April 25,1889.1 THE JOURNAL OF THE SOCIETY OF DYERS AND COLOURISTS. 71

sul hide of iron.

pipes without destro ing the coating. Block t pipes are also most iifficult to manipulate from plumber’s point of view. In Bournemouth thi insist upon all pipea being of iron, but I do not thir that would answer with moorland water, because tl interior would soon be corroded up by the pear acids. If we could get over the plumbing difficuli with tin-linedlead pipes, they would certainly be tl. most satisfactory substitute for those at resent i use. It may interest ou to know that fextracte an ingot of lead from &hefield water. I precipitate the lead CM chromate. I used a ten gallon an i water, and added bichromate of potassium. Ever morning the supernatant water waa syphoned off an the pan refilled a little fresh bichromate being addec Subsequently f used phosphate of sodium insteac As the phosphate was very finely divided, and did nc settle well, i added chloride of calcium, which ri duced a precipitate that carried down the phospfat of lead with it. In that way I got the lead out of very considerable quantity of water, and I showed as a small ingot on a previous occasion alon with white block of phosphate of calcium whic% 1 ha made for the filtering of lead water. As to the eff cacy of different kinds of carbon, I have practical1 tried 50grms. of each kind of animal charcoal an charcoal supplied by various filter makers, an actual1 tested how many litres of lead-contaminate water fcould pass through them before they lost thei efficacy. They varied very much in that respect. I using these filters the phosphate of lead whitens th animal charcoal, so that you can see when it ceases t, be efficacious. It is efficacious until it gets white a1 through. I t is a very curious thing that thi epidemic of lead poisoning only occurs occasionally It is due probably to oxidisation in autumn, produc ing organic acid from the peat and other organit matter. At the same time we have not had fresl sources of supply in Shefield as you have had ii Bradford. Our reservoir which has been doing thc mischief is eighty or a hundred years old. I thin1 they have increased the gathering ground, but tha point is so suggestive I should like to go into it : little more before I make any statement in public Mr. Wilkinson said he did not think caustic sods was a safe substance to use in this district for soften ing water. I should not think of putting it into thi boiler. I was thinking of adding it to the depositing tank and letting the precipitate settle out. If yo1 argue that caustic soda is not safe because peoplc will use it in a reckless manner, I can only say1 wa: not talking to reckless people so much as chemists What I suggested was that caustic soda should bf used in quantit sufficient to combine with tht C 0 2 ; but Mr. $ilkinson seemed to suppose thal sufficient would be added not only to do this, but t c precipitate all the salts and leave a surplus i n solution.

Mr. RAWSON : The object of addin acetic acid in testing for lead with sulphuretted fydrogen is to prevent the formation of sulphide of iron.

Mr. ALLEN: Do you find iron produces a black colour I!

Mr. R A W ~ O N : No; the acid.prevents that. Mr. ALLEN : Do you find if iron is present it gives

a reaction with sul huretted hydroeen 1 Mr. RAWSON: f f the solution is alkaline. The

Bradford low-level water is usually alkaline, so that it is-necessary to add acetic acid, otherwise you get

ffect. I. lpok upon Breinl’s feaults as most valu-

--

see if you get a reaction with iron. Mr. RAWSON : I quite agree with Mr. Allen that

potassium chromate is an exceedingly delicate test

but for estimation it r uires a ver long time, as it is necessary to allow th8iquid testedY to stand many hours to settle.

Mr. ALLEN : I never attempted to usechromate for the estirnation of lead in water.

Mr. RAWSON : You simply use it for testing? Mr. ALLEN : Yes, merely to assure myself that the

colouration produced by sulphuretted hydrogen is really due to lead.

uneven dyeing. In the second aper I showed further that if the

solution of woof in sulphuric acid was carefully

---Mwwo4wW--

Meeting held March 19, 1889,

MR. CHRISTOPHER RAWSON, F.I.C., F.C.S., IN THE CHAIIl. --

COMMUNICATIONS FROM THE CHEMISTRY AND DYEING DEPARTMENT OF THE BRADFORD TECHNICAL COLLEGE.

BY EDMUND KNECHT, PH.D., F.I.C.

VII.TOn Some Chemical Properties of Wool and Allzed Bodies, and on the Behaviour of these Bodus towards the Substlrntive Dyes. Edmund Knecht and J. K. Appleyard.

LAST session I communicated to this Society in two 3apers entitled “On the Chemical Chan es which ,ake place when Wool and Silk are dye! with the Basic Coal-tar Colours,” and“0n the Behaviour of the 4nimal Fibres towards the Acid Colouring Matters,” ;he results of experiments which had been carried mt a t the College under my guidance by 3ome of the nost advanced students. In the first paper it was ihown that when wool or silk is dyed with basic :oal-tar colours, a complete decpmposition of the dye akes place, the base uniting with the fibre to form In insoluble coloured lake, while all the acid remains n the dyebath. This affords us an almost undeniable roof that in those cases, a t least, the dyeing is not a nechanical absorption, but a strictly chemical eaction. In the secoud paper I endeavoured to lxplain the behaviour of these fibres towards the acid oal-tar colours,. and showed that when the fibres vere dissolved in .moderately dilute sul huric acid,

If precipitating any of the acid colouring matters rom their solutions. It was also shown that when roo1 was boiled with very dilute sul huric acid, and hen extracted repeatedly with distiled water until 11 free acid had been removed it cou!d be dyed a ull shade in neutral ?elutions ol the acid colouring iatters. From this it appears to be evident that by he action of the acid there is produced in the fibre a ubstance which possesses the property of forming bkes with the acid colouring matters which did not reviously exist in the fibre. This latter question as since been dealt with more exhaustively by keinl in aninteresting andvaluable paper published in )ecember in the Zeitschrift fiir angezuandte Chemie. [e finds that when woollen or wqrsted pieces are nevenly steamed or impre nated in patches with

ons which .have been sub‘ected to !he biggest :mperature in steaming, or dave bee0 impregnated iplashed) with acid or alkali, will d e up darker

