it is again let off by a cock into the bucking-copper, heated to a greater degree, and then put on the cloth again. This courfe is repeated for 6 or 7 hours, and the degree of heat gradually increafed, till, at the laft turn or two, it is thrown on boiling hot. The cloth remains after this 3 or 4 hours in the ley; after which the ley is let off, thrown away, or ufed in the firft buckings, and the cloth undergoes another kind of process.

(10.) III. The cloth is carried out, generally early in the morning, fpread on the gras, pinned, corded down, expofed to the fan and air, and watered for the first fix hours, so often, that it never is allowed to dry. Afterwards it is allowed to lie till dry spots appear before it is watered. After 7 at night it gets no more water, unless it be a very drying night. Next day, in the morning and forenoon, it is watered twice or thrice if the day be very dry; but if the weather be not drying, it gets no water; after which it is taken up dry if the green be clean; if not, it is rinfed, mill-wafh. ed, and laid out to dry again, to become fit for bucking.

(11.) This alternate courfe of bucking and watering is performed for the moft part from 10 to 16 times, or more, before the linen is fit for fouring; gradually increafing the ftrength of the ley from the first to the middle bucking, and from that gradually decreafing it till the fouring begins. The leys in the middle buckings are generally as bout a third ftronger than the first and laft.

(12.) IV. The 4th operation is SOURING, or the application of acids to cloth. It is not eafy to fay when this operation fhould commence, as it depends mostly on the experience of the bleacher. When the cloth has an equal colour, and is moftly freed from the outer bark of the lint, it is thought fit for fouring, which is performed in the following manner.

(13.) Into a large vat is poured fuch a quantity of butter-milk, or four milk, as will fufficiently wet the first row of eloth; which is tied up in loofe folds, and preffed down by two or three men barefooted. If the milk be thick, about an eighth of water is added to it; if thin, no water. Sours made with bran, or rye-meal and water, are often ufed inftead of milk, and ufed milk-warm. Over the first row of cloth a quantity of milk and water is thrown, to be imbibed by the fecond; and fo it is continued till the linen to be foured is fufficiently wet, and the liquor rifes over the whole. The cloth is then kept down by covers filled with holes, and fecured with a poft fixed to the joift, that it may not rise.

(4) Some hours after the clothi has been in the four, air-bubbles arife, a white fcum is formed on the furface, and an inteftine motion goes on in the Hquor. In warm weather it appears fooner, is stronger, and enda Sooner, than in cold weather. just before this fermentation, which lafts 5 or 6 days, is finished, (at which time the fcum falls down,) the cloth fhould be taken out, rinfed, mille wafhed, and delivered to the women to be walhed in foap fuds.

(15.) V. The 5th operation is WASHING with foap and water. It is performed by two women, ch placed oppofite at a tub, made of very thick fo that the edges, which lope inwards, are

about 4 inches in thickness. A fmall veffel full of warm water is placed in each tub. The cloth is folded so that the felvage may be first rubbed with foap and warm water lengthwife, till it is sufficiently impregnated with it. In this manner all the parcel is rubbed with foap, and afterwards carried to be bucked.

(16.) The ley now used has no soap in it, except what it gets from the cloth; and is equal in ftrength to the strongest formerly used, or rather ftronger, because the cloth is now put in wet. From the former operation thefe leys are gradually made ftronger, till the cloth feems of an uniform white. After this the ley is more speedily weakened than it was increased; fo that the laft which the cloth gets is weaker than any it got before. But the management of fours is different; for they are ufed ftrongest at first, and decreased fo in ftrength, that the laft four, confidering the cloth is then always taken up wet, may be reckoned to contain three fourths of water.

(17.) The cloth, after bucking, goes to the watering, as formerly, obferving only to overlap the felvages, and to tie it down with cords, that it may not tear; then it returns to the four, milling, washing, bucking, and watering again. These o perations facceed one another alternately till the cloth is whitened; at which time it is blued, ftarched, and dried. This is the method used in the whitening FINE cloths.

