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Malting consists in making grain germinate artificially to a certain extent, and then stopping the process. Every species of grain may be subjected to it, but some species answer the purposes of the distiller and brewer much better than others, and in this country in general only barley is malted. With some species of grain, such as Indian corn, the germination must be carried to a considerable extent, and it is actually buried under the earth, or sown for a
short time, and when it has sprung up, it is removed and washed, or otherwise cleaned, and then dried in the kiln like other malt. In this country the process, as described by an accurate chemist, is as follows :—
The barley is steeped in cold water for a period which (as regulated by law) must not be less than forty hours; but beyond that period the steeping may be continued as long as is thought proper. Here it imbibes moisture, and increases in bulk; while at the same time a quantity of carbonic acid is emitted, and a part of the substance of the husk is dissolved by the steepwater. The proportion of water imbibed depends partly on the barley, and partly on the length of time that it is steeped. From the average of a good many trials, it appears that the medium increase of weight from steeping may be reckoned 0.47; that is to say, every 100 pounds of barley when taken out of the steep weighs 147 pounds. The average increase of bulk is about a fifth; that is to say, that 100 bushels of grain, after being steeped, swell to the bulk of 120 bushels. The carbonic acid emitted while the barley is in the steep is inconsiderable; and it is probable, from the experiments of Saussure, that it owes its formation, at least in part, to the oxygen held in solution by the steep-water.
The steep-water gradually acquires a yellow colour, and the peculiar smell and taste of water in which straw has been steeped. The quantity of matter which it holds in solution varies from l-50th to l-100th of the weight of barley. It consists chiefly of an extractive matter, of a yellow colour and disagreeable bitter taste, which deliquesces in a moist atmosphere, and contains always a portion of nitrate of soda. It holds in solution most of the carbonic acid disengaged. This extractive matter is obviously derived from the husk of the barley, and is that substance to which the husk owes its colour. Accordingly, grain becomes much paler by steeping.
After the grain has remained a sufficient time in the steep, the water is drained off, and the barley thrown out of the cistern upon the malt-floor, where it is formed into a rectangular heap, called the couch, about 16 inches deep. In this situation it is allowed to remain about 26 hours. It is then turned, by means of wooden shovels, and diminished a little in depth. This turning is repeated twice a day or oftener, and the grain is spread thinner and thinner, till at last its depth does not exceed a few inches.
When placed on the couch, it
begins gradually to absorb oxygen from the atmosphere, and to convert it into carbonic acid; at first very slowly, but afterwards more rapidly. The temperature, at first the same with that of the external air, begins slowly to increase; and in about ninety-six hours the grain is, at an average, about 10° hotter than the surrounding atmosphere. At this time the grain, which had become dry on the surface, becomes again so moist that it will wet the hand, and exhales at the same time an agreeable odour, not unlike that of apples. The appearance of this moisture is called sweating. A small portion of alcohol appears to be volatilized at this period. The great object of the maltmen is to keep the temperature from becoming excessive. This they do by frequent turning. The temperature which they wish to preserve varies from 55° to 62o, according to the different modes of malting pursued.
At the period of the sweating the roots of the grains begin to appear, at first like a small white prominence, at the bottom of each seed, which soon divides itself into three rootlets, and increases in length with very great rapidity, unless checked by turning the malt. About a day after the sprouting of the roots, the rudiments of the ftiture stem, called acrospire by the maltsters, may be seen to lengthen. It rises from the same extremity of the seed with the root, and advancing within the husk, at last issues from the opposite end: but the process of malting is stopped before it has made such progress.
As the acrospire shoots along the grain, the appearance of the kernel, or mealy part of the corn, undergoes a considerable change. The glutinous and mucilaginous matter is taken up and removed, the colour becomes white, and the texture so loose that it crumbles to powder between the fingers. The object of malting is to pro* duce this, change: when it is accomplished, which takes place when the acrospire has come nearly to the end of the seed, the process is stopped by drying the malt upon the kiln. The temperature at first does not exoeed 90°; but it is raised very slowly up to 140o, or higher, according to circumstances. The malt is then cleaned, to separate the rootlets, which are considered as injurious.
Such is a short sketch of the process of malting. Barley, by being converted into malt, generally increases two or three per cent, in bulk; and loses at an average about a fifth of its weight, or 20 per cent. But of these 20 parts 12 are to be ascribed to kilndrying, and consist of water, which the barley would have lost had it been exposed, to the same temperature: so that the real loss does not exceed eight per cent. From a good many trials, made with as much attention to all the circumstances as possible, the following seems to be the way of accounting for this loss:—
Carried off by the steep-water .. 1.5
Dissipated in the floor 3.0
Roots, separated by cleaning.... 3.0
The loss on the floor ought to be entirely owing to the separation of carbon by the oxygen of the atmosphere; but were this the only cause, it would be. much smaller, than three per cent. Two other causes concnr to produce this loss:—1. Many of the roots are broken off during the turning of the malt; these wither and are lost, while ethers grow in their place. 2. A certain portion of the seeds lose the power of germinating, by bruises or other accidents, and these lose a much greater portion than three per cent, of their real weight. From a good many trials, made with as much care as possible, I am disposed to conclude that the quantity of carbon separated during the whole process of malting, by the formation t)f carbonic acid gas, does not exceed two per cent., and that the weight of the roots formed amounts often to four per cent.