olutions were obtained which possessed t i e property

ilute alkalies or acids, and t P en steamed those or-

ian the others. thus causing a clou 1 y or uneven

~~~ .~ - -~ -~

which, when collected, washed, dried, and ground, formed an amorphous brown owder, insoluble in water,. but soluble in acids and alialies. The solution fn acids gave reactions similar to those of the original solution. I have since endeavoured to purify this product, but found that after standing for some time in the air i t had become changed, being only partially soluble in caustic alkali& ; moreover, the yield from the wool was so small (less than 1 per cent.), that I was o b l i e d t o look for some better means for isolating the lake-giving constituent.

By dissolving wool in caustic soda,+and acidulating the solution with dilute sulphuric acid, a solution is obtained which shows properties identical with those of the original sulphuric-acid solution. I think I was thereforejustifiedin assuming that itcontained thesame lake-giving constituent, and I therefore determined to discard the sulphuric-acid solution and to restrict my attention to the solution in caustic alkalies. After numerous futile attempts (extending over a period of many weeks) to isolate the lake-giving substance from the alkaline eolution, I determined to try whether the so-called lanuginic acid, prepared from wool many years ago by Champion,t possessed the property of precipitating the substantive dyes from their solu- tions. This was found to be the case, and we consequently set to work at once to prepare a quantity of this substance. The following was our nrodua operandi :-

About 500 rms. of Botany noils were first carefully washed and fissolved in a pretty strong solution of barium hydrate. The barium was then preci itated by means of carbonic acid, and from the htered solution the lanuginic acid was thrown down by means of lead acetate. After having removed all the excess of lead acetate by re eated washing with water, the lead Ealt was suspenled in a large volume ~f water, and decomposed by sul huretted hydrogen. 1 he filtrate from the lead sulphi&i was evaporated to dryness. I n this manner we obtained about Ngrms. of a brownish-yellow powder mass, which on grinding yielded a light dirty yellow powder. Here we were struck by a great discrepancy between our results and those of Cham ion. H e describes the Froduct obtained a9 a l igi t y l l o w deliquescent mass, while ours was not in the east deliquescent. By working, however, exactly according to his method-viz., dis- solving in barium hydrate, precipitating with carbonic acid, then with lead nitrate (instead of acetate), and decomposing the (perhaps not thoroughly washed) precipitate with sulphuretted hydrogen-we obtained on evaporating to dryness a product which corre- sponded exactly to his description ; but it contained nitric acid and there is no doubt that his also con- tained nitAc acid. Prom analyses of the barium and lead salts., Cham ion ascribes to lanuginic acid the composition C 1 9 ~ ~ ~ o N ~ 0 1 0 . The analyses agree indeed very closely with the formula, but he has left altogether out of consideration that the substance contains about 3 per cent. of sulphur,and his f o r m u k cannot, therefore, be accepted as correct.

The lanuginic acid which we obtained possesses the following properties :-It dissolves slowly in cold, easil in hot water. In alcohol it is sparingly soluble, in e t ie r insoluble. The aqueous solution precipitates the acid and'b&c colouring matters forming coloured lakes. Tannic'acid and bichromate of potash also yield precipitates. When heated to 1000 i t becomes

* The amount of caustic tioda neceatiary to completely dis- integrate the wool flbre was rough1 etitimated and it was found that whereati after boilins for tgree hours k i th 0'3 per cent. of caustic scda (of thc wcight of the wool). the flbre was not disintegrated. When the aniount wae increased to 0'6 per cent., complete disintegration and itlniosL complete aolution had taken place.

t Comptes Rendues, lxxii. X!4.

- ~ ~

soft and plastic, and this roperty is shown more strikingly by the coloured lales, most of which melt %t this temperature. If heated still further it swells u turns brown, and gives off a smell just like that ,!burning wool. On ignition a considerable quantity ,f ash is left, which consists chiefly of barium car- bonate. Suspecting that the reactions described might have been partially due to the presence of barium, we prepared a fresh uantity of the product by dissolviog in caustic so88 instead of barium hydrate, proceeding further as already indicated. The product obtained, which contained a much smaller imount of ash, exactly resembled, however, our first product, not only in external appearance, but in all ts properties.

Bichromate of potash yields a copious yellow arecipitate soluble in alkalies. On heating it melts to L brown mass. The following further reactions were ioted with the aque6us solution :-

Alum, in presence of sodium acetate, yields on stand- ng a white precipitate.

Staaaous chloride and sodium acetate give a similar mcipitate.

Co per sulphate, in presence of sodium acetate, gives

' % ~ r i c chloride, in presence of sodium acetate, yields a ight brown precipitate.

Fewous sulphate, in presence of sodium acetate, yields iirt white rccipitate.

Cirome &m, in presence of sodium acetate, a white mcipitate.

Salver nitrate, in presence of sodium acetate, white mecipitate.

Platinum chloride yields a light yellow precipitate, which melts on heatiiig the liquid.

Lanuginic acid shows all the properties of a proteid, tnd may therefore be classed among the albumenoids; t is soluble in water at all temperatures, and its iolution is not coagulated. With Millon's reagent, md with the double compound of phosphoric and ,ungstic acids, it shows the characteristic albume- ioid reactions. An ultimate analysis yielded the 'ollowing figures :- I. O'l2lOgrrn. Rubstance gale 0'8'Bgrni. H,O and 01891grm.

11. 0'1640grin. substance gale 1'0ilgrm. H,O m d 0'2494grm.

111. 0'1958grm. substance gdve 1'278grm. l ILO and 0'2383grm.

1. By Kjeldahl's method Igrm. of siibstance dried at 120" C., nentralised 1 0 . 6 ~ ~ . normal sulphuric acid, which s equivalent t o 16'22 er cent. nitrogen.

2. By the same metgod Igrm. of substance neutralised 1 0 . 7 ~ ~ . normal sulphuric acid, which is equivalent to 16.33 per cent. N.

The sulphur was estimated by fusin with soda md saltpetre in a platinum crucible, anfi precipitat- ng with barium chloride.

1. 0'436grm. of substance yielded O'lOGgrm. of barium inlphate, which is e ual to 3 3 4 er cent. sulphur.

2. 0 8513 rm. of s&stance yielied 0'2118grm. oi barium iulphate, wtich is equal to 3.35 per cent. sulphur.

Calculating the percentages from these results, we )btain the following :-

ft green curdy precipitate.

co,. CO2,

co..

I. I 11.

I

