Conveyer screwFig.105.is the screw by which the ground or bruised malt is raised up, or conveyed from one part of the brewery to another.Kis an inclined box or trough, in the centre of which the axis of the screwHis placed; the spiral iron plate or worm, which is fixed projecting from the axis, and which forms the screw, is made very nearly to fill the inside of the box. By this means, when the screw is turned round by the wheelsE F, or by any other means, it raises up the malt from the boxd, and delivers it at the spoutG.This screw is equally applicable for conveying the malt horizontally in the troughK, as slantingly; and similar machines are employed in various parts of breweries for conveying the malt wherever the situation of the works require.Mashing-machineFig.106.is the mashing-machine.a ais the tun, made of wood staves, hooped together. In the centre of it rises a perpendicular shaft,b, which is turned slowly round by means of the bevelled wheelst uat the top.c care two arms, projecting from that axis, and supporting the short vertical axisdof the spur-wheelx, which is turned by the spur-wheelw; so that, when the central axisbis made to revolve, it will carry the thick short axledround the tun in a circle. That axledis furnished with a number of arms,e e, which have blades placed obliquely to the plane of theirmotion. When the axis is turned round, these arms agitate the malt in the tun, and give it a constant tendency to rise upwards from the bottom.The motion of the axledis produced by a wheel,x, on the upper end of it, which is turned by a wheel,w, fastened on the middle of the tubeb, which turns freely round upon its central axis. Upon a higher point of the same tubebis a bevel wheel,o, receiving motion from a bevel wheel,q, fixed upon the end of the horizontal axisn n, which gives motion to the whole machine. This same axis has a pinion,p, upon it, which gives motion to the wheelr, fixed near the middle of a horizontal axle, which, at its left hand end, has a bevel pinion,t, working the wheelu, before mentioned. By these means, the rotation of the central axisbwill be very slow compared with the motion of the axled; for the latter will make seventeen or eighteen revolutions on its own axis in the same space of time that it will be carried once round the tun by the motion of the shaftb. At the beginning of the operation of mashing, the machine is made to turn with a slow motion; but, after having wetted all the malt by one revolution, it is driven quicker. For this purpose, the ascending-shaftf g, which givesmotion to the machine, has two bevel wheels,h i, fixed upon a tube,f g, which is fitted upon a central shaft. These wheels actuate the wheelsmando, upon the end of the horizontal shaftn n; but the distance between the two wheelshandiis such, that they cannot be engaged both at once with the wheelsmando; but the tubef g, to which they are fixed, is capable of sliding up and down on its central axis sufficiently to bring either wheelhoriinto geer with its corresponding wheeloorm, upon the horizontal shaft; and as the diameters ofn o, andi m, are of very different proportions, the velocity of the motion of the machine can be varied at pleasure, by using one or other.kandkare two levers, which are forked at their extremities, and embrace collars at the ends of the tubef g. These levers being united by a rod,l, the handlekgives the means of moving the tubef g, and its wheelsh i, up or down, to throw either the one or the other wheel into geer.The object of boiling the wort is not merely evaporation and concentration, but extraction, coagulation, and, finally, combination with the hops; purposes which are better accomplished in a deep confined copper, by a moderate heat, than in an open shallow pan with a quick fire. The copper being encased above in brickwork, retains its digesting temperature much longer than the pan could do. The waste steam of the close kettle, moreover, can be economically employed in communicating heat to water or weak worts; whereas the exhalations from an open pan would prove a nuisance, and would need to be carried off by a hood. The boiling has a four-fold effect: 1. it concentrates the wort; 2. during the earlier stages of heating, it converts the starch into sugar, dextrine, and gum, by means of the diastase; 3. it extracts the substance of the hops diffused through the wort; 4. it coagulates the albuminous matter present in the grain, or precipitates it by means of the tannin of the hops.The degree of evaporation is regulated by the nature of the wort, and the quality of the beer. Strong