(18.) The following is the method ufed in the whitening of COARSE cloths. Having forted the cloths according to their quality, they are steeped in the fame manner as the fine, rinfed, washed in the mill, and dried before boiling. In this procefs boiling fupplies the place of bucking, as it takes lets time, and confequently is cheapest.

(19.) It is thus performed: 200 lb. of Cafhubs aflies, roolb. of white Mufcovy, and 30lb. of pearlathes, boiled in 500 gallons of water for a quarter of an hour, make the mother or first ley. The cloth boiler is then to be filled two thirds full with water and mother ley, about 9 parts of the former to one of the latter; fo that the ley ufed for boiling the coarfe cloth is about one third weaker than that used in bucking the âne. Such a quantity of cloth is put into the foregoing quantity of ley, when cold, as can be well covered by it. The ley is brought gradually to tite boil, and kept boiling for two hours; the cloth being fixed down all the time, that it may not rife above the liquor. The cloth is then taken out, fpread on the field, and watered, like the fine cloth.

(20.) A3 this boiling dees not exhauft the falts of the ley, the fame liquor is continued to be used all that day, adding, at each boiling, fo much of the mother ley as will bring it to the fame strength as at first. The ley by boiling lofes in quantity fomewhat betwixt a 3d and a 4th; and it is fuppofed, that in ftrength it lofes about a half, becaufe, in practice, it is found that adding to it half its former ftrength in fresh ley, has the fame effect on cloth. Therefore fome fresh ley, containing a 4th part of the water, and the half of the frength of the first ley, makes the 2d boiler equal in ftrength to the firft. To the 3d boiler they add fomewhat more than the former proportion, and go on ftill increasing gradually to the 4th and 5th

which is as much as can be done in a day. The boiler is then cleaned, and next day they begin with freth ley.

(1.) Thefe additions of freth ley ought always to be made by the master bleacher, as it requires judgment to bring fucceeding leys to the fame frength as the firft. When the cloth comes to get the fecond boiling, the ley fhould be stronger by about a goth part, and the deficiencies made up in the fame proportion. For 6 or 7 boilings, or fewer, if the cloth be thin, the ley is increased in this way, and then gradually diminished till the cloth is fit for fouring.

(22.) The whiteft cloth ought always to be boiled firft, that it may not be hurt by what goes before. In this procefs, if the cloth cannot be got dry for boiling, bufinefs does not stop as in the fine; for after the coarse has been drained, on racks made for that purpose, it is boiled, making the ky ftrong in proportion to the water in the cloth. (23.) The common method of fouring linen is, to mix fome warm water and bran in the vat; then put a layer of cloth; then more bran, water, and cloth; and fo on, till the cave is full. The whole is trampled with men's feet, and fixed as in the former procefs. A thousand yards of cloth, yardwide, require betwixt 4 and 6 pecks of bran. The Cloth generally hes about 3 nights and two days the four. Others prepare their four 24 hours before, by mixing the bran with warm water in a Leparate veffel; and before pouring it on the cloth, they dilute it with a fufficient quantity of water. (24.) After the cloth is taken from the four, it cught to be well washed and rinsed again. It is given to men to be well foaped on a table, and afterwards rubbed betwixt the rubbing-boards. When it comes from them, it should be well milled, and warm water poured on it all the time, if convenience will allow of it. Two or three of thefe rubbings are sufficient, and the cloth feldom requires more. After the fouring begins, the ley is diminified in strength by degrees; and 3 boilings after that are commonly fufficient to finish the work.

(15.) VI. The laft operation is to starch, blue, dry, and bittle it, in a machine made for that purpole, which fupplies the place of a calender, and is preferred by many. This method of bleaching Coarfe cloths refembles that practifed in Ireland for both fine and coarfe. The only material difference is, that there the bleachers use no other afhes but keip or cathub. A ley is drawn from the former by cold water, which diffolves the falts, and not the fulphureous particles of the kelp-athes. This iis ufed till the cloth is half whitened, and then they lay afide the kelp ley for one made of calhub ales.

