Part 3 (2/2)

The case is just the sa: without the presence of iron (”copperas,” etc), sulphate of copper (”bluestone”), or bi+chroet no black at all We will now try si three si been first treated with a hot solution of alum and cream of tartar, and the other with copperas or sulphate of iron solution, and then washed Turenta, however, permanently dyes the woollen as it did not the cotton Alizarin only stains the untreated woollen, whilst the piece treated with alumina is dyed red, and that with iron, purple If, however, the pieces treated with iron and aluenta solution, only one colour would have been the result, and that a Magenta-red in each case Here we have, as proved by our experi matters The one class comprises those which are of themselves the actual colour The colour is fully developed in the in their unchanged state upon that fabric Such dyes are terenerate or yield different shades of but one colour Indigo is such a dye, and so are Magenta, Aniline Black, Aniline Violet, picric acid, Ultramarine Blue, and so on

Ultraet Ultramarine Green, and even rose-coloured Ultramarine; but still, in the hands of the dyer, each shade remains as it caenetic colour Monogeneticto the other class, which comprises, as we have shown, Alizarin, and, besides, the colouring principle of logwood (Haematein), Gallein, and Cochineal, etc, we have bodies usually possessed of some colour, it is true, but such colour is of no consequence, and, indeed, is of no use to dyers These bodies require a special treat out or develop the colours, for thereWeprinciples, and so we terenerating several or many In the various colours and dyes we have all phases, and the enetic The mode of application of the two classes of colours is, of course, in each case quite essentially different, for in the case of the enetic class the idea is mainly either to dye at once and directly upon, the unprepared fibre, or having subjected the fabric to a previous preparation with a metallic or other solution, to fix directly the one colour on that fabric, on which, without such preparation, it would be loose In the case of the polygenetic class, the idea is necessarily twofold The dyeing enerators Hence in all cases the fabrica , with the dyeit on the fibre in an insoluble and perone so far into this mode of classification, because it does afford soetting into a territory that presupposes a knowledge and acquaintance with the cheanic substances, which would be, at present, beyond us I shall now turn to anotheras the other, is at least an exceedingly useful one The two methods may be combined to a considerable extent By the latter plan the colours roups: I, substantive colours; II, adjective colours; III, ment colours

_Substantive Dyestuffs_--The substantive colours fix themselves readily and directly on anist theetable fibres like cotton and linen directly Almost all substantive coloursor etable fibres Silk, wool, fur, etc, act like fibre and ether, for they absorb and fix the substantive colours firmly In our experimentsthat tur itself on both cotton and wool, without any aid froenta was also a substantive colour, but Alizarin was certainly not one of this class

_Adjective Dyestuffs_--Some of these substances are definitely coloured bodies, but in some of them the colour is of no consequence or value, and is quite different and distinct from the colour eventually formed on the fibre, which colour only appears in conjunction with a special ain, some of them are not coloured, and would not colour the fibre directly at all, only in conjunction with soenetic colours are, of course, cowood (Haeenetic colours as annatto and turmeric are substantive, for they will fix themselves without a mordant on cotton and wool The adjective colours can be conveniently subdivided into--(_a_) those existing in nature, as logwood (Haematein) and Cochineal; (_b_) those artificially formed from coal-tar products, as Alizarin (ment Dyestuffs_--These colours are insoluble in water and alcohol They are either fixed on the fibre by mechanical means or by precipitation For exao to colour or darken your hats, and you work on this pigment colour by mechanical means I will show you by experiar of lead), and to it I add some solution of bi+chrome (potassium bi+chromate)

Acetate of lead (soluble in water) with bi+chro the two, acetate of potash (soluble in water), and chromate of lead, or chrome yellow (insoluble in water), and which is consequently precipitated or deposited Now suppose I boil some of that chrome-yellow precipitate with lie This, you see, takes place without any reference to textile fibres I will noork a piece of cotton in a lead solution, so that the little tubes of the cotton fibre shall be filled with it just as the larger glass tube or vessel was filled in the first experiment I next squeeze and wash the piece, so as to relass tube by roughly dipping it bodily into the lead solution, and then washed and cleansed the outside of that tube Then I place the fabric in a warm solution of bi+chromate of potash (bi+chrome), when it becomes dyed a chrome yellow, for just as chrolass tube, so it is now precipitated in the little tubes of the cotton fibre (see Lecture I) Let us see if we can now change our chrolass vessel by boiling in li lie In each little tubular cotton fibre the salass vessel, and as the tube or glass vessel looks orange, so does the fabric, because the cotton fibres or tubes are filled with the orange chromiu a colour mechanically on to the fibre