ale and stout for keeping, require more boiling than ordinary porter or table-beer brewed for immediate use. The proportion of the water carried off by evaporation is usually from a seventh to a sixth of the volume. The hops are introduced during the progress of the ebullition. They serve to give the beer not only a bitter aromatic taste, but also a keeping quality, or they counteract its natural tendency to become sour; an effect partly due to the precipitation of the albumen and starch, by their resinous and tanning constituents, and partly to the antifermentable properties of their lupuline, bitter principle, ethereous oil, and resin. In these respects, there is none of the bitter plants which can be substituted for hops with advantage. For strong beer, powerful fresh hops should be selected; for weaker beer, an older and weaker article will suffice.The hops are either boiled with the whole body of the wort, or extracted with a portion of it; and this concentrated extract added to the rest. The stronger the hops are, the longer time they require for extraction of their virtues; for strong hops, an hour and a half or two hours boiling may be proper; for a weaker sort, half an hour or an hour may be sufficient; but it is never advisable to push this process too far, lest a disagreeable bitterness, without aroma, be imparted to the beer. In our breweries, it is the practice to boil the hops with a part of the wort, and to filter the decoction through a drainer, called thejack hop-back. The proportion of hops to malt is very various; but, in general, from a pound and a quarter to a pound and a half of the former are taken for 100 lbs. of the latter in making good table-beer. For porter and strong ale, 2 pounds of hops are used, or even more; for instance, one pound of hops to a bushel of malt, if the beer be destined for the consumption of India.During the boiling of the two ingredients, much coagulated albuminous matter, in various states of combination, makes its appearance in the liquid, constituting what is called thebreaking or curdling of the wort, when numerous minute flocks are seen floating in it. The resinous, bitter, and oily-ethereous principles of the hops combine with the sugar and gum, or dextrine of the wort; but for this effect they require time and heat; showing that the boil is not a process of mere evaporation, but one of chemical reaction. A yellowish-green pellicle of hop-oil and resin appears upon the surface of the boiling wort, in a somewhat frothy form: when this disappears, the boiling is presumed to be completed, and the beer is strained off into the cooler. The residuary hops may be pressed and used for an inferior quality of beer; or they may be boiled with fresh wort, and be added to the next brewing charge.Figs.107,108.represent the copper of a London brewery.Fig.107.is a vertical section;fig.108., a ground-plan of the fire-grate and flue, upon a smaller scale:ais the close copper kettle, having its bottom convex within;bis the open pan placed upon its top. From the upper part of the copper, a wide tube,c, ascends, to carry off the steam generated during the ebullition of the wort, which is conducted through four downwards-slanting tubes,d d(two only are visible in this section), into the liquor of the panb, in order to warm its contents. A vertical iron shaft or spindle,e, passes down through the tubec, nearly to the bottom of the copper, and is there mounted with an iron arm, calledarouser, which carries round a chain hung in loops, to prevent the hops from adhering to the bottom of the boiler. Three bent stays,f, are stretched across the interior, to support the shaft by a collet at their middle junction. The shaft carries at its upper end a bevel wheel,g, working into a bevel pinion upon the axish, which may be turned either by power or by hand. Therousershaft may be lifted by means of the chaini, which, going over two pulleys, has its end passed round the wheel and axlek, and is turned by a winch:lis a tube for conveying the waste steam into the chimneym.Brewery copperFig. 