(26.) Agreeably to the preceding account, bleaching is naturally divided into, 1. Steeping and millag: 2. Bucking and boiling: 3. Alternate watering and drying: 4. Souring: 5. Rubbing with foap and warm water: and, 6. Starching and blueing. We fhall treat of these different parts in their order, more particularly.

SECT. II. Of STEEPING and MILLING. (27) LINEN, in the different changes which it undergoes, before it arrives at the fate of what is

called Green linen, contracts a great degree of foulnefs. This is chiefly communicated to it by the matters ufed in the drefling, which thould be effectually cleared off.

(28.) The first thing, therefore, that is to be done in bleaching, is to take off all the filth that is foreign to the flax, and might, in unfkilful hands, be fixed in the cloth. This is the objec of teeping; and to accomplish this end, the cloth is laid in a blood-warm water. A finaller degree of heat than that would not diffolve the dreiling fofoon; and a greater might coagulate and fix, in the body of the linen, thofe particles which fhould be carried off. In a few hours the dreffing made ufe of in weaving is diffolved, and mixed with the water; and as it had acquired fome degree of acidity before application, it becomes a fpecies of ferment.

(29.) Each ferment promotes its own particular fpecies of inteftine motion; the putrid ferment fets in motion the putrefactive fermentation; the vinous ferment gives rife to the vinous fermentation; and the acid ferment to the acetous fermentation. That there is a real fermentation going on in fteeping is evident from the air-bubbles which arife, from the fcum which gathers on the furface, and from the inteftine motion of the whole liquor. That it must be the acetous fermentation, appears from this, that the vegetable particles, already foured, must first-undergo this procefs. The confequence of this operation on the whole is, that the cloth comes out freed in a great measure from its fuperficial dirt, and more pliant and foft than it was before.

(30.) When this inteftine motion is pretty much abated, and before the fcum fubfides, bleachers take out their cloth. The fcum, when no more air-bubbles rife to fupport it, feparates and falls down; and would again communicate to the cloth great part of the filth. But a longer stay would be attended with a much greater disadvantage. The putrid follows close upon the acetous fermentation; when the latter ends, the former begins, and were this to take place in any confiderable degree, it would render the cloth black and tender; fo that this fhould be carefully prevented.

(31.) On these principles, the first question to be confidered, is, What is the most proper liquor for fteeping cloth? The bleachers use plain water; white linen ley and water, equal parts; and ryemeal or bran mixed with water; but they always make use of ley when they have it.

(32.) After fteeping, the cloth is carried to the putstock mill, to be freed of all its loofe fouineiles. There can be nothing contrived to answer the purpose-so effectually as this raill. Its motion is eafy, regular, and fafe. While it preffes gently, it turns the cloth; which is continually washed with a ftream of water. Care must be taken, however, that no water be detained in the folds of the linen, otherwise that part may be injured.

SECT. III. Of BUCKING and BOILING. (33.) The fubject of this fection is the most important part of the whole procefs, and deferves a very nice examination. Its defign is to loofen, and carry off, by the help of alkaline lixivia, that particular fubftance in cloth, which is the caufe

A 2

of

of its brown colour. All afhes ufed in ley, pearl afhes excepted, ought to be well pounded, before they are put into the copper; for the marcoft and cafhub are very hard, and with fome difficulty yield their falt. As these two laft contain a very confiderable proportion of a matter, which will in fome degree tinge white cloth; and as this is diffolved much more by boiling than by the inferior degrees of heat, while the falts may be as well extracted by the latter; the water thould never be brought to boil, and fhould be continued for fome time longer under that degree of heat, The pearl afnes fhould never be put in till near the end, as they are very foluble in water. If thefe falts were always of an equal ftrength, the faine quantities would always make a ley equally strong; but they are not. Salts of the fame name dider very much from each other.

