March, 1904.1 THE JOURNAL OF THE SOCIETY OF DYERS AND COLOURLBTS. 63 - - - - __ ~_ _ _ . _ _ . - . __ -

Mr. White (being appealed to) : Not more than 5 per cent.

Another thing, said the Lecturer, which caused great trouble was unsaponifiable fat. Those using paraffin wax had a great deal of trouble. Paraffin wax would not emulsify well. and was apt to come up in large lumps, leaving the other materials. It also formed into lumps in the pipes leading to the sizing troughs. That had been one of the chief causes of trouble to dyers of cotton yarn. Sizing could be done without fat, but that was not often attempted. I n a light size a very small quantity could be added to the flour or farina-just enough to make the warp weave properly. Before dyeing it would be washed out in a solution of soap. The conditions in Bradford were very different from those in Lancashire. Then as to sizing wool yarns generally. No doubt a great number of mixtures were used in small quantities. Some nostrums were made up from glue and other materials not very soluble in water. These no doubt were what caused the trouble in washing. The sizers did the best they could for themselves, which was to make the materials weave properly. That was the first consideration all along. (The Lecturer here threw plates on the screen illustrating difficulties in treating certain fibres.)

Dr. Herz proposed a vote of thanks to Messrs. Stocks and White for their lecture, and ex- pressed the pleasure he had derived from hearing so valuable a paper.

The motion was seconded by Mr. Goddard, supported by Mr. Barlow, and carried unani- mously, and Mr. Stocks expressed the thanks of Mr. White and himself for the manner in which the paper had been received.

_____

MANCHESTER SECTION.

MEETIHG held a t the Mancliester Municipal School of Technology, on January 29th.

Mr. W. H. PENNINGTON in the chair.

Some Compounds of Titanium and their Applications.

By HOWARD S r s ~ c e .

In common with many bodies, a t the

- _ ~ ~_ ~ _ _ ~- ~- ~ ~-

been practically an unexplored field from the technical standpoint. I n passing, it may be noted that if the published results of the trials so far made by Rossi are confirmed by further and large scale practice, there appears to be an important future for titanium ores in the pro- duction of iron and steel. The results available up to the present seem to indicate that the rcjle played by metallic titanium is that of an eliminator of impurity rather than of an active component of the alloy. As suggested by Rossi, its very active deoxidising power very probably plays an important part in the result attained, in which its strong affinity for nitrogen may also share.

As early as May, 1885, Mr. J. Barnes, of Accrington, contributed to the Society of Chemical Industry some notes on the property possessed by titanic acid of combining with colouring mattcrd ; but the earliest technical application of the soluble compounds of titanium was made by Barnes in 1806 by his British patent for the production of fast colours upon vegetable fibre, by means of the basic coloiirs on titanium tannate mordant.

At this time the author was experimenting on the technical extraction of titanic acid from the residues of bauxite ores employed in the production of aluminous compounds. Titanic acid is, in this material, associated with about one to five times its weight of silica, tog~ther with some alumina and iron oxide, and is soluble only in hydrofluoric and concentrated sulpliuric acids. For obvious reasons the former is not available, and in experimenting w-ith the latter in the form of sodium hisulphatr a new com- pound which has proved of considerable technical interest was discovered. This compound con- sists of a crystallised basic titanium sodium sulphate of the formula TiOS04Na,S0,2H,0 crystallised in well-defined needles. The salt is only slowly though completely soluble in water, requiring agitation over a considerable timo to produce a saturated solution. One hundred parts of cold water dissolve about 30 parts of the double sulphate, and it is decomposed by hot water.

The potassium and ammonium salts are readily prepared, and apart from less solubility have similar properties. Still more basic su1- pliates exist, soluble in part in dilute sulphurio acid. From the sodium salt the ortho hydratr of titanic acid is conveniently prepared, and forms a ready means of producing the soluble titanium salts for which the ortho hydrate is

h a s shown the reverse to be the' fact: Apart from the use of titanic acid in pottery and in metallurgicnl applications, with regard to which very high anticipations were expressed some forty or fifty years ago by R. Musliet. whose researches have recently bren continued and amplified by A. J. Rossi, of New York, titanium and its compounds have until recent years

the titanium compounds. Jt is an interesting fact that, in the

production of fluorides by the aolution of titanic acid in hydrofluoric acid, the ortho hydrate cannot be employed if lead vessels are used, as the latter are attacked and the solution reduced to titanous fluoride. This, howzver, does not apply to the meta hydrate or to a basic