108 enlarged(41 kB)The heat is applied as follows:—For heating the colossal coppers of the London breweries, two separate fires are required, which are separated by a narrow wall of brickwork,n,fig.107M,108.The dotted circlea′a′indicates the largest circumference of the copper, andb′b′its bottom;o oare the grates upon which the coals are thrown, not through folding doors (as of old), but through a short slanting iron hopper, shown atp,fig.107., built in the wall, and kept constantly filled with the fuel, in order to exclude the air. Thus the lower stratum of coals gets ignited before it reaches the grate. Above the hopperp, a narrow channel is provided for the admission of atmospherical air, in such quantity merely as may be requisite to complete the combustion of the smoke of the coals. Behind each grate there is a fire-bridge,r, which reflects the flame upwards, and causes it to play upon the bottom of the copper. The burnt air then passes round the copper in a semicircular flue,s s, from which it flows off into the chimneym, on whose under end a sliding damper-plate,t, is placed, for tempering the draught. When cold air is admitted at this orifice, the combustion of the fuel is immediately checked. There is, besides, another slide-plate at the entrance of the slanting flue into the vertical chimney, for regulating the play of the flame under and around the copper. If the platetbe opened, and the other plate shut, the power of the fire is suspended, as it ought to be, at the time of emptying the copper. Immediately over the grate is a brick arch,u, to protect the front edge of the copper from the first impulsion of the flame. The chimney is supported upon iron pillars,v v;wis a cavity closed with a slide-plate, through which the ashes may be taken out from behind, by means of a long iron hook.Sluice-cockFig.109.represents one of the sluice-cocks, which are used to make the communications of the pipes with the pumps, or other parts of the brewery.B Brepresents the pipe in which the cock is placed. The two parts of this pipe are screwed to the side of a box,C C, in which a slider,A, rises and falls, and intercepts, at pleasure, the passage of the pipe. The slider is moved by the roda. This passes through a stuffing-box,in the top of the box which contains the slider, and has the rackbfastened to it. The rack is moved by a pinion fixed upon the axis of a handlee, and the rack and pinion are contained in a framedwhich is supported by two pillars. The frame contains a small roller behind the rack, which bears it up towards the pinion, and keeps its teeth up to the teeth of the pinion. The sliderAis made to fit accurately against the internal surface of the boxC, and to bear against this surface by the pressure of a spring, so as to make a perfectly close fitting.Small cockFig.110.is a small cock to be placed in the side of the great store vats, for the purpose of drawing off a small quantity of beer, to taste and try its quality.Ais a part of the stave or thickness of the great store vat; into this the tubeBof the cock is fitted, and is held tight in its place by a nut,a a, screwed on withinside. At the other end of the tubeB, a plug,c, is fitted, by grinding it into a cone, and it is kept in by a screw. This plug has a hole up the centre of it, and from this a hole proceeds sidewise, and corresponds with a hole made through the side of the tube when the cock is open; but when the plugcis turned round, the hole will not coincide, and then the cock will be shut.Dis the handle or key of the cock, by which its plug is turned to open or shut it: this handle is put up the bore of the tube (the coverEbeing first unscrewed and removed), and the end of it is adapted to fit the end of the plug of the cock. The handle has a tube or passage bored up it, to convey the beer away from the cock when it is opened, and from this the passagef, through the handle, leads, to draw the beer into a glass or tumbler. The hole in the side of the plug is so arranged, that, when the handle is turned into a perpendicular direction, with the passagefdownwards, the cock will be open. The intention of this contrivance is, that there shall be no considerable projection beyond the surface of the tun; because it sometimes happens that a great hoop of the tun breaks, and, falling down, its great weight would strike out any cock which had a projection; and, if this happened in the night, much beer might be lost before it was discovered. The cock above described, being almost wholly withinside, and having scarcely any projection beyond the outside surface of the tun, is secure from this accident.Vent pegFig.111.is a small contrivance of a vent peg, to be screwed into the head of a common cask when the beer is to be drawn off from it, and it is necessary to admit some air to allow the beer to flow.A Arepresents a portion of the head of the cask into which the tubeBis screwed. The top of this tube is surrounded by a small cup, from which project the two small handlesC C, by which the peg is turned round to screw it into the cask. The cup round the other part of the tube, is filled with