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Description of the mode of manufacturing starch, in France
Manufacture o f Stc~rch irt France.
7~
his inventive talents and chemical knowledge, to the improvement of his favourite manufkcture, during the course of a long and indus, trious tit'e~ I have no doubt that chemistry might still confer many benefits on tl~e notter~s . . art, . if . the manufacturers in general would bestow such an education upon their cluldren as would enable them to pay a proper attention to the cultivation of this science. Impressed with this idea~ I have myself frequently inspected se, veral'of the largest m anutkctories of earthenware in this kingdom, as well as many others of inferior note, and have examined their various processes with the utmost care and attention. A residence of several years at Stoke-upon-Trent, in the midst of the Staffordshire potteries, aflbrded me the best opportunities for this purpose~ and enabled me to make those inquiries at my leisure, and to acquire that information, which none but an inhabitant could easily have obtained. It will not, however, be necessary for m% while giving an account of this tnanufactorv as at present conducted~ to go much into detail; because, if this were the object I bad in view, it would be necessary to devote a volume or more'to the purpose; for I am acquainted witk few ntanufitetories in which the operations are more numerous and diversified. On this account, 1 shall content myself with giving such an outline of the business as will aflbrd the general reader a correct idea of tho nature of tile tlitlL~rent operalionsj and at the same time shall propose, fi~r the consideration of tile manufacturers themselves, such hints for the improvement of some of the processes, as I conceive to be worth tltei r attention. ~'ro nt: cox~rI~tS~,l
1)escripUo~, of the ?,lode of 3]an~factz~'ing Starch, in t'~'ance.* "I'm.: starch of" wheat, rye, barley, &c., beifig prepared by the same method, we shall treat of these grains without distinction, eitl!er as to their being used singly, or mixed in various proportions.: The manulitctuvers prefer that grain which has been injured by remaining long in damp warehouses, and rendered improper tbr most other purposes ; not oillV because it is cheaper, but because the starch, being less alterable titan most other itnnmdiate products fi'om vegetables~ is still obtained in great abundance, with more filcility, and often even in nearly an equal quantity, as fi'om uninjured grain. They corn inonce the tq~eration by coarsely grinding the grain; which is etti'~cted in the ordinary ntills I~y raising the upper mill-stone, by which means the space between the two stones is augmented, and the grain passes through, merely bruised. If the grain employedbe too wet, it sticks between the stones, from which it is with difficulty disengaged, and more power is required to obtain even this small quantity; but this inconvenience is avoided by a previous desiccation. After this lh'st preparation; they steep the grain, thus bruised, in * ti'vom the I)ictionnalro Technolofflque.
2rfanufaclure of Slarch i~* France.
80
large tubs half filled with water~ to which they add an eighth, el..~ tenth, part of the sour water, remaining from a former operat.io!!: by de_~rees fermentation takes i)lac% and laroceeds w i t h a rapl(nty m proportion as the grain emplo:~ed contains'a greater quantity of ~l.uten, or as the temperature of the atmosphere is more elevated. When fermentation has commenced, the liquor becomes viscous, acquires a degree of acidity~ and at length is covered with a thickish crust of mould. In this state they term it sour water:* this water is drawn offb~ means of a cock~ placed at the height which the deposit oceuies'in the tub; or by means of a portable syphon, which serves for many tubs: but~ prevmusly~ they take off the crust of mould, or head, with a skimmer; the greater part of the gluten is decomposed; and ¢l~e products of this decomposition, with the extractive matter of the grain, are separated by this first decantation: they wash the deposit many times, and afterwards mix it with water, and throw It lnlo a t~auor wire-sieve, resting ui3on two l)ieces of wood~ placed across the top of a vat. They have lately applied to this operation (in order to sei)arate the eoa[-sest bran) a revolvinz siev% made in the manner of the Aehimedian screw, This instrument is a cylinder~ the interior of which is traversed by a continued band of diaphragms, disposed m'ound an axis in the Ibrm of a screw; and on these t|~e cloth is retained, in a c~'lindt'ic~,l lbrm. The axis of this sieve is made cylindrical at each extremity, and turns uI)on two proper bearings; it is placed obhquely, so as to form an angle of tram ~20° to ,,0 °wtth the Imrizon: ~t may either be turned round b); means of a winch or handle, in the same manner as the Archimedian scre% used in draining morasses$ or b)~a leafiaer strap and a pulley. The construction of this