04 THE JOURNAL OF THE SOCIETY OF DYERS AND COLOURISTS. [March 1904. ~ -

sulphate. A further point of some analytica interest is the fact that under conditions ir which the titanic acid in a solution is largelj converted-say, by boiling -into the insohiblc meta form, the rcmaining titanic acid still ir solution i,r also present to a considerable exteni in the meta state, and no longer reacts, or onlj slightly, with peroxide of hydrogen. Evapora tion with concentrated acid is necessary to re convert this titanic acid to the ortho condition

One of the salts of titanium which has found very considerable and extending application more particularly in the leather industry, ir titanium potassium oxalate, a basic salt which forms well-defined crystals of the compositior TiO~C,O;~C,O, H,O. It is readily, thougk not largely, solubl:: in cold water, but freely sc in hot water, and is one of the most stable ol the crystallised salts. The sodium and ammo. nium salts are soluble to a much greater degree in cold water, and therefore less readily crystal- lised.

In general the single salts of titanic acid, such as the sulphate and oxalate, form easily decom- posed solutions, but the double compounds formed by the addition of the corresponding alkali salt are much more stable. Titanic fluoride, however, forms an exception to thk rule.

A solution of titanium tannate in oxalic acid, known as L‘ titanium tanno oxalate,” is perhaps the most convenient form of applying the tannate to vegetable fibre as a self C O ~ O U K or for mordanting purposes, and has also been found more suitable for certain purposes in leather dyeing and staining than the crystallised oxalate ; this is especially the case with chrome- tanned and aliimed leathers. For mordanting purposes it is prepared with a somewhat higher proportion of tannic acid than that for employ- ment in leather work. The double fluorides are too well known to require more than mention. The high solubility of the ammonium and sodium salts are in marked contrast to the slight solu- Eility of titanium potassium fluoride.

Of the salts of TiO, the hydrated seaquisul- phate and sesquichloride have most practical interest. Until recently the only described methods for their preparation in the piire state consisted in the solution of the metal in acid, and also, in the case of the chloride, the electro- lysis of anhydrous TiCl, in solution in concen- trated hydrochloric acid followed by the passage of dry hydrochloric acid gas through the electro- lysed solution to salt out the compound TiC1, 6H,O. Contrary to the text-book statements the aqueous solutions of both titanous sulphate and chloride have been found to iorm stable solutions capable of evaporation in the open without material decomposition. They both form crystallised bodies, the chloride TiCI, 6H,O being better defined than the sulphate, and are of equal reducing power. Of the double salts the sesquisulphate and sodium sulphate ‘Ti,(SO,) ,* Na$O; 5H,O is a compound of interest. It is readily salted from its deep

- -~~~ - ~ -

purple black solution a t the boil, crystallising in cubes, and when dry is a stable salt of a lilac colour easily soluble in water. A more hydrated titanous sodium sulphate Ti,(SO,) :. Na,SO, 12H,O forms much larger crystals, and i4 a more rapidly oxidised body.

Titanous chloride does not form hydrated double chlorides with the alkalis. Concen- trated solutions of both sulphate or chloride kept in closed vessels for long periods of time undergo little or no material alteration.

By the electroly9is of titanium solutions or by the solution of the metal in acid it is ini- possible to obtain a lower oxide than Ti,O,, and yet, in comparison with stannous chloride, titanous chloride is a t least 20 times more powerful as a reducing agent with azo colours. The results of one or two comparative tests are interesting :-Cotton yarn dyed with Benzopur- purin 4B was put into boiling water, and a 2 per cent. solution of tin crystals added until decolourised. Time about 45 minutes. The same experiment was done with TiCl: solution of the same strength. In this way it was found that a fairly full shade required about 24 per cent. of titanous chloride to destroy it. Of stannous chloride it required 28.5 times as much. Similarly, cotton dyed with Chrysophenine required 37.2 times as much tin crystals as titanous chloride. In another experiment cotton yarn dyed with Benzo- purpurin 4E required 2 per cent. titanous chloride and the equivalent of 37 per cent. of zinc in the form of sodium hydrosulphite pre- pared according to the indigo book of the Badische Anilin und Soda Fabrik.

Dr. Knecht, of Manchester, has been the pioneer in indicating many purposcs to which titanous salts are applicable, and has carried out considerable research work on these com- pounds, drawing attention last year in an article in the Berichte to their powerful reducinq action on organic compounds, indigo, for example, and on other bodies. Employing dilute solutions of titanous salts, he has worked out some very valuable analytical methods for the volumetric estimation of azo dyes, of nitro and nitroso compounds, and of ferric iron. His recently published note on the qualitative reaction of titanous suiphatc on copper salts in excessively dilute solution is also of much interest.

