136 EDGE-"A NEWLPBOTECTIVE AGENT FOR ANIMAL FIBRES." LXay 1922

the oxidised cellulose was greatly diminished. The reduction in the nitrogen content of the cellulose product was not nearly so marked.

In the nitrations tabulated above the weight of the acid mixture was forty times that of the cellulose material, which was dried before nitration. The nitric esters of oxidised cellulose were soluble in caustic soda, giving a deep yellow colour on warming. They were almost completely soluble in alcohol-ether. On keeping in loosely stoppered bottles the dried product gave off nitrous fumes in considerable quantity after about a month.

Experiments were carried out similar to those described by Knecht (Ber., 1904, 649), using oxidised cellulose instead of cellulose. In the case of cellulose immersed for two minutes in nitric acid of 83" Tw., and after expressing the acid dried i n vacuo over quicklime, cellulose retains acid in amount cQrresponding to a mono-nitrate. This was considered to be com- bined to a ketone group in the cellulose. In the case of oxidised cellulose it was found that the nitric acid was invariably reduced, consider- able quantities of nitrous fumes being formed before the product could be dried, and further attempts to obtain a labile nitrate were conse- quently abandoned. This action did not take place in the case of cellulose.

Xummary.--In the initial stages of oxidation of cellulose by permanganate. in cold acid solution, the rise in copper number is nearly proportional to the amount of oxidant used up. After the use of a half atomic proportion of oxygen the rise in copper number is very gradual

The acetylation of oxidised cellulose was not found to give any indication of the effect of oxidation on the hydroxyl groups of cellulose. This was due to the very great reduction in the yield; highly oxidised cellulose gives a high yield of water soluble products on acetylation.

When nitrated under identical conditions oxidised cellulose gives products containing considerably less nitrogen than cellulose, and it is inferred that oxidation results in a suppres- sion of the hydroxyl activity.

Owing to the strong reducing action of the oxidised cellulose i t was not found possible to obtain a labile nitrate.

DISCUSSION. Mr. J. R. HANNAY said that the research

served to throw Borne light on the manner in which OH groups were attached in the cellulose molecule, and might have great importance in respect to various aspects of the cotton industry.

Mr. Wm. Thomson said that the peculiarity that a different amount of nitration was ob- tained from cotton after oxidation was very remarkable.

Mr. Wm. Marshall said that he did some work on the acetylation of cellulose some years ago, with the idea of keeping the fibre intact, and

not to produce a solution, and he found that mercerised cotton would not readily acetylate. He believed that the chemical constitution was tltered by mercerisation. With bleached cellu- lose the acetylation would start at once, but with mercerised cellulose there was no action For some considerable time; but the action would eventually overtake that of pure cellu- lose. It was observed that the acetylated mercerised cotton was tender, and could be powdered if the process was carried far enough, and the action of mercerisation appeared to have altered the molecule in some way.

Prof. Knecht said he could not offer any xplanation as to why mercerised cotton should behave so differently from ordinary cotton.

At the close of the discussion the Chairman mnounced that he had succeeded, in collabora- tion with Mr. Hatton, in isolating the nitrogenous cell content of the cotton fibre. The substance, which represented somewhat over 1 per cent. of the weight of the fibre, was albuminoid in character, and aa it was considered that its further study might prove useful, this was being undertaken.

A New Protective Agent for Animal Fibres. ALFRED EDGE.

The cleansing or scouring of wool by means of aoap and alkali is a delicate operation, and inexact or careless manipulation may easily result in serious deterioration of the valuable raw material. A means of avoiding this danger has now been placed on the market by the Actien Gesellschaft f i i r Anilin Fsbrikation of Berlin under the names of " Protectol, A.G.F.A.," Nos. 1 and 2. These new preparations possess the useful property of protecting animal sub- stances, such as wool, silk, leather, furs, or the human skin, against the injurious effect of alkalis.

They are marketed in the form of brown syrupy liquids of 62" and 48" Tw. respectively, possessing a neutral reaction and ready solu- bility in water. No. 1 is precipitated by alkaline carbonates and is intended for use with caustic alkalis (soda, potash or ammonia). No. 2 protects against alkaline carbonates or sulphide of soda. It has therefore a wider field of use- fulness than No. 1 in the treatment of textiles, furs, and leather. In wool scouring, in order to obtain thorough

saponification or emulsification of the grease, the temperature of the scouring liquor must be above the melting point of the wool fat (105'- 108" F.), and when the scouring is carried out at between 110"-120" F., some damage to the fibre always results, particularly in the cam of the 6ner grad- of wool.

