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Essays on bleaching
A M E R I C A N btECHANIC$ ~ M A G A Z I N E ,
3~7
developed.in thin plates on its surface~ often amounting.to a. pearly,. _, and somehmes almost metallic appearance; an effect wh:eh9 it :s believed, has not been hitherto investigated. Solution of potash acts ver~" rapidly upon glass, as the chemist, oRen, inconveniently, learns fly the effect prodhced upon the bulb of a thermometer e~v,ploy~d to de(ermine its boilin~ point, and which is ahvays found corroded to a considerable extent after the experiment. It may also here be remarked, (although not perhaps immediately connected with the subject,) that fi'om fi-equet~t observations of a !~,rson, !n th.e habit of using solid carbonate of ammonia, the flint' glass oo:tles m which it has been for some time keot, are invariably ~endered much more brittle, and pieces of glass fall out upon very slight motion of its contents. This fact is merely mentioned as curious~ and may, probably, be hereafter more fldly examined.
[Journal ~" the Ro2/al Institution.
ESSAYS ON B L E A C I t I N G .
By James Rennie, ~'1. AL Lecturer on Philosophy, ,~'c. ,~.c. Zondo~o No. III.--CHE~rCAL A G E N T S U S E D I N BI, E A C H I N ( i , SEca':o.n III.~()f the Mineral 31katL SODAiS procured in a ~imilar manner with potash, by incineration, and afterwards lixiviating; but from vegetables of a very dil~rent i~abitat. Potash is manufactured chiefly from trees~ while soda, when i~ is procured from vegetahles, is made exclusively fi'om marine pla,ts. Sometimes it is found native, as in Russia, and in Egypt, where it is called natron. But, however much it may differ from potash, in its appearance, and in the plants whence it {s obtained, when used as an agent in bleaching, there is little dii~rence in its effects, provided that the strength of the Icy, and other circumstances, shall l)e equal, ttitherto, the exorbitant price of this commodity has excluded it fi'om being used in the bleach-field; but as more economical modes are now contrived, and as it is made of great purity, there is little doubt that it will now soon be introduced, particularly as it is admirably calculated for the finishing process of the finer t~abrics of muslin. Ramsay, from whom I take these remarks, adds, that six ounces of pure carbonate of soda, with ten ounces of soap, produce detergent effects equal to a pound and a half of soap used alone. The oxymuriate of soda, as will afterwards be detailed~ is sometimes used in calico bleaching, and must require this alkali in a crude slat% for its manufacture. , Barilla is obtained chiefly on the shores of the Mediterranean, from the salsoia knit, the saficornia, and the ch~nopodia of Linn~eu% ~vhich are dried to the same degree as hay, and burned iu pits, like those ttsed with us for kelp, which reduces them to a grayish-blue
328
THE FRANKLI~JOUR~At, AND
mass~ containing more or less mineral alkali. W h e n broken, it pro; sents a blackish fracture. It usually contains fi'om 20 to ~4 per cent. of pure alkali; but the superior sort of it, called sweet barilla, some: times contains 33 per cent. The contaminating substances, are charcoal, and sulphate, o1" muriate, of soda.* This alkali is also manufactured in Britain fl'om marine plants, dliefly fuel, which grow on our shores. It is called kelp, and is much. ialbrior to the barilla imported fi'om Alicant and Carthagena, con: raining only fi'om three to eight per cent. of pure alkali. Its inferi, ority has been ascribed, and apparently with much justice, to the rude and careless manner in which it is commonly manufactured. (See Jamieson's M. of the S. Isles, vol. II. 44.) Sulphur commonly exists in a considerable proportion in kelp. Mr. Kirwan found this proportion as high as four grains in the ounce, ~n the best Cunnamara kelp, and that of Strangford seemed equaliy sulphurous. (Trans. R. L Acad. I I I . ~5-4.) Before stating the mode of analyzing barilla and kelp~ it may not be inq)roper to mention a prejudice, which commonly iufluences bleachers in