(34.) The Mufcovy athes become weaker every day, as every bleacher must have obferved, till at Jaft they turn quite erfete. A decoction from them when new, mult differ very much from one when they have been long kept. Hence a neceflity of fome exact criterion to difcover when leys are of an equal ftrength. The talte cannot ferve, as that is fo variable, cannot be defcribed to another, and is blunted by repeated trials. The proof-ball will ferve the purpose of the bleachfield fufficiently; and, by difcovering the specific gravity, will show the quantity of alkaline faits diffolved. But it cannot show the dangerous qualities of thefe falts; for the leís cauftic and lefs heavy this liquor is, the more dangerous and corrofive it may be for the cloth. The third ley, which they draw from thefe materials by an infution of cold water, in which the taste of lime is discoverable, appears plainly to be more dangerous than the firft. The fecond ley, which they extract from the fame afhes, and which is reckoned about a third in ftrength, when compared with the first, must be of the fame nature; nor should it be used without an addition of pearl-afhes, which will correct it. (35.) One general rule is, That the folution of any body in its menftruum is equally diffufed through the whole liquor. The bleachers, depending on this, ufe equal quantities of the top and bottom of their ley, when once clear and fettled; taking it for granted, that there is an equal quantity of falts in equal quantities of the ley. But it is a fact, that the ley will be in fome places much ftronger than the cloth can with fafety bear; and hence there is a neceffity for ufing a degree of caution to avoid mifchief. That general law of folution must have taken its rife from particular experiments, and not from reafoning.

(36.) Whether a fuficient number of experiments have been tried to ascertain this point, and to eftablish an undoubted general rule, may very reasonably indeed be called in question. DrHOME fays, "When I had difcovered that lime makes part of the diffolved fubftance, and reflected how long its groffer parts will continue fufpended in water, there appeared ftronger reafons for fufpecting that this rule, though it may be pretty general, does not take place here; at leaft it is th the purfuit of experiment. I weighed at shfield a piece of glafs in fome cold ley, 1 been boiled, Rood for two days, and

about the fourth part of it had been used. The glafs weighed 3 drams 1 grains in the ley, and 3 drams 74 grains in river water. The fame glafs weighed in the fame ley, when almost all used, 2 grains lets than it had done before. This fhows, that the laft of the ley contained a third more of the diffolved body; and, confequently, was a third stronger than the first of the ley.

(37.) "As this might, perhaps, be owing to a continuation of the solution of the falts, I repeated the experiment in a different way. I took from the furface fome of the ley, after the falts were diffolved, and the liquor was become clear. At the fame time I immerfed a bottle, fixed to a long ftick, fo near the bottom, as not to raise the alhes there, and, by pulling out the cork by a ftring, filled the bottle full of the ley near the bottom. The glafs weighed in river-water 3 drams 384 grains; in the ley taken from the furface 3drams 341 grains; and in the ley taken from the bottom 3 drams 31 grains. This experiment shows, that the iey at the bottom was, in this cafe, 4ths ftronger than the ley at the surface.

(38.) "At other times when I tried the fame experiment, I found no difference in the specific gravity; and therefore, I leave it as a question yet doubtful, though deferving to be afcertained by thofe who have an opportunity of doing it. As the ley ftands continually on the ashes, there can be no doubt but what is ufed laft must be ftronger than the firft. I would therefore recommend, to general practice, the method used by Mr John Chriftie, who draws off the ley, after it has fettled into a fecond receptacle, and leaves the allies be hind. By this means it never can turn stronger; and he has it in his power to mix the top and bottom, which cannot be done fo long as it stands on the afhes."