Y s ~ I s Z j EDGE-"A NEWf PROTECTIVE AGENT FOR ANIMAL FIBRES." 1 37

The addition of Protectol to the scouring bath makes it possible to keep the temperature above the melting point of the wool fat, without danger to the material properties of the fibre.

The quantity to be added varies according to the quantity of alkali present, and the tem- perature of the bath. As a rule half as much Protectol as soda ash is sufficient to afford complete protection.

Protectol may also be used with advantage in the scouring of piece goods, both all wool and, more especially, unions. It is specially useful in thc treatment of pile fabrics, such as plushes and astrachans, where injury to the animal fibre may easily occur.

Dark coloured rags may be treated with sul- phide of soda in presence of Protectol, and thus a much lighter coloured material obtained than when stripping with soda alone.

Vut Dyeing.-An obvious application of the new product is in the dyeing of wool with vat dyes in the hydrosulphite-caustic vat. The difficulty of obtaining satisfactory results with this vat has been the chief obstacle in the introduction of this class of dyestuffs for the dyeing of wool.

This application of Protectol has been very thoroughly investigated, and its use is attended with many advantages. The wool is thoroughly protected against the injurious effect of the alkali; a better exhaustion of the bath is noticed, and a superficial fixation of the colour is pre- vented. No alteration of the method of working the vat need be made; the addition of Protectol varying from 4 to 14 ozs. per gallon, according to the depth of shade required. It is to be noted that when using Protectol, the oxidation takes place somewhat more slowly.

The Use of Protectol in Union Dyeing.- There has, up to the present, been no suitable method of applying the sulphide dyes in sulphide of soda solution in the dyeing of union piece goods. By using Protectol with sulphide colours the wool is only slightly stained, and may be afterwards cross dyed with acid, metachrome or after-chroming dyes. This gives a result which is much superior in fastness to anything that can be obtained by the single bath method, or by wool dyeing and burl dyeing. iIt is of great interest for expensive union materiah, such as gabardines, when the utmost degree of fastness is essential.

It is advantageous to dye the-sulphide coloui in as short a bath aa possible, and the mosi successful results have been obtained by dyeing on a jigger. The colour may be applied by thc usual sodium sulphide process, but the besl results have been obtained by reducing with hydrosulphite. This may also be carried out h the jigger.

After dyeing, the goods are waahed- acidified with sulphuric acid and again well waahed, afterwards wool dyeing in the winch machine with metachrome or other chroming dyes

The process is also very well adapted for woollen piece goods which contain vegetable impurities, cotton burls and " shives," which may be dyed on the jigger with sulphide dyes When the burle are well covered, the goods may be wool dyed by the metachrome or after- chrome methods.

The one-bath method of union dyeing has the disadvantage that the goods are liable to form crimps and winch marks, and frequently do not handle well, the cloth being what is known as '' boardy " in feel. This is due to a deterioration of the wool or shoddy, and makes the process unsuitable for the more expensive and delicate union fabrics, such as plushes, astrachans, and lustre goods.

The use of Protectol has been found to be a practical means of overcoming the drawbacks associatad with this very convenient and economical method of dyeing, particularly in garment dyeing, for which the one-bath method ia very well adapted.

With certain dyestuffs which are readily precipitated from their solutions by acids, it is necessary either to use neutral dyebaths or baths containing ammonium salts, which de- compose on boiling and set acid free gradually.

It has been found that Protectol prevents the precipitation of such dyestuffs by acid, and they may be dyed with acetic acid if Protectol is added to the bath. The process has been thoroughly worked out in the case of the Indocyanines, a very useful class of dyestuffs possessing exceptional fastness. This new pro- cess may be used for all coloura which require to be dyed with sulphate or acetate of ammonia.

A patent has been applied for covering the use of Protectol in the dyeing of chrome colours, either by the after-chroming, metachrome, or chromate methods. An addition of 2-4 per cent. Protect01 to the dyebath has a very remarkable effect on the spinning qualities, softness, and elasticity of the dyed wool or shoddy-the effect being specially noticeable in the caae of the latter material-and more level results are obtained.

Silk-Many attempts have been made to substitute soap in the degumming of silk, but the processes hitherto suggested have not met with much success, either because the silk fibre is affected, or the proceRs offered no advantages over the old method of " boiling-off " with soap. By the use of Protectol it is now possible to rapidly and safely degum raw silk in a caustic alkaline bath without the slightest risk of damage to the fibre, and with great saving in steam and labour.

The treatment is carried out by treating for one hour a t 100" F. in a solution containing-

1-1.g oz. Caustic soda ) per gallon 1+2 ozs,l?rotect0l

afterwards rinsing and lightly souring.

