The London Encyclopædia: Part II. The Practise of Dyeing. Of Dyeing Red.

The London Encyclopædia: Part II. The Practise of Dyeing. Of Dyeing Red.



Kappale teoksesta:

The London Encyclopædia, or Universal Dictionary of Science, Art, Literature, And Practical Mechanics, Comprising A Popular View of The Present State of Knowledge.

By The Original Editor of The Encyclopædia Metropolitana, Assisted By Eminent Professional And Other Gentlemen.

In Twenty-Two Volumes

Vol. VII

London:
Printed For Thomas Tegg, 73, Cheapside;
R. Griffin & Co., Glasgow; Tegg and Co., Dublin; Also J. & S. A. Tegg, Sydney and Hobart Town.

1839

Part II. The Practise of Dyeing. Of Dyeing Red.
s. 602-608



168. Red colors are known by different names according to their degrees of intensity, as crimson, scarlet, &c., besides innumerable shades that [...] under no particular denomination. The [...]stances usually employed in dyeing red, are cochineal, madder, kermes, lac, carthamus, brasil-wood, archil, and logwood. All [...]

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[sivun alkuosa puuttuu]

Dyeing Wool Red. -When woollen [...] [...]yed, they are first boiled for two [...] with alum and tartar: they are [...], slightly wrung out, put into a [...] carried into a cool place, where [...]n for some days. The quantities [...] of the alum and tartar are varied [...] object of the dyer, and the shade [...] is wanted. Some recommend [...] alum, and one ounce of tartar to [...] wool. By increasing the porportions [...] a certain degree, a deep and per[...] color is produced. This arises [...]tinge induced by the acid on [...] particles of the madder. Others [...]ainish the proportion of tartar, and [...] seventh part. In conductiong the dyeing with madder, the bath should [...] to a boiling heat, because, at that [...] the fawn-colored particles would be [...] a different shade obtained from [...] desired. When the water is at such [...] as the hand can bear, Hellot [...] the addition of half a pound of grape [...] every pound of wool to be dyed. It [...] well stirred before the wool is in[...]bich must remain for an hour with[...] excepting for a few minutes towards the process, that the combination of [...] particles with the stuff may be more [...].

Madder reds are sometimes rosed, as it is with archil and Brasil wood. In this way [...]me more beautiful and velvety, but [...]tness is not permanent. But madder [...] when at best, are far inferior to those [...] from lac and cochineal, and even to [...]duced by kermes; but, as the expense [...] materials is comparatively small, they are good for coarse stuffs.

[...] Different authors recommend different [...]ons of madder. Poerner proposes to [...] one-third of the weight of the wool, while [...] limits the quantity of one-fourht. Por[...]ed to the alum and tartar a quantity of [...] of tin, equal in weight to the tartar, and [...] two hours boiling, allowed the cloth to re[...] the bath, which had been left to cool for [three?] or four days. He then dyed it in the usual [...] and obtained a fine red. On another occasion he prepared the cloth by the common boiling and dyed it in a bath slightly heated, with [...]per proportion of madder, tartar, and solution of tin. The cloth remained twenty-four hours [in the?] bath, and, when it had become cold, he [put it?] into another bath, made with madder only, [...] it remained for twenty-four hours. By [this?] process he got a fine red, somewhat brighter than the common, but inclining a little to yellow. [...]heffer says that he obtained an orange red by [...] wool with a solution of tin, and one-fourth [...] alum, and then dyeing with one-fourth of [...] madder. A cherry color, says Bergman, is obtained by using one part of a solution of tin, and two of madder, without previously boiling the wool. BY exposure to the air, this color becomes deeper. By boiling the wool for two hours with one-fourth of sulphate of iron, then washing it, and afterwards immersing it in cold water with one-fourth of madder, and boiling it again for an hour, the result is a coffee color. But if the wool has not been soaked, and if it be dyed with one part of sulphate of iron and two of madder, the color is a brown approaching to red.