machine, is exactly the same as that of the elevating screw; only their functions being dllli'.t'ent, the movement given to them must be in a contrary direction; st) that instead of tim screw, as usual, raising 1,,orti,qns of liquid from below, at interwAs quickly succeeding eacl~ other, until they m'e tinnily discharged a:: the top of the screw, the machine is. in this case, constantly fed at its highest part, with the mixture formed by the dcposii: which we have before spoken at: A small stream of wafer runs upon the exterior of the metallic cloth, and incessantly washes it: the operation is thu~ carried (;n in a continued m,ume.'; a n d the brat b or Jigueous cove,'in,~ of the grai'n~ escapes at the lower part of the sieve, perfectly fi'ee t?om the starch which it conIained. That which has passed either througt~ the revolving sieve of the new machine, or the ordinary sieve of the starch-makers, atlbrds, by repose and decantation, a sour water, which is emploged in the same manner as that we have before described. The ~leposit however, contains, besides starch, a quantity of very fine bran; to effect the separatlml of these two substances, it is beaten up with water, and lelI to settle: the starch precipitates first, and occupies the bottom of the vat; the bran falls next, and forms the upper part of the deposit. They renmve the surface until they arrive at the starch, which is •
•
.
-
.
o
-
.
•
* It is compo~ed, according"to M. Vauquelln, of water, acetic acid, acetate ~Jl"arammlia, ph,~@n~te of lime, and gqutem
Mat~facture o f Starch in Fra nee.
81
known by its whiteness and firmness: they rinse the surface of the starch, to fi'ee it from those particles Of bran which may still adhere to it~ they azain beat up the white mass, thus rinsed~ and pour the whole into a'silk sieve, or into a machine similar to the one we have above described; but with this difference, that its exterior covering is fin-t-ned e t a cloth closer in its texture, resembling that e t a silken sieve. By on% or other~ of these means, they se arate an additional quantity of fine bran, and the starch which passes is Muter, and purer: nevertheless, it must be again beaten up with water, suffered to repose, the supernatant water decanted, and the surface of the dm)nsit be ao.ain rinsed, which is still a little soiled by the finest par° ticles of braze. The starch is now very wlfite: in general, however, its whiteness, and purity, depend open the precautions which have been taken in the m a @ washings, and on the fineness of the last sie~e through which it has been passed. Desicc**tibn.--This operation, although very simple, nevertheless requires lnany precautions; for tim whitest starcl b when taken fi'om the last washings, often becomes of a brownish or greenish.eoloUr~ which requires it to be again mixed with the common starch which is obtained from the rinsmgs, or from those grains which are the niost injured , and which are classed, according to their whlteness(into varmus qualities. They put the starcib ready to be dried, into square baskets, (whose angles however are rounded off,) each being furnished with a loose cloth.- These baskets are generally of the fi~lhm,ing dimensions: ~o0 inches long, 14 wide, and 11 high; they fill them as fall as possible with starch, aml compress it by slight 3erks; they leave it awhile t~ drain, and stittbn; it is then car,'ied to the dryinghouse. This is a large building, whose upper part is divided intO' many eompartments~sun'ounded with shutters, and the interior furnished, near its sides, with stages of wooden planks, laid horizon. tally, at the distance of about 16 inches apart; there is also a level bed of plaster of Paris, formed close to these stages. They deposit the contents of then" baskets upon t]ns bed, and r ,move the cloth~, Milch have quitted the baskets with the moulded blocks of starcE The starch is tMs brought to its first degree of desiccation: they carry it afterwards to the stages, anti divide each block into sixteen parts, for the purpose of presenting a greater surface to the drying action of the air: these are very t'requently turned, as well to accelerate the desiccation, as to avoid the least mouldiness, or dust, &e. which might soil the starch, and which there is less chance ofguardin~,~ against,, by a hmger continuance. . on the stages: thev~.then carry. these pmces to a stove, hrst taking care to scrape their surfaces slightly; they are then divided into smaller pieces, by the hand, al~ ways keeping in view the drying of this substance as quickly asp~gsible; they should be turned, fi'om time to time, with a wooden~spatula, to change their surl'aces. By these precautions, which.it is ln'oper to increase, or diminish~ according to the hygrometric sta,te and temperature of the atmosphere, it is ce,'tai,1 that the starch ;rill be pr,,>crved in its original whiteness. K m~wing the c~mposltion of tim variou.~ ;~;rain,~ of barley, whea/~ &co \ m . I V . ~ N o . '2.--At:c, usr, 1 F 2 7 , ~ I I P
.