To Knecht must further be attributed the application of titanous salts to the discharge of azo and other dyes, whether in stripping, clearing, discharge, or resist work. For the former there is no acid reducing agent which is comparable with titanous salts for efficiency, but although the same would naturally be held to apply to discharge and resist work in calico piinting, this has not so far been satisfactorily demonstrated. From some cause n hich has not up to the present been fn!ly elucidated the powerful reducing properties of titanous serqui- oxide salts have not been made genernlly avnil- sble for this purpose. From the foregoing comparison, however, between the relative

mrch. 1mO4.l THE JOURNAL OF THE SOCIETY OF DYERS A S D COLOURISTS. 65 - ~ __

~

efficiencies of titanous salts and stannous chloride there is every probability that this difficulty, one incidental to any new process at the outset, will be surmounted. Similar difficulties were encountered with stannous chloride itself for a long period.

For the removal of the last traces of colouI from dye-vats-in job dyeing, and generally where an active reducing agent is required titanous sulphate is particularly useful. The reducing action of titanous salts is more marked on dyed vegetable than on animal fibre, although dyed woollen goods in some cases readily yield to stripping. In this connection the late Prof. Humniel wrote to the following effect to the author’s Firm in August, 1902, a few weeks before his widely regretted death :-“With respect to tlie sample of titanium chloride received from you some time ago, I tried it as a stripping agent on some dyed clothing which had to be re-dyed in a lighter colonr, and compared it with a variety of other stripping agents, including several reducing agents. In this particular case we found it to strip the wool to a much lighter colour than all the others, but it tendered considerably the cotton lining and sewing. I have no doubt, however, that titanous chloride could be advantageously used as a stripping agent for all-wool material, and if the price is not too high it would be a valuable agent for this purpose in the preparation, &c., of shoddy, for which it might find a large sale.’’

A process has recently been patented by the Bleachers’ Association for the reduction, by means of dilute titanous salt solutions, of oxycellulose on cotton and similar textiles, with tho object of avoiding the formation of stains and light-coloured patches frequently caused by its presence. Tlis patches tendered by the presence of oxycellulose are stated to be materially strengthened by the treatment.

Still more recently the Farbwerke, formerly Meister, Lucius & Mining, have claimed the catalytic action of small aniounts of titanous oxide salts for the reduction, in situ, of organic compounds such as nitrobenzene and quinone (which are reduced to aniline and hydroquinne respectively), the Ti,O I being continuously regenerated electrolytically. A low current density is employed.

As further illustrating the extremely energetic reducing action of Ti,O,, mention may also be made in this connection of Knecht’s process for tlie production of hydrosulphites by the reduc- tion of bisulphites with titanous salts and the immediate absorption in alkali of the hydro- sulphurous acid thereby produced.

Returning to the application of titanic salts, the samples shown indicate to some extent the results that may be obtained on cotton, silk, and cellulose, dyed with titanium tannate or mordanted with titanium salts. The ease with which cotton may be dyed with the tannate shade and its resistance to light and soap make it peculiarly suitable for the dyeing of art embroidery materials, and the yellowish gold

~ ~ _ _ _ _ _ _ _ _ _ _ ~ - _ _ _ _ ~ __ ___ _ _ ~ ~ - _ _

of the tannate is in itself very effective-it may perhaps be best seen on mercerised cotton. When employed as a mordant this ground colour must always be taken into account; it is, however, an advantage for certain coloiirs although necessarily barring the production of others-blue, for example. I n paper-staining titanium tannate gives a very rich red brown, and is applicable to the preparation of imitation leather papers. Some two or three years ago Hummel carried out a very extensive and careful research on the mordanting properties of titanic acid on wool. For most purposes it was found not to possess any advantage over aluminium or chromium mordants, but in a few particular cases its employment as a mordant gives distinctly superior resnlts. One or two notes from Hummel’s report may be of interest. He wrote :--“ Alizarin orange gives a particu- larly bright shade when applied by this method ; dyeing is commenced with the colouring matter and a little acetic acid, the bath is raised to the boil in the course of half an hour, and after boiling for half an hour addition is made of 15-20 per cent. of the mordant solution (a solution in water of titanium sodium sulphate containing 4 per cent. TiO,) and 7.5-10 per cent. of oxalic acid, after which boiling is con- tinued for 20 to 30 minutes. Several other dyestuffs give useful shades by this method ; among these are :-

Alizarin Yellow (M. L. B.). Coerulein SW. (B. A. S. P.). Alimrin CJ dnni Green (BtLyer). Anthracene Blue (B. A. S. F.). Brilliant Alimrin Blue (Bajer) Gallocyanin (U. & H.).

Since we find in this group a good red, yellow, blue, and green it is possible to obtain an infinite variety of compound shades by means of suitable mixtures, and the colours thus obtained are extremely level.

