Class IV.]

BURCH’S EXHIBIT OF DYE-STUFFS AXD THEIB PRODUCTS.

87

to have caused the dyers to be generally divided intowoollen, silk, and cotton dyers. It is found that, asregards the use of the strong mineral acids, which areemployed both to brighten, and—assisted by heat—to fixsome colouring matters, an important difference existsbetween wool, or silk, and cotton. Animal substanceswill bear, uninjured, a much greater proportion of acid,and of the two, wool being the coarser fibre, is less easilyinjured than silk ; but both will bear, with advantage, aproportion of acid which would corrode and destroy thefibre of cotton. It is necessary, therefore, to be verycautious in the use of acids on cotton goods: and thedyeing of a mixed fabric constitutes one of the nicestparts of the art, where a mixture of animal and vegetablefibres has to be printed with perhaps six or eight brilliantcolours at the same time.

In illustration of these processes, Mr. Burch shows acomplete collection, vt supra, of the various chemicalagents employed by the dyer, including acids, alkaline,and alkaline salts; metallic salts, used both as mordantsand in the formation of metallic colours, and a verynumerous series of vegetable and animal dye-stuffs. Themode of block-printing, and the manner in which severalcolours are successfully applied, are also well illustrated.The more important of these substances may be brieflyenumerated as follows :—

1. Sulphuric acid, or oil of vitriol.

2. Muriatic or hydrochloric acid.

3. Nitric acid, or aquafortis.

4. Nitro-muriatic acid.

5. Acetic or pyroligneous acid.

6. Citric acid.

7. Tartaric acid.

8. Oxalic acid.

9. Iron sulphate, or green vitriol.

10. ,, acetate, or iron liquor.

11. ,, nitrate.

12. ,, chloride, or muriate.

13. Tin chloride, or muriate.

14. .. ferroprussiate.

15. Alumina.

16. Alum.

17. Alumina, acetate.

18. Copper sulphate, or blue vitriol.

19. ,, chloride, or muriate.

20. ,, nitrate.

21. ,, acetate.

22. Lead, nitrate.

23. ., acetate, or sugar of lead.

24. Zinc sulphate, or white vitriol.

25. Potassa carbonate, or pearlash.

26. ,, bitartrate, or cream of tartar.

27. Potash binoxalate, or salt of sorrel.

28. ,, ferroprussiate.

29. ,, chromate.

30. ,, bichromate.

31. Soda, carbonate.

32. Ammonia muriate, or sal ammoniac.

33. Lime, quick.

34. ,, chloride, or bleaching powder. ,

All these substances are used by the dyer, either in

preparing the fibre to receive colouring matter, or asmordants to enable it to combine with the colour, in thedirect formation of coloured compounds; to heightenanimal or vegetable colours; or as “resists,” or “dis-charges,” either serving to prevent certain parts of thefabric, to which they have been applied, from receivingan}* colour in the vat, or to discharge or remove it inplaces when the whole has been dyed one uniform colour.For this important series a Prize Medal was awarded,

The dye-stuffs exhibited are as follows:—

Colouring Matters or Dye-Stuffs.

1. Logwood \ — obtained from Campeachy in SouthAmerica , the wood of the Hdmatoxyhn campechianum :it is exhibited, 1st, in the block ; 2nd, in the chips as cutup for the dyer’s use; 3rd, an aqueous extract of thehematin, or colouring principle; 4th, the extract orhematin ip the dry state: 5th, the colouring matter pre-cipitated with iron, with which it forms a black dye:6th, precipitftVcu with tin, with which it forms a purpledye; 7th, with alupi, a purple dye; 8th, with copper, a :

i brown. Specimens are shown of these various colours; dved on cotton, silk, and wool.

2. Peachwood, or Nicaragua wood:—from Lima, SouthAmerica : the wood of a Casalpinia, exhibited in theblock, chips, aqueous extract, and the colouring matterprecipitated black with iron, red with tin, red with alum,and brown with copper. Specimens of dyeing on silk,wool, and cotton.

3. Sappanwood, from Siam ;—the wood of the Casal-pinia sappan, exhibited in the block, chips, aqueous ex-tract, and precipitated dark brown with iron, red with tinand with alum, brown with copper; with dyed samples.

4. Fustic, from Cuba ;—the wood of the Rhus cotinus,exhibited in the block, chips, aqueous extract, and thecolouring matter precipitated olive-brown with iron,yellow with tin, and yellow with alum; with dyedsamples.

5. Ebony, the wood of the Diospyros ehenum ;—exhibitedin the block, chips, aqueous extract, and the colouringmatter precipitated—olive-brown with iron, yellow withtin and with alum ;—with dyed samples.

6. Harwood, from the west coast of Africa ;—the woodof tii e JJaphia Jiitida (i); exhibited in the block, chips,aqueous extract, and the colouring matter precipitated,—dark brown with iron, red with zinc; red with alum;brown with copper;—with dyed samples.

7. Camwood, from Sierra Leone ;—the wood of theBaphia nitida , shown in the block, chips, aqueous ex-tract, and the colouring matter precipitated, — blackwith iron, red with tin, red with alum ;—with dyedsamples.

8. Indigo, from the East Indies;—a well-known bluecolouring matter obtained from the leaves of the Indigoferutinctoria. The process of dyeing with indigo consists indeoxidizing it, or depriving it of a portion of its oxygen,when it assumes a green hue, becomes soluble in water,and then readily enters the pores of the cloth immersed

\ in the indigo vat. When the cloth is properly saturated,

1 it is exposed to the action of the air, and the indigoi speedily reabsorbs oxygen, and again assumes its originalcolour and its stability; or, if united with a yellowcolouring matter, the result is—a green. It is exhibitedin the lump, in powder, in its green deoxidized statedissolved in water; and also in a state of pulp, or minutesubdivision, effected by treating it with strong sulphuricacid. In the last case it is not a “ fast” d}*e, but by thefirst mode of treatment, it is one of the most permanentcolours. Samples of indigo dyes are shown.

9. Woad ;—from France and the north of Europe , acolouring matter analogous to indigo, but of a duller hue,obtained from the leaves of the Isatis tinctoria; it is nowbut little used. Exhibited in the lump.

10. Quercitron Bark, from South America ;—the barkof the Quercus tinctoria; it is exhibited in the crusted orground state, in the aqueous extract, and the colouringmatter precipitated—olive-brown with iron, and yellowwith alum dyed samples are shown.

1 11. Alder bark;—the bark of the common alder of

: Great Britain. Alnus glutinosa , shown as chips, as aqueousextract, and the colouring matter precipitated,—grey withiron, and pale amber with alum.

12. Catechu, from the East Indies;—an extract of thewood of the Acacia catechu , containing much tannin ;it is shown in lump, and its colouring or tannin matterprecipitated,—black with iron, brown with copper.

13. Valonia, from Turkey and Asia Minor ;—the cupor shell of the acorn of the Quercus agilops; it is ex-hibited as gathered. Also the aqueous extract and thecolouring matter as precipitated,—black with iron.

14. Nut-galls, from Turkey;—an excrescence growingon the Quercus infectoria , which contains a very largequantity of tannin. It is exhibited as gathered. Alsothe colouring matter precipitated,—black with iron.

15. Madder;—from France and the north of Europe ,the root of the Ruhia tinctoria. This substance is ofgreat importance in the art of dyeing, furnishing some ofthe most permanent dyes. It is shown in the root, andground. Also “ garancine,” or the colouring principle,separated by the action of strong sulphuric acid; the

; black precipitate formed with iron, and the red precipitate