Meeting held at the College of Technology on January 17th, 1919, Prof. E. KNECHT in the c h i r.

The Properties and Uses of Some Titanium Compounds.

By .JOSEPH BaxNES.

It is beyond the scope of this paper to give a cheinical history of titanium from its discovery by Gregor, in 1789, and only those points of interest to the colourist will be dealt with.

About forty years ago I had to give instruction in elementary qualitative analysis to a class of boys preparing for the Oxford " Local." I t was with them, of course, a frequent mistake to record alumina instead of phosphate of lime in the analysis of simple salts. I showed them how they could identify alumina by boiling the well- washed precipitate proclucecl bj7 ammonia with a little Alizarin. Some time afterwards i t occurred to me to try if this test was reliable in the presence of rare earths, and I discovered that titanium and, to a certain extent, Ziroonium, gave colour reactions very like alumina. I then prepred bits of yarn with 8 salt of titanium in a manner similar to that used in the Turkey Red process, atid dyed thein up with various colours. A short paper was given in 1,885" to the Society of Chemical Inclustry, and Prof. Roscoe face- tiously remarked that i t was satisfactory to know that when we had finished all the alumina we coixlcl fall back on titanium. causing thereby a considerable amount of amusement, for in thosc (lay9 we looked UJJOI~ titanium as one of the rsrc elements. In 1887, having charge of a section of the show case of Messrs. Kearns Allan & Co., a t the Manchester Exhibition. which was devoted to exhibits of scientific interest, I arranged a series of dyed patterns showing the inorclanting effects of less common metals, including titanium. This was revicwcd in Dingler's Polytechnisches Journal and in ChemiscJLe Indzcstrie by the late Otto N. M7itt whoin I hnd the fortune to havc somc con. versation with and who showed great interest in the titanium results. About eight yeare aftermards my attention was drawn to trhe fact that titaiiium was not such a rare thing after all, seeing that the bauxite which was being used in large quantities in the innnufactme oi sulphate of alumina and 21uin contained in some cases as much as 7 per cent. of TiO,, and that this latter substance must eithcr be thrown a w a y or be accumulating in large quantities. This inclucd me to go once more carefnlly into the matter, and I made experiments with titanium as a mordant for wool. A paper was read before the Yorkshire Section of the Society of Chemical Industry in 18967, and i t was a t that meeting that Prof. H. R. Procter, referring to the colou~

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-. ~ .__. _ _ _ Im(lucec1 with tnniiic acid, wggcated that. t8itaiiium might he uaeful in the dyeing of leather. This proved to be a happy forecast, as is testified by the large and increasing quantities of titanium salts used by leather dressers. The next qnest,ion was how to obt,ain a. ,suitctblc compound of titanium from t,he titaniferons resiclues of the alum works. My experiinents had been made with cornpounds prepared from pure titanic chloride, TiCl,, and in my endeavours to prepare a soluble salt from the nat,ural ores and residues, I found the greatest rlifficulty i n obtaining a product satisfactorily free from iron by any method giving promise of pract,ical utility. A t this stage Messrs. Peter Spence and Sons, of this city, came to the rekcue, and Mr. Howard Spence, who had heen working in Heiclelberg on bauxite residues, brought nic a sample of a peculiar salt ha,ving t.he composi- tion TiO(SO4Nn),~2H,0, which they had sue- ceded in making by a practicable proccss. This was a beantifully-white product sufficient.ly free from iron to allow of its use in the mordant,- jng of wool. - Prof. Hunmel niade a large number of t.rials with bhis subst,ance arid reported that the black given with Logwoocl was distinctly superior to that obtained with chromium mordants. Alizarin Orange ga,ve, when the mordanting was done in a proper manner, a very good scarlet. Alizarin Yellow produced a brighter a,nd faster colour on titaninm mordant ehan on alumina. Messrs. Spence & Sons wcre not long in putting on the market a number of other compoimds of t'itaniurn, incluclirig the double oxalate of titanium and p~t~assiuni, a beautiful salt of grea't, piirity, which wa.s pre- eminent1 siiitable for leather dyeing. In 1901 Dr. Kne& iutroduced the titanoiis coinpoui:ds as st,ripping and clischarging agents, mid these have proved of great use. I need only refer to the most vahmble work of Ki?echt ant1 Hibbert on the use of titaiious salts in various analytical processes, resulting in an extensive scheme of working of as great, if not greater, applicability as the famous Bunsen iodimetry.