purchasing those commodities, and which is founded on a mistaken view of their chemical properties. W h e n a parcel of thos6 crude alkalies has lain in the storehouses for any. considerable length of time, the action of the air causes the larger pteces to break down, and to assume a very ditt~rent appearance from those recently in,ported. When the ignorant bleacher sees this, he sets a very inferior. value~ on the g.'oods, and fi'equently refuses to have. them at. any price. Now, chemJstry teaches us, that the fixed alkahes are nnpefishable, and cannot be injured by keeping, except they be dissolved by moisture, or washed away by rain. The only circmhstance wlfich could depreciate alkalies, in the state just described, is their absorption of carbonic acid and water, whose proportions can be easily ascertained,• and. the conse(j.uent de p recmtnm of value ded~.lcted . Nay,, these alkalies are rather nnproved, for the purposes of bleaching, by agel for, by the ab~rption of carbonic acid, the alkaline sulphureL which tbev may haw; contained, is decomt)osed, and the sulphur separated;~whence a much purer ley can be obtained, than from bariila or kelp, recently procured. I am of opinion, that this mistaken notion, concerning alkalies, may have arisen from a remark made by Dr. Ifome. (Exl)er. o. 158.) " T h e s e ashes," he says, "ought to be close shut up ~a casks'; for, if exposed to the open air, though in a room, the alterna.te moisture, and drought, must fix theh' most useful parts. They become les's pungent by keeping, and that on the outside, while tlleir pungency "reu;'ai~s * Some very peculiar doctrines are stated by Mr. Parkes, respecting" oariih. He says,that all marine plants, except those cultivated for barilla, yield potash, ~n~n~ot~soda, by !ncin~'afion; He was !ed into this opinion] by obtaining great tI t uesol murmte ot potash ~rom Kelp, to tile extent even of inany handrea weig'hts per ton. He imagines, that the soda, of kelp, is not derived fi,omthe burnt weeds, but from the operation of the potash on the sea salt, producing a decomposition, tbrminff carbonate of soda, and rnuriate oF potash. Chem. Catech,p. I58,
AMERICAN MECHANICS~ MAGAZINE.
~
i~ternally!" Aud again, (p. 47,) " M u s c o v y ashes turn Weaker every day, till at last they become quite eflhte:" This is obviously from the absorption of carbonic acid; and he does not seem to have known, that thts could speedily be extracted by quick lime. I would earnestly advise the bleacher, in no'case to trust to tables for ascertaining the qualities of the alkalies he is about to purchase. Such have been given by Kit'wan, and Descroizille% senior; but they are calculated only to mislead; lot" every parcel of the crude article's of commerce, differs in its pro0ortions of real alkali, erda suol)osiu~ ~t to con e from the same manu facto,-y. He must ascertain for h~mself the purity of every parcel, if lie wishes to protit by his business. l]arilla and kelp may be examined in the same manner which has been ah'eady directed for trying potash, or by the method which I shall here lay down, and tbr wh{ch [ am indebted to Mr. Parkes. WherL any parcel of kelp, or barilla, is to be analyzed, as fair an a~'erage sample as possible is to be selected, bv breaking small chips flora several larce pieces, and mixing those with a fair proportion of t}/e small, wbich' may belong to the ldt Let a sample, tiros-s-leered ~e pulverized in an'iron mortar, that the whole ma~y be equally mixed; about an ounce of this is to be ~round to an impalp'~ble powder to facthtate the &sengaging of the pure alkali. Take of this powder, 100 grs., and pour ui~on it~two (maces of pure ware,'; stir it occasionall)" for a few hours, wi/b a glass ~-od; allow the insoluble matters to subside; pour tile super~mtaltt liquid on a paper filter; and add other two ouuces of water to the residuum. Tim whole is then tin-own on the filter, in order to secure an~ lime, or carbonate of lime, which raay be present, and would occasmn inaccuracy; upon which a little water is also poured, to wash out what