water; into this a small cup,D, is inverted; in consequence, the air can gain admission into the cask when the pressure within is so far diminished, that the air will bubble up through the water, and enter beneath the small cupD.The most efficient substance for fining beer hitherto discovered is isinglass, which is prepared by solution in vinegar or old stale beer, and this solution is afterwards reduced with thin mild beer generally brewed for the purpose, in all large establishments, from a raw or return wort. It must next be passed through a fine hair sieve, by means of rubbing it down with a hard hair-brush, and brought to the proper consistency by thin mild beer. If properly made, it will be clear, transparent, and free from feculencies. Finings serve excellently to remove any extraneous matter that may be found floating in the beer, and thus changes it from bright to brilliant. The common quantity used is from a pint to a quart per barrel, according to the nature of the beer.To ascertain whether the beer is in a fit state for fining, put it into a long glass cylindric vessel, and add to it a teaspoonful, or thereby, of the fining; then give the mixture a good shake, by turning the vessel up and down, after closing its mouth withthe palm of the hand. If the beer has been well brewed, its aptitude to become bright will be soon shown by the mixture getting thick and curdy; a bright portion will generally show itself at the bottom or middle; after which the finings will gradually mount to the top, taking up all the impurities along with them, till the whole becomes brilliant. Some have said that the finings should carry the impurities down to the bottom; but this, according to Mr. Black[8], takes place only with stubborn beer, which would not become thoroughly bright with any quantity of finings which could be introduced. Finings have usually a specific gravity of from 1·010 to 1·016, and, when added to beer in a fit condition for fining, invariably go to the top, and not to the bottom. In fining beer in a barrel laid on its side, if the finings do not make their appearance at the bung-hole, the beer will not become bright. The isinglass must not be dissolved with heat, nor in hot water.[8]Treatise on Brewing, 8vo, p. 68.Beer brewed from imperfectly malted grain, or from a mixture of malt and raw corn, gives a fermentation quite different in flavour from that of beer from sound malt. The nose is, in fact, the best guide to the experienced brewer for ascertaining whether his process is going on well or ill.Ropiness is a morbid state of beer, which is best remedied, according to Mr. Black, by putting the beer into a vat with a false bottom, and adding, per barrel, 4 or 5 pounds of hops, taken gradually away after the first boilings of the worts; and to them may be added about half a pound per barrel of mustard-seed. Rouse the beer as the hops are gradually introduced, and, in some months, the ropiness will be perfectly cured. The beer should be drawn off from below the false bottom.For theoretical views, seeFermentation; and for wort-cooling apparatus, seeRefrigerator.
Conveyer screw
Fig.105.is the screw by which the ground or bruised malt is raised up, or conveyed from one part of the brewery to another.Kis an inclined box or trough, in the centre of which the axis of the screwHis placed; the spiral iron plate or worm, which is fixed projecting from the axis, and which forms the screw, is made very nearly to fill the inside of the box. By this means, when the screw is turned round by the wheelsE F, or by any other means, it raises up the malt from the boxd, and delivers it at the spoutG.
This screw is equally applicable for conveying the malt horizontally in the troughK, as slantingly; and similar machines are employed in various parts of breweries for conveying the malt wherever the situation of the works require.
Mashing-machine
Fig.106.is the mashing-machine.a ais the tun, made of wood staves, hooped together. In the centre of it rises a perpendicular shaft,b, which is turned slowly round by means of the bevelled wheelst uat the top.c care two arms, projecting from that axis, and supporting the short vertical axisdof the spur-wheelx, which is turned by the spur-wheelw; so that, when the central axisbis made to revolve, it will carry the thick short axledround the tun in a circle. That axledis furnished with a number of arms,e e, which have blades placed obliquely to the plane of theirmotion. When the axis is turned round, these arms agitate the malt in the tun, and give it a constant tendency to rise upwards from the bottom.