These two, in reality, include the whole real loss of weight which barley sustains when malted.—What is lost in the steep, being husk, need scarcely be reckoned. - The roots appear, from the process, to be formed chiefly from the mucilaginous and glutinous parts of the kernel. The starch is not employed in their formation; but undergoes a change, intended no doubt to fit it for the future nourishment of the piumula. It acquires a sweetish taste, and the property of forming a transparent solution with hot water. In short, it approaches somewhat to the nature of sugar; butismuch more soluble, and much more easily decomposed, than that principle. From the experiments of Saussure on the conversion of starch into sugar, there is reason to conclude that this change is brought about by the combination of the starch with water. The action of hot water on barley-meal seems gradually to induce a similar one.
Our plate represents a side view of a malt-kiln, in which the malt is dried by heated air, but in which the air necessary for the combustion of the fuel descends through the grate, a, the fire, b, the grate, c, the door of the furnace, d, the door of the ash-pit. e, the air cylinder. /°, the ash-pit. g, the end of the air cylinder entering the space below, A, the kiln head, which is composed of tiles perforated with small holes lying on the joists i, and supporting the malt k. I, I, the windows, through which a current of air may freely enter or escape, m, the air outlets above. If a distiller finds his works so relatively situated that he can lead the air cylinder of his malt-kiln through the flue of his still or mash boiler furnace, the expense of fuel for drying malt will be saved.
ON THE CUTTING OF STEEL BY SOFT IRON.
The fact that soft iron made to revolve very rapidly will cut steel, has long been known. The followiag is an interesting account of the mode by -which it is effected, as well as a good explanation of the principles of the operation:—
It seems to have been discovered by the Shakers, who are remarkable for the neatness and expertness of their mechanical operations. As it is desirable that the experience of others on this subject should be made known, I will now add, that in June last I saw Professor Robert Hare, at Philadelphia, execute, with a common foot-lathe, operations similar to those described by Mr. Daggett: they were, however, less energetic and decisive, as the machine did not produce so rapid a motion as that of Mr. Barnes.
I have, however, since repeatedly seen the experiment succeed, in the most perfect manner, at the manufactory of arms belonging to Eli Whitney, Esq., near this town (New Haven, Connecticut). As water power is here applied with great facility and energy, -a wheel of soft and -very thin plate iron, six inches in diameter, and furnished with an axis, was made to revolve with such rapidity that the motion became entirely imperceptible, and the wheel appeared as if at rest. When pieces of the best and hardest steel, such as files, and the steel of which the parts of gunlocks are made, were held against the edge of the revolving soft iron plate, they were immediately cat t»y it, with a degree of rapidity which was always considerable, but which was greater as the pieces of steel were thinner; pieces as thick as the plate of a common joiner's saw, were cut almost as rapidly as wood is cut by the saw itself. Considered as an experiment merely, it is a very beautiful one, and in no degree exaggerated in Mr. Daggett's.account: there is a very vivid coruscation of sparks, ilying off in the direction of tangents to the periphery of the, cutting-wheel; and an intense ignition of the steel; extending for a considerable distance ahead of the section, and on its sides, attends
the operation. The impulse against the steel is so strong, that in several instances it was thrown against the opposite side of the room with a velocity that might not have been without danger to a person standing in the way. It may be said, I believe, with safety, that none of the ordinary mechanical operations commenced upon cold and hard steel, will divide it with so much rapidity as this mode of applying soft iron. After all, it is evident that it is only a peculiar method of cutting red hot, or possibly white hot steel; for the mechanical force produces these degrees of heat, and it is one of the best methods of evolving heat by mechanical impulse. The steel of course loses its temper at the place of section, and there only; for the softening extends but a little way, and is limited to a narrow portion, markby the iris colours known to be produced by heat upon steel.
The iron plate, as Mr. Daggett states, becomes only warm, and wears away, only very slowly; yet it does wear, for the edges are left rough, and the channel of section in Hie steel exhibits, with a magnifier, minute striae or grooves, running in the direction of the wheel's revolution. I know not that there is any reason to suppose any peculiar electrical phenomenon, except that electricity always accompanies heat. It is plain from the important use made of this mode of cutting steel by the Shakers and by Mr. Barnes, that it may be of considerable practical importance.
As a philosophical experiment it is highly interesting: and it remains yet to be shown, why, the heat evolved by the impulse should nearly all be concentrated in the steel, and be scarcely perceptible in the iron: neither is it perfectly clear that even ignited steel should be so easily cut by the impinging of soft iron. No smith probably ever thought of attempting to divide steel by applying an iron tool, -r- SiUiman's Journal, vol. Tii. p. 342.