remains in the residuum. Both the littered solutions are then to be put into a vessel, and re. due@, by bofli~g, to two or three ounces. "rake two ounces of rill'at-. ed sulphuric acid, of tim Specific gravity of 1,100; weigh it accurately, together with the phial, and note down their weight m grain~ Pour some of this acid, very gradually, im;o the soluti(m, and st;i: it tilt it ceases ~o ett~rvesce; wt~en, if it turn red litmus paper blue, more acid, sa) a dracmn, l~ to be cau~ttously added, and alter stating, it is to be aaain tried with tlxe test paper. When the paper begins to be affected but sli~atly, the acid should only be ad(lat by a tew drops at a time. T m'con;piete saturation of thesoluti,ul with aeid~ will be known from the eiti~rveseeuce wholly ceasing: the separation of the sulphur held in soluti(m; and from its not tinging the test paper. The alkali having thus been rendered neu*ral, the acid in the phial~ wlaieh has not been used~ is to he agaiv accurately weighed, to as-, certain how much it has renuired t0-~aturate the alkali; whence it can easily be calculated, how much real alkali the sample contained. ~hen it is known hmv much acid a pure alkali will take up. l~lr~ Parkes ascertained, that 100 gr:dns of fmre potash require 5~0 grains of salphuric acid, of the sFecilic g:-avity of t. 100, to saturate it; and 100grains of pure soda reqtfirc 8[~ of dte acid. From this, it is evident, that~ before ¢ommm~cing the analysis, it will be necessary te h'.arn whether the san ple is ~potash, or soda, or a mixture of butlx CoL, IlI,--~Na. 5+--..%l~', 18q7, 4~
~0
THE FRANKLIN JOURNAL A N D
The crystals of nitro-muriate of olatina, dissolved in water, %rill fur. nisb a test lbr this purpose; as, when it is dropped into any alkaline solution, it will precipitate potash, but will not aft~ct the soda. 12ecovery of Alkali f r o m ~'aste Le~s. It is a very bad practice among bleachers, and it is almosf~ univer. sal, to use, again and agairb the alkaline le5% which must be loaded with impurity: they are often so much so, indeed,~ as to approach to coagulation. They are led to this. from a notion of economy, being unwilling to throw away any alkal~i which they can any way employ. But it would often be more economical to purify the ley, betbre using it; and a method of doing this is also a desideratum for procuring fi'esh alkali from leys which can no loIlger be used. Several plans for this purpose have been suggested, but few have been successful, or~ at least, economical. Des Charmes advises the residual ashes to be moistened with the ley~ and burned in a Common kitchen fire~ ia which wood is ~he usual fuel. lie also recommends boiling the waste leys with quicklime, which is found to be one of tile best ways of management, as the lime decomnoses the imoure veo~etable matter floating in the leys, and renders tli'em transpare'nt and c'anstic, thougk not altogether so pure as fresh made ley. (See Art of Bleach. p. 558.) This is chiefly practicable, however, when the lays have been used for cottons; f~r the resinous extract of linens is not so easily acted on by the lira% without adding, along" with the lime, as may easily be done~ a small quantity of tl~-e fresh precioitated earth of alum. ~l'he mixture should be constantly agitated dth.tng the process~ in order to expose every particle of the resinous and extractive matter to the action of the lime. Des CharoJes, in this, gives directitms quite op~tsite from those practised by the bleachers around Glasgow. They final,that the lime acts better in a cold solution, than with the add~-on o~heat , (See Ramsay's Treatise.) Another ,,ode is by calcining ne was~ teys in a reverberating furnace, or in the apparatus called t!~e stone %oiler~ ah'eady described; and by these means, alkali can ttaus be obta~ed purer than that which is imported; which~ in exten. sire bleach-wb~k % that can attbrd the expanse of the apparatus, is of great consequerke ' I'he Icy is first evaporated~ till it t~ecomes of the consistence Of treble, (see Des Charmes, p. 9~,) when it is put into
~!