(39.) Let us inquire how the ley acts. On this inquiry depends almoft the whole theory of bleaching, as its action on cloth is, at least in this country, abfolutely neceffary. It is found by experi ment, that one effect leys have on cloth is the di minishing of its weight; and that their whitening power is generally in proportion to their weakening power. Hence arifes a probability, that these leys act by removing fomewhat from the cloth, and that the lofs of this fubftance is the cause of whitenefs. This appears ftill plainer, when the bucking, which lafts from Saturday night to Monday morning, is attended to.

(40.) Chemifts differ greatly with regard to the operations of these falts; whether they act by altering the external texture of the cloth, or by feparating the mucilaginous parts from the reft, or by extracting the oil which is laid up in the cells of the plant. The laft is the general opinion, or rather conjecture, for none of them deferves any better name; but we may venture to affirm, that it is fo, without any better title to pre-eminence than the others have. Alkaline falts diffolve oils, therefore that thefe falts diffolve the oil of the cloth, is all the foundation which this theory has to reft on; too flight when unsupported by experiment, to be relied on.

(41.) Dr Home endeavours to fettle this queftion by the following experiments and obfervations."Wax (fays he) is whitened by being expofed to

the

the influence of the fun, air, and moisture. A difcovery of the change made on it by bleaching, may throw a light upon the queftion. Six drams of wax were fliced down, expofed on a S. window, Sept. 10, and watered. That day being clear and warm, bleached the wax more than all the following. It seemed to me to whiten quicker, when it had no water thrown on it than when it had. Sept. 15, it was very white, and I dram 3 grains lighter. 34 drams of this bleached wax, and as much of unbleached, taken from the fame piece, were made into two candles of the fame length and thicknefs, having cotton wicks of the fame kind. The bleached candle burnt 1 hour 33 minutes; the unbleached 3 minutes longer. The former ran down 4 times, the latter never. The former had an obfcure light and dull flame; the latter had a clear pleasant one, of a blue colour at the bottom. The former, when burning, feem, ed to have its wick thicker, and its flame nearer the wax, than the latter. The former was brittle, the latter not.

(42.) It plainly appears from these facts, that the unbleached wax was more inflammable than the bleached; and that the latter had loft fo much of an inflammable fubftance as it had loft in weight; and confequently the fubftance loft in bleaching of wax is the oily part. As I had not an opportunity of repeating the former experiment, I do not lock on it as entirely conclufive; for it is poffire that some of the dust, flying about in the air, might have mixed with the bleached wax, and fo have rendered it lefs inflammable. Nor do I think the analogical reasoning from wax to linen with ort objections. Let us try then if we cannot procure the substance extracted from the cloth, fhow it to the eye, and examine its different properties. The proper place to find it, is in a ley already uled, and fully impregnated with these colouring particles.

(47) “I got in the bleachfield fome ley, which had been uted all that day for boiling coarfe in, which was tolerably white, and had been twice boiled before. There could be no drefling remaining in thefe webs. No foap had ever touched that parcel; nor do they mix foap with the ley tied for coarse cloth. Some of this impreg, sated ey was evaporated, and left a dark-coloured matter behind. This fubftance felt oily betwist the fingers, but would not lather in water as top does. It deflagrated with nitre in fufion, and afforded a tincture to spirit of wine. By this periment the falts feem to have an oily inflamfubftance joined with them.

44 Could we feparate this colouring fubftance from these falts, and exhibit it by itself, fo that it might become the object of experiment, the question would be foon decided. Here chefry lends us its affiftance. Whatever has a ftrongerathnity or attraction to the falts with which its joined, than this fubftance has, muft fet it at kterty, and make it vifible. Acids attract alkaine falt from all other bodies; and therefore will ferve our purpose.

(45.)" Into a quantity of the impregnated ley mentioned in the former experiment, I poured in cul et vitriol. Some bubles of oil arofe, an inteftite motion was to be perceived, and the liquor

changed its colour from a dark to a turbid white. It curdled like a folution of foap, and a feum foon gathered on the furface, about half an inch in thicknefs, the deepness of the liquor not being above 6 inches. What was below was now pretty clear. A great deal of the fame matter lay in the bottom; and I obferved that the fubftance on the furface was precipitated, and fhowed itself heavier than water, when the particles of air, attached to it in great plenty, were difpelled by heat. This fubftance was in colour darker than the cloth which had been boiled in it.

