol-taking alcohol-is reduced in amount in order to give a product richer in percentage of oxygen. That indicates two ways of looking a! the subject. That was pretty much my own meaning. But the query comes in then whether it is better to speak of the term oxidation generally, or get a new term to signify that special kind of oxi- dation. If we did this we should then have to bring in some special kind of terms to define these actions, and students might be troubled with an over-refine- ment of definition. I daresay, when the matter is put that way, hlr. Shirp would have no objection to keeping to the general term of oxtdation.

The CHAIKBIAN then suggested that a hearty vote of thanks be given for the paper, and on the motion of Mr. C. W. WAUE, seconded by Jlr. KAY, this was accorded.

The vote of thanks was adolited, and a vote of thanks to the Chairman, moved by Mr. SHARP, seconded by A h . SLATTER, and supported by Mr. HICKSON, terminated the meeting. _ _ ~ - ~

8fiatracta from eEngtwf) anD soreign Xournais;.

111.-MORDANTS, C/womiz~m Fluoride. Th. Stricker. Bull. Soc. Ind. de

Mnl., Oct.-Nov., 1890. CHRW,I!UM I ~ L U O l ~ I D E , proposed by the firm 1:. Kiipp and Co. as a substitute for chromium acetate, is a green crystalline powder, containing 60 per cent. anhydrous chromium fluoride and 40 per cent. water of crystallisa- tion, thus corresponding to the formula Cr,FI, +SH.,O.

Comparative trials have been made with chromiim acetate, prepared by dissolving chromium hydrate in acetic acid. This acectate contained, according to an analysis, 8'28 per cent. chromic oxide (Cr203j-i.e,, 20.5 per cent. chromium acetate [Cr (C2H:i02)2(OH)2], which correspond8 to 1185prms. of anhydrous Iluoride and 19igrnis. of Ilumide at 60 per cent. per kilo. of acetate.

These 197grms. of Huoridegive I kilo. of solution mark- ing l ip RI;.--i.p., a solution containing 24;lgrrna. of lluoride per litrc.

The following trial3 by printing have sliown that the shades obtained with the acetate are purer and deeper. It is probable that this difference is caused by the