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freed from the fixed air, with which in the usual published in Edinburgh, we have collected the experiments of chemistry it appears to have a following particulars. greater affinity than with oil; for soap may be

SECT. I. ACCOUNT Of M. BERTHOLLET's partially decomposed by fixed air, nor can it be prepared without an exceedingly coustic alkaline

METHOD of BLEACHING. ley.

(96.) I. M. BERTHOLLET having procured the 03.) In this light the matter has appeared to dephlogisticated maține acid, in as strong and consome very eminent chemifts; and Dr BLACK centrated a state as he could, immerted into it thougiit it of importance futhcient to publiíh thread and cloth ; which by that means were conprinted directions to the practical bleachers how fiderably whitened. In a short time the liquor to render their alkali sufficiently cauftic with lime, seemed to lose its ftrength; upon which it was ard at the same time recover' it from the chalky poured off, and more put in its place; and so on refiduum with as little lofs as poflible. This me. until the substance immersed became perfectly thod has accordingly been tried ; but does not al- white. 'Thus, however, the process was not only together answer the fanguine expectations at firit very expensive, but the fuff was considerably inraised by the proposal. In the large way of ope- jured ; fometimes even losing its cohetion altogerating, fixed alkali quits the fixed air to unite with ther, so that there was a neceility for trying some the oily or other matter to be extracted from the other method. cloth. The only advantage therefore to be gain- (97.) 11. Uting a diluted spirit, he succeeded pered by Dr Black's improvement is, that the action fectly in rendering the cloths completely white; of the alkali is thus quickened, and some quantity but by keeping them for some time, or exposing of fuel saved ; but this is not, by the bleachers, them for a little to the action of an alkaline ley, Teckoned an equivalent to the trouble of render: they became again brown or yellow. ing the alkali caustic, unless in places where fuel 198.) ill. On considering the process of bleachis very scarce,

ing in the common method, he found that the ac

tion of the fun and air are subfervient to bleachPART. II.

ing only as they prepare the colouring particles

for being dissolved and separated by alkaline lixiOF OF THE NEW METHOD OF BLEACHING. via. To investigate this subject, he examined the

nature of the dews, both luch as are precipitated INTRODUCTION.

from the atmosphere and thole which tranipire (94.) The use of acids, in bleaching, was for- from vegetables. Both these were found fo Itrongmerly in a great measure unaccounted for ; but ly impregnated with dephlogisticated air, that from the late discoveries concerning the use of de- ' they deftroyed the colour of paper when faintly phlogisticated spirit of falt in this art, it appears tinged with turnfole. Hence he observes, that it probable that they act by means of the dephlogif is by no means improbable, that the ancient preticated air they contain: This, however, is not judices concerning May.dews might have anfen always the case; for silk is rendered yellow by the from some observations analogous to this; more action or dephlogisticated air, though rendered cipecially as in that month the transpiration of white by the action of the volatile fulphureous a- plants is extremely copious. cid, which undoubtedly contains a portion of this (99.) IV. By imitating with the dephlogisticated kind of air, though much less than the concen- marine acid and alkaline ley the common process trated vitriolic acid. The nitrous acid, which of bleaching, he fucceeded in making a perfect contains a great quantity of dephlogisticated air, and permanent white. For this purpose an alka: likewise communicates a yellow colour to filk; line lixivium was employed alternately with the and indeed seems very much inclined to produce dephlogisicated marine acid ; the latter being no rhis colour upon all the substances it touches. At longer used in a concentrated state. Thus he aany rate, its price would be a suiticient objection voided both the inconvenience arising from the against its use in' bleachirg.

