FLOUR; FLOITR.M!I.I> 



FLUID. 



110 



gruaux principle of grinding. The grain b first ground in a mill ; the 

 white middlings are then separated by course neves and re-ground ; 

 and, finally, the flour is repeatedly psssod through fine silk sieves. 

 The flour produced by this tedious and expensive prneeas is of the very 



description, especially for pdtct and the most delicate bread. 

 The average produce of flour thui obtained u only 25 per cent, the 

 weight of the grain ; therefore, it U necessarily high in price. 



We may hare notice a singular mode of drying grain adopted by 

 Meaan. Kennedy and Armstrong at Lisburn, in Ireland They employ 

 an old shot-tower, in which perforated pistes are fixed in a ligxag direc- 

 tion from top to bottom ; hot air U admitted to the under surface of 

 each plate, and grain falls on the upper surface. Down these plates the 

 grain passes ; and, by an ingenious contrivance, at the zigzag corners it 

 is turned over during its passage, so as to be acted on equably. The 

 peed of descent and the neat of the air can be regulated according to 

 circumstances. The weight of the grain turns a discharging wheel at 

 the bottom ; and a pendulum, attached to the wheel, regulates the 

 rapidity of the discharge of the grain, and also acts as a meter of quan- 

 tity. This mode of drying grain is found to be cheap, easy, and 

 healthy, irrespective of any particular mode of grinding the corn into 

 flour. 



An experiment in corn-grinding of a very important kind was made 

 during the Crimean war, affording testimony which may be, and cer- 

 tainly ought to be, suggestive of improvements in our army and nary 

 services. In order to lessen the difficulties in the way of supplying 

 bread to the troops, the British government sent out to Bal.ildav.-i two 

 steamers, one fitted up with machinery for grinding corn, and the other 

 with baking ovens. Mr. Fairbairn, the engineer, being consulted, he 

 prepared plans and drawings of the requisite machinery. The govern- 

 ment purchased the Bruiser and Abundance steamers ; and in three 

 months all the fittings, novel as they were, were completed. The mill 

 was capable of grinding 20 bushels of flour per hour, even while the 

 steamer was moving at 7 or 8 knots an hour. The steamer and the 

 jnill were both worked by the same steam-engine, made by Robert 

 Stephenson. When the two steamers reached Balaklava, about the 

 end of 1855 or early in 1856, the Bruiser was at once set to work Jag a 

 corn-mill ; it ground 24,000 Ibs. per day, taking any kind of corn that 

 happened to be procurable, and never got out of order during three 

 months' operation. The flour produced from this weight of grain was 

 made up into 18,000 Ibs. weight of 4 Ib. loaves, served out daily to the 

 troop*. So few were the interruptions in this course, that in the first 

 three months of 1856 the mill ground 1,800,000 Ibs. of corn, yielding 

 1,330,000 Ibs. of flour (the rest being bran and waste). The total cost 

 of the wheat and grinding the flour was about one penny per pound. 

 It does not fall within the province of the present article to notice the 

 arrangements of the bread-making and baking apparatus ; but it may 

 suffice to say that the Abundance baked into bread all the flour which 

 the Bruiser could grind. The steamers and the machinery were sold at a 

 Hiniill price when the war was over ; but the lesson afforded is not 

 likely to be lost. A competent authority has observed : " The expe- 

 riment forcibly suggested the necessity of a light portable steam-engine 

 and mill for grain being constantly attached to the camp when an army 

 takes the field. This could be done at a very moderate cost. The 

 whole affair need not exceed the weight of a large-sized gun, such as 

 now accompany our armies. There is no practical difficulty in the way 

 of introducing an engine capable of supplying newly-baked bread from 

 an oven constructed in the smoke-box of a portable locomotive engine, 

 mounted on wheels, and prepared with grinding apparatus at the same 

 time." Some recent experiments on army cookery, made at Woolw irli, 

 induce a hope that corn-grinding and bread-baking vehicles will by and 

 bye be attached as regular component items in the materiel of an 

 army. 



Some of the flour-mills recently constructed arc establishments main- 

 tained on a very extensive scale. One, on the banks of the Thames near 

 Blackfriars Bridge, contains 32 pairs of millstones and 16 dressing- 

 machines. All the movements are effected by steam-power, and great 

 ingenuity U displayed in every part of the arrangements. The 

 Americans, also, have begun the application of machinery on a large 

 scale to the grinding of flour, not only for home consumption, but for 

 export to England. Some of the millers in the United States adopt 

 a singular mode of filling the flour-sacks. A trough is suspended on an 

 axis ; and beneath one end of the trough is a pair of scales, or rather 

 the flour-pan of a pair of scales. The flour-barrel Is placed on the 

 wale-pan; flour flows through the trough into it; and when the 

 proper quantity has been thus precipitated, and the scale-pan and 

 barrel have descended by their weight, a small piece of apparatus 

 catches hold of the trough, and tilts it into the contrary direction, so 

 that no more flour can flow through it into the barrel. The apparatus 

 thereby effect* the double purpose of filling and weighing. 