alkaliY'for all the r f.~hus melted, and is tbund to consist of pure ; . . esin~id extractive matter are completely con• 1. ' P ,' "~tate of a carbnnate~ anti this carbon is again taken up by the quicklin~ used to render it causticj so that it is nearly in a state of purity, If Milers are used, their safety should be insured by the ingenious methoff--e^~-~ , , - -'~ -~ of Glasgow. (See A~n, of Philos. I. ~o~gt'i'mermect oy ~vxr.,,an, say, The home manufacture of alkalies, iS'~but slightly connected with the direct subject of the sketch; ~et I ca ~". . . . . "~. " - ..... ; ou-'ht t" ~". . . . . ~ . . . . . '~, ~ P-uaut netp remarzlng, u m t ~ ~ u ue cat'emtty attenaetl to. w e are i~debted to Spain~ fbr an
AI~IERICAIq MECHANICS~ MAGAZINE,
331
annual supply 0fseveral thousand tons of barilla, and to America aml Ru "a, for incalculable quantities of pot and pearl ashes; while wg possess considerable resources at home, which are either altogethe¢ neglected, or ignorantly and unskilfully managed. The Yrencl~ with tile most laudable spirit of industry and enterprise~ take advantage of their wine leysi to prepare an ash (Cendre GraVel~es) from the leys ofwine~ which contains no tess than 60 or 70. per cent, o t pure alkali, (Des Charmes, p. ~79,) We cannot, indeed, for want of mate~ riM, prOduCe this alkaii; bat let us turn to account the resources we possess~ Let endeavours be made to improve" the kelp manufacture~ Dy constructing proper furnaces for its combustion, and by preparing the sea-weeds~ whence it is to be made~ according to well ascertair~ ed chemical principles; L e t the,furze, [)room, and fern~ which grow in such great abundance in some Of our waste lands~ be turned into potash; or let such plants as best afford alkali, be cultivated express. lyfor its manufacture; The tansey (Taneetl~m vulg. Lin,) is~ aceord~ ing ~to Lord Dundofiald, one of tffose; and as if F.rows in abundance in a wild state~ on ~h,e banks of the Clj;de, it is ~ighty probable that its cultivation. ~vould be e~tremely easy. Potash may b e prOcured from saltpetre~ by heating it with charcoal, so as to ~leeompose its acid. in'this Way, we a ~ tzld b y Parkes, that one hundred weight of ihe nitre!will i)~oduce half that quanttty of pure potash. During our late dis tires with Ameriea~ a ~reat quafitity of saltpetre was used for thi~Pgery purpose; and wheff the prices W~IIadmit Of it, cousiderable profit ~aay in this way be gained. Potash may also be madg from peat ashes,
On the Theory and Practice of Chler maklng~ ~ y a CoRa~sro~nsNT.
Exete~ ~ug. 9, 1896o S~rL---~In maklng eider, very tntich indeed depends on the maoagement ~,as from the sa~ne fruit, eiders very different in coloar, and ia quality, may be produced: for instance, if the appies are g~ouffd down and submitted to the action of the press at once~ then committed to the vat, and there fermented~ the eider will be barsh(ahd nearly colourless: but, if apples fi-omthe same tree, arid gathered at tlie same time~are ground down'inthe latter part of the day~ and not committed to the press till the following dffy, the action of the air oa the pulp will cause the eider to acquire k ¢onsiderable degree of ¢olo~r, ~17ormaking strong Ciders the p¢ocess ts as follows~--~A la~er o~' wheat-straw is placed on the bottom of tile pres@in a square form~ and on this a layer of the pulp of aboiat a)i inch in thickness; a second layer,of 'straw is then place~l on this, but in a contrary direction to the former, and seas to lie aeros~ it at right angles; and then anOther layer of ,the pulp, aild so on alternately; layers of straw and pulp are continued~ until a~ much is put in as you propose to submit to the action of the pre~s, at once. The press is now brought down
3~7
developed.in thin plates on its surface~ often amounting.to a. pearly,. _, and somehmes almost metallic appearance; an effect wh:eh9 it :s believed, has not been hitherto investigated. Solution of potash acts ver~" rapidly upon glass, as the chemist, oRen, inconveniently, learns fly the effect prodhced upon the bulb of a thermometer e~v,ploy~d to de(ermine its boilin~ point, and which is ahvays found corroded to a considerable extent after the experiment. It may also here be remarked, (although not perhaps immediately connected with the subject,) that fi'om fi-equet~t observations of a !~,rson, !n th.e habit of using solid carbonate of ammonia, the flint' glass oo:tles m which it has been for some time keot, are invariably ~endered much more brittle, and pieces of glass fall out upon very slight motion of its contents. This fact is merely mentioned as curious~ and may, probably, be hereafter more fldly examined.