172. When sulphate of copper is employed as the mordant, the madder dye yields a clear brown, inclining to yellow; and a similar may be produced by dyeing the wool simply soaked in hot water, with one part of sulphate of copper, and two of madder. But when this mordant and dye-stuff are used in equal proportions, the yellow is somewhat more obscure, inclining to green; and in both these instances, exposure to the air does not produce a darker color. Berthollet says that he employed a solution of tin in various ways, both in the preparation and the application of the madder; and, by the use of different solutions of tin, he found that, although the tint was a little brighter than what is obtained by the common process, it was always more inclined to yellow or fawn color.

173. Of Dyeing Silk Red. - The red color obtained from madder has not been dound of sufficient brilliancy for dyeing silks; M. De la Folie, however, has given the following process for employing it for this purpose: - Half pound of alum is to be dissolved in each quart of hot water, to which two ounces of potassa are to be added; after the effercescence is over, and the liquor has begun to grow clear, the silk must be soaked in it for two hours; it is then to be washed and put into the madder bath. Silk dyed in this way, he says, becomes more beautiful by the application of the soap proof. Another process is described by Mr. Gulichie, of which the following is the substance.

174. For every pound of silk he proposes a bath of four ounces of alum, and one ounce of solution of tin. When the liquor has become clear, it is decanted, and the silk carefully soaked in it for twelve hours, after which it is to be immersed in a bath with half a pound of madder softened by boiling, with an infudion of galls in white wine. The bath must be kept moderately hot for an hour, and then made to boil for two minutes. The silk, being taken from the bath, is to be washed in a stream of water, and dried in the sun. The color thus produced is said to be very permanent; and, if the galls are omitted, its brilliancy is improved.

175. The color obtained when Brasil-wood is used, is denominated false crimson, to distinguish it from that produced by cochineal, which is much more durable, and which is styled grain crimson. This very beautiful color is obtained by the following process: - The silk, being well cleansed from the soap, is to be immersed in an alum bath of the full strenght, and to remain for a night. It is then to be washed, and twice beetled at the river. The bath is prepared by filling a long boiler two-thirds with water, to which are added, when it boils, from half an ounce to two ounces of powdered white galls for every pound of silk. When it has boiled for a few moments, from two

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to three ounces of cochineal, also powdered and sifted, for every pound of silk, are put in, and afterwards one ounce of tartar to every pound of cochineal. When the tartar is dissolved, one ounce of solution of tin is added for every ounce of tartar. In the preparation of this solution of tin, the following proportions are recommended by Macquer. For every pound of nitric acid two ounces of sal ammoniac, six ounces of fine grain tin, and twelve ounces of water are employed. When these ingredients are mixed together, the boiler is to be filled up with cold water, and the proportion of the bath, for every pound of silk, is about eight or ten quarts of water. In this the silk is immediately immersed, and turned on the winch till it appear to be of a uniform color. The fire is then increased, and the bath is kept boiling for two hours, observing to turn the silk occasionally. The fire is afterwards put out, and the silk put into the bath, where it is allowed to remain for a few hours longer. It is then taken out, washed at the river, twise beetled, wrung, and dried.

176. Carthamus, says M. Berthollet, is used for dyeing silk poppy, a bright orange red, cherry, rose color, and flesh color. The process differs according to the greater or less tendency to flame color that is wanted. The following is his account of the preparation of the carthamus bath: The yellow matter of the carthamus having been first extracted, the cakes containing the red coloring matter are broken down and put into a trough of fir-wood, where they are several times sprinkled with finely powdered soda in the proportion of six pounds of soda to every hundred pounds of carthamus. The whole is then put into a small trough lined with closely woven cloth, and having a grated bottom; this small trough is then placed over the larger one, and water is poured on the mixture till the larger trough is full. Fresh water is poured over the carthamus and suffered to run into another trough, and so on successively, adding a little fresh soda till all the red color is extracted. These liquors are then mixed, and lemon-juice is added to give a fine cherry color, which the liquor imparts to the silk that is dipped in it. Poppy-color, given in this way, required that the silk be immersed in a second bath, and that the colors be brightened by turning the silk several times through a bath of hot water impregnated with lemon-juice. The lighter hues of red are given by the weaker solutions of carthamus the silk, after being scoured, should, for poppy of fire color, receive a ground of annotto. The carthamus bath should be prepared at the time of using, and the process of dyeing should be conducted as speedily as possible.