.
.
82
Mamff'aclure of Nlarch in France.
we can thu~ establish the theory of what takes place in the preparation of atarch. These ~rains contain much starch~ the ligneous matter~ formin~ the husks (if the ~rain; a small variable quantity of gluten, albumen~ and certain saltd;, amongst others, the phosphate of li-me. The re-action of the ~lutex~ upon the starclb occasmns the formation of a little saccharine matter; the co,tinued ferment in the lnixtare, causes the .,]Ji~fflttmtsjlrmcntaliom and produces alcohol, and carbonic acid. Thi~ last is disengaged in the gaseous form~ and from thence are derived the rabbles 'a'likl arlsc~ and burst, atthe surface of the liq,ov. 'File .rid ['crmcJ~lalim~ i..mediately tbllows; the a o t t r IPttlt:'t" Itv( t'~'qt 'i V ~txt: l e s ' this fermentation, front which results a new quantit v . f ~i~.',,~;.'; and s.on aJ'(cr, the glvteu, by reason of the lar~_;c ( U;tl;tity ~.f a/.l)tc which it coniailis, an~i its facility of spont;me~.~s' altcrati(m. ~ives bhlh t. the pulrid/~rme~d.lion, which dcvehq)es amm..ia; tii ;~ ~le~ and tl e phosl~h'tte tf llme are, in l)art~ .liss~lved i. th,~ li~ uor by the, accti(" acid, and a.'e partly held in suspeI~ iol, l,: lht! l'eqHliOIL ()1~ these l~vin(:ij~lcs forms tl~e sour waters of which we have sp.keu. It oOen ha l, ),,~ (hat d,~ .s,~t~"re,lets, when they are poured upon the bruised 'zrain. in the tirol par( ()[' ill(! ~q~(w;tlion. subsid% without occasi(~tlh~g arl)' di>-vllga~vm¢,l~l, of ('acl~()ni(: acid gas, any sensible movet,ellt, of ally ol},'v (;ha,~e than Inaki~; all t]w. liquor thick~ gluey, andropv. This alteration, to which they havegive~ the name of the vlscous)'ermentutloa, although of little in~l)Ortancc here, is very remarkable: it is accidentally i)vcset~ted in miu~y other cases, and particularly in the treatment of sacchari~;e m.'ttters, where it is ahnost always in'uri(ms, and often occasions considerable loss. Uses.'--nJStarch is employed in many of the arts, although but in amall quantities: painters, coufectioi~evs, laumtresses} &c. make great u~e of it; physicians prescribe it as an aliment of a peculiar nature, aml a~ a medicine; but in this case, as also in the manufac~.ure ()f sugar fi'mn starch, they give the prel~rence to the starch, or fecula, of the Imtah). (~,mpo.~iti,m.~,~taH.h is formed in weight, according to M. Berzelius, of Carbon . . . . . . . . 43~481 ()xyg~!n . . . . . . . . . 49,455 llydrogen . . . . . . . . 7,064
100.
P.
ESSA'~ S ON B L E A C I H N G .
B21 James Rennie, ./1. ~IL L~ c{~fcr o~ Philosophy, ,S'c. 4"c., London. No.
I[[.--(~tlE.MI(?AL
AtII'N'I'S USI,iD IN BLEA(~II.IING.