[Journal ~" the Ro2/al Institution.
ESSAYS ON B L E A C I t I N G .
By James Rennie, ~'1. AL Lecturer on Philosophy, ,~'c. ,~.c. Zondo~o No. III.--CHE~rCAL A G E N T S U S E D I N BI, E A C H I N ( i , SEca':o.n III.~()f the Mineral 31katL SODAiS procured in a ~imilar manner with potash, by incineration, and afterwards lixiviating; but from vegetables of a very dil~rent i~abitat. Potash is manufactured chiefly from trees~ while soda, when i~ is procured from vegetahles, is made exclusively fi'om marine pla,ts. Sometimes it is found native, as in Russia, and in Egypt, where it is called natron. But, however much it may differ from potash, in its appearance, and in the plants whence it {s obtained, when used as an agent in bleaching, there is little dii~rence in its effects, provided that the strength of the Icy, and other circumstances, shall l)e equal, ttitherto, the exorbitant price of this commodity has excluded it fi'om being used in the bleach-field; but as more economical modes are now contrived, and as it is made of great purity, there is little doubt that it will now soon be introduced, particularly as it is admirably calculated for the finishing process of the finer t~abrics of muslin. Ramsay, from whom I take these remarks, adds, that six ounces of pure carbonate of soda, with ten ounces of soap, produce detergent effects equal to a pound and a half of soap used alone. The oxymuriate of soda, as will afterwards be detailed~ is sometimes used in calico bleaching, and must require this alkali in a crude slat% for its manufacture. , Barilla is obtained chiefly on the shores of the Mediterranean, from the salsoia knit, the saficornia, and the ch~nopodia of Linn~eu% ~vhich are dried to the same degree as hay, and burned iu pits, like those ttsed with us for kelp, which reduces them to a grayish-blue
328
THE FRANKLI~JOUR~At, AND
mass~ containing more or less mineral alkali. W h e n broken, it pro; sents a blackish fracture. It usually contains fi'om 20 to ~4 per cent. of pure alkali; but the superior sort of it, called sweet barilla, some: times contains 33 per cent. The contaminating substances, are charcoal, and sulphate, o1" muriate, of soda.* This alkali is also manufactured in Britain fl'om marine plants, dliefly fuel, which grow on our shores. It is called kelp, and is much. ialbrior to the barilla imported fi'om Alicant and Carthagena, con: raining only fi'om three to eight per cent. of pure alkali. Its inferi, ority has been ascribed, and apparently with much justice, to the rude and careless manner in which it is commonly manufactured. (See Jamieson's M. of the S. Isles, vol. II. 44.) Sulphur commonly exists in a considerable proportion in kelp. Mr. Kirwan found this proportion as high as four grains in the ounce, ~n the best Cunnamara kelp, and that of Strangford seemed equaliy sulphurous. (Trans. R. L Acad. I I I . ~5-4.) Before stating the mode of analyzing barilla and kelp~ it may not be inq)roper to mention a prejudice, which commonly iufluences bleachers in purchasing those commodities, and which is founded on a mistaken view of their chemical properties. W h e n a parcel of thos6 crude alkalies has lain in the storehouses for any. considerable length of time, the action of the air causes the larger pteces to break down, and to assume a very ditt~rent appearance from those recently in,ported. When the ignorant bleacher sees this, he sets a very inferior. value~ on the g.'oods, and fi'equently refuses to have. them at. any price. Now, chemJstry teaches us, that the fixed alkahes are nnpefishable, and cannot be injured by keeping, except they be dissolved by moisture, or washed away by rain. The only circmhstance wlfich could depreciate alkalies, in