177. Those who have made the nearest approach towards producing a scarlet on sik, says Berthollet, begin with dyeing the silk crimson. It is then dyed with carthamus, and after that dyed yellow in a cold bath. By this process a fine color is produced, but it is not permanent, as the dye of the carthamus is affected by the action of the air. The following is the process given by Dr. Bancroft in his Philosophy of Permanent Colors. In a solution of [...] sulphate of tin, diluted with five times [...] of water, the silk is to be soaked for two hours, and, after being taken out, it is to be wrung [...] partially dried. It is then to be dyed in [...] prepared with four parts of cochineal, and [...] of quercitron bark, In this way color [approach?]ing to scarlet is obtained. To give the [...] body, the immersion may be repeated [...] solution of tin and in the dyeing bath; [...] brightness of the scarlet is increased by [...] the addition of carthamus. A lively [...] is produced by omitting the quercitron [...] and dyeing the silk with cochineal [...] by adding a large proportion of water to the cochineal, a yellow shade is obtained, [...] changes the cochineal to the compound [and?...] color.

178. Of Dyeing Cotton and Linen Red. Madder is employed for dyeing linen and cotton red, and even for giving them several [...] colors, by means of different mixtures. [...] coloring drug most helpful for this kind of [...]ing. It is proper therefore to show, in [...] detail, the different methods by which [...] may be rendered more permanen, [beautiful?] and diversified in its effects. Linen [takes?...] color of madder with more difficulty [than?] cotton: but the processes which succeed [...] with the one, are also preferable for the [cotton?].

179. Two species of madder red, [...] are distinguished; the one called simply madder red, the other, possessing far more [...] is called Turkey-red, or Adrianople-red, because it was for a long time obtained from the Levant.

Vogler tried the effect of a great member [...] the substances employed as mordants, or [...] dyeing bath, and he found that those which produced the best effect were glue, or gall, and other animal matters, as sheep's dung. [...] of soda rendered the color faster, mut more [darker?]. Galling likewise procured a richer color. [...] astringents, sumach and pomegrenate rind, [...] instance, produced a similar effect. A [...] alkali added to the alum improves it. When the stuff has passed through the different pre[...] operations, it must be dyed with the best madder that can be procured, in the proportion of three-quarters of a pound to each pound of stuff.

The temperature of the madder bath must be raised in a gradual manner, that may [...] about an hour to boil after te stuff has been immersed in it; and, when it has boiled [a few?] minutes, the stuff is taken out, slightly [...] and dyed second time in a second bath, [with?] the same quantity of madder; after the [...] dyeing, and subsequent rinsing and drying [...] stuff is commonly steeped in a solution of [...] soad, made just milk-warm, in the propotion[...] two ounces of soap to one pound of stuff. The effect of this process is to remove all the uncomined coloring matter, and, as is supposed [to?] give a higher degree of brilliancy to what remains. This process is completed by [...] and drying.

180. Of all the reds produced by the [...] madder, the Adrianople or Turkey-red [...]


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[...] most beautiful: it possesses a brilliancy which can be communicated to cotton by none [...] common processed of dyeing, and has, more[ov?]er, the propterty of more effectually resisting [...] action of the different re-agents, as alkalis, sap, alum, and acids. For many years the dyeing of this color was confined to the east, and came to us through our Levant trade only. Om [proc?]ess
of time the art fpimd oys way from India [...] the western parts of Asia, and to Greece; and from Greece to France, whence it was brought to this country by one of the French dyers, M. Papillon, who settlet at Glasgow, where, for a considerable time, he carried on with great success the business of dyeing Turkey-red.