The motion of the axledis produced by a wheel,x, on the upper end of it, which is turned by a wheel,w, fastened on the middle of the tubeb, which turns freely round upon its central axis. Upon a higher point of the same tubebis a bevel wheel,o, receiving motion from a bevel wheel,q, fixed upon the end of the horizontal axisn n, which gives motion to the whole machine. This same axis has a pinion,p, upon it, which gives motion to the wheelr, fixed near the middle of a horizontal axle, which, at its left hand end, has a bevel pinion,t, working the wheelu, before mentioned. By these means, the rotation of the central axisbwill be very slow compared with the motion of the axled; for the latter will make seventeen or eighteen revolutions on its own axis in the same space of time that it will be carried once round the tun by the motion of the shaftb. At the beginning of the operation of mashing, the machine is made to turn with a slow motion; but, after having wetted all the malt by one revolution, it is driven quicker. For this purpose, the ascending-shaftf g, which givesmotion to the machine, has two bevel wheels,h i, fixed upon a tube,f g, which is fitted upon a central shaft. These wheels actuate the wheelsmando, upon the end of the horizontal shaftn n; but the distance between the two wheelshandiis such, that they cannot be engaged both at once with the wheelsmando; but the tubef g, to which they are fixed, is capable of sliding up and down on its central axis sufficiently to bring either wheelhoriinto geer with its corresponding wheeloorm, upon the horizontal shaft; and as the diameters ofn o, andi m, are of very different proportions, the velocity of the motion of the machine can be varied at pleasure, by using one or other.kandkare two levers, which are forked at their extremities, and embrace collars at the ends of the tubef g. These levers being united by a rod,l, the handlekgives the means of moving the tubef g, and its wheelsh i, up or down, to throw either the one or the other wheel into geer.
The object of boiling the wort is not merely evaporation and concentration, but extraction, coagulation, and, finally, combination with the hops; purposes which are better accomplished in a deep confined copper, by a moderate heat, than in an open shallow pan with a quick fire. The copper being encased above in brickwork, retains its digesting temperature much longer than the pan could do. The waste steam of the close kettle, moreover, can be economically employed in communicating heat to water or weak worts; whereas the exhalations from an open pan would prove a nuisance, and would need to be carried off by a hood. The boiling has a four-fold effect: 1. it concentrates the wort; 2. during the earlier stages of heating, it converts the starch into sugar, dextrine, and gum, by means of the diastase; 3. it extracts the substance of the hops diffused through the wort; 4. it coagulates the albuminous matter present in the grain, or precipitates it by means of the tannin of the hops.
The degree of evaporation is regulated by the nature of the wort, and the quality of the beer. Strong ale and stout for keeping, require more boiling than ordinary porter or table-beer brewed for immediate use. The proportion of the water carried off by evaporation is usually from a seventh to a sixth of the volume. The hops are introduced during the progress of the ebullition. They serve to give the beer not only a bitter aromatic taste, but also a keeping quality, or they counteract its natural tendency to become sour; an effect partly due to the precipitation of the albumen and starch, by their resinous and tanning constituents, and partly to the antifermentable properties of their lupuline, bitter principle, ethereous oil, and resin. In these respects, there is none of the bitter plants which can be substituted for hops with advantage. For strong beer, powerful fresh hops should be selected; for weaker beer, an older and weaker article will suffice.
The hops are either boiled with the whole body of the wort, or extracted with a portion of it; and this concentrated extract added to the rest. The stronger the hops are, the longer time they require for extraction of their virtues; for strong hops, an hour and a half or two hours boiling may be proper; for a weaker sort, half an hour or an hour may be sufficient; but it is never advisable to push this process too far, lest a disagreeable bitterness, without aroma, be imparted to the beer. In our breweries, it is the practice to boil the hops with a part of the wort, and to filter the decoction through a drainer, called thejack hop-back. The proportion of hops to malt is very various; but, in general, from a pound and a quarter to a pound and a half of the former are taken for 100 lbs. of the latter in making good table-beer. For porter and strong ale, 2 pounds of hops are used, or even more; for instance, one pound of hops to a bushel of malt, if the beer be destined for the consumption of India.
During the boiling of the two ingredients, much coagulated albuminous matter, in various states of combination, makes its appearance in the liquid, constituting what is called thebreaking or curdling of the wort, when numerous minute flocks are seen floating in it. The resinous, bitter, and oily-ethereous principles of the hops combine with the sugar and gum, or dextrine of the wort; but for this effect they require time and heat; showing that the boil is not a process of mere evaporation, but one of chemical reaction. A yellowish-green pellicle of hop-oil and resin appears upon the surface of the boiling wort, in a somewhat frothy form: when this disappears, the boiling is presumed to be completed, and the beer is strained off into the cooler. The residuary hops may be pressed and used for an inferior quality of beer; or they may be boiled with fresh wort, and be added to the next brewing charge.