“ Particularly worthy of notice is the black given with logwood on titanium mordant, which is a much more dead black than that obtained with chromium mordant. The latter is a blue- black, and when it is desired to dye a dead black on chromium mordant it is necessary to add to the dye-bath a small quantity of a yellow dye-stuff, e.g., fustic. By the use of titanium mordant, or possibly by combining chromium and titanium mordants, it would be possible to dye a full dead black with logwood

It is, however, in leather dyeing and staining that, so far, titanic salts have found most applica- tion, and although the particular colour pro- duced directly on tanned leather by means of soluble titanium salts is not so largely in vogue as formerly, the ease with which the shade may be modified to meet any requirement still leaves a wide field for t’ieir employment. Titanium salts produce colours which are very fast to light and. rubbing, and effect considerable saving in dyestuff. They substitute tartar emetic with advantage in dyeing with the basic colours. Prof. Procter, of Leeds. and Mr. M. C. Lamb,

66 THE JOURNAL OF THE SOCIETY OF DYERS AND COLOURISTS. LJiarcli, 1904.

1"- ~. - - - - - . ._ ____

Herold's Institute, have carried out very exhaustive investigations as to the best methods of application. Continental firms appear t>o have been more successful than English in the production of very good black on leather by employing titanium salts.

A method which has been found to give ex- cellent resnlts with chrome-tanned leather is as follows :-The skins are treated in the tumbler with the aniline blue employed, thir is followed by the addition of the logwood, and finally the iron black mixed with titanium tanno oxalate, care being taken not to employ too much tanno oxalate with the iron blzck, in order to avoid the prodnction of a greenish shade, and to use the acid and basic dyes separately, not mixed. Equally successful results in coloured shades are obtained with the crystallised oxalate. Thus, for examlde, in hat leather staining-in the tray -Messrs. Dean & Co., of Stockport, have used the oxalate for about a couple of years, and state that, owing to the use of titanium potassium oxalate as a mordant, they make a speciality of fast-dyed leathers, and that by its use fully 25 per cent. of aniiine colour is saved.

Two new applications of titanium salts which have promise of an important future are of considerable interest. M. C . TJanib has

~ . - - this particular app€ication and for means of carrying the process into effect. The titanic acid may readily be fixed alone on the material to be proofed, or may be fixed in conjunction with other oxides, such as stannic acid and silica, both of which have fireproofing properties to some extent. A very important feature is the remarkable degree with which the titanic acid may be incorporated with the fibre. The materials may be dyed a t the boil after the proofing process without detriment, and the titanic acid may be fixed so as to become in effect an integral part of the fibre. Unlike tunqstic acid, which has a tendency to combine with alkali and become soluble, titanic acid is unaffected by soap or alkaline attack, and continually repeated washing has little or no apprepiable effect.

The degree to which such highly inflammable materials as flannelette, lace, and substances of a similar nature may be rendered non- flammable is remarkable, and should go a long way to prevent the appalling loss of life, not only in such catastrophes as the recent fire in Chicago and that in Paris in 1897, but in the child life of our own country.

The properties of a number of titanium comDounds are in manv resnert,s of R iininiie

The continued investigation of th; process is affording encouraging results. One of the skins on the table, tanned with titanium sodium siilphate solution, will indicate its possibilities. An example of one method of carrying the procesq into effect is the following :-The skins, after the preparatory depilatory processes, are first drummed in a 1" Tw. solution of titanium sodium sulphate for one hour, after which the liquor is strengthened by the addition of 5" Tw. solution of basic sulplrate, mtde more basic by rradually adding dilute sodium carbonate solution to 5" Tw. titanium sodium sulphate solntion. A t the end of the third hour an additional quantity of the same liquor is added, and the diumming continued for three hours. After the addition of a somewhat stronger basic solution, the drumming is further continued,

that has dready been done ;n this direction, may perhaps to some extent indicate possi- bilities of further usefulness in other fields.

DISCUSSION. The Chairman said that the meeting was

much indebted to Mr. Spence for the paper he had read. The author wished to illusbrate the fire-proof properties of titanic acid by specimens which had been prepared, and it appeared from the samples shown that the fire-proofing process does not affect the subsequent dyeing or printing operations.

Mr. Radclifte asked whether any experiments had been made, or whether any evidence was forthcoming as to the efhct which the material precipitated upon the fibre has on the skin in

strengthening the solution with more sulphate the presence of pcrspiration. Some statements liquor if necessary, until the goods are sufficiently had been made about the fire-proofillg of tanned, when they are washed up in a weak flannelette to the effect that the oxide had solution of cnmmon salt, again washed, dyed, ' a deleterious effect on the skin, especially in and fat liquored. , young children, particularly under the influence

has been made is that in which the fireproofing I Mr. Spence : Titanic acid is in itself one of properties of titanic acid nlav the chief r d e . the most inert bodies known in its free state.