fuffocating imell of the liquid, and that of its des (95.) The marine acid, more generally known stroying the texture of the stuff immersed in it. hy the name of spirit of salt, in its common state, (100.) V. The cloth is prepared for bleaching in is said by M. Berthollet to be ned with fuccefs by this manner; by steeping it 24 hours in water, to fome bleachers in France, innead of the vitriolic; extract the dreiling it receives from the weaver: but such experiments as have been made upon it a little old ley, which has already lost the greatest in this country have net answered the purpose. part of its strength in other procefles, may be The new method of bleaching is founded upon used with advantage. It is next to be exposed the remarkable property, which that acid when once or twice to the action of some good fresh aldephlogisticated poffeffus, of defroying vegetable haline ley; to feparate, by means of this cheaper colours; and various attempts have been made to liquid, all the colouring matter which ít can exintroduce it into practice, though in this country tract, and thereby fave the dephlogisticated acid. the difficulties or disadvantages attending it bare (101.) VI. The ituff muft next be carefully wanh. prevented it from coming into general use, fo that ed with water, to separate any remains of the ley inany of our bleachers oblinately persevere in the which might adhere to it, and weaken the action old method. M. Scheele was the inventor of this of the liquor. It is then to be disposed of in kind of acid; but M. Berthollet seems to have wooden troughs, so that the dephlogilticated acid been the first who attempted to apply it in the o. may pals freely through every part of it; to alperation of bleaching:- From a treatise on the low which, it inult lie quite loote, without being new method of bleaching, which has been lately tightened or traitered in any part. . All there

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TUB.

troughs ought to be constructed entirely of wood openings of that vessel. The corks G and I ought without any iron, as that would easily be corroded to be prepared before-hand, and well fitted to and tain the cioth.

each end of the tube of communication H, which (102.) VII. The first immersion in the dephlo. is to be so disposed that it may be fitted in isomegitticated acid is to continue 3 hours ; after which diately after the mixture is made in the matrass. the doth is to be removed, and the liquor wrung (108.) The intermediate veíTel K is about part out of it. It must then be washed a second time full of water; into it is plunged the tube of safety with alkaline ley; which being also washed out, L, to prevent danger from regurgitation. This it is to be again immersed in dephlogisticated tube ought to be so higi, that the weight of the act.

water which enters into it, by the prefiure of the (183.) VIII. The second immersion in the acid gas, may be great enough to cause the gas to pass is to continue only about half an hour ; after into the pneumatic tub NOP, by the tube of which it is to be taken out and wrung as before. comunication M, which is plunged therein, and The fane liquor may serve for several immersions; reaches to the bottom, where it is bent horizoncals when it appears to be much exhausted, it is tally, so that the gas may be emitted under the to be reitored by an addition of fresh liquor. first of the three wooden, or (if they can be pro

(104.) IX. After the cloth seems to be fufficient- cured) stone ware cavities, or receivers, which ly waitened, excepting only some few black threads are placed in the inside of the tub, one above the and the icirages, it is to be filled with black foap, other. O is a handle which serves to turn the a. ard frongis rubbed for some time ; after which it gitator E, the movement of which facilitates the is to be again wiihed in alkaline ley, and receive combination of the gas with the water. Pis a another inmertion in the acid liquor.

spigot and faucet to draw off the liquor. 1105.) X. It has not yet been determined what (109.) Fig. 2. UPPER PART of the PNEUMATIC number of immersions in the acid are necessary to In this QR ST are four staves which are wita linen cloth, though our author fuppofes' thicker than the others, and which project withfrom 6 to 8 to be suficient for the purpose. in the tub, where they are hollowed so as to reSECT. II. METHOD of PREPARING the DEPALO

ceive the ends of two wooden bars U V, which GISTICATED MARINE ACID; with a DESCRIP

ferve to keep in their places the cavities or recei.

vers X. Tion of the APPARATUS.