SECTIO.U VlX. Continued. 4 . ~ 3 L ' . 7"cmzunt's Blcaching~ S.It, m" the Oxymuriute of' Lime. Ll.~ll,: ~a~ impregnated with chlorit~e, fiw the purposes of bleaching, at an early stag~; of the improvements we ave now detailing, by
7~
his inventive talents and chemical knowledge, to the improvement of his favourite manufkcture, during the course of a long and indus, trious tit'e~ I have no doubt that chemistry might still confer many benefits on tl~e notter~s . . art, . if . the manufacturers in general would bestow such an education upon their cluldren as would enable them to pay a proper attention to the cultivation of this science. Impressed with this idea~ I have myself frequently inspected se, veral'of the largest m anutkctories of earthenware in this kingdom, as well as many others of inferior note, and have examined their various processes with the utmost care and attention. A residence of several years at Stoke-upon-Trent, in the midst of the Staffordshire potteries, aflbrded me the best opportunities for this purpose~ and enabled me to make those inquiries at my leisure, and to acquire that information, which none but an inhabitant could easily have obtained. It will not, however, be necessary for m% while giving an account of this tnanufactorv as at present conducted~ to go much into detail; because, if this were the object I bad in view, it would be necessary to devote a volume or more'to the purpose; for I am acquainted witk few ntanufitetories in which the operations are more numerous and diversified. On this account, 1 shall content myself with giving such an outline of the business as will aflbrd the general reader a correct idea of tho nature of tile tlitlL~rent operalionsj and at the same time shall propose, fi~r the consideration of tile manufacturers themselves, such hints for the improvement of some of the processes, as I conceive to be worth tltei r attention. ~'ro nt: cox~rI~tS~,l
1)escripUo~, of the ?,lode of 3]an~factz~'ing Starch, in t'~'ance.* "I'm.: starch of" wheat, rye, barley, &c., beifig prepared by the same method, we shall treat of these grains without distinction, eitl!er as to their being used singly, or mixed in various proportions.: The manulitctuvers prefer that grain which has been injured by remaining long in damp warehouses, and rendered improper tbr most other purposes ; not oillV because it is cheaper, but because the starch, being less alterable titan most other itnnmdiate products fi'om vegetables~ is still obtained in great abundance, with more filcility, and often even in nearly an equal quantity, as fi'om uninjured grain. They corn inonce the tq~eration by coarsely grinding the grain; which is etti'~cted in the ordinary ntills I~y raising the upper mill-stone, by which means the space between the two stones is augmented, and the grain passes through, merely bruised. If the grain employedbe too wet, it sticks between the stones, from which it is with difficulty disengaged, and more power is required to obtain even this small quantity; but this inconvenience is avoided by a previous desiccation. After this lh'st preparation; they steep the grain, thus bruised, in * ti'vom the I)ictionnalro Technolofflque.
2rfanufaclure of Slarch i~* France.
80
large tubs half filled with water~ to which they add an eighth, el..~ tenth, part of the sour water, remaining from a former operat.io!!: by de_~rees fermentation takes i)lac% and laroceeds w i t h a rapl(nty m proportion as the grain emplo:~ed contains'a greater quantity of ~l.uten, or as the temperature of the atmosphere is more elevated. When fermentation has commenced, the liquor becomes viscous, acquires a degree of acidity~ and at length is covered with a thickish crust of mould. In this state they term it sour water:* this water is drawn offb~ means of a cock~ placed at the height which the deposit oceuies'in the tub; or by means of a portable syphon, which serves for many tubs: but~ prevmusly~ they take off the crust of mould, or head, with a skimmer; the greater part of the gluten is decomposed; and ¢l~e products of this decomposition, with the extractive matter of the grain, are separated by this first decantation: they wash the deposit many times, and afterwards mix it with water, and throw It lnlo a t~auor wire-sieve, resting ui3on two l)ieces of wood~ placed across the top of a vat. They have lately applied to this operation (in order to sei)arate the eoa[-sest bran) a revolvinz siev% made in the manner of the Aehimedian screw, This instrument is a cylinder~ the interior of which is traversed by a continued band of diaphragms, disposed m'ound an axis in the Ibrm of a screw; and on these t|~e cloth is retained, in a c~'lindt'ic~,l lbrm. The axis of this sieve is made cylindrical at each extremity, and turns uI)on two proper bearings; it is placed obhquely, so as to form an angle of tram ~20° to ,,0 °wtth the Imrizon: ~t may either be turned round b); means of a winch or handle, in the same manner as the Archimedian scre% used in draining morasses$ or b)~a leafiaer strap