The second application to which reference 1 of perspiration. '

Salk of alumina, tungstii &id, and other oxides have, for many years. been known to exert a certain fireproofing effect on textiles and other inflammable substances to which they have been applied, but this property appears to be rossessed by titanic acid in a degree in excesa of any hitherto known. Within a recent period several patents havc been taken out for

almost as inert as silica, and when it is properly fixed on any material washing has no effect. As illustrating the point from one aspect, the samples shown are hat leathers, and are not in the least affected by perspiration. Titanium salts have been shown here to give per- fectly fast colours. Titanic acid is perfectly harmless and not poisonous.

.Marck1W4.1 THE JOURNAL OF THE SOCIETY OF DYERS AND COLOURISTS. 67 ~ ~ ~ ~ ~ ~ _ _ _ _ _ _ _ _ _ ~ ~ ~ ~ ~ ~ ~

Mr. Hubner: As to the amount of fastness will it resist washing with soap or alkali and soaps ?

Mr. Spence stated he had not had any ex- perience as to that personally, but had been informed by those who had gone very fully into the subject that repeated washings have practically no effect on material proofed with titanic acid, though other acids, such as tungstic acid, might be affected by alkali. As is well known titanic acid is not affected by or soluble in alkali a t all. This is one of the great ad- vantages claimed for titanic acid as compared with other oxides. At the first blush it might appear that titanic acid might not give so powerful fire-proof results as other oxides, but, as had been pointed out, continued washing is really the best test in the case of material for domestic purposes, such as flannelette.

Mr. Hubner referred particularly to domestic washing where clothes are very often boiled with soap or soda solution, not ordinary washing.

Mr. Spence thought that would be answered by the fact that in the fixation on the flannelette of the titanic acid the process of boiling in caustic soda forms a part.

The Chairman : As to what Mr. Hubner said in regard to repeated domestic washing of flannelette you have not only to take into consideration that all sorts of soaps, many of them containing a considerable amount of free alkali, but a great many varieties of paraffin compounds are used. Will Mr. Spence tell us the effect that would have upon the proofing Z

Mr. Spence could not say from actual know- ledge. It should be further investigated before he could speak definitely, but, a priori, he should say it would have no effect.

Mr. Wagstaffe asked whether Mr. Spence could give any idea about the cost per piece, say, of 75 yards to make it fireproof '2

Mr. Spence understood it is now being done a t a price which is very little different to the ordinarv mice, and one which would bring it

~- _ _ ~ - ~ ~ _ _ _ _ _ _ __ _ _ __ Mr. Hubner said he noticed that, according

to Prof. Hummel, when using szlts of titanium the cotton was tendered. He should like to know whether the action of these salts on the cotton fibre had been studied. If cotton is acted upon by these salts it will be dangerous if the solution were not very carefully used. For this reason it would be interesting to know what action actually takes place; has the strength of the cotton threads or of piece goods been tried after treatment with various strengths of titanium solutions, and have the dyeing properties, and especially the behaviour, of basic colours towards cotton treated with these

Mr. Spence: The remark was not made by Prof. Hummel in dealing with the mordanting properties of titanic salts, but with reference to the stripping properties of titanous chloride on wool, and in the particular case in which he employed it the stuff was tendered. This, he thought, was much more probably due to the strength of the solution which he employed than to the special character of the reducing agent. It was more likely the ordinary action of hydrochloric acid, which tendered ordinary vegetable fibres, rather than the special action of the titanous salts on the cotton. With regard to mordanting by titanic salts, he doubted very much whether the titanium oxide had any very appreciable effect on the fibre.

In answer to Mr. Leek, he could not say what was the result in the matter of sulphur colours.

A Member said that, as regarded the tendering 3f cotton with salts of titanium, he did not think that titanium itself had any peculiar action in that respect. If any tendering did occur it was caused by acidity. The same effect was produced by boiling the cotton in water contain- ng acid. Sulphate of titanium could be used

without any appreciable effect. He had never noticed that there was any more danger in using titanic salts than in using any other salts- aluminium, iron, or chromium.

solutions, been ascertained. It" 1

" I Y Dr. Kneclit remarked with reference to within reach of large users of flannelette, and tile tendering of cotton by titanous salts in all probability, with the extension of the that, in his opinion also, action was process, the price will be considerably reduced. due to tile presenc~ of free nlineral acid.