Silk inay very easily hc inortlanted with titanium by siniply steeping i t in a sohitioil of t,he titanium socliuin sitlpha,te. The late (E. H. Hurst read a paper before this section in 1903*, and exhibited samples illustrating this method, and drew attention to the excellent results obtained with M'eld. Mr. Howard Spence g a w a rCsumt of various uses of titanium compoiiiitls before the Manchester Section in 1904t.

In concluding this brief survey I map remind you of the work done by Dreher and by Lmnh on the application of titanium to the d-p ing of lent'her.

Titaniudm Xodizcm Xulphate.-This-the most iinportaiit of bhe commercial salts-is a white powdery suhsta.nce which under the microscope is found to consist, of minute needle-shaped cqstals. It is very difficult to dissolve in pure

This Jo ta . , 19 141, lip. 10.5 :Lnd 2 " X . t 'r'his J , J ~ V . . Vnl. XS., 1 8 . c i

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water. Boiling water a t once decomposes it, giving rise to the formation of insoluble and inert meta-titanic acid. By adding a certain amount of acid, e.g., sulphuric or oxalic, it may readily be dissolved by heating. A strong solution may be obtained by stirring it with cold water for a long time ; one part of the salt mixed with two or three parts of cold water and stirred frequently for several days will yield a liquor of high sp. gr., which may be diluted down to a certain point without suffering decomposition. When highly diluted, the titanium hydroxide-titanic acid-is mostly thrown down. This decomposition may be prevented by adding an acid to the diluting water. The strong liquor may be neutralised to a great extent by the addition of an alkali, and i t is possible to obtain an extremely basic product which remains in solution so long as i t is kept cold and concentrated, but when diluted even to a moderate extent the bulk of the titanium is thrown down as hydroxide. Heating will, of course, quickly convert the precipitate into meta-titanic acid. It is noteworthy that this meta form of titanium hydroxide is practic- ally useless for tinctorial purposes, and the dyer should always be on the alert with regard to the failures arising from its accidental formation. All unnecessary heating and dilution should be avoided. By adding a certain amount of sulphuric acid, however, a highiy diluted solution of the sulphate may be heated up to 44" C. without suffering material change, and in this way a. Herbert Wrjgley has made it possible to use the titanium sulphate in place of the more expansive oxalate compounds in the dyeing of leather. He has, after a great number of experiments, determined the right proportion of acid as well as other conditions necessary to yield the best results.

An excellent way of obtaining a solution-of titanium sodium sulphate is as follows :-One part of the salt is mixed with nine parts of a cold solution of Glauber's salt of 5" Tw., and by stirring the mixture from time to time foi several days a stable solution will be obtained with only a trifling amount of residue, and will contain about 2 per cent. of Ti02. It will k e q in the cold almost indefinitely and may be diluted with a considerable amount of cold water. If instead of diluting with pure watei a solution of Glauber's salt of 2" Tw. be used the dilution may be caried to almost an j extent. A liquor prepared in this manner serve5 as a most suitable fixing bath for tanned yan or cloth ; the sodium sulphate not only increase5 the stability of the bath, but retards the trans fusion of tannic acid into the fixing liquor.

Titanium Potassium Oxalate (or perhaps morc correctly speaking, Potassium titano oxalate TiO(C,04K),.2H,0) is produced comrnerciallj in a very pure form, and was, until the higl price of potash rendered its economical inanu facture an impossibility, extensively used bj leather dyers. It yields very stable solutiom which may readily be obtained by the assistanec

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If heat,. A sodium oxalate compound has been iut on the market under the name of " Titox," vhich replaces quite satisfactorily the, at iresent, expensive potash salt. It does not lissolve quite so quickly, but if one or two very iinple precautions are taken a solution may be btained which will answer just as well as the )otash salt. It may be mentioned here, with egard to the use of these oxalates in leather lyeing, that the hardnesfi of the water may Lave a disturbing effect. Hard water should be orrected by adding to it sufficient oxalic acid o convert t-he whole of the calcium, whether it ie in the form of carbonate or sulphate, into balcium oxalate.