Lanuginic acid parts with all its moisture a t llOo C., the weight remaining constant when the tempera- ture wm raised to 130° C. The product used in these estimations contained a considerable uantity of barium, which was estimated in the m% in the usual manner, and was taken into account in calculating the above percentages. It is noteworthy that this barium is combined so tenaciously with the lanuginic acid that it cannot be removed from the aqueous solution by means of carbonic acid.

Another but more expensive method which we have devised for isolating lanuginic acid is based upon the fact that this substance is completely thrown down by means of night blue as a coloured lake. The method adopted was as follows : Wool wasdissolved incaustic soda, the solution sliehtly acidulated with sulphuric acid, and, after filtering, precipitated with a strong solution of night blue. The night blue lake was then decomposed with barium hydrate, which left behind the night blue base in an insoluble state, while the lake-giving substance passed into solution. After precipitating the excess of barium with carbonic acid, the liquid was filtered and evaporated to dryness. The residue showed properties similar to our first lanuginic acid, and we have reason to believe that the two substance are identical.

When acidulating the solution of wool in caustic soda, a precipitate is almost invariably obtained which variRs in quantity according to the strength ?f caustic soda employed and the dilution of the liquid when acidulating. 'Ithis substance forms a curdy yellowish-white mass, which is frequently called lanuginic acid, but which appears in our o inion to be an intermediate between the substance of &ewooland lanuginic acid. When dried a t looo C. it formsa brown horny substance, which ields on grinding a yellowish-white powder. If boired with water this powder partially dissolves, and we find that the aqueous solution, after acidulating, possesses the pro- perty of precipitating the acid dyes like lanuginic acid.

As is well known wool is slowly changed by boiling water ; at higher temperatures this change is still more marked. Leyer and Koller #'first drew attention to the solubilit of feathers, human hair. etc., in water at 20O0 C. $rein1 describes the solution of wool in water at 2009 C., and notes that the solu- tion thus obtained also possesses the property oi precipitating the substantive colouring matters. Pre. vious to the publication of Rreinl's results, we carried out the following experiment :-1Ogrms. of wool were heated with about 50cc. distilled water in a sealed tube for four hours to a temperature of 200-230° C On opening the tube there was a considerahlc pressure, and foul smelling gases, consisting chiefly oj sulphuretted hydrogen, were given off. Most of the wool was dissolved, leaving a small quantity of a brown residue in the tube. The liquid, which was oj a dirty orange colour, was strongly alkaline, owing t c the resence of ammonia ; it was distilled to aboui one-{alf of its volume, and the distillate, which Waf of a yellow colour, smelt strongly of ammonia, and gave no precipitate with crystal scarlet. Oc evaporating the aqueous solution to dryness, a residue was obtained which resembled glue while hot, and when cooled, solidified to a light brown hydroscopic mass, which weighed 5'5grms. From the acidulated aqueous solution of this substance ether extracts a light yellow oil, the smell of which resembles some oj the higher fatty acids. The aqueous solution give8 with sulphuric acid a yellow recipitate. Bichromatc of potash yields with the firtrate of this a yellom precipitate. Hydrochloric acid also yields a yello*

Liebig's Jahr. Ber .1%2, pago 697. ______ __

precipitate, which is soluble in excess, and in this solution bichromate of potash yields a brown pre- cipitate. Lead acetote gives a light yellow precipitate, soluble in dilute nitric acid.

The acidulated aqueous solution yields precipitates with the! acid colours.

From these results it is evident that the aqueous aolution of wool also contains lanuginic acid.

Horn boiled with caustic soda alsq dissohes, and the acidulated solution gives reactiocs similar to those of wool, Human epidermis, treated in a similar manner, was only partially dissolved, but tlie icidulated solution gave precipitates with the acid colours.

In his classical treatise of the " Theory Of Tan.ninf" A. Reimer t describes a substance contained In t e raw hides, to which he gives the name coriin, and which resembles in certain respects the lake-giving wbstance of wool. Reimer's coriin is soluble in alkalies, but is precipitated from the solutip by acetic acid ; in strong mineral acids the recipitate redissolves. This chemist already noticex that the 3olution of coriin gave precipitates with tannin, litmus, indigo extract, etc., but was not able to come to the conclusion that these were chemical conibina- tions. He ascribes to coriin the composition 2. oH50NloSla, and draws attention to the analogy which exists between its composition and that of the Bbrous substance of the leather, on the one hand, and iericine and fibroine on the other. Whilst sericine may be supposed to have been produced from fibroine by the absorption of oxygen and water, accordlng to the 3quation-

C30H4HN10012 +0+ 2H20=C,,H- NloO,,, Fibroine. sek'in,,.

the same is the case with coriin-

Fibrous subAtance of hide. cd4in.

We p r e r d .a q,uantity of coriin from the waste liquors of ime pits in which raw sheeps' hides had been treated. The filtered solution was precipitated with acetic acid, the precipitate collected on a filter, washed, and dried. It formed in the ulverised state a dirty white powder which showed t1e same proyer- ties as Reimer's coriin. Our product, however, con- tained sulphur which we found by means of the nitro-prusside reaction, but whether this sulphur is contained as an integral part, or is present as an impurity, we did not decide. The acidulated solution of coriin gives precipitates with the acid dyes like lanuginic acid. These reactions explain suficiently the dyeing of skin or leather with these dyes.

A substance very similar to coriin in its properties was obtained by dissolving wool in barium hydrate, passing carbonic acid through the solution for the removal of the barium, and acidulating the filtered solution with acetic acid. -4 curdy recipitate is thus obtained, which is soluble in altalies and hydrochloric acid. In the dry state, it forms a light brown powder ; the acid solution was precipi- tated by scarlet, soluble blue, naphthol yellow, etc. This substance only contained a trace of sulphur ; owing to tlie fact that it was only formed in small quantities, it was not further examined.

Sdphur tn Wool.-Chevreul has shown that, by treating wool with alkalies. the greater part of the sulphur is removed as sulphuretted hydrogen, but he was not able to remove all in this manner. By steep- ing wool 28 times in lime water, 24 hours each time, and washing with hydrochloric acid between each treatment, he was able to reduce the percentage of snl- phur to 0'46. The wool treated in this manner was M

t Dingler's Polyt. Jour., vol. 195, pp. 113,248,35& 457.

C.I"H,,Nl"Ol*+O+2H,O=C,"lI- Nl"O1;.

- - - -

?4 THE JOURNAL OF THE SOCIETY OF DYERS AND COLOUHlSTS. [April % 1W.

C . . ......... H