Mr. Leek : In the application of titanic acid By adding sodium fluoride or sodium formiate to silk the result is a harsh feeling. IS there to tile solution, the tendency could be any suggestion that in fire-proofing the same avoided. In answer to 31r. Leek's question, effect is produced. In stripping cotton with said he might say he had tried the effect of chloride of titanium and washing, the cotton titallour cllloride on a considerable number of always has a harsh feel afterwards. sulphur dyes, and he had invariably made the

Mr. Spence explained that his chief experience following observations. If a heavy shade of a was more in the preparation of these materials sulphide dye was used, and the cotton treated than in their use, and that he was a t a dis- with titanous chloricie, sulphure~ied liyarogen advantage in addressing a meeting of experts was a t first invariably given uf i ; that uuulc~ in their applications. At the same time the sulphur Hummel's report, that the application of titanic colour was reduced, and practically the whole acid in mordanting wool has the effect of pro- colour had disappeared, leaving a dirty brown. ducing rather a harsh feeling, but was not aware By exposure to the air, or better still, plunging it applied to silk. Mr. Hurst and Prof. Hummel the material into a dilute solution of per- had both carried out experiments in the mor- oxide of hydrogen, the colour was completely danting of silk with titanum salts, and had restored. He had never yet been able to destroy not raised that point. even a light shade of a sulphide colour.

He had seen, from Prof. be detected.

GS THE JOURNAL OF THE SOCIETY OF DYERS AND COLOURISTS. LMarck 1904.

A rote of thanks, moved by Prof. W. J. Pope, and seconded by Mr. J. R. Appleyard, was carried.

Some further Observations on the Action of Nitric Acid on Cellulose.

By EDMUND KNECHT.

At a meeting of this section, held on April 17th, 1896, I communicated in a paper entitled " Notc on the Action of Nitric Acid on Cotton" the results of some experiments which I had carried out on the action of nitric acid of different strengths on calico and on cotton yarn. The results showed that up to 62" Tw. there was scarcely any perceptible action, but that a t 82" Tw. the action of the acid resembled that of strong caustic soda, inasmuch as it had the effect of mercerising the cotton.

Since that time the mercerising action of nitric acid has become fairly generally known and has been the subject of several patents, such as those of Scheulen, in which textile fibres generally are subjected to the action of strong nitric acid under tension with the object of producing a permanent gloss. That such an effect could be obtained on cotton yarn in this manner I recognised in 1896, some months after the reading of my paper, but on account of the expense and the danger attending the use of nitric acid on a large scale, I did not foresee any practical application of the process.

Some three years ago I again took up the study of the action of nitric acid on cotton with a view to ascertaining, if possible, whether any definite chemical changes could be traced in its action on cellulose, similar to those given by Mercer to account for the changes which take place in the cotton fibre when it is acted upon by strong caustic soda. As is well known, these changes are represented as taking place in such a manner that the cellulose first combines with the caustic soda to form a definite compound (Ct,H,,O,);Na,O, which is decomposed on washing with water into caustic soda and a hydrated cellulose.

When cotton is steeped in nitric acid of 83" Tw. it very soon acquires a gelatinous appear- ance, in fact, to judge from appearances, the action would appear to have reached a maximum in the course of two minutes. Taken out of the acid and washed with water till neutral, the material resumes its normal appearance, but is found to have shrunk considerably, a t the same time acquiring increased strength, an increased amount of moisture in the air-dried condition, and a greater affinity for direct colours ; in fact, it shows properties similar to cotton mercerised with caustic potash, which are known to be not so pronounced as those shown by cotton mercerised with caustic soda of the same strength. and sulphide colours is, however, greater than , cold caustic soda, and to a griat eitent soluble that of ordinary mercerised cotton. The solution in caustic soda gives

Its affinity for direct

j in ammonia.

Attempts were made to remove the excess of acid from cotton so treated by means of solvents, but without success. It was subsequently found, however, that after having removed as much acid as possible by pressing between filter paper, the rest of the uncombined arid could be got rid of by leaving the material in a vacuum over freshly-burnt lime for 3-4 days. When taken out it is crisp to the feel, fumes strongly in moist air, and if pressed tightly between finger and thumb gives one the impression of being hot. In this condition the material appears to repre- sent a combination of cellulose with nitric acid corresponding nearly to the formula, C,H,,O; HNO,. The compound is instantly decomposed by water into free nitric acid and a slightly nitrated cellulose, which is, however, considerably tendered.