138 EI)UE-"A NEW PBOTECTlVE AGENT BOR ANIMAL YIBJUS." [May 10.12

By nieltns of Protectol i t is also possible to dye silk with the sulphide dyes in a mlpbide of soda bath, the dyeing being carried out a t B

temperature of L40"-170" F. in the ORSC of colour, and for blacks up to 190" F.

In the treatment of cotton and silk fabrics, ti preliminary treatment with caustic soda is given in some cases in order to increase the affinity of the cotton for dyes. This is usually carried out with caustic soda of about 40" Tw. When Protectol is used there is no shrinkage of the cotton during the partial mercerisation, but the increase of affinity for dyes is still obtained, and the silk is degummed without injury to the fibre.

In the dyeing of half-silk with sulphide dyes, various effects may be obtained by a proper regulation of the temperature. Dyeing at 20"-25" C. the cotton only is dyed, and if the temperature is raised to 7O0--8O0 C. solid shades may be produced. By dyeing a t the lower temperatun: with suitable acid colours added to the bath, a two-coloured effect is produced. The use of Protectol renders it possible to carry out these processes without fear of injury to the fabric.

Furs.-Very satisfactory results have been obtained by the use of the new product in the treatment of furs. It is usually necessary, in order to obtain satisfactory results in dyeing, to subject the furs to an alkaline treatment known as "killing." The object is to make the hair more receptive for the dye-particularly the tips of the hair, which would otherwise take the dye poorly-and to remove the natural grease, Superfluous tannin is also removed by the treatment.

Protectol has given excellent results in practice when used with the " killing )' liquors. No. 1 is used where killing is done with caustic soda, ammonia or milk of lime, and No. 2 when the process is carried out in the "Tumbler" with soda solution.

The process generally employed with Rmall skins is to brush on to the hair a solution of caustic soda (2"-3" Tw.) containing Protectol, leave overnight, and then wash well.

The dyebath, when using fur dyes of the Ursol class, is frequently alkaline. Protectol in this case prevents injury by the alkaline liquor and also against the oxidising action of the hydrogen peroxide without influencing the dyeing process.

Leather.-In the leather industry, Protectol has been found to give beneficial results in the ' * liming " process, which is now frequently carried out with sulphide of soda. The object of this treatment is to loosen the hair, but there is risk of damage to the skins.

It haa also been used in the dyeing of chamois leather with sulphide dyestuffs, which are exceptionally well adapted for this purpose.

The alkalinity of the dycbtith is again a drau- back, and the addition of Protectol is found to give an effectual protection.

In dyeing with basic dyes on chrome leather. in order to makc the leather receptive for these dyes i t is necessary to treat i t with a tanning agent It has been proved that Pro- tectol can he successfully employed instead of sumach or gambier. The leather is treated in the tumbler with 15 per cent of Protectol 11. €or half an hour, then rinsed, and the dyeing with basic colours follows.

In the dyeing of feathers highly satisfactory results have also heen obtained.

It is the intention of the Berlin Co. t o place on the market a brand of Protectol in the solid Eorm, which will have many times the protective effect of the two existing brands, and by reducing the cost of carriage-at present a serious item- will make its use possible for even the cheapest class of goods.

1)ISCUSSION.

The Chairman (Prof. E. Knecht) said that apparently the substance acted as a protective colloid, with a selective action.

Mr. J. R. Hannay asked whether, when Protectol was used, union goods could be dyed with sulphide dyes on the ordinary type of jig in which the top rollers were outside the liquor. If that was possible it would be interesting to see whether Protectol would give similar results with cotton piece goods. MI-. Edge stated that, in giving certain union goods a preliminary partial mercerisation, the addition of Protectol to the bath had the rather surprising result that there was no contraction of the cotton fibre though the mercerisation was quite as effective as when the fibre contractcd in the usual way. If this was not simply due to the straining effect of the interwoven animal fibres, it was obvious that by the use of Protectol they could merceriw cotton and not contract i t ; which would save a great deal of trouble in many processes.

The Lecturer said that the union goods were dyed cold in the ordinary type of jig. He could offer no explanation for the curious behaviour of the silk and cotton goods where there was no shrinking of the cotton, and still the increase in the affinity for dyes was quite the same. It cer- tainly appeared worth while to investigate the possibilities of the phenomenon in the mercerisa- tion of cotton.

Mr. P. G. Jones referred to the Lodge-Evans process where sulphide of sodium was turned into sulphide of ammonia, and asked whether the Protectol was cheaper to use than the other process. With regard to the dyeing of cotton goods on the jig, such as sulphide blues, which were known to be very apt to bronze and become dark coloured, did the use of Protectol obviate this ?