h'. . . . . . . . . . s . . . . . . . . . .

...........

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

longer blackened by an alkaline solution of lead. It was thus shown that the sulphur in wool exists in two different forms.

Havin found that lanuginic acid is not blackened by an alfaline solution of lead, we considered that the sulphur, which cannot be removed from wool by treatment with alkalies, must be contained in it in this or in a similar condition. We thought it of interest to estimate quantitative1 the amount of sul hur which could be removeg as sulphuretted hyjrogen by another process.

For this purpose, the sulphur was estimated in wool by fusing with soda and saltpetre, and precipi- tating as barium sulphate. The sulphur removable by alkali was estimated by dissolving a known weight of wool in caustic soda, and passing the gas given off on acidulating, and boiling with sulphuric acid into 3 iodine solution. 10

In the first experiment,wool containing2'36per cent. sulphur was found to give off 1'66 per cent. as sulphur. etted hydrogen ; the rest, 0.70 per cent., remaining in the liquid. An endeavour was made to ascertain the amount of free sulphur left in the residue, and for this purpose a fresh quantity of the same wool was dissolved in caustic soda, the solution acidulated with hydrochloric acid, and the precipitate, after washing and drying, was ground as fine as possible, and extracted from 2 to 3 hours in a Soxhlet, with carbon bisulphide. The extract was fused with soda and saltpetre, and the sulphur estimated as usual with barium chloride. In this manner, only 0 07 per cent. of sulphur was found to exist as such. On re- grinding the once extracted precipitate, and extract- ing again with carbon bisulphide, we found, however, that the sulphur was not by any means completely extracted, and is probably so intimately mixed with the horny precipitate that it is scarcely possible to obtain the latter in a sufficiently fine state of division, by mechanical means, for the complete extraction of the sulphur.

The percentage of sulphur (calculated on the total sulphur) which I S evolved as sulphuretted hydrogen is, according to this experiment, about i 0 per cent.

I n the second experiment, a different quality of wool was used. It contained 1-45 per cent. sulphur, of which 1'02 per cent. (or again about 70 per cent. of the total) was given off as sulphuretted hydrogen. From the results of these two experiments, it would appear that the percentage of active to that of inactive sul- phur in wool is in a constant ratio.

Coloured Lakes from Wool.-Lanuginic acid pre- ci itates in acidulated aqueous solution all the acid sutstantive dyes. We have prepared a large number of these coloured lakes, including those formed with crystal scarlet, oran e, picric acid, naphthol yellow S, fast red, naphthol bfack, soluble blue, acid violet, and indigo extract. All these lakes are intensely coloured ; in cold water they are almost insoluble ; in boiling water they mostly melt and partially dissolve, but se arate out again on cooling. They are all easily sofuble in alkalies, and are re-precipitated by acids.

recipitate, which, when finely round, forms a brig!t yellow powder. For its furt%er examination, it was dissolved in caustic soda, re-precipitated with hydrochloric acid, well washed with water, and dried a t 100" C. The sul hur was estimated in the usual manner by fusing wit[ soda and saltpetre, and was found equal to

er cent. Ultimate analyses gave the following Egures ;--

The Picrate forms an orange

4l"iO;a' 1?'07% - _- 11'88

l'(i2 4'61 - - 4'61

- - 15'57 - I 15'57 I

- 1 - 1 - 1 1.46 1%

........... I --

0. l - I - -

1 - - In preparing these lakes, we roughly estimated the

Velative weights of the precipitates formed from the Lcidulated solution of wool in caustic soda. From 15grms. of wool we obtained- - Grms, Per cent.

Crvstal scarlet lake .................. 2'4 = 16'0 Fast red lake.. ........................ 2'5 Soluble bluc lake.. .................... '2.7 Orange lake .......................... 3'1 Acid:-iolct lake ...................... 2'9 Naphthol black lake .................. 2'1 Picric acid lake ...................... 2'45

16'6 18'0 20'6 19'3 14'0 l(i'3

The lakes formed with the basic dyes may be Ibtained by adding the solution of the basic dye to the neutral solution of lanuginic acid. These lakes 3iffer from those formed by the acid dyes, in being 3oluble in acids. In only one case-namely, that of magenta-was the weight of lake formed roughly estimated. logmis. of wool were dissolved in caustic 3oda, the solution carefully neutralised with sulphuric mid, and filtered. Excess of magenta was then added, and the precipitate formed was collected, washed, and dried. It yielded 0'5 rm.

Mciximum amount of tolour absorbed by Wool in Dyeing.-In order to obtain an idea of the amount of colour which wool is capable of combining with, we dyed small pieces of flannel with a large excess of pjcric acid, naphthol yellow S, and tartrazin, under similar conditions. The excess of colouring matter was then estimated in the residual solution in each case by titrating with night blue. The amount of colour used was 50 per cent. of the weight of wool, and the dyebath was acidulated with 50 per cent. of sulphuric acid. We found that the amount of acid used in dyeing did not materially effect the amount of colour fixed ; thus, whether we used 50 per cent. or 10 per cent. sulphuric acid in dyeing with picric acid, exactly the same quantity was fixed. The maxi- mum amount of colour had been fixed in the first hour ; the amount fixed by prolonging the treatment to 3 hours was not greater. The estimations were effected by diluting the residual liquids to 24 litres, and titrating with the solutions thus obtained into a known quantity of night blue.

The following amounts were fixed :- (A) PICWIC ACID. Time-1 how.

Per cent. I. 11.

Amount fixed.. ........ 13'00 ............ 13'3 Amount in solution .. 37'00 ............ 36.7

"00 a '0

Per cent,

__ -- Time--8 hourh.

Amount Axed .............. W20 Amount in solulion . . . . . . . . 36'8

jo'00

Per cent.

.- -

These results were checked by estimating the actual increase in weight of a piece of flannel weighing 10 grms., after dyeing with 50 per cent. picric, and were found to agree exactly with those already obtained.

(B) NAPHTHOL YIGLLOW S. 'Mile-1 hour. Per cent.

Amount flxed.. .............. 20% Amount in solution., ........ 2J.Z

500 -

~ _ _ __ _ _ - ~~

( C ) TARTRIZINE. Tho-1 honr. Per cent.

Amount Axed 222'6.5

50~00

Amount in qolution 27'35 _- These figures show something very striking and

almost exactly f and Qmol. respectively. Calcuhteil. Fonnd.

Picric Acid.. .. ._ ., .. .. .. Siiphthol elki in. ( I l n G l . ) 20'6 pcrccnl. . . 20.8 ,, Tnrtrnrinc (Imol.) . . .. . . B.1 ,, .. 2'2'6 ., Crystal Violet ($niol.) .. 7.94 ., . . 8.4 ,,

- . . . . 13'3 per ccnt.

been asserted that when wool is boiled with solutions of the metallic salts a more or less complete disso- ciation of the salt takes place, and the hydrate, or a very basic salt, becomes precipitated on the fibre. I t appears to us more probable that the mordants are not fixed ill this manner, but actually combine with