The estimation of the nitric acid was effected by steeping a known weight of bleached and purified cotton ysrn in nitric acid of 83" Tw., drying over lime in a 5-acuum desiccator, and after transferring the dried compound to a beaker containing distilled water, titrating directly with normal sodium carbonate and Nethyl orange as indicator. The amount of nitric acid thus found experinientally was 35.8 per cent., while, according to theory, 37.2 per cent. should have been present. The low figure is probably due to the fact that the compound gradually loses nitric acid in the desiccator, and it is impossible to exactly hit the point a t which the mechanically-adhering acid is evaporated. In its behaviour towards nitric acid, cellulose would appear to be analogous to phenanthrene quinone, which, according to Kehrmann, yields with ordinary strong nitric acid a definite nitrate forming beautiful orange-red crystals. which are instantly decomposed by water into phenan- threne quinone and nitric acid. These crystals also lose their nitric acid in a vacuum over lime, but much more rapidly than is the case with the celluloss compound. Both are stable, however, when kept in close vessels.

According to Cross and Bevan the cellulose molecule probably contains a ketonic group, and, assuming this for the moment to be correct, we might represent the formation of the unstable nitmte by analogy with Kehrmann's results as follows :-

CH,(CH,OH),CO + HNO,, /ONO,

= CH,(CH,OH),C\, OH.

It is not probable that the nitric acid sliould attack the liydroxyl groups which are known to exist in the cellulose molecule, as a stable nitrate would thereby result.

Though stable a t the ordinary temperature when kept in a closed vessel, the new nitrate is rapidly decomposed if heated to loo", with copious evolution of nitrous fumes. When the action has ceased a residue is left consisting of tl friable white substance comdetelv soluble in

March, 1QOU THE JOURNAL OF THE SOCIETY OF DYERS AND COLOURISTS. G9

which had been dried with the acid in it had acquired an affinity for certain acid dyes (Crysta

20- Tw. 40" ., 60" .. 65" ,, 70" .,

1 6 :. 80" ..

r - 0 - .3 (:J ..

83" ,,

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. . . . . . . . . .

. . . . . . . . I/, I /

p"/

1%

1 3

. . . . . . . . . . la$

. . . . . . . . . 1A

13/,

. . . . . . . . .

............ Prom this it would appear that the action of

the acid takes place in three phases, of which the third (at which mercerisation begins) takes place quite suddenly, viz., at 76" Tw.

If the concentration of tlie acid is taken beyond 83" Tw. the amount of nitric acid taken up increases somewhat, but a t the same time the degree of actual nitration rapidly increases. Thus cotton steeped in nitric acid of 90" Tw. was found to contain 40.6 per cent. after-drying, but was found after drying to be nitrated to such an extent that it showed in places a decreased affinity for Erika as compared with ordinary cotton. Cotton steeped for two minutes in acid of 1.415, and then washed, was found to contain only 0.54 per cent. of combined nitrogen. When steeped in the acid for a longer period the amount of nitric acid firmly combined with the cellulose increases, but a t the same time there is a decrease in the strength of the material.

In conclusion I may say that what I claim to have established is that when cellulose in the

__-- ~- ~ ___~___ ~ _ _ _ ~ .

form of bleached cotton is treated with nitric acid of 1-415 sp. gr. (i.e., the acid which shows a constant boiling point of 120" -5) combination of the acid with the fibre ensues so as to form a nitrate which corresponds very nearly to the formula, C,H,,,O;HNO,%, and which is resolved by water into a hydrated cellulose and nitric acid.

Cotton steeped in concentrated hydrochloric acid, in glacial acetic acid, and in anhydrous formic acid, was found to retain, after squeezing and drying over lime in a vacuum, only very small quantities (2-3 per cent.) of these acids.

My best thanks are due to Mr. G. T. Yates and to Miss E. Hibbert for their assistance in the above investigation.

DiscussroN. Prof. W. J. Pope remarked that a number of

terms seemed to be used in connection with textile chemistry in such a loose kind of way that the chemist has considerable difficulty in under- standing what was meant; personally he had not yet been able to ascertain the meaning conveyed to the mind of the textile chemist by the term "mercerisation," and would be very glad if Dr. Kneclit could enlighten him on the point. The action of caustic soda, followed by washing with water, upon cellulose was generally sup- posed to involve the addition of sodium hy- droxide to a ketonic group, and the conversion of this addition compound into a hydroxy- derivative owing to the hydrolysing action of the water. This would be represented thus :-

c/"n I \OH I

and would result in the formation of a hydrated sellulose in which one atom of carbon in the molecule ?as attached to two hydroxyl groups ; as every organic chemist was aware, such dilly- droxy-compounds are too unstable to exist in the free state. On theoretical grounds it was therefore difficult to see how the action of soda, followed by that of water, had the effect simply of hydrating the cellulose, and the difficulty of learning what does take place was increased when me searched the literature and found that no malytical data exists such as would justify the xganic chemist in accepting any of the views which have been put forward as to the chemistry 3f the process.