and a pulley. The construction of this machine, is exactly the same as that of the elevating screw; only their functions being dllli'.t'ent, the movement given to them must be in a contrary direction; st) that instead of tim screw, as usual, raising 1,,orti,qns of liquid from below, at interwAs quickly succeeding eacl~ other, until they m'e tinnily discharged a:: the top of the screw, the machine is. in this case, constantly fed at its highest part, with the mixture formed by the dcposii: which we have before spoken at: A small stream of wafer runs upon the exterior of the metallic cloth, and incessantly washes it: the operation is thu~ carried (;n in a continued m,ume.'; a n d the brat b or Jigueous cove,'in,~ of the grai'n~ escapes at the lower part of the sieve, perfectly fi'ee t?om the starch which it conIained. That which has passed either througt~ the revolving sieve of the new machine, or the ordinary sieve of the starch-makers, atlbrds, by repose and decantation, a sour water, which is emploged in the same manner as that we have before described. The ~leposit however, contains, besides starch, a quantity of very fine bran; to effect the separatlml of these two substances, it is beaten up with water, and lelI to settle: the starch precipitates first, and occupies the bottom of the vat; the bran falls next, and forms the upper part of the deposit. They renmve the surface until they arrive at the starch, which is •
•
.
-
.
o
-
.
•
* It is compo~ed, according"to M. Vauquelln, of water, acetic acid, acetate ~Jl"arammlia, ph,~@n~te of lime, and gqutem
Mat~facture o f Starch in Fra nee.
81
known by its whiteness and firmness: they rinse the surface of the starch, to fi'ee it from those particles Of bran which may still adhere to it~ they azain beat up the white mass, thus rinsed~ and pour the whole into a'silk sieve, or into a machine similar to the one we have above described; but with this difference, that its exterior covering is fin-t-ned e t a cloth closer in its texture, resembling that e t a silken sieve. By on% or other~ of these means, they se arate an additional quantity of fine bran, and the starch which passes is Muter, and purer: nevertheless, it must be again beaten up with water, suffered to repose, the supernatant water decanted, and the surface of the dm)nsit be ao.ain rinsed, which is still a little soiled by the finest par° ticles of braze. The starch is now very wlfite: in general, however, its whiteness, and purity, depend open the precautions which have been taken in the m a @ washings, and on the fineness of the last sie~e through which it has been passed. Desicc**tibn.--This operation, although very simple, nevertheless requires lnany precautions; for tim whitest starcl b when taken fi'om the last washings, often becomes of a brownish or greenish.eoloUr~ which requires it to be again mixed with the common starch which is obtained from the rinsmgs, or from those grains which are the niost injured , and which are classed, according to their whlteness(into varmus qualities. They put the starcib ready to be dried, into square baskets, (whose angles however are rounded off,) each being furnished with a loose cloth.- These baskets are generally of the fi~lhm,ing dimensions: ~o0 inches long, 14 wide, and 11 high; they fill them as fall as possible with starch, aml compress it by slight 3erks; they leave it awhile t~ drain, and stittbn; it is then car,'ied to the dryinghouse. This is a large building, whose upper part is divided intO' many eompartments~sun'ounded with shutters, and the interior furnished, near its sides, with stages of wooden planks, laid horizon. tally, at the distance of about 16 inches apart; there is also a level bed of plaster of Paris, formed close to these stages. They deposit the contents of then" baskets upon t]ns bed, and r ,move the cloth~, Milch have quitted the baskets with the moulded blocks of starcE The starch is tMs brought to its first degree of desiccation: they carry it afterwards to the stages, anti divide each block into sixteen parts, for the purpose of presenting a greater surface to the drying action of the air: these are very t'requently turned, as well to accelerate the desiccation, as to avoid the least mouldiness, or dust, &e. which might soil the starch, and which there is less chance ofguardin~,~ against,, by a hmger continuance. . on the stages: thev~.then carry. these pmces to a stove, hrst taking care to scrape their surfaces slightly; they are then divided into smaller pieces, by the hand, al~ ways keeping in view the drying of this substance as quickly asp~gsible; they should be turned, fi'om time to time, with a wooden~spatula, to change their surl'aces. By these precautions, which.it is ln'oper to increase, or diminish~ according to the hygrometric sta,te and temperature of the atmosphere, it is ce,'tai,1 that the starch ;rill be pr,,>crved in its original whiteness. K m~wing the c~mposltion of tim variou.~ ;~;rain,~ of barley, whea/~ &co \ m . I V . ~ N o . '2.--At:c, usr, 1 F 2 7 , ~ I I P
.