(46.) "I procured a confiderable quantity of it by fkimming it off. When I tried to mix it with water, it always fell to the bottom. When dried by the air, it diminished very much in its fize, and turned as black as a coal. In this state it deflagrated strongly with nitre in fufion; gave a ftrong tincture to fpirit of wine; and, when put on a red hot iron, burnt very flowly, as if it contained a heavy ponderous oil; and left fome earth behind.

(47.) "From the inflammability of this substance, its rejecting of water, and diffolving in fpirit of wine, we difcover its oleaginous nature; but from its great specific gravity we fee that it differs very much from the exprcfled or cellular oil of vegetables; and yet more from their mucilage. That it diffolves in fpirit of wine, is not a certain argument of its differing from expreffed oils; because thefe when joined to alkaline falts, and recovered again by acids, become foluble in spirit of wine. The quantity of earthy powder left behind after burning, fhows that it contains many of the solid particles of the flax. The fubftance extracted from cloth by alkaline leys appears then to be a compofition of a heavy oil, and the folid carthy particles of the flax.-In what manner these falts act, fo as to diffolve the oils, and detach the folid particles, is uncertain; but we fee evidently how much cloth must be weakened by an improper ufe of them, as we find the folid particles themfelves are feparated."

(48.) That the falts may enter into the body of the cloth along with the water, it is abfolutely neceffary that the cloth be dry before bucking; for they will not enter in fuch quantity if it be wet, and, by acting too powerfully on the external threads, may endanger them. The degree of heat is a very material circumftance in this ope ration. As the action of the falts is always in proportion to the heat, it would appear more proper to begin with a boiling heat, by which a great deal of time and labour might be faved. The reas fon why this method is not followed appears to be this: If any vegetable, or vegetable fubftance, is to be foftened, and to have its juices extracted, it is found more proper to give it gentle degrees of heat at first, and to advance gradually, than to plunge it all at once in boiling water. This laft degree of heat is fo ftrong, that, when applied at once to a vegetable, it hardens inftead of foftening its texture. Dried vegetables are immediately put into boiling water by cooks, that thefe fubftances may preferve their green colour, which is only to be done by hindering them from turning too foft. Boiling water has the fame etfect on animal fubftances; for, if falt beef is put

nto

into it, the water is kept from getting at the falts from the outside of the beef being hardened.

(49.) If we confider how much of an oily fubtance there is in the cloth, especially at firft, which will for some time keep off the water, and how the twisting of the threads, and clofenefs of the texture, hinders the water from penetrating, we shall find that, if boiling water were put on it at once, the cloth might be liable, in several parts, to a dry heat, which would be much worfe than a wet one. That the leys have not accefs to all parts of the cloth at first, appears plainly from this, that when it has lain after the firft bucking, till all the leys are washed out, it is as black, in fome parts, as when it was steeped. This muft be owing to the difcharge of the colouring particles, from those places to which the ley has accefs, and to their remaining where it has not. It deems advifeable, then, in the first bucking or two, when the cloth is foul, to use the ley confiderably below the boiling point; that by this foaking or maceration, the foulnefs may be entirely difcharged, and the cloth quite opened for the speedy reception of the boiling ley in the buckings which fucceed. The leys fhould likewife be weakeft in the first buckings, because then they act only on the more external parts; whereas, when the cloth is more opened, and the field of action is increafed, the active powers ought to be fo too. For this reafon they are at the strongest after fome fourings.