Let us now turn to the substantive colours (Group I), and see if we can further sub-divide this large group for the sake of convenience We can divide the group into two--(_a_) such colours as exist ready formed in nature, and chiefly occur in plants, of which the following are the o, archil or orchil, safflower, turroup of the artificial or coal-tar colours We will briefly consider now the dyestuffs mentioned in Group (_a_)

_Natural Substantive Colours_--Indigo, one of the e nu different species of _indigofera_, which belong to the pea faofera tinctoria_ is the chief) contain the colouring matter in the free state, ready-made, so to say, but only as a peculiar colourless compound called _indican_, first discovered by Edward Schunck When this body is treated with dilute ar But so easily is this change brought about that if the leaf of the plant be only bruised, the decoh separation of the Indigo Blue The possibility of dyeing with Indigo so readily and easily is due to the fact that Indigo Blue absorbs hydrogen from bodies that will yield it, and becoo White, a body richer in hydrogen than Indigo Blue, and a body that is soluble If this white body (Indigo White) be exposed to the air, the oxygen of the air undoes what the hydrogen did, and oxidises that Indigo White to insoluble Indigo Blue Textile fabrics dipped in such reduced indigo solutions, and afterwards exposed to the air, becoo Blue, and are so dyed This is called the indigo-vat o-vat by sio Blue, copperas (ferrous sulphate) solution, and milk of li the mixture stand The clear liquor only is used A piece of cotton dipped in it, and exposed to the air, quickly turns blue by absorbing oxygen, and is thus dyed

The best proportions for the indigo-vat are, for cloth dyeing, 4000 parts of water, 40 of indigo, 60 to 80 of copperas crystals, and 50 to 100 of dry slaked lime The usual plan is to put in the water first, then add the indigo and copperas, which should be dissolved first, and finally to add the o has been made from coal-tar products The raw material is a coal-tar naphtha called toluene or toluol, which is also the raw enta formidable rival to the natural product

Orchil paste, orchil extract, and cudbear are obtained by exposing the plants (species of lichens) containing the colouring principle, called _Orcin_, itself a colourless substance, to the joint action of aes that orcin by oxidising it into _Orcein_, which is the true red colouring matter contained in the preparations naradually a deep purple colour, and form the products called ”cudbear” This dye works best in a neutral bath, but it will do what not htly alkaline or slightly acid bath as well Orchil is not applicable in cotton dyeing Being a substantive colour nosilk and ith it The colour produced on wool and silk is a bright enta-red with bluish shade

Litmus is also obtained fro, and is a violet-blue colouring matter when neither acid nor alkaline, but neutral as it is termed It turns red with only a trace of acid, and blue with the least trace of alkali, and so forent when pieces of paper are soaked with it, and dipped into the liquids to be tested

Safflower: This vegetable dyeingpink colours on cotton without the aid of a mordant, consists of the petals of the flower of _carthamus tinctorius_ It contains a principle termed ”Cartha saffloith cold acidulated water (sulphuric acid) to dissolve out a yellow colouringfree from acid is treated with a dilute solution of soda crystals, and the liquid is then precipitated by an acid A red precipitate is obtained, which fixes itself directly on cotton thread immersed in the liquid, and dyes it a delicate rose pink, which is, unfortunately, very fugitive

Silk can be dyed like cotton The colour is not fast against light

Turmeric is the root portion of a plant called _curcurows in Southern Asia The principle for matter is ”Curcumin” It is insoluble in cold water, not much soluble in hot, but easily soluble in alcohol From the latter solution it separates in brilliant yellow crystals Although the colour it yields is very fugitive, the wool and silk dyers still use it for producing especially olives, browns, and siht yellow colour without the aid of anywith turmeric is effected, I arm some powdered turmeric root in a flask with alcohol, and add the extract to a vessel of water warmed to about 140 F (60 C), and then dip a piece of cotton in and stir it about, when it will soon be perht yellow A piece of wool similarly worked in the bath is also dyed However, the unfortunate circuht nor alkalis Contact with soap and water, even, turns the yellow-dyed cotton, reddish-brown

Annatto is a colouring principle obtained fro the seeds of the fruit of a tree, the _Bixa orellana_, growing in Central and Southern Aitive, and so its use is li The yellow compound it contains is called ”Orellin,” and it also contains an orange compound called ”Bixin,” which is insoluble in water, but readily soluble in alkalis and in alcohol with a deep yellow colour

To dye cotton with it, a solution issolution of carbonate of soda The cotton is worked in the diluted alkaline solution whilst hot By passing the dyed cotton through water acidulated with a little vitriol or alum, a redder tint is assumed For wool and silk, pale shades are dyed at 106 F (50 C) with the addition of soap to the bath, dark shades at 200 to 212 F (80 to 100 C)