The titanium ammonium oxalate is much more ,oluble in cold water than the potassium com- )ound, and is therefore not so readily obtained ree from iron. When slowly crystallised i t orins beautiful and well-defined large crystals. t h solution mRy be mixed with sodium acetate tnrl acetic acid, giving a potential titanium tcetate that can be dried on cotton cloth without endering it.

Hydrofluoric acid yields the most stable corn- Iounds of titanium, and the fluoride (TiF,) and Llso the well-known fluotitanate of potassium K,TiF,) are excellent mordants for wool. " Titanium-tan.no-oxalale " is simply a solution

If tannate of titanium in osalic acid. Its uses were described in a paper read before this Section in 1916.

The use of titanous salts for the discharge and stripping of certain colouring matters has been nvestigated by Prof. Knecht, and their uses as malytical reagents by Knecht and Hibbert . A method of mordanting with a titanons salt is iescribed iii Knecht, Rawson, and Loementhal'fi treatipe on dyeing, and is briefly as follows :- The yarn or cloth is first dyed a Manganese Brown and is then stripped with a titanoils salt ; the reduction of the peroxide of manganese to the monoxide results in the formation of titanic oxide, which becomes fixed on the fibre. This mordauting effect is also noticeable in the removal of iron stains by means of titanous sulphate or chloride. The removal of iron stains is more rapidly effected if an addition of oxalic acid or an acid oxalate is made to the titanous salt, and a t the same time the deposition of TiO, on the fibre is prevented ; such a mixture is of special use to laundry workers.

When clean cloth is soaked in a solution of titanous chloride or sulphate, there is a consider- able deposition of TiO., on the fibre, and this is much increased in amount by exposing the cloth to the air after soaking and squeezing. By repeating these operations of soaking, squeezing, and hanging in the air, i t is possible to obtain a full mordanting effect. The effect is con- siderably increased if the cloth is given a Turkey Red oil or a tin prepare. One of the advantages in the use of titanous salts in place of titanic salts for mordanting is that any iron present as an impurity has 110 deleterious effect. For light shades requiring only one application of the

iiiordant, this process affords a ready means of obtaining a variety of pinks which moreover have the good quality of being level. I inay draw your attention to the salnion pink morclanted by this method and dyed with Alizarin Orange.

Attention has already been drawn to the clifficulty of obtaining titanium compounds free from iron, and i t is this fact that iiicreases largely the cost in the manufacture of pure titanium salts. Where iron does not interfere, or where i t may even be an advantage, i t is possible to make use of a cheap material. Such a inaterial has recently been introduced by Messrs. Spence & Sons, and with which I have inade a considerable number of experiments. Iron taunate, as before mentioned, is more sensitive to the action of acids than is the caFe with titanium taiuinte, and by varying the degree of neutralisation of the iron-titaniuin Liquor, every shade of brown intermediate between buff and greyish-blue may be obtained by very simple operations. As an example of the process, the following may be given :-The cloth or yarn is first tanned in the ordinary way. I t is then passed into a liquor prepared as follows :-70 cc. of the strong liquor having a sp. gr. of 1.400 is partially neutralised with a solution of soda ash containing 17 grim. of Na,CO,. Then add 450 cc. of a solution of Glauber's salt of 5" Tw., ancl cldute the whole down to 1 litre with cold water. The cloth or ,yarn is then squeezed or wrung up, allowed to lie off for about a quarter of an hour, and then washed. By putting the dyed niaterial through these operatiom a second or third timo, any depth of shade iiiay reacliily be obtained. For pale shades the strength of the tsiuiiii bath may be reduced, but i t is not advisable tb reduce tho strength of the titanium bath. Brighter and rather redder shades of brown arc got by finish- ing off in a warm tannin bath. It is needless to say that material treated in this inanner may at once be dyed up with any basic colonr. It nisy also be dyed up with the alizarins, although the tannic acid in combination with the titanium mid iron may retard more or less the absorption of the colour, and it is bctter therefore to pass tlic cloth before dyeing with Alizarin througk i~ warm alkaline dunging bath. which ma) consist simply of water containing onc or twc grms. of Na,CO, per litre. The above nietliod of dyeing resembles in some respects a inethod suggested by the late John Mercer for dyeing a LOqwood Black on mercerised cloth.* Hc says, b'' Contracted cloth may be dyed a fin< black by soaking i t in Logwood Liquor of 1" Tw for some time, then wringing, thqi soaking ii cold iron liquor of 10' Tw., wring, expose to ail for a little, and wash in hot water."