The flour sold in the London market U sometimes adulterated, but 

 not to so great an extent as some other articles of food. Dr. Normandy 

 ays that " The physical characteristics of wheat-flour of good quality 

 are the following : It has a dull white colour, somewhat inclining to 

 yellow. It should exhibit to the eye no trace of bran, even when 

 pressed smooth with the hand or with a polished surface. It should 

 have a homogeneous appearance, and should not lose more than from 

 6 to 12 per cent, after drying in a stove ; the less it loses by drying the 

 better it is." The adulteration of flour, when it exists, is usually made 



by means of potato starch, bean flour, Indian corn flour, and rice flour > 

 these are innocuous, and the dishonesty consists mainly in soiling these 

 cheap substances at the price of good wheaten flour. Some of the 

 adulterants, however, are less innocent ; such as alum, chalk, bone-dust, 

 ami plaster. 



It is not necessary to enter in this place into the subject of the 

 flour-trade, sufficient on that matter having been given in the article 

 CORK-LAWS AND CORN-TRADE. The relative quantities obtained from 

 different countries vary widely and rapidly, owing chiefly to the 

 fluctuating richness of the harvests. 



FLOWKRS. A term invented by the alchemists, and still in use, 

 to denote the light flocculeut sublimates obtained by heating volatile 

 noliiln in close vessels; for instance, flowers of sulphur, benzoin, and 

 antimony. 



KI.UK. [HOUSE.] 



FLUENTS. [FLUXIONS.] 



I I. I'll). This term is applied to substances of which the parts 

 possess perfect mobility amonpst themselves, but more rigorously it 

 depends on the relative intensities of the forces which act on the com- 

 ponent particles of masses. In bodies of permanent form, denominated 

 tiJiili. these forces not only preserve the particles in a state of rest 

 when undisturbed, but also, on the communication of a slight disturb- 

 ance relative to their mean positions, reduce them, after the lapse of a 

 very short time, to the places they possessed before ; hence arises the 

 permanence of figure and arrangement characteristic of solid bodies. 

 On the other hand, the gases have an elastic or expansive power, 

 which is usually attributed to caloric, because the gaseous state is 

 induced in all substances by the communication of a high degree of 

 heat ; the particles of gases have therefore a tendency, when external 

 forces are removed, to fly from their places in obedience to the rr|ml- 

 sion exercised by the parts in their vicinity ; they are therefore t"i 1 y 

 movable amongst each other. But the conditions of the motion of any 

 our ]tirticle are nevertheless limited by the condensations of the 

 particles on which they impinge, and the rarefactions of those which 

 they abandon, and therefore, even in a gas, the disturbance of a particle 

 only makes it describe a curve round its mean position, and the con- 

 densations and rarefactions thence generated produce inequalities of 

 pressure which propagate like motions in the particles in the vicinity. 

 These motions, gradually conveyed throughout the entire mass, 

 produce vibrations, the phenomena of sound, and, it is thought, those 

 also of light. 



This yielding to the internal forces called into play by the motion of 

 the particles of a gas is by no means opposed to but rather implies 

 their perfect mobility. If we diminish or increase their specific weight 

 by an alteration of temperature, they will accordingly rise or sink 

 amongst the myriads of particles by which they are surrounded. Yet 

 they will not rise or sink as if in vacuo, for they still will be encum- 

 bered by the influences of the adjacent particles, ami tl. 

 motions must suffer resistance. 



But in liquid*, which also come under the denomination of fluids, 

 this alteration of density and elasticity is imperceptible in ordinary 

 motions, from whence, in physico-matheinatics, they have been gene- 

 rally treated as incompressible bodies ; still a small alterat 

 specific gravity is sufficient to produce a distinct motion on the 

 particles subject to such change. By the application of a blow-pipe to 

 the lower part of a glass vessel containing any liquid, a current, due to 

 the alteration of density of the particles in contact with the heated 

 part of the glass, is generated, and there is much reason to believe that 

 many of the permanent currents of the ocean originate from a similar 

 cause, namely, the unequal temperature of different parts of the 

 bottom of the sea, either from the difference of their depths, or 

 of the conductibility of the solid strata with which the fluid is in 

 contact. 



The particles of a fluid being thus surrounded by others which are 

 subject to external forces, such as that of gravity, undergo a pressure 

 which is estimated by considering how great it would be if continued 

 uniform over any surface taken as a unit. The direction of such a 

 surface is immaterial, for the particle can only be in repose when the 

 pressures from all quarters are equal When fluids are inelastic this 

 pressure is entirely due to extraneous forces, such as the weight of the 

 superincumbent mass ; but in elastic fluids, as in air, the pressure is 

 necessarily proportional to the elasticity of the particle which supports 

 it; and this elasticity is known. to increase with the diminution of the 

 volume compressed ; such fluids therefore, under the influence of ex- 

 ternal forces, acquire variable densities in their different parts. 



We reserve for the articles HYDROSTATICS and HYDRODYNAMICS the 

 principles from whence the equilibrium and motion of fluids are 

 deduced when subject to known forces ; and for the article TIDK8 the 

 case when those forces are the attractions of the sun and moon upon 

 the ocean. 



The equilibrium of a body floating on a fluid depends on two simple 

 conditions ; namely, that the centre of gravity of the whole body and 

 of the displaced fluid must be in the same vertical line, ami the 

 weight of this displaced fluid must be equal to that of the body : but 

 for the conditions of the stability of the equilibrium we refer to 

 MF.TACKNTRK. 



When a body moves in a fluid it suffers a resistance depending on 

 its velocity ; and when the body is small compared with the mass in 