(110.) Fig. 3. SECTION of the TUB. Each ca. 1.5.! For preparing the dephlogisticated acid, vity X is to constructed that it may receive the M. Berthollet recommends fix ounces of black gas which is emitted at i from the tube of commuzozanese finely powdered, 16 ounces of sea-lärt munication M. The gas, as it comes out, is colkbewife in powder, and 12 ounces of concentrated lected under the lowest cavity, and increases in Frolic acid to be diluted with 8 ounces of water: quantity until it passes by the funnel Z to that in but the quantity of this last must be varied accord- the middle, and afterwards to the upper one.ing to the Rrength of the acid and the dryness of The opening through which the agitator E pafles, Lelakt

. If the manganese is impure, its quantity in the centre of each cavity, is in the shape of a is to be auginented in proportion to the supposed funnel, and is fo formed as to hinder the gas from impurty; and it is known whether a sullicient escaping along the agitator, which is furnished (23tty has been employed, by a portion remain- with three transverse arms, coc, c, each being faft. ? Dehird and retaining its black colour. When ened by a wedge d, e, d, e f represents one of the maerials are prepared, the manganese and these arms in a horizontal direction. The bent Cutwa falt, both reduced to fine powder, must tube g h ferves to draw of the atmospheric air be m red accurately together, and put into the which is contained under the cavities, after the da z veifel placed in a sand-bath ; the vitriolic tube has been filled with water. To make use of a 1o ciluted with water and allowed to cool, is this tube, the bent part is fucceffively introduced then to be poured upon tnem, and the junctures under each cavity, as is thewn at g; we must then

; luted. The receiver may be of wood co- blow into it, at the end h, till the water in it is Sated in the inside with wax, and of a very large forced out; after which the air contained under Ste; forire gas is abforbed in proportion to the the cavity will immediately make its escape. te of the water it acts upon.

(111.) fig. 4. APPARATUS for the DISTILLA!!Co. M. BERTHOLLET describes an apparatus, TION OF MURIATIC ACID. In this, I represents a res complicated, but of which we have given retort, which is to be placed in a reverbatory furdrept citation in Plate XXXIX. Fig. 1. is an pace; the mouth of the retort is to be closed by Cruz:90 of the apparatus, in which is represent. a cork m, having two holes, through one of which et a reverberatory furnace AB CD, having; on palie's the tube n, bent at o, and terminating at dine with B, many small openings in its circum- the top in the form of a funnel p, by means of berce

, to serve as chimneys; within which, upon which the vitriolic acid is to be introduced into a-bath a, is placed a matrafs b, the neck of the retort. The other hole of the cork on receives wicho ftands out above the furnace, running the end of a tube q, which forms a coinmunicathe vazh the opening D, which is to be closed tion between the retort and a vefiel r; which velo with clay. The mouth F, of the neck of the fet has thrée openings, and is to be about part El 27els, is closed by a cork G, through the mid- full of wattr, into which is to be plunged the tube ce of which paffes a tube II, Willich forms a com- of safety są to prevent danger from regurgitation: Maricar on between the intide of the matrass by the vetiel'r has a communication with a second as the intermediate vetfel K, where it alto paties vessel u, by means of the tube t: this second vesEspergilla cork I, which cloles one of the three fel is to be half full of water, and is to have a communication with a 3d similar veffel: this 3d but fo much of that article is prepared otherwise, vessel should be also provided with a tube of safe. that at present the making of it is no object. M. ty, and should communicate with a 4th.

coo.muni. able

Berthollet mentions the separation of the mineral (112.) In the construction of an apparatus for alkali from the refiduum; and says he has receithis purpose, it is evident the requifites are, that ved some instructions on this head from M. Morthe receiver should not only be capacious but veau and others, but conceals them on account broad, that the gas, which is very volatile, may of their being communicated as fecrets. meet with a large furface of water to absorb as (115.) To enable the reader to judge for himself much of it as possible. It is very improbabie, of the expence of M. Berihallet's method, we in. however, that all the gas can be absorbed by a sert the latter part of his memoir, in which this single receiver, let us make it as large as we will; part of the subject is more particularly considered. for which reason it will be proper to have several (116.)“ If (says he) at present, when the oxyof them connected with each other by glass tubes, genated muriatic acid costs nearly three deniers so that what escapes from one may be observed (about half an English farthing a quart,) in the proby another. Thus we are sure of having the wa- vinces which are not subject to the GABELLE, (a ter fully impregnated with the gas; though we tax no longer existing in France,) the new method cannot by any means concentrate this liquid like of bleaching, when properly conducted, is frethe mineral acids.