181. M. Papillon communicated his process [...] commissioners and trustees for manufactures in Scotland, to be by them published at the expiration of certain term of years. For this he received a handsome premium; and the process was made public in the year 1803.

We need hardly mention the celebrity of the manufactory of Messrs. Monteith and Co. of Glasgow, since it is known to the world at large. The excellency and beauty of their cotton fabrics will not soon be surpassed; the madder-reds which they dye rival, in brilliancy and in solidity, any ever produced at Adrianople; and the white figures, distributed over the cloth by the discharging process, surpass in purity, elegance, and precision of outline, the original Bandana outlines.

182. The art of dyeing Turkey-red has been described by different writers, who vary a little from each other in some particulars, but who agree in leading features of the process. We prefer inserting here an account of it as given by Dr. Bancroft, as it affords us an opportunity of following it up by the insertion of some of his truly valuable remarks upon the subject in reference to the process observed at Rouen in France.

The process is very tedious, and is divided by the dyers into nine different steps.

Step 1. Cleaning. For 100 pounds of cotton take an equal weight of Alicant barilla, twenty pounds of pearl-ashes, and 100 pounds of quicklime. The barilla must be mixed with soft water in a deep tub, which has a small hole near the bottom of it, stopped at first with a peg. - This hole is covered in the inside with a cloth supported by two bricks, that the ashes may be prevented from passing through it or stopping it up while the lie filters through it.

Under this tub is another to receive the lie; and pure water is repeatedly passed through the first tub to form lies of different strength, which are kept separate at first until their strength is examined. The strongest required for use must swim an egg, and is called the lie of six degrees of the French hydrometer, or peseliqueur. The weaker are afterwards brought to this strength, by passing them through fresh barilla. But a certain quantity of the weak, which is of 2° of the above hydrometer, is reserved for dissolcing the oil and gum, and the salt, which are used in subsequent parts of the process. This lie of 2° is called the weak barilla liquor, the other is called the strong.

Dissolve the pearl-ashes in ten pails, of four gallons each, of soft water, and the lime in fourteen pails.

Let all the liquors stand till they become quite clear, and the mix ten pails of each.

Boil the cotton in the mixture five hours, then wash it in runnin water and dry it.

Step 2. Take a sufficient quantity, say ten pails (of four gallons each), of the strong barilla water in a tub, and dissolve or dilute in it two pails full of sheep's dung; then pour into it two quart bottles of oil of vitriol, and one pound of gum arabic, and one pound of sal ammoniac, both previously dissolved in a sufficient quantity of the weak barilla water, and lastly, twenty-five pounds of olive oil, which has been previously dissolved or well mixed with two pails of weak barilla water.

The materials of this steep being well mixed, tramp or tread down the cotton into it, until it is well soaked; let it steep twenty-four hours, and then wring it hard and dry it.

Steep it again twenty-four hours, and again wring and dry it.

Steep it a third time twenty-four hours, after which wring and dry it, and lastly wash it well and dry it.

Step 3. This part of the process is precisely the same with the last, except that the sheep's dung is omitted in the composition of the steep.

Step 4. Boil twenty-five pounds of galls, bruised, in ten pails of river water, until four or five are boiled away; strain the liquor into a tub, and pour cold water on the galls in the strainer, to wash out of them all their tincture.

As soon as the liquor is become milk-warm, dip your cotton hank by hank, handling it carefully all the time, and let it steep twenty-four hours.

Then wring it carefully and equally, and dry it well without washing.

Step 5. Dissolve twenty-five pounds of roman alum in fourteen pails of warm water, without making it boil; skim the liquor well, and add two pails of strong barilla water, and then let it cool until it be lukewarm.

Dip the cotton, and handle it hank by hank, and let it steep twenty-four hours, and wring it equally and dry it well without washing.