(50.) As to the management of the coarfe cloth, where boiling is fubftituted in place of bucking, this species of linen cannot afford the time and dabour neceffary for the latter operation; and therefore they muft undergo a fhorter and more active method. As the heat continues longer at the degree of boiling, the leys used to the coarfe cloth must be weaker, than those used to the fine. There is not fo much danger from heat in the coarfe as in the fine cloth, because the former is of a more open texture, and will allow the ley to penetrate more fpeedily. In the clofer kinds, however, the firft application of the falts fhould be made without a boiling heat being used.

SECT. IV. OF ALTERNATE WATERING and
DRYING.

(51.) When the cloth has been bucked, it is carried out to the field, and frequently watered for the first fix hours. For if, during that time, when it is ftrongly impregnated with falts, it is allowed to dry, the falts approaching closer together, and assisted by a greater degree of heat, increating always in proportion to the drynefs of the cloth, act with greater force, and deftroy its very texture. After this, dry spots are allowed to appear before it gets any water. In this ftate it profits moft, as the latter part of the evaporation comes from the more internal parts of the cloth, and will carry away most from thofe parts. The bleaching of the wax, in Dr Home's experiment (41,) confirms this; for it seemed to whiten moft when the last particles of water were going off.

(52.) This continual evaporation from the furface of the cloth fhows, that the operation carries of fomewhat remaining after the former procefs

of bucking. This appears likewife from a fact known to all bleachers, that the upper fide of cloth, where the evaporation is ftrongeft, attains to a greater degree of whitenefs than the under fide. But it is placed beyond all doubt by the fact, that cloth turns much lighter by being expofed to the influence of the fun, air, and winds, even though the falts have been washed out of it. (53.) What is the nature then of this substance? As it appears (§ 40,) that the whitening, in the operation of bucking, depends on the extracting the heavy oil, and folid particles of the flax; it is highly probable, that the effects of watering, and expofure to the fun, air, and winds, are produced by the cvaporation of the fame fubftance, joined to the falts, with which compofite body the cloth is impregnated, when expofed on the field. That thefe falts are in a great measure carried off or deftroyed, appears from the cloth being allowed to dry without any danger, after the evaporation has gone on for fome time. "If we can fhow (fays Dr Home) that oils and falts, when joined together, are capable of being exhaled, in this manner, by the heat of the atmosphere, we thall reduce this queftion to a very great degree of certainty. Sept. 10, I expofed in a S. W. window half an oz. of Caftile foap, fliced down and watered. Sept. 14, when well dried, it weighed abut 3 dr. 6 gr. Sept. 22, it weighed 2 dr. 2 g Sept. 24, it weighed 1 dr. 50 gr. It then feemed a very little whiter; but was much more mucilaginous in its tafte, and had no degree of faltnefs which it had before.

(54.) “It appears from this experiment, that foap is fo volatile, when watered, and expofed to air not very warm, that it lofes above half its weight in 14 days. The fame must happen to the faponaceous fubftance, formed from the conjunction of the alkaline falts, heavy oil, and earthy particles of the flax. The whole defign, then, of this operation, which by way of pre-eminence gets the name of BLEACHING, is to carry off, by the evaporation of water, whatever has been loo fened by the former procefs of bucking.

(55.) Against this doctrine there may be brought two objections, seemingly of great weight. It is a general opinion amongft bleachers, that linen whitens quicker in March and April than in any other months: but as the evaporation cannot be fo great at that time as when the fun has a greater heat; hence the whitening of cloth is not in proportion to the degree of evaporation; and therefore the former cannot be owing to the latter. This objection vanifhes, when we confider, that the cloth that comes first into the bleachfield, in the fpring, is closely attended, having no other to interfere with it for fome time; and as it is the whiteft, gets, in the after buckings, the first of the ley; while the fecond parcel is often bucked with what has been used to the firft. Were the fact true, on which the objection is founded, this would be a fufficient aafwer to the objection.But it appears not to be true, from an obfervation of Mr John Chriftie, That cloth laid down in the beginning of June, and finished in September, takes generally lefs work, and undergoes fewer operations, than what is laid down in March and finished in June.

(56.) "The