the state just described, is their absorption of carbonic acid and water, whose proportions can be easily ascertained,• and. the conse(j.uent de p recmtnm of value ded~.lcted . Nay,, these alkalies are rather nnproved, for the purposes of bleaching, by agel for, by the ab~rption of carbonic acid, the alkaline sulphureL which tbev may haw; contained, is decomt)osed, and the sulphur separated;~whence a much purer ley can be obtained, than from bariila or kelp, recently procured. I am of opinion, that this mistaken notion, concerning alkalies, may have arisen from a remark made by Dr. Ifome. (Exl)er. o. 158.) " T h e s e ashes," he says, "ought to be close shut up ~a casks'; for, if exposed to the open air, though in a room, the alterna.te moisture, and drought, must fix theh' most useful parts. They become les's pungent by keeping, and that on the outside, while tlleir pungency "reu;'ai~s * Some very peculiar doctrines are stated by Mr. Parkes, respecting" oariih. He says,that all marine plants, except those cultivated for barilla, yield potash, ~n~n~ot~soda, by !ncin~'afion; He was !ed into this opinion] by obtaining great tI t uesol murmte ot potash ~rom Kelp, to tile extent even of inany handrea weig'hts per ton. He imagines, that the soda, of kelp, is not derived fi,omthe burnt weeds, but from the operation of the potash on the sea salt, producing a decomposition, tbrminff carbonate of soda, and rnuriate oF potash. Chem. Catech,p. I58,
AMERICAN MECHANICS~ MAGAZINE.
~
i~ternally!" Aud again, (p. 47,) " M u s c o v y ashes turn Weaker every day, till at last they become quite eflhte:" This is obviously from the absorption of carbonic acid; and he does not seem to have known, that thts could speedily be extracted by quick lime. I would earnestly advise the bleacher, in no'case to trust to tables for ascertaining the qualities of the alkalies he is about to purchase. Such have been given by Kit'wan, and Descroizille% senior; but they are calculated only to mislead; lot" every parcel of the crude article's of commerce, differs in its pro0ortions of real alkali, erda suol)osiu~ ~t to con e from the same manu facto,-y. He must ascertain for h~mself the purity of every parcel, if lie wishes to protit by his business. l]arilla and kelp may be examined in the same manner which has been ah'eady directed for trying potash, or by the method which I shall here lay down, and tbr wh{ch [ am indebted to Mr. Parkes. WherL any parcel of kelp, or barilla, is to be analyzed, as fair an a~'erage sample as possible is to be selected, bv breaking small chips flora several larce pieces, and mixing those with a fair proportion of t}/e small, wbich' may belong to the ldt Let a sample, tiros-s-leered ~e pulverized in an'iron mortar, that the whole ma~y be equally mixed; about an ounce of this is to be ~round to an impalp'~ble powder to facthtate the &sengaging of the pure alkali. Take of this powder, 100 grs., and pour ui~on it~two (maces of pure ware,'; stir it occasionall)" for a few hours, wi/b a glass ~-od; allow the insoluble matters to subside; pour tile super~mtaltt liquid on a paper filter; and add other two ouuces of water to the residuum. Tim whole is then tin-own on the filter, in order to secure an~ lime, or carbonate of lime, which raay be present, and would occasmn inaccuracy; upon which a little water is also poured, to wash out what remains in the residuum. Both the littered solutions are then to be put into a vessel, and re. due@, by bofli~g, to two or three ounces. "rake two ounces of rill'at-. ed sulphuric acid, of tim Specific gravity of 1,100; weigh it accurately, together with the phial, and note down their weight m grain~ Pour some of this acid, very gradually, im;o the