Step 6. Is performed in every particular like the last; but after the cotton is dry, you steep it six hours in the river, and wash and dry it.

Step 7. The cotton is dyed by about ten pounds at once, for which take two gallons and a half of ox blood, and mix it in the copper with twenty-eight pails of milk-warm water, and stir it well; and add twenty-five pounds of madder and stir all well together. Then, having beforehand put the ten pounds of cotton on ticks, dip it into the liquor, and move and turn it constantly one hour, during which you gradually increase the heat, until the liquor begin to boil at the end of the hour. Then silk the cotton, and boil it gently one hour longer; and, lastly, wash it and dry it.

Take out so much of the boilin liquor, that what remains may produce a milk-warm heat with the fresh water with which the copper is again filled up, and then proceed to make up a

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dyeing liquor as above, for the next ten pounds of cotton.

Step 8. Mix equal parts of the gray steep liquor, and of the white steep liquor, taking five or six pails of each. Tread down the cotton into this mixture, and let it steep six hours, then wring it moderately and equally, and dry it without washing.

Step 9. Ten pounds of white soap must be dissolved most carefully and most completely in sixteen or eighteen pails of warm water; if any little bits of the soap remain undissolved they will make spots in the cotton. Add four pails of strong barilla water, and stir it well. Sink your cotton in this liquor, keeping it down with cross sticks, and cover it up and boil it gently two hours, then wash and dey it and it's finished.

Such is the provess of M. Papillon, on which Dr. Bancroft makes the following observations.

Step 1. At Rouen two courses of operations are practised to produce the Turkey-red. One is called the gray course, and the other the yellow course. In the former, the cotton, after being alumed, receives no more oil, but goes to the dyeing vessel, retaining the gray color, which naturally results from its being impregnated with alum and galls in combination. But, in the yellow course, the cotton, after being alumed, is again immersed in the oleaginous mixtures or steeps, by which it acquires a yellow color. The gray course may consist etiher of fifteen steeps or of nineteen, and the yellow of twenty. The first of these courses has most similitude to that of M. Papillon. At Rouen, the cleansing operation if performed with a very weak lie of soda, of only one degree of the areometer, employing 150 gallons to 100 pounds of cotton, which is to be boiled therein six hours, then drained, well rinsed in running water, and afterwards dried. This operation is intended to free the cotton from all impure or extranous matter; but not to produce effects like those of bleaching by exposure upon the grass, which, until lately, it was believed, would lessen the durability of the colors to be subsequently dyed.

Step 2. The steep here described contains three ingerdients not employed by any other person; and one of these, the sulphuric acid, seems to indicate a want of chemical knowledge in M. Papillon, because, by neutralising the soda, it must obstruct the effecy which the latter is intended to produce (that of rendering the oil miscible with water), or at least render a greater proportion of it necessary in order to obtain that effect. In regard to the other two ingredients, ciz. the gum and sal ammoniac, the quantity of the former is by much too small to produce any considerable effect, and it is not wasy to form any conjecture what purpose the latter is to answer. At Rouen, this steep is prepared by steeping twenty-five or thirty pounds of sheep's dung several days in a lie of soda, marking four degrees, which is to be diluted until it amounts to forty gallons; and the dung being squeezed and broken by the hands, is afterwards made to pass through a copper pan, provided with numerous small holes, into a tub containing twelve pounds and a half of fat oil, and in this the oil and dung are, by sufficient stirring, to be well mized [with?] the lie and with each other; and, in the [...] which contains but half the quantity of [...] described by M. Papillon, the cotton is [...] steeped, &c., as directed by the latter. [It is?] highly important that, after this and each of [the?] succeeding operations, the cotton [...] thoroughly and completely dried by a [...].