Figs.107,108.represent the copper of a London brewery.Fig.107.is a vertical section;fig.108., a ground-plan of the fire-grate and flue, upon a smaller scale:ais the close copper kettle, having its bottom convex within;bis the open pan placed upon its top. From the upper part of the copper, a wide tube,c, ascends, to carry off the steam generated during the ebullition of the wort, which is conducted through four downwards-slanting tubes,d d(two only are visible in this section), into the liquor of the panb, in order to warm its contents. A vertical iron shaft or spindle,e, passes down through the tubec, nearly to the bottom of the copper, and is there mounted with an iron arm, calledarouser, which carries round a chain hung in loops, to prevent the hops from adhering to the bottom of the boiler. Three bent stays,f, are stretched across the interior, to support the shaft by a collet at their middle junction. The shaft carries at its upper end a bevel wheel,g, working into a bevel pinion upon the axish, which may be turned either by power or by hand. Therousershaft may be lifted by means of the chaini, which, going over two pulleys, has its end passed round the wheel and axlek, and is turned by a winch:lis a tube for conveying the waste steam into the chimneym.
Brewery copperFig. 108 enlarged(41 kB)
Fig. 108 enlarged(41 kB)
The heat is applied as follows:—For heating the colossal coppers of the London breweries, two separate fires are required, which are separated by a narrow wall of brickwork,n,fig.107M,108.The dotted circlea′a′indicates the largest circumference of the copper, andb′b′its bottom;o oare the grates upon which the coals are thrown, not through folding doors (as of old), but through a short slanting iron hopper, shown atp,fig.107., built in the wall, and kept constantly filled with the fuel, in order to exclude the air. Thus the lower stratum of coals gets ignited before it reaches the grate. Above the hopperp, a narrow channel is provided for the admission of atmospherical air, in such quantity merely as may be requisite to complete the combustion of the smoke of the coals. Behind each grate there is a fire-bridge,r, which reflects the flame upwards, and causes it to play upon the bottom of the copper. The burnt air then passes round the copper in a semicircular flue,s s, from which it flows off into the chimneym, on whose under end a sliding damper-plate,t, is placed, for tempering the draught. When cold air is admitted at this orifice, the combustion of the fuel is immediately checked. There is, besides, another slide-plate at the entrance of the slanting flue into the vertical chimney, for regulating the play of the flame under and around the copper. If the platetbe opened, and the other plate shut, the power of the fire is suspended, as it ought to be, at the time of emptying the copper. Immediately over the grate is a brick arch,u, to protect the front edge of the copper from the first impulsion of the flame. The chimney is supported upon iron pillars,v v;wis a cavity closed with a slide-plate, through which the ashes may be taken out from behind, by means of a long iron hook.
Sluice-cock
Fig.109.represents one of the sluice-cocks, which are used to make the communications of the pipes with the pumps, or other parts of the brewery.B Brepresents the pipe in which the cock is placed. The two parts of this pipe are screwed to the side of a box,C C, in which a slider,A, rises and falls, and intercepts, at pleasure, the passage of the pipe. The slider is moved by the roda. This passes through a stuffing-box,in the top of the box which contains the slider, and has the rackbfastened to it. The rack is moved by a pinion fixed upon the axis of a handlee, and the rack and pinion are contained in a framedwhich is supported by two pillars. The frame contains a small roller behind the rack, which bears it up towards the pinion, and keeps its teeth up to the teeth of the pinion. The sliderAis made to fit accurately against the internal surface of the boxC, and to bear against this surface by the pressure of a spring, so as to make a perfectly close fitting.