soluti(m, and st;i: it tilt it ceases ~o ett~rvesce; wt~en, if it turn red litmus paper blue, more acid, sa) a dracmn, l~ to be cau~ttously added, and alter stating, it is to be aaain tried with tlxe test paper. When the paper begins to be affected but sli~atly, the acid should only be ad(lat by a tew drops at a time. T m'con;piete saturation of thesoluti,ul with aeid~ will be known from the eiti~rveseeuce wholly ceasing: the separation of the sulphur held in soluti(m; and from its not tinging the test paper. The alkali having thus been rendered neu*ral, the acid in the phial~ wlaieh has not been used~ is to he agaiv accurately weighed, to as-, certain how much it has renuired t0-~aturate the alkali; whence it can easily be calculated, how much real alkali the sample contained. ~hen it is known hmv much acid a pure alkali will take up. l~lr~ Parkes ascertained, that 100 gr:dns of fmre potash require 5~0 grains of salphuric acid, of the sFecilic g:-avity of t. 100, to saturate it; and 100grains of pure soda reqtfirc 8[~ of dte acid. From this, it is evident, that~ before ¢ommm~cing the analysis, it will be necessary te h'.arn whether the san ple is ~potash, or soda, or a mixture of butlx CoL, IlI,--~Na. 5+--..%l~', 18q7, 4~
~0
THE FRANKLIN JOURNAL A N D
The crystals of nitro-muriate of olatina, dissolved in water, %rill fur. nisb a test lbr this purpose; as, when it is dropped into any alkaline solution, it will precipitate potash, but will not aft~ct the soda. 12ecovery of Alkali f r o m ~'aste Le~s. It is a very bad practice among bleachers, and it is almosf~ univer. sal, to use, again and agairb the alkaline le5% which must be loaded with impurity: they are often so much so, indeed,~ as to approach to coagulation. They are led to this. from a notion of economy, being unwilling to throw away any alkal~i which they can any way employ. But it would often be more economical to purify the ley, betbre using it; and a method of doing this is also a desideratum for procuring fi'esh alkali from leys which can no loIlger be used. Several plans for this purpose have been suggested, but few have been successful, or~ at least, economical. Des Charmes advises the residual ashes to be moistened with the ley~ and burned in a Common kitchen fire~ ia which wood is ~he usual fuel. lie also recommends boiling the waste leys with quicklime, which is found to be one of tile best ways of management, as the lime decomnoses the imoure veo~etable matter floating in the leys, and renders tli'em transpare'nt and c'anstic, thougk not altogether so pure as fresh made ley. (See Art of Bleach. p. 558.) This is chiefly practicable, however, when the lays have been used for cottons; f~r the resinous extract of linens is not so easily acted on by the lira% without adding, along" with the lime, as may easily be done~ a small quantity of tl~-e fresh precioitated earth of alum. ~l'he mixture should be constantly agitated dth.tng the process~ in order to expose every particle of the resinous and extractive matter to the action of the lime. Des CharoJes, in this, gives directitms quite op~tsite from those practised by the bleachers around Glasgow. They final,that the lime acts better in a cold solution, than with the add~-on o~heat , (See Ramsay's Treatise.) Another ,,ode is by calcining ne was~ teys in a reverberating furnace, or in the apparatus called t!~e stone %oiler~ ah'eady described; and by these means, alkali can ttaus be obta~ed purer than that which is imported; which~ in exten. sire bleach-wb~k % that can attbrd the expanse of the apparatus, is of great consequerke ' I'he Icy is first evaporated~ till it t~ecomes of the consistence Of treble, (see Des Charmes, p. 9~,) when it is put into
~!