Step 3. At Rouen this steep is prepared [by?] mixing thirty-eight gallons of lie of soda [with?] ten pounds of olive oil, stirring until the [...] becomes uniformly milky; which it [...] without any separation of the oil be suited to this use; this they [...] what may have been left of the former [...] and, after mixing them properly, they [...]nate the cotton by the usual treatment, [...] after an interval of twelve hours, first in the [...] air, and afterwards by a stove heat. This [...]ing and subsequent drying must be [...] once, twice, or three times, according to [circum?]stances.

Between this white steep and the [following?] gall steep, it is the practise at Rouen to [...] three salt steeps and one cleansing [...] at first, twenty-four gallons of the lie of [...] marking two degrees and a half, are [...] tub with the remnant of the white steep [...] the cotton is impregnated and dried, as [...] former operations. IN the next the [...] the last steep is mixed with twenty gallons of [...] lie of soda, marking three degrees; and [...] cotton is steeped and dried as before. In the [...] the remnant of the preceding steep is mixed [...] twenty-four gallons of the lie of soda, [...] three degrees and a half, and with this the [...] is impregnated and dried as before. The [...]duum of this steep is preserved to be used [in the?] brightening operation.

In the celansing operation the [...] steeped one hour in lukewarm water, [then?] wrung by hand, and afterwards washed [...] stream of water to remove any [...] which might get obstruct the equal [...] uniform effect of the following [...] thereby render the color unequal. [After being?] so washed, the cotton is dried first in [...] air, and afterwards by a stove-heat.

Step 4. This constitutes the eighth [...] in the gray course at Rouen, where, [...] in M. Papillon's process, galls , [...] now to be employed- At Rouen, the [...] soon as it has sufficiently imbides the [...] matter of the galls, and been very [...] wrung, is spread as expeditiously as [...] the open air, if the weather be dry, or [...] under cover; but the drying is always [...] by a stove heat.

Step 5. At Rouen, thirty or thirty-five [...] of the purest alum are commonly [...] this steep, with only seven [...] of [...] adding, when the alum has been [...] gallons only of the lie of soda, [...]grees. But when these propotions [are em?]ployed, the cotton is not subjected [...] steep with alum. Sometime, [...] two steeps with the aluminous [mordants em?]ployed ; an in that vase twenty [pouns of ...?] are dissolved for the first, and fifteen for [...]

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cond, leaving an interva, of two days between them, during which the cotton should retain its moisture after being slightly wrung from the first steep. It should, however, be well dried before it goes into the second.

Step 6. At Rouen, the cotton is dyed in parcels of twenty-five pounds each, and the dyeing vessel is of a quadrangular form, containing about [...]00 gallons of liquor. One quart of ox-blood is employed for each pound of cotton, with two pounds of Provence madder, or one pound of this with one of Smyrna madder. Some persons, however, think it best to effect the dyeing by two separate operations, employing half the above proportion of madder for one dyeing, and half for the other; but always taking care not to dry the cotton between the dyeings. There are some [...] Rouen who give cotton another alum steep between these dyeing operations, employing for that purpose half as much alum as was used for the first steep, and afterwards washing, &c.

Step 8. For this steep they employ at Rouen the residuum of the third salt-steep before mentioned; but the application of it is considered a part of the following step.

Step 9. This constitutes the fourteenth operation in the first set of gray courses at Rouen; where, after having macerated the cotton with the sikiou, they boil it for the space of five or six hours with six or eight pounds of white soap, previously dissolved in 145 gallons of water, in a vessel covered at the top, so as to leave only a very small opening for the necessary escape of the steam, which might otherwise occasion an explosion. The effect of this boiling with soap, is to dissolve and separate from the cotton all the yellowish-brown matter of the madder color which may have been applied to it in the dyeing operation, and thus to change the color from the dull brownish-red which it would otherwise retain, to a bright lively color, nearly equal to that of the finest cochineal scarlet. It is only by the singular degree of fixity which the pure red part of the madder color acquires, in consequence of the operations just described, that this beautiful red can be obtained. Such, indeed, is the stability of the Turkey-red when well dyed, that it is said to sustain boiling with soap for thirty-six hours without injury.