quently advantageous notwithstanding this ex(113.) By means of condensing engines, indeed, pence; it is not to be doubted but that it may bea greater quantity of it might be forced into the come much more fo, by means of these econowater than it can naturally contain: but this could mical practices which I have just mentioned. But, answer no useful purpose'; for the moment that a fo long as the preparation of the bleaching liquor bottle containing such liquor was opened, the line is at all expensive, there will always be a great adperfluous gas would fly off, with violence and vantage in favour of fine cloths ; because, in equal danger to the person who opened it. The bottles quantities of surface, they prefent a less quantity themselves would also be liable to burst on every of matter, and are bleached much easier ; so that 1light alteration of temperature in the atmosphere. an ell, or a pound, of fine cloth, requires much It is proper, therefore, not to attempt the prepa- less liquor than an ell, or a pound, of coarter ration of the liquor, in my great degree of strength; cloth. though this is indeed attended with a very con- 117.)“ But, that the advantages of this proliderable inconvenience, viz. the dificulty of trans- cess may be fully enjoyed, it is necessary to ettaporting it from the place where it is prepared to blish it in a country which is not subject to the the bleachfield, on account of the great bulk and tax on salt, called the gabelle ; for, where salt is weight of it. M. Berthollet proposes to have it not at a low price, the oxygenated muriatic acid made at the place where the cloth is to be bleach- becomes too expensive. ed; and so near that the dephlogisticated spirit of (118.) “ Nevertheless, it is not by the expence falt might be conveyed by spouts to the troughs of the new process, rigorously compared with that which contain the cloth. This, however, must of the ordinary method of bleaching, that we in many cases be impracticable, unless we fup- must judge of its advantages, as it is attended pose the generality of bleachers to be possessed of with some particular ones which would compena skill in managing chemical operations, which at fate a superior price. Cloths and thread, which present they have not. When great quantities of in some places require many months, may be caliquor are to be brought from distant places, howe sily bleached in five or fix days, even in a large ever, it must undoubtedly be a great discourage manufactory; and the bleaching of a few pieces ment, especially if the best methods, and the only, may, without difiiculty, be terminated in cheapest also, have not been used in the prepa. two or three days. Betides, the new method of ration of the acid.

bleaehing may be executed in the winter as well SECT. III. ADVANTAGES of the NEW METHOD

as in the summer, only the drying requires more

time. of BLEACHING.

(119.) “An industrious countryman, whose fa(114.) It would add much to the importance mily employ their intervals of leisure in spinning, of this new method of bleaching, if a comparative is obliged to wait for favourable weather, and perestimate of the expence of that and of the old haps to fend his thread and cloths to a great dirmode were fairly laid before the public, and the tance, where they remain a long time in bleachpreference in this respect appeared justly due to ing; or, if his necessities are preting, he is oblithe former. This, however, has not yet been ged to sell them, at a lots, to some intermediate done; nor even the first and most effential step factor, who lays a tax upon his poverty. But, if towards it taken, viz. the determining how much the manufactories for making oxygenated muriastuff a certain quantity of dephlogisicated spirit tic acid increase in number fufficiently, those who of salt will whiten. From such experiments as weave a piece of cloth will be able to bleach it have been made on the subject, it is probable, themselves, and to enjoy the whole fruit of their that the acid drawn from one pound of falt will labour, as foon as it is out of their hands. whiten 4 of linen cloth without any addition.- 120.) “ The warehouscinan, in a feafon which This may seein a finall expence; but if we con- is unfavourable to the ordinary method of bleachfider the vitrielic acid to be made use of, and ing, is not able to fulfil his engagements without that the residuum is uselets, it would soon be found great difficulty; he is obliged to employ a convery considerable. Glauber's falt may indeed be liderable capital to fill his warehouse, in the scaprepared from the rcliduum of the distillation; fun in which the blcaching is exccuted; he is un.

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