The amount of basic dyes absorbed is considerably less ; on1 one estimation was made-viz., cryetal violet. $he amount of this dye absorbed under similar conditions as already given, was found to be only 8 per cent. This corresponds to about a of a mole- cule. I n order to obtain an idea of the amount of lanu- ginic acid necessary to precipitate a known weight of picric acid, 2'5grms. wool were dissolved in caustic soda, the solution acidulated with sulpburic acid, and a solution of I'Igrms. picric acid added. The precipi- tate formed was filtered, washed, dried and weighed and amounted to O'Bgrm. The excess of picric acid was then estimated in the filtrate by means of night blue, and was found to be O'Slgrm ; so that O'16grm picric acid was actually combined with 0'38grm of the lake-giving substance ; in other words,. picric acid combines with about twice its weight of lake giving substance ; and we might, therefore, infei from this, and the maximum amount of picric acic capable of being absorbed by wool, that wool contain1 about 25 to 30 per cent. of lake-giving substance.

Summary and Conclusions.-The main object o this investigation, the results of which we have jus laid before you, has been to prove as clearly as possible the correctness of the chemical theory o+ dyeing. During the course of our work a number o other points have been elicited, which we havi considered of sufficient interest to include in thi!

p a g t h a v e isolated from wool a substance soluble ir water, which possesses many of the characteristic properties of keratine. I t yields precipitates with a1 the metallic salts used in mordanting; and alsc coloured precipitates with the substantive dyes. Tha actual chemical combination takes place is shown bj the analysis of the picrate, which was found to contair sulphur as a n essential constituent, whereas picric acid itself contains no sulphur. The percentages o carbon, hydrogen, nitrogen, and oxygen also point tc the existence of a new compound.

We do not wish to assert definitely that lanugini, acid exists as such in the wool, although it might b, assumed that it is held there in an insoluble state b! some other constituent of the fibre. We consider i more feasible to assume that lanuginic acid is : sim le decompoaition product, or a more soluble forn of t&t portion of the wool which does not give up i t sulphur to alkalies. On a former occasion I ha( ex ressed the o inion that the formation of thes la&w wtw proba&y due to the presence of an amid acid, or of amido acids contained in the wool; bu this view can now no longer hold good, since we hav proved the body to belong to the albumenoids. Thes substances can, indeed, be looked upon as complicatec amido acids, but their chemical nature is so comple: and little studied that it would be fruitless to ente now into any arguments regarding their constitution

Aseuniin however, our hypothesis to be corred we can e x p k n by means of it all the reactions whicl take place in the mordanting and dyeing of wool As far as nlnrdanting is concerned, i t hats hithertc

interesting * taking the amount of picric acid absor- bed by wool &s a basis, i t is easy to calculate that the amounts of naDhthol yellow S and tartrazine are ompounds, like those which we have actually pro-

luced from the solution of lanuginic acid; the acid iberated during the reaction being neutralised by ,ome other constituent of the fibre, and assists in the ormation of a fresh quantity of lake-giving sub- ,tance. These compounds are capable of yielding :oloured lakes with the. adjective dyes, a property which is not possessed in all cases by the metallic iydrates. Thus we found that, whereas a solution :ontaining alizarin 8, oxalic acid, and alum, could ) 3 boiled for an indefinite period without undergoing my ap arent change, when lanuginic acid was added t brigit scarlet precipitate rapidly formed a t the ,oiling temperature. A similar reaction was noticed with cochineal, stannous chloride, and oxalic acid.

The behaviour of wool towards the colouring matters is still more noteworthy. Here, again, the theory of simple mechanical absorption is quite out of the question. This has already been made evident by the results of investigations already brought before you last session. The quantitative results which we have obtained with picric acid, naphthol yellow, and tartrazine are especially noteworthy, and point unmistakably to strictly chemical reactions betn een the fibre and the colouring matters.

There is little more to add to complete our com- munication. The question of alkali blue was one which we could not a t first easily explain, but we found subsequently i t was precipitated in neutral solution by lanuginic acid, and that the colour of the precipitate was considerably darker on the addition of sulphuric acid. An interesting result was also obtained with a solution of camwood in very dilute soda, which yields, with lanuginic acid, a copious red-brown precipitate, thus explaining the curious action of this class of insoluble woods in wool dyeing.

constituent of the wool to form different chemical

DISCUSSION.

The CHAIRMAN : The interesting paper which we have just heard forms the third of a series by Dr. Knecht and his students bearing on the theory of dyeing. The two previous papers have been received and commented upon, both in this country and on the Continent, in a very favourable manner. They will, I feel sure, form a most important contribution to our knowledge regarding the relationship existing between animal fibres and substantive dyes on dyed fabrics. A great lesson to be learnt from these researches is the importance of quantitative work. There has, in past times, been much theorising u on probabilities, but very little real practical work. gor many years past two theories regarding dyeing have obtained-viz., the mechanical and the chemical theory, and yet to my knowledge practically no quan- titative determinations have hitherto been made. The opponents of the chemical theory have urged that two great signs of chemical combination are entirely wanting-viz., the union of the fibre and colouring matter according to definite chemical equivalents, and the disappearance of the special characters of each. With regard to the first objec- tion, I think that Dr. Knecht has clearly shown that the colouring matter and a constituent of the fibre do combine in definite molecular proportions. Animal fibres may certainly be dyed, up to a certain limit, with practically any proportion of colouring matter ;

70 THE JOURNAL OF THE SOCIETY OF DYERS AN]) COLOURISTS. [April%, 1889 - _- ~