The fastness to light and ordinary washing of the colour produced by tannin and titaniulr has already been mentioned, and I may nom say that recent experiments have showr, thai tho browns dyal in the above-describsd waj

tie aecidedly better with iegard to their ie- ,istance to light than the sulphur colours. Then Lgaiii, the method of dyeing is one which .equircs scarcely any steam, a consideration iiider present circunistancea of great moment. Lt may be of interest t o the calico printer to mow that good whites inay readily be obtahed 111 these tannin-titanium colours by means of t chloratc discharge, and also that a still greater 'aiige of shades inay bc got by mixing adjective :olours, such as Gomilein, Logwood, and the llizarins with the tannin bath, in which the 'loth is padded.

These colours can be dyed on yarn just as :asily as on cloth.

D I S G U S ~ I O ~ The Chairman (Prof. Knecht) said that the

ecturer had been identified for the past forty years with industrial applications of titanium :omponnds. Developments in the application )f titanium had not been so rapid as might have been expected, and there were considerable ~ossibilities in the future. Titanium was one if the commonest elements, standing seventh KI the distribution of the elements, and was, iccorcling to F. W. Clarke, more than twice i s plentiful as carbon.

The author's reference to t h e special con- lition of the oxide of titaniun~ Eeirg eseentjal o its possessing mordanting properties, biought orward the general question, when is a metallic x ide a mordant ? The conditions in which ron and chromium were deposited on the [ibre detcririinrd their utilty as mordants. rhe use of sodium sulphate in keeping titanium n solution was very interesting.

The beautiful specimens exhibited by the ecturer showed some of the practical applications 3f titanium salts. It was not generally known that most linings in felt hats a t the present time \\ere dyed with tannate of titaniuni.

Mr. W. Marshall called attention to the excellent penetration of the titanium dyes. He thought that if a dark brown, such as was now so fashionable in boots and shoes, could be obtained by the use of titanium salts, there would bc a very great incre;tse in their use. He asked whether i t was possible to top the titanium tannate with direct colours for the purpose of shading, and whether there was any difficulty in applying titanium again to bring up to shade.

Mr. C. W. Doxey mentioned that several years ago he had inade experiments on the application of titanium in calico priiit,ing, and had obtained a very good black with titanium and Logwood, but the result was found to bc rather expensive. He would like to h o w which titanium compound was best for use in calico printing '1

Mr. J. R. Hannay expressed his appreciation of the useful historical survey which the lecturer had givcn. He was especially interested in the application of titanium salts in calico printing. Was i t possiblc to obtain caustic dischtcrgc

G2 CHOSS, GREENWOOD A N D LAMB--'- COLLOIDAL TANNIN COMPOUNDS." [AI:trvh, 1919.

cffccts Z He observed with satisfaction- the results obtained with chlorate. The cheaper form of salt exhibited by the lecturer was, he understood, a titanic sulphate. Would i t not be possible to prepare a similar titanous salt which would allow of the fixation of oxide of titanium, and prevent the fixation of the iron ? With regard to direct printing, he had obtained some excellent results, but found them rather expensive. If the cost compared favourably with aluminium, there would be rnany deinands for titanium, and would lead to its more general technical application.

Mr. T. A. Holroyd asked if ralciiini salts were iiecessnry to procliice the effects as ill the case of al~uniniuin ?

The Lecturer said the meta foim of titanic acid could exist in solution in the same way as the ineta form of tin, but did not give the ordinary colour tests, such as the hydrogen peroxide and ferro-cyanide reactions. Certainly, as regards rnordanting. there were inert forms of iron, aluminium, and chromiiim. With regard to topping with direct colours, he saw no reason why this should not be applied, and a mild alkali would not disturb the original shade, yo that any colour which could be applied in a neutral or slightly alkaline bath was applicable for topping.