In addition to the steps prescribed by M. Papillon, they employ another at Rouen, which is intended to make the red incline more to the rose color, and at the same time increase its vivacity. For this operation, with the former quantity of 100 pounds of cotton they dissolve, in 145 gallons of water, sixteen or eighteen pounds of white soap, and as soon as the liquor begins to boil, they add to it from one pound and half to two pounds of the crystallised muriate of tin, previously dissolved in two quarts of water, and mixed with eight ounces of single aqua-fortis; and having equally dispersed this mixture through the boiling solution of soap, by stirring, &c., the cotton is put in and boiled with the same precautions as in the brightening operation, till the desired effect has been obtained, which is to be discovered by frequent examinations. Care must be taken not to employ more nitric acid or aqua-fortis than the quantity here mentioned, lost it should decompose the soap, and cause the oil to separate and rise to the surface of the liquor.

183. We cannot leave this truly important branch of dyeing without noticing the indenious remarks of Mr. Thomson of Glasgow, published in the eight volume of the Annals of Pholosohpy, on the theory of the Turkey-red process.

He observes that silk and worsted have a natural varnish which cotton does not possess. To supply this defect, the repeated immersions, followed by exposure to the atmosphere, and to the heated air of a stove, may give the oil the proper consistency, by the absorption of oxygen, for forming a varnish, with which the coloring matter unites, and through which it may be said to shine, which causes that superior brilliancy which the goods attain when they are cleared, or, as it may be called, polished. I therefore presume, that the fixedness and brilliancy of the color will depend on the quantity of oil imbibed, as every repetition of drying presents new fibres to be varnished with an additional quantity; for I have always found, that the permanency was in proportion to bumber of manipulations in the saponaceous liquor, and a proportionable freedom could also be used in reducing or clearing. The white immersions, omitting the sheep's dung, are just applying successive coats of varnish. Clearing is never attempted from the madder copper, without immersing the goods again in soda and oil, and drying them in a stove, which I consider to be also supplying them with and additional coat.

The alkaline lie occasions a greater separation in the particles of the oil, by which it combines more closely with the fabric of the cloth. The sheep's dung in the first immersions may serve as a covering, to keep the goods moist for a considerable time, that they may more fully imbibe the liquor, by preventing the evaporation from being too quick in the great heat to which they are exposed.

After the frequent immersions the cloth feels like leather, no doubt from a superfluity of liquor. It is then steeped in a lie of carbonate of soda, and afterwards well washed and dried, as a preparation for the galling and aluming. The astringent principle has been long known for darkening and fixing common red colors on cotton, by uniting with the earth of alum, and strengthening the basis. To the use of blood in the madder copper I attribute nothing; as in the rancid and putrid state in which I have seen it used, were it not for the prejudice of the operator, it might he safely dispensed with.

In proof of the above idea, that it is only the oil uniting with the earth of alum that is of use, I may refer to the mode of dyeing that color in the east, quoted by Dr. Bancroft, viz. soaking their cotton in oil (no matter of what description), during the night, and exposing it to the sun and air during the day, for seven successive days, rinsing it only in running water, and then immersing it in a decoction of galls and the leaves of sumach previous to aluming.

I would therefore request the practical dyer, who wished to arrive at a knowledge of this unaccountable process, to give up the idea of ani-

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malisation, if by it he meant impregnanting the cloth with an animal matter, and by the power of the microscope, or any better method, look for the whole truth from some other source than chemical analysis. I am at present inclined to believe that it is a mechanical operation united to a chemical, and that the frequent immersions in the imperfect soap are equivalent to laying on the first, second, third, &c., coats, preparatory to finishing a fine painting in oil. A very eminent calico manufacturer, whom I consulted on the Turkey-red process, assured me that the only essential mordants are oil and alumina; and that bright and fast reds, equal to any produced by the usual complicated process with sheep's dung, galls, and blood, may be obtained without these articles.