LECTURE X

DYESTUFFS AND COLOURS--_Continued_

_Artificial Substantive Dyestuffs_--Youthemselves directly on ani this, however, on vegetable fibres, like cotton We sub-divided the in nature, and (_b_) those prepared artificially, and chiefly, but not entirely, the coal-tar colouringthemselves only in conjunction with a etable fibres, and including all the polygenetic colours III Mineral or pigment colours I described experienetic colours, and indicating that the roup of substantive colours, whilst the polygenetic colours are mainly included in the adjective colours

But I described also an illustration of Group III, the ue that chro to the treatment, ere able to obtain either chroe (basic lead chromate) I also said there was a kind of borderland whichever mode of classification be adopted Thus, for example, there are colours that are fixed on the fibre either directly like indigo, and so are substantive, or they enerally are, applied with a enetic colours; examples of these are Coerulein, Alizarin Blue, and a few more We have now before us a vast territory, naroup of substantive colours, or, the largest proportion, indeed almost all of those prepared from coal-tar sources; Alizarin, also prepared froard to the source of these coal-tar colours, the word ”coal-tar,” I was going to say, speaks voluas retorts at the highest teas, also yields us tar But, coal distilled at lower temperatures, as well as shale, as in Scotland, will yield tar, but tar of another kind, fro substances cannot be obtained practically, but instead, paraffin oil and paraffin wax for e number of different substances, but only a few of the All the useful sources of colours and dyes froen--hydrocarbons, as they are called, with the exception of one, na here of those coal-tar constituents useful fordyes, but of those actually extracted from coal-tar for that purpose, _ie_ extracted to profit For example, aniline is contained in coal-tar, but if we depended on the aniline contained ready made in coal-tar for our aniline dyes, the prices of these dyes would place thest diamonds and precious stones in rarity and cost, so difficult is it to extract the small quantity of aniline from coal-tar The valuable constituents actually extracted are then these: benzene, toluene, xylene, naphthalene, anthracene, and phenol or carbolic acid One ton of Lancashi+re coal, when distilled in gas retorts, yields about 12 gallons of coal-tar Let us now learn what those 12 gallons of tar will give us in the shape of hydrocarbons and carbolic acid, mentioned as extracted profitably fro table (Table A)

The 12 gallons of tar yield 1-1/10 lb of benzene, 9/10 lb of toluene, 1-1/2 lb of carbolic acid, between 1/10 and 2/10 lb of xylene, 6-1/2 lb of naphthalene, and 1/2 lb of anthracene, whilst the quantity of pitch left behind is 69-1/2 lb But our table shows us more; it indicates to us what the steps are froht of aniline, and the toluene (9/10 lb) about 3/4 lb of toluidine, the enta From carbolic acid are obtained both Aurin and picric acid, and here is the actual quantity of Aurin obtainable (1-1/4 lb) From naphthalene, either naphthyla phenol) may be prepared The amounts obtainable you see in the table There are two varieties of naphthol, called alpha- and beta-naphthol, but only one phenol, namely, carbolic acid Naphthol Yellow is of course a naphthol colour, whilst Ver both naphthylamine and naphthol

You see the quantities of these dyes, namely 7 lb of Scarlet and 9-1/2 lb of the Naphthol Yellow The amount of pure anthracene obtained is 1/2 lb This pure anthracene exhibits the phenomenon of fluorescence, that is, it not only looks white, but when the light falls on it, it seeht Our table shows us that froain 2-1/4 lb

of 20 per cent Alizarin paste Cheht-red needles; it is the colouring principle of madder, and also of Alizarin paste But theabout substantive coal-tar colours is their immense tinctorial power, _ie_ the very little quantity of each required compared with the immense superficies of cloth it will dye to a full shade

TABLE A[2]

------------------------------------------------------------------------------- TWELVE GALLONS OF GAS-TAR (AVERAGE OF MANCHESTER AND SALFORD TAR) YIELD:-- ---------+---------+------+----------+----+--------------+---+---+--------+---- Benzene| Toluene| P |Solvent | H N| Naphthalene | C | H | A | P | | h |Naphtha | e a| | r | e | n | i | | e |for | a p| | e | a | t | t | | n |India | v h| | o | v | h | c | | o |rubber, | y t| | s | y | r | h | | l |containing| h| | o | | a |

| ||the three | a| | t | O | c | | | |Xylenes | | | e | i | e | | | | | | || l | n | | | | | | | || e | ---------+----------------+----------+----+--------------+---+---+------------- 110 lb=|090 lb=|15 |244 lb, |240|630 lb = |17 |14 |046 lb|696 110 lb |077 lb |lb |yielding |lb |525 lb of |lb|lb|= 225 | lb