but this fact, in my opinion, is no proof that chemica action does not take place. One need not admit tha the fibre, or a constituent of the fibre, combines witl colouring matters in all roportions. If a piece o filter paper be saturated) with a solution of leac acetate, and laced in an atmosphere containini sulphuretted lydrogen, it will become uniforml: tinted any shade from a light drab to a black, accord ing to the amount of sulphuretted hydrogen resent The colour is due to the formation of sul i i d e o lead, but in the case of the lighter shades t f e who11 of the lead in the paper is not combined with thl small amount of sulphur present. The sulphide o lead is simply distributed over a surface containinl an excess of acetate of lead. I n like manner, accord ing to Dr. Knecht’s researches, wool dyed a ligh shade of scarlet, for example, may be considered tc contain a small quantity of a compound of the scarle dye and the lake-giving body evenly distribute( among an excess of that lake-giving body, lanuginic acid. As a further illustration, everyone will adinii that chemical action takes place when Prussian blu( is formed by the admixture of a ferric salt witl potassium ferrocyanide. Now, if cotton be impreg nated with ferric hydrate, it iiiay be dyed, up to 2 certain degree, any shade of blue or bluish-green bj immersing it i n a solution of hydroferrocyanic acid or, what amounts to the same thing, a mixture 01 potassium ferrocyanide and sul huric acid. The depth of shade depends upon t f e strength of the ferrocynnide bath. The lighter shades contain a small amount of Prussian blue mixed with B certain amonnt of ferric hydrate. Dr. Knecht finds that the wool fibre contains from 25 to 30 per cent. of a lake- giving substance-lnnuginic acid. In the dyeing of acid substantive colours, this lanuginic acid appa- rently acts in a similar manner to ferric hydrate in the case just mentioned. Another argument against the chemical theory is that the colouring matter may be more or less easily removed, leaving the wool fibre in its original condition. If wool which has been dyed with indigo extract be boiled with a weak solution of carbonate of soda, the blue colonr is removed, and the fibre is left in the same condition a3 before dyeing. But we have an analogous case in cotton dyed with Prussian blue, where the combina- tion is undoubtedly of a chemical nature. If cotton which is dyed with Prussian blue be treated with a weak alkali, the blue compound is broken up ; the solution contains an alkaline ferrocyanide, and the cotton simply ferric hydrate. Regarding the preci- pitates formed with lanuginic acid and the metallic salts, I should like to ask Dr. Knecht if he considers them to contain any of the acid radical, or if the consist entirely of lanuginic acid in combination wit{ a metallic base? Dr. Knecht considers lanuginic acid to be an albuminoid, and found it to contain rather more than 3 per cent. of sulphur. Albu- menoids contain from 1’3 to 1.8 per cent. of sulphur. Does Dr. Knecht consider the 3‘5 per cent. which he found in the sample of lanuginic acid to be in actual combination, or might not a portion of it have been derived from the sulphuretted hydrogen used in the process of extraction ‘1 Dr. Knecht finds that wool which has been boiled in a solution of sulphuric acid and subsequently thoroughly washed, may be dyed with an azo colour without addition of acid to the bath. If I mistake not, he considered that the acid converts a constituent of the wool fibre into a body which practically acts as a mordant for the azo-dye. If the wool which has been treated with an acid be washed with a weak solution of carbonate of soda, is the substance reconverted into its original inactive form, so that the azo-colours no longer dye the wool without an addition of acid to the bath ?

- - -_ Dr. KNECHT: I n answer to Mr. Rawson’s first

question as to whether the recipitates which we have obtained with metallic gases in a solution of lanuginic acid contained any of the acid radical or not, I must confess that we have not experimented to see whether they did or not; but I think it is highly immobable that they would contain any. They are salts of lanuginic acid, like the lead salts or barium salts, both of which have been isolated and examined by Champion. With regard to the second question, as to the percentage of sul hnr in lanuginic acid, I think that it is improbable t i a t the high per- centage can be accounted for by the treatment with sulphuretted hydrogen. It is not a t all likely that the lanuginic acid would combine with sulphuretted hydrogen. The latter is not a very active substance, and it scarcely appears robable to me that a sub- stance like lanuginic acici) should absorb considerable quantities which are not given off again by boiling ; the solution was evaporated down a t boiling tem- perature.

The CHAIRMAN : Rut was the sulphur present, mechanically, owing to the decomposition of the sul huretted hydrogen 1 &. KNECHT : No ; the solution was filtered after- wards, and was perfectly clear, so there could not have been an elementary sulphur present. The experiment wiich Mr. Rawson mentioned last of treating wool with dilute sulphuric acid, and then subsequently treating with sodium carbonate, we have carried ont, and we find if we use the exact equivalent of sodium carbonate, it still partly retains the propert of combining with the acid dyes. Of course, iP you use an excess of sodium carbonate, the wool will absorb alkali, and it is well known that in the alkaline condition thePe acid dyes are not taken up by the wool. It would be necessary to a t least neutralise the sodium carbonate absorbed by the wool befare you could get any dye taken up.

Mr. WHITAKER : I should like to ask Dr. Knecht whether he means (by the figures given as to the :ombination of picric acid and naphthol yellow) to ihow the actual amount of these substances which :ombined with the fibre, or can be actually combined more or less than these amounts? I su pose he 3ases his calculations upon picric acid j Rut is it possible the picric acid result may be in error to iome extent, as the figures given seemabnormally ii h ?

%r. KNECRT : It comes exactly. the same whether base my calculations u on the picric acid or some

Ither constituent. If !wished to take naphthol fellow as a basis, I should take 13‘3 per cent.

Mr. WHITAKER : It is, then, really a comparative :alculation 1

Dr. KNECHT : Yes. Mr. WHITAKER : My reason for asking was this,

,hat a piece of cloth dyed with many of the coal-tar :olours will actually bleed out in cold water after ,tanding a short time. For instance, a shade is d ed with picric acid until it will take up no more. Wgen his point is reached, run down the vessel, fill up with told water, and boil again, and you can boil half the olour off. There is another thing : Take one of hese colours dyed in this way and steam it ; it will deed off on to white. Then, again, with respect to .cid in dyeing. I think ou said that even 50 per ent. of acid gave no difkulty. What I want to :now is whether it would make any actual difference vhether you used 1, 5, or 10 per cent., because it is Iretty well known that some of these colours will lot dye so well with 2 per cent., but better with 5 per ent. Others, on the contrary, will not dye so well vith 5 per cent., but will dye better with 1 or 2 per

April%, 1889.1 THE JOURNAL OF THE SOCIETY O F DYERS AND COLOURISTS. 77 ~- ~ ~ ~~ ~