alkaliY'for all the r f.~hus melted, and is tbund to consist of pure ; . . esin~id extractive matter are completely con• 1. ' P ,' "~tate of a carbnnate~ anti this carbon is again taken up by the quicklin~ used to render it causticj so that it is nearly in a state of purity, If Milers are used, their safety should be insured by the ingenious methoff--e^~-~ , , - -'~ -~ of Glasgow. (See A~n, of Philos. I. ~o~gt'i'mermect oy ~vxr.,,an, say, The home manufacture of alkalies, iS'~but slightly connected with the direct subject of the sketch; ~et I ca ~". . . . . "~. " - ..... ; ou-'ht t" ~". . . . . ~ . . . . . '~, ~ P-uaut netp remarzlng, u m t ~ ~ u ue cat'emtty attenaetl to. w e are i~debted to Spain~ fbr an
AI~IERICAIq MECHANICS~ MAGAZINE,
331
annual supply 0fseveral thousand tons of barilla, and to America aml Ru "a, for incalculable quantities of pot and pearl ashes; while wg possess considerable resources at home, which are either altogethe¢ neglected, or ignorantly and unskilfully managed. The Yrencl~ with tile most laudable spirit of industry and enterprise~ take advantage of their wine leysi to prepare an ash (Cendre GraVel~es) from the leys ofwine~ which contains no tess than 60 or 70. per cent, o t pure alkali, (Des Charmes, p. ~79,) We cannot, indeed, for want of mate~ riM, prOduCe this alkaii; bat let us turn to account the resources we possess~ Let endeavours be made to improve" the kelp manufacture~ Dy constructing proper furnaces for its combustion, and by preparing the sea-weeds~ whence it is to be made~ according to well ascertair~ ed chemical principles; L e t the,furze, [)room, and fern~ which grow in such great abundance in some Of our waste lands~ be turned into potash; or let such plants as best afford alkali, be cultivated express. lyfor its manufacture; The tansey (Taneetl~m vulg. Lin,) is~ aceord~ ing ~to Lord Dundofiald, one of tffose; and as if F.rows in abundance in a wild state~ on ~h,e banks of the Clj;de, it is ~ighty probable that its cultivation. ~vould be e~tremely easy. Potash may b e prOcured from saltpetre~ by heating it with charcoal, so as to ~leeompose its acid. in'this Way, we a ~ tzld b y Parkes, that one hundred weight of ihe nitre!will i)~oduce half that quanttty of pure potash. During our late dis tires with Ameriea~ a ~reat quafitity of saltpetre was used for thi~Pgery purpose; and wheff the prices W~IIadmit Of it, cousiderable profit ~aay in this way be gained. Potash may also be madg from peat ashes,
On the Theory and Practice of Chler maklng~ ~ y a CoRa~sro~nsNT.
Exete~ ~ug. 9, 1896o S~rL---~In maklng eider, very tntich indeed depends on the maoagement ~,as from the sa~ne fruit, eiders very different in coloar, and ia quality, may be produced: for instance, if the appies are g~ouffd down and submitted to the action of the press at once~ then committed to the vat, and there fermented~ the eider will be barsh(ahd nearly colourless: but, if apples fi-omthe same tree, arid gathered at tlie same time~are ground down'inthe latter part of the day~ and not committed to the press till the following dffy, the action of the air oa the pulp will cause the eider to acquire k ¢onsiderable degree of ¢olo~r, ~17ormaking strong Ciders the p¢ocess ts as follows~--~A la~er o~' wheat-straw is placed on the bottom of tile pres@in a square form~ and on this a layer of the pulp of aboiat a)i inch in thickness; a second layer,of 'straw is then place~l on this, but in a contrary direction to the former, and seas to lie aeros~ it at right angles; and then anOther layer of ,the pulp, aild so on alternately; layers of straw and pulp are continued~ until a~ much is put in as you propose to submit to the action of the pre~s, at once. The press is now brought down