Small cock
Fig.110.is a small cock to be placed in the side of the great store vats, for the purpose of drawing off a small quantity of beer, to taste and try its quality.Ais a part of the stave or thickness of the great store vat; into this the tubeBof the cock is fitted, and is held tight in its place by a nut,a a, screwed on withinside. At the other end of the tubeB, a plug,c, is fitted, by grinding it into a cone, and it is kept in by a screw. This plug has a hole up the centre of it, and from this a hole proceeds sidewise, and corresponds with a hole made through the side of the tube when the cock is open; but when the plugcis turned round, the hole will not coincide, and then the cock will be shut.Dis the handle or key of the cock, by which its plug is turned to open or shut it: this handle is put up the bore of the tube (the coverEbeing first unscrewed and removed), and the end of it is adapted to fit the end of the plug of the cock. The handle has a tube or passage bored up it, to convey the beer away from the cock when it is opened, and from this the passagef, through the handle, leads, to draw the beer into a glass or tumbler. The hole in the side of the plug is so arranged, that, when the handle is turned into a perpendicular direction, with the passagefdownwards, the cock will be open. The intention of this contrivance is, that there shall be no considerable projection beyond the surface of the tun; because it sometimes happens that a great hoop of the tun breaks, and, falling down, its great weight would strike out any cock which had a projection; and, if this happened in the night, much beer might be lost before it was discovered. The cock above described, being almost wholly withinside, and having scarcely any projection beyond the outside surface of the tun, is secure from this accident.
Vent peg
Fig.111.is a small contrivance of a vent peg, to be screwed into the head of a common cask when the beer is to be drawn off from it, and it is necessary to admit some air to allow the beer to flow.A Arepresents a portion of the head of the cask into which the tubeBis screwed. The top of this tube is surrounded by a small cup, from which project the two small handlesC C, by which the peg is turned round to screw it into the cask. The cup round the other part of the tube, is filled with water; into this a small cup,D, is inverted; in consequence, the air can gain admission into the cask when the pressure within is so far diminished, that the air will bubble up through the water, and enter beneath the small cupD.
The most efficient substance for fining beer hitherto discovered is isinglass, which is prepared by solution in vinegar or old stale beer, and this solution is afterwards reduced with thin mild beer generally brewed for the purpose, in all large establishments, from a raw or return wort. It must next be passed through a fine hair sieve, by means of rubbing it down with a hard hair-brush, and brought to the proper consistency by thin mild beer. If properly made, it will be clear, transparent, and free from feculencies. Finings serve excellently to remove any extraneous matter that may be found floating in the beer, and thus changes it from bright to brilliant. The common quantity used is from a pint to a quart per barrel, according to the nature of the beer.
To ascertain whether the beer is in a fit state for fining, put it into a long glass cylindric vessel, and add to it a teaspoonful, or thereby, of the fining; then give the mixture a good shake, by turning the vessel up and down, after closing its mouth withthe palm of the hand. If the beer has been well brewed, its aptitude to become bright will be soon shown by the mixture getting thick and curdy; a bright portion will generally show itself at the bottom or middle; after which the finings will gradually mount to the top, taking up all the impurities along with them, till the whole becomes brilliant. Some have said that the finings should carry the impurities down to the bottom; but this, according to Mr. Black[8], takes place only with stubborn beer, which would not become thoroughly bright with any quantity of finings which could be introduced. Finings have usually a specific gravity of from 1·010 to 1·016, and, when added to beer in a fit condition for fining, invariably go to the top, and not to the bottom. In fining beer in a barrel laid on its side, if the finings do not make their appearance at the bung-hole, the beer will not become bright. The isinglass must not be dissolved with heat, nor in hot water.
[8]Treatise on Brewing, 8vo, p. 68.
[8]Treatise on Brewing, 8vo, p. 68.
Beer brewed from imperfectly malted grain, or from a mixture of malt and raw corn, gives a fermentation quite different in flavour from that of beer from sound malt. The nose is, in fact, the best guide to the experienced brewer for ascertaining whether his process is going on well or ill.
Ropiness is a morbid state of beer, which is best remedied, according to Mr. Black, by putting the beer into a vat with a false bottom, and adding, per barrel, 4 or 5 pounds of hops, taken gradually away after the first boilings of the worts; and to them may be added about half a pound per barrel of mustard-seed. Rouse the beer as the hops are gradually introduced, and, in some months, the ropiness will be perfectly cured. The beer should be drawn off from below the false bottom.
For theoretical views, seeFermentation; and for wort-cooling apparatus, seeRefrigerator.