__ ~ ~~~

cent. ; and green will dye better with 5 per cent. than with 2 per cent., and magenta with 5 rather than 2. Host of the other coloure, especially basic colours-induline, for instance- resent peculiarities in this direction. I know indu?ine some time ago would not go on above a certain strength whatever the amount of acid used. I believe it is better now. This all bears upon the question I was asking as to what Dr. Knecht bases his figures upon. You might say the fibre will combine with 20 per cent of a cer- tain dyestuff, but if you boil it in water, part of it would come off again. Then, again, these percentages are too high-very high. We think 5 per cent. very high, and a proportion that cannot be used in some

Dr. KNECHT : The amount absorbed, which I have given in these figures, is the maximum amount which you can force upon the fibre. If you boil it after- wards in a small quantity of ammonia, you can get nearly all the colour off again. I take it that the coinbination roduced between the lake-giving sub- stance and t l e dye is not a very stable one. It .is decomposed with comparative ease down to a certain point. Then the more you remove from the fibre the taster it becomes, and then I think that the small quantit of colour lake that remains is held in the wool fitre in a state of solid solution. When you have as much present it8 20 per cent. of colouring matter, it will dissolve out certainly, because the wool is not capable of holding such a large uantity in solution. But when it comes down to a%out 2 per cent. it becomes fast and cannot be boiled out with water.

The CHAIRMAN : I s it sim ly the colouring matter which is boiled out, or the cofouring matter combined with lanuginic acid 1

Dr. KNECHT : The colouring matter itself boils out, and does not bring with it the constituent of the wool with which it was combined to form a coloursd lake. This constituent is present, ~ 1 9 I have mentioned in an insoluble state in the wool. You would scarcely ex ect to render it soluble by simply dyeing with one o! the coal-tar colours.

Mr. WHITAKER: If ou take the same fabric again and put it into a 98th of picric acid, or any other colour, you can get it up to the old strength; you re-dye it, in fact. Therefore, the lake-giving substance cannot have gone out.

Mr. BECKETT : I should like to ask Dr. Knecht whether he has been able to determine the combining equivalent of lanuginic acid? I suppose the com- pound you will have to take is the equivalent of combination of one of these colours or would you determine it from an analysis of the barium or lead Ralt 1

Dr. KNECHT : We had intended to do an analysis of the barium salt, but we have not had time. It has taken us all our time to get done with the other part of our work. But we have determined the com- bining weight with picric acid. I gave that in the paper, and showed it would combine with twice its weight of picric acid. It is only a rough determina- tion, and I do not place very much reliance upon it, not nearly so much as I would place upon an analysis of the barium salt.

Mr. WHITAKER : If you take some of the naphthol colours and dye with them, they rush on almost immediately. Take another colour ; you cannot persuade it to o on beyond a certain strength, and that only slowfy, whilst you cannot exhaust the bath. Have you one into that in any way to find out why it should %e 80 when both colours are dealt with under the same conditions 1

Dr. KNECHT: I do not know the actual reason why some of these colours do not go on ; but I mn

CaSeS.

answer the question very briefly by saying one has a greater affinity for lanuginic acid than the other.

Mr. SHARP : I have taken ver great interest in the paper which Dr. Knecht Eas read. He has broken practically new ground and has brought before us a wide field of practicai thought and action, and I think it requires very careful consideration and digestion before anyone should commit himself to an opinion on the matters which he has placed before us. He has a great advantage over his auditors in having travelled over the field again and again, until, I presume, evory point has become perfectly familiar to him now that he places the result of his labours before us. When new matters affecting the principle of dyeing so much and so important as these appear to be, are brought before us aa a body of practical dyers, we should do an injustice to the writers of the

If we 1 e an,on the other hand, to accept all that is put before us before we have an opportunity of verifying ste by step, we should do an injustice to our own ju&ment, and it is on that account that I prefer to pass no decided opinions now u n the various points raised. I see much in what ras come before the meeting in which I thoroughly agree with L)r. Knecht. Mr. Rawson brought forward, by way of illustration, ferrocyanide of iron. As dyers we scarcely look upon the use of this form of iron with cotton as a mordant. It is a mordant unquestionably in one sense ; but when the ferrocyanide of potassium is decomposed you really form a new product, ferric ferrocyanide. In dissolving off,it is really a decomposi- tion of the blue which takes place. Therefore youget, no doubt, a considerable proportion of the ferro- cyanide removed. Now, if you take a woollen sub- stance on which blue has been dyed with yellow prussiate without iron, soda and alkalies have no effect in removing the ferrocyanide. I think that is an illustration that proves unquestionably that alkalies are not a solvent of ferrocyanide, when united with a textile fibre, but that they do unquestionably decompose any Prussian blue which you have formed u on the fibre. Take another case, that of indigo sufphate. You take the wool dyed with indigo sulphate, and subject it to‘, the action of car- bonate of soda. You say you dissolve” the dye; but it is not a question of dissolving but a question of the decomposition of the coiour, and it is shown by the fact that you cannot restore the blue. The colour is destroyed, or practically so. Mr. Rawson was quite right in saying that the ferric oxide salt was a mordant, but it is something more- it is both a mordant and an essential part of the new colouring matter. With regard to the fixing of colour upon the textile fibres, I should have been glad to have heard from l)r. Knecht whether he is not of opinion that the salt undecomposed remains upon the fibre. I think he stated that the acid remained in one instance, but I did not gather clearly that the colour he spoke of was in the basic state. If so, several curious queries would arise, because in niany cases the bases of the colouring matters are colourless.

Dr. KNECHT : But when they are combined with the wool they are colours, because they form salts with the constituents of the wool.

Mr. SHARP : Then if they are salts they cannot be bases 1

Dr. KNECHT : No. Mr SHARP : That is the point. I want to see how

decomposition can take place. Wool contains certain constituents which act u on dyes, as you have very clearly shown us to-nigit, and one feels a little curiosity whether decomposition or not goes on, or how the salt is going to be reduced to a basic titate,