.
.
82
Mamff'aclure of Nlarch in France.
we can thu~ establish the theory of what takes place in the preparation of atarch. These ~rains contain much starch~ the ligneous matter~ formin~ the husks (if the ~rain; a small variable quantity of gluten, albumen~ and certain saltd;, amongst others, the phosphate of li-me. The re-action of the ~lutex~ upon the starclb occasmns the formation of a little saccharine matter; the co,tinued ferment in the lnixtare, causes the .,]Ji~fflttmtsjlrmcntaliom and produces alcohol, and carbonic acid. Thi~ last is disengaged in the gaseous form~ and from thence are derived the rabbles 'a'likl arlsc~ and burst, atthe surface of the liq,ov. 'File .rid ['crmcJ~lalim~ i..mediately tbllows; the a o t t r IPttlt:'t" Itv( t'~'qt 'i V ~txt: l e s ' this fermentation, front which results a new quantit v . f ~i~.',,~;.'; and s.on aJ'(cr, the glvteu, by reason of the lar~_;c ( U;tl;tity ~.f a/.l)tc which it coniailis, an~i its facility of spont;me~.~s' altcrati(m. ~ives bhlh t. the pulrid/~rme~d.lion, which dcvehq)es amm..ia; tii ;~ ~le~ and tl e phosl~h'tte tf llme are, in l)art~ .liss~lved i. th,~ li~ uor by the, accti(" acid, and a.'e partly held in suspeI~ iol, l,: lht! l'eqHliOIL ()1~ these l~vin(:ij~lcs forms tl~e sour waters of which we have sp.keu. It oOen ha l, ),,~ (hat d,~ .s,~t~"re,lets, when they are poured upon the bruised 'zrain. in the tirol par( ()[' ill(! ~q~(w;tlion. subsid% without occasi(~tlh~g arl)' di>-vllga~vm¢,l~l, of ('acl~()ni(: acid gas, any sensible movet,ellt, of ally ol},'v (;ha,~e than Inaki~; all t]w. liquor thick~ gluey, andropv. This alteration, to which they havegive~ the name of the vlscous)'ermentutloa, although of little in~l)Ortancc here, is very remarkable: it is accidentally i)vcset~ted in miu~y other cases, and particularly in the treatment of sacchari~;e m.'ttters, where it is ahnost always in'uri(ms, and often occasions considerable loss. Uses.'--nJStarch is employed in many of the arts, although but in amall quantities: painters, coufectioi~evs, laumtresses} &c. make great u~e of it; physicians prescribe it as an aliment of a peculiar nature, aml a~ a medicine; but in this case, as also in the manufac~.ure ()f sugar fi'mn starch, they give the prel~rence to the starch, or fecula, of the Imtah). (~,mpo.~iti,m.~,~taH.h is formed in weight, according to M. Berzelius, of Carbon . . . . . . . . 43~481 ()xyg~!n . . . . . . . . . 49,455 llydrogen . . . . . . . . 7,064
100.
P.
ESSA'~ S ON B L E A C I H N G .
B21 James Rennie, ./1. ~IL L~ c{~fcr o~ Philosophy, ,S'c. 4"c., London. No.
I[[.--(~tlE.MI(?AL
AtII'N'I'S USI,iD IN BLEA(~II.IING.
SECTIO.U VlX. Continued. 4 . ~ 3 L ' . 7"cmzunt's Blcaching~ S.It, m" the Oxymuriute of' Lime. Ll.~ll,: ~a~ impregnated with chlorit~e, fiw the purposes of bleaching, at an early stag~; of the improvements we ave now detailing, by