Mr. Hubner said that Prof. Pope and he had nade a great number of experiments during the ast two years, with a view of studying the nfluence of various reagents on the cotton fibre, md they could bear out the statement made by Dr. Knecht that nitric acid of 83" Tw. ?reduces a very marked effect on cotton a s "egards tlie behaviour towards colouring matters, L'hey had noticed that cotton treated with itrong nitric not only dyed stronger with Benzopurpurin 4B, but that the shade turned :onsiderably yellower ; this was still more pro- iounced if the cotton is treated with nitric acid If 100" Tw. for a very short time.

He agreed with the remarks made by Prof. Pope, that the term “ mercerising ” wa.s now rather too widely applied. Mercer had already discovered that reagents other than caustic soda produced a similar effect upon cotton, and Prof. Pope and he had further shown that similar changes were produced by iodides and double iodides such as Barium mercuric iodide. They had ascertained that whilst the affinity of cotton towards substantive colouring matters was increased in every instance, the physical changes produced differed considerably. A number of reagents produced the characteristic swelling and shrinking of the fibres, whilst the peculiar action of uncoiling or twisting of the fibres, first noticed by Prof. Pope and himself, was produced by certain reagents, such as caustic soda, nitric acid, &c., but was entirely absent when barium mercuric iodide, alcoholic potash, &c., was used. It was therefore clear that these reactions, although producing results which are to a certain extent similar to that obtained with caustic soda, were by no means identical. He thought it would therefore be advisable to limit the application of the term ‘L mercerising ” to effects produced by using strong caustic soda solutions upon cotton, and i t might be of some importance if the Society could move in this matter, so as to have the term distinctly specified, especially as this term was a t present applied to certain less permanent finishes which had been produced without the use of caustic soda or any other agent producing a similar effect.

Mr. L. G. Radcliffe said he thought that until we knew more about the chemistry of cellulose and the exact nature of the changes which were brought about in the complex molecule by various reagents, practical men would prefer to use the term “ mercerising ” for caustic soda treatment alone.

Mr. J. R. Appleyard said that manfmaterials were a t present put upon the market which were regarded as mercerised finished which had not been mercerised in any way. He was inclined to think that the changes brought about by inercerisation were entirely physical, and .that there was no chemical chanpe whatever.

Mr. 1Tarshall doubted qery much whether people were gulled by the term “ mercerising.” He thought that for anything known in the mar- ket as mercerising, they must produce on the hank or cloth a very close approach to a silk fabric.

X Member said that from a trade point of view he considered that it did not matter what a finisher used as long as he produced an effect which was physically the same as mercerising.

Prof. Knecht said that in reply to Prof. Pope, he did not think it necessary to restrict the term

merc rising ” to the action of caustic soda only, hut that it might equally well apply to the action of other substances which produced in the vegetable fibre physical and chemical alterations similar to those brought about by strong caustic soda. In his patent specification Mercer also included the action of caustic potash, sulphuric acid, and zinc chloride, and having found that

“

nitric acid bore in its action on cotton such a striking resemblance to that of caustic soda, he thought he was justified in employing the term mercerising in speaking of such action. His (the lecturer’s) suggestion that in the formation of the labile nitrate mentioned in the paper, the nitric acid might first attack the ketonic gr?up was put forward with a view to a possible explanation of its formation, and not to account for the hydration which ensues. He, too, had been struck by the lack of direct experimental evidence in support of the views a t present generally held in regard to the chemistry of the mercerising process.

The Chairman proposed a vote of thanks to the lecturer, which was seconded by Mr. Radcliffe.

XI.-DYEING A N D STAINING. -

On the Theory of the Formation of Turkey Red, and Schlieper and Baum’s Method of Dyeing the same.

J. PERSOZ.

When mordanted goods are dyed a t the boil in a bath containing 14 to 2 grms. of 10 per cent. Alizarin, and an equivalent quantity of lime per litre, a deep red is obtained in a few minutes. If the goods are immediately washed with cold water and dried, a dull yellowish-brown is obtained, or a dull Bordeaux when the dyebath has been too alkaline. This dull shade when t,reated with a fatty acid and steamed gives a bright red, while the red dyed in the ordinary way and treated with a fatty acid does not change and a t the same time is not fast to soap. When a pattern dyed this yellowish-brown shade is steamed or boiled for 10-15 minutes a deep red is obtained similar to that produced on dyeing in the ordinary way, which does not possess the property of combining with fatty acids to convert it into a brilliant red.

These facts lead to the supposition that by changing the conditions of dyeing a red with Alizarin, aluminium mordant, and lime, two modifications can be obtained : one which combines with fatty acids and one which does not The former can be transformed into the latter by boiling with water or steaming, but once it is changed it cannot be reconverted to its original stat:.

The dull shade dyed quickly a t the boil and then cooled or dyed slowly a t the lowest tem- perature possible can be represented a4 follow-

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