apers if we began to criticise them hastily.

78 THE JOURNAL OF THE SOCIETY OF DY‘ERS AHD COLOURMTS. [April 25, isas. __- _ _ - __

I think dyers are generally agreed, and chemists also that the salts of aniline dyes are not decomposed ir fixing upon the fibre, so aa to reduce them to thc basic state a t all events.

The CHAIRMAN: I quite agree with Mr. Sharr that Prussian blue cannot be considered to be, strictlj s eaking, a mordant upon cotton, but it seems to mc t i a t this scarcely etfects the point which I wished t c prove. Prussian blue on the one hand and extract 01 indigo on the other, are not destroyed by carbonatc of soda. If you take wool dyed with extract 01 indigo and treat it with a weak solution of sodiun: carbonate, the extract of indigo is removed, and, to a certain extent, a portion of the colour appears to haw been destroyed ; but on acidulating the alkalinf solution, the blue colour of the indigo extract is fullj develo ed. I have found b quantitative estimations that tge whole of the suLhindigotic acid may. bt obtained from the fibre by careful manipulation When cotton dyed with Prussian blue is boiled wit1 sodium carbonate, the blue is decomposed, sodiun ferrocyanide entering into solution and ferric hydratc remaining on the fibre. If the solution be acidulated and ferric chloride added, Prussian blue is agair formed.

Dr. KNECHT : There is one point to which I omitted to refer. It may be of importance some time. Wher we were trying to estimate for the sulphur contained in the acidulated solution of wool in caustic soda, wz extracted the dried and ground precipitate with bisul. phide of carbon. We found that the solution obtained in this manner contained grease. That was witl- some wool which we carefully washed first with soap Now, in order to be sure about this, and to see whethei this grease was not derivad from the soap, a furthei quantity of wool was first treated with hydrochloric acid in order to decompose any lime soaps which might be on the fibre. It was then dried and exhausted for three hours with bisul hide of carbon, One would natural1 expect that by %is method ou would remove all t i e grease out of the wool. But we found that after we had treated the wool in this manner, and then dissolved it in caustic soda, the precipitate formed by sulphuric acid, when dried, ground, and extracted again with bisulphide of carbon, contained grease, which in all its properties resembled cholesterin. conclusively that it is not possible to remove ay?:;: grease from wool, even by a somewhat prolonged treatment with bisulphide of carbon. The woollen fibre is a horny substance which appears to contain grease in its interior, and it evidently takes a long time for bisulphide of carbon to percolate into the interior of this dense horny substance. This might be of importance if the bisulphide process is a success, because it proves that by treating with bisul hide of carbon you do not remove all the grease in t i e wool. At all events you will leave sufficient in for stinning purposes. You do not take all the “nature out of the wool.

Mr. STEEL proposed a vote of thanks to Dr. Knecht and Mr. A pleyard for the paper, which he charac- terised as t i e most valuable which had ever been presented to the Society. He had a very strong opinion that lanuginic acid was not a simple com-

und by any means, but very complex in structure. f?e should very much like to hear something more of some of the other substances which could be got from wool, and he should like to know what was the character of the lanuginic acid crystals if it could be crystallised.

Dr. KNECHT : I do not think we have ever obtained

I think this proves

an crystals.

the specimens. &r. STEEL : There were some passed round amongst

~ --__

Dr. KNECHT : They looked like crystals, but they are simply horny masses. The appearance is decep- tive. Being an albumenoid, I scarcely think it can be expected to crystallise.

Mr. STEEL: As I say, I think it is a compound substance.

The CHAIRMAN : -4 mixture of compounds. Mr. STEEL : Yes, a mixture of compounds. How-

ever, further work will show that, no doubt. Mr. WHITAKER seconded the vote of thanks,

which was carried unanimously. Dr. KNECHT, in returning thanks, said : Consider-

ably more work has been necessary to obtain the results which we have laid before you this evening than we had a t first anticipated. We have fre uently spent weeks in carrying out experiments whi& have proved absolutely useless ; but we had no means of telling beforehand whether they would be productive or not, It needs, therefore, a certain amount of moral courage to continue with a work of this kind, which was rendered more difficult than ordinary chemical investigations by the fact that we had neither constitutional formulz, empirical formulze, nor even definite preliminary information of any kind to guide us. On the contrary, we were greatly misled by Champion’s results, and only discovered after several months’ work that they were incorrect. I may again be allowed to express my opinion that work of this kind should be carried out a t our technical colleges. It should be encouraged and fostered by those who are in authority, and every opportunity ought to be gven to advanced students to carry out before leaving college an origmal investi- gation of some kind, be it however small. It will be of infinitely more value to him in after life than the mere ac uisition of book knowledge, because it teaches %im to think and try for himself. The community a t large benefits by the publication of the results, and the country should derive a benefit, through the student, of a real and well-directed technical education. This is, in my opinion, the chief secret of the success which has attended technical education on the Continent, more especially in Switzsrland and Germany ; and until the same system has been introduced into this country, little real headway will be made bey,ond, erhaps, an increased percentage of “passes at 8overnment 3xaminations.

--- ‘ ANTIMONY SALT ” AS A SUBSTITUTE FOR

TARTAR EMETIC. COMMUNICATION FROM DAVID PATERSON.

rms salt, possessing the composition SbF, -t (NH,)2 30 , is one of the new group of antimoniuin fluoride lou%le salts discovered by E. de Haen. rhere are two groups, consisting of the xystallised combinations of the chlorides and sul- ,hates of the bases potassium, sodium, and tmmonium with antimony tri fluoride. The consti- ation of these two classes of double sa!ts will be mmediately understood by looking at their formula

IbF, KCl -Antimony fluoride, pota@Im chlo7ide salt. IbFa: NaCl =Antimony fluoride, sodlum chloride s+t. SbNS, NHaCl -Antimony fluoride, ammonlum chlorlde salt.

I. CHLORIDE GROUP.

11. sULPHATE GROUP. lbFa K&O =Antimony fluoride potassium sulphate salt. IbFa: NalSd =Antimony fluorid;, sodium sul hate salt. IbF (NHa)aSb, = Antimony fluoride (norm.& ammonium ruiphate ealt. This last-mentioned double salt is the one em-

iloyed, as it possesses greater advantages for dyeing