The depth of shade in the case of leather was determined by the amount of taniiic acid present, and the browns referred to by Mr. Marshall could be obtained 'tvith inixtures of titanium and iron. A basic or an acid dye could be used for shading.

In 1901 he had obtained fast effects by the application of titanium hi calico printing. He found that titanium -potassium-oxalat e was inclined to cryshalliw out in the printing colour, ltut this difficulty was overcome by using tbe sodiuiii salt,, and coagulation of the thickening was prevented by thc a-ltlition of tartaric acid.

With regard to the prescnce of lime, he did iiot consider this to be essential, as hi the case of alurniiuum, seeing that with Manchester tap water he had obtained .satisfactory results without the addition of lime salt.

In testing for fastness, the samples had been subniitted to the ordinary soaping test and to csposnrc to a south light from August 1st until lleceuibcr, 191s.

LONDON SECTION.

Meeting held a t the Leathersellers' Company's 'l'echnical College, on ,January 23rc1, 191 9. Dr. CHAS. DOREE in the chair.

Colloidal Tannin Compounds and their Applications.

and M. C. LAMB. It ih gel1 cra llg recmgni secl that 11 111 tiiti 1 ii ~l ustry

ib 111 Iiirge ptr t i~ further IJhLtSC or' (lo\ elopiiie~it of OWSWK of tlw natural \torltl, a i i t l that the

By c. F. CROSS, c. v. GREENWOOD,

Taw inaterials of iiidustrg are also, in large part, iatural products: the properties and qiialities of which are its conditioning factors, as they arc if t'he applications and uses of its products. rhe industries based upon ergatiic prod iictR arc arge1.y concerned in the fashioning of these into 'abrics, for which the raw inaterials are the itnic tu rd f orins of organi sed ma tter-ani 111 a1 md vegetable.

These raw materials are colloids, and hence Jhe technology of our more important industries If this group, (a) the textile arts, including twine md rope making, paper making, (a) leather, [c) rubber manufactures, are based on the iiechanical-p~ysl'cal-cheiiiical properties and re- actions of colloidal matter as such.

Since the specialised study of pheuomena and *eactions in this field is relatively recent, the ndustrial arts of which they are the prime :actors have been elaborated to a high grade of perfection, independently of forinal science.

In applying to these arts the forinal criticisin )f later birth, we find very much to appreciate and justify in the light of more exact lniowledge ; in many cases, on t'he other hand, we find that wnpiricisni has developed prejudice, aiid that the prejudice is the more deeply rooted because i t reflects fundamental features of colloid phenomena. There are two groups of factors particularly involved in this aspect of industry ; (1) the Time Factor. Thus, i t requires many weeks to carry through the bleaching of fine linen goods; it take4 months to produce a pit-tanned sole leather of stan+& quality ; mcl years to "season" a timber for special &ructural applications. (2) The Life History Factor. The natural structural colloids have their individixal characteris ics, but, a uniformity

3r in another aspect, a highly resistant aggregate quality, associated with extreme reactivity of coinponen t groups.

As the subject of this cominunication is sectional, we limit the consideration of these factors to their incidents in the leather industry.

The two factors are associated in their effects for the reason that the skin-substance is highly reactive a11 d changing throughout the period of duration of the entire process of coiiversioii to leather, as of each of the succession of treat- ments. It may be, therefore, that in attempting a quick tannage, by applying a certain principle to control the main reaction between the collagen and tannins, we rnay disturb the system in respect of secondary reactions, the results of which are factors of leather quality.

Any question of this order is decided by a tebt of quality, of which t h e standard is one of einpirical recognition md definition. There cannot, in the nature of colloidal thiiigs, be an '' ideal " leather, for that would aclnzit of coin- preliensive exact definition. Our hiowledge of leather, as of its antecedent foniis, is iiicoinpletc iii iiiiportaiit, details, therefore inesact. Heiiccr t tw cmpiricnl staritlartl is R standard of sciencc,

which masks extreme uiid L lying variability ;