May 18'221 WILSON-'' HYDROGEN PEROXIDE." 13e

The Lecturer said that the LodgeEvan process was one for applying sulphide dyes tc wool. In the case under consideration the: were only aiming at dyeing the cotton, and dic not want to dye the wool at all. It waa whai was known as burl dyeing, not dyeing the wholi fabric.

Mr. P. G. Jones said it was quite usual to dyi the cotton in half-wool goods by the Lodge Evans process, and afterwards dye the wool ir an acid bath.

Mr. Wni. "homson enquired whether frobecto could be used in conjunction with strong alkalint soap. Would it prevent the irritation to thi skin which was caused by the barium sulphidt used as a depilatory ?

The Lecturer said that it could be used ir connection with barium sulphide. It wai possible to put the hands in caustic liquon containing Protectol without injury. He did not know that it has been used in connection with soap, but he thought it was a very likelj and advantageous method of using it. He had used Protectol up to a temperature of 180" F for scouring wool, and there was no deteriorating effect a t that temperature.

Replying to Mr. C. Doxey, he did not know that Protectol had been used on a practical scale in the printing of sulphide dyes on wool and silk fibres.

Mr. N. B. Maurice asked whether a satisfactory explanation could be given of the action of Protectol. I n the boilingoff of silk, particu- larly crepe de chine, which contained fast boiling colours in the stripes, the boiling-off usually required six to eight hours, but by adding Protectol and a small amount of caustic soda to the bath, he found that the time for boiling off was greatly decreased. If i t was possible to cut down the time for boiling to one or two hours, and a t the same time dye the silk previously with sulphide colours instead of vat or mordant colours, there would be an cnormous saving in labour and in cost.

The Lecturer said that he had brought the paper forward with some reluctance, as he was not a t liberty to disclose the nature of t.he sub- stance dealt with. Great interest had been taken in i t on the Continent. He could not state what its composition was until the patent came out.

Meeting held on Friday, March loth, at the George Hotel, Huddersfield, Dr. L. GORDON PAUL in the chair. The Manufacture and Appliccrtiom of Peroxide

of Hydrogen. H. WILSON.

Hydrogen peroxide was discovered in 1818 by Thenard, who prepared it by the action of dilute hydrochloric acid on barium peroxide.

There are a. number of compounds, the per- compounds, which easily give off oxygen, and the following are practically employed in various industries as a source of oxygen-hydrogen, sodium, and barium peroxides, sodium per- borate, zinc and magnesium peroxides, and barium percarbonate. Carbamide compounds are also used.

The oxygen which can be split off from these substances has in the moment of fiberation (the

powerful olriciising agent, with highly disinfecting properties and strong bleaching action.

Sodium Peroxide (Na,O,) is made by heating metallic sodium to 200" C. in a current of air. It is a yellow, highly hygroscopic powder and has a strongly alkaline reaction. It is sent out in well-closed, soldered tins, and if stored care- fully will keep well. It contains about 20 per- cent. active oxygen. By carefully adding sodium peroxide to a solution containing dilute sulphurio acid, hydrogen peroxide is fornied-

Na,O, and H,SO, = H,O, and Na,SO, Thus hydrogen peroxide made from sodium peroxide will always contain sodium sulphate as impurity, which for many purpoRes is ob- jec tionable.

A further disadvantage of this process is the olimparative danger of handling sodium per- Dxide. It is a Tery dusty powder, and particles tlj-ing about will damage any textile material. Cn adding the sodium peroxide to the sulphuric acid bath, great care must be exercised, or the heat which ia generated will decompose some sf the newly-formed hydrogen peroxide. The iolution also splutters and is apt to burn the skin of the workman and is specially dangerous to the eyes.

Sodium peroxide is further used for the nanufacture of sodium perborate. Barium Peroxide (BaO,) is formed by heating

Iarium oxide to dull redness in a stream of air. Qt a still higher temperature i t loses the second Ltom of oxygen, being reconverted into the nonoxide, and this double reaction is used for Jhe preparation of oxygen on a large scale.

Hydrogen peroxide prepared from barium Ieroxide is fairly pum, but the product is rather !xpensive.

A small addition of hydrochloric or phosphoric mid is made when precipitating the barium salt vith sulphuric acid, and this is continuously megenerated. Hydrogen peroxide can also be Pbtained from barium percarbonate, and this )recess, which produces very pure hydrogen ieroxide, has been used for making the medicinal woduct, but being expensive has been super- ieded by the electrolytic process.

In order to get the greatest advantage out of (he use of hydrogen peroxide i t should be used n its purest possible form, in which case, the )leached material will contain no substance which requires washing out or gives rise to itains.

tltatw naeaadi) the property of acting 8.9 H