Cooley's Cyclopaedia of Practical Receipts Volume Ii Part 189

In buying artificial manures the purchaser is recommended to obtain a guarantee that they shall be delivered in a sufficiently dry and powdery condition to allow of sowing by the drill.

Samples, taken out of three or four bags, should be well mixed together, and they should be a.n.a.lysed not later than three days after delivery. Two tins, holding about half a pound each, should be filled in the presence of a witness, sealed up, one sent to the a.n.a.lyst, and the other retained for future reference.

=RECTIFCA'TION.= The redistillation, &c., of a fluid, for the purpose of rendering it purer.

=RED.= A term denoting a bright colour, resembling blood. Red is a simple or primary colour, but of several different shades or hues, as scarlet, crimson, vermilion, orange-red, &c.

=RED, AN'ILINE.= _Syn._ ROSANILINE. This artificial base is prepared by the action of bichloride of tin, mercurial salts, a.r.s.enic acid, and many other oxidising agents, upon aniline. The aniline reps of commerce, now so largely used for dyeing, are saline compounds, more or less pure, of rosaline, with 1 equiv. of acid. These compounds are known under the names of 'magenta,' 'fuchsine,' 'roseine,' 'azaleine,' &c. In England the aniline red commonly employed is the acetate of rosaniline, which has been prepared by Mr Nicholson in splendid crystals of very considerable dimensions. In France the hydrochlorate of rosaniline is chiefly employed.

The free base presents itself in colourless crystalline plates, but its compounds with 1 equiv. of acid have, when dry, a beautiful green colour, with golden l.u.s.tre, and furnish with water an intensely coloured red solution. See PURPLE (Aniline) and RED DYE, also TAR COLOURS.

=RED DYE.= The substances princ.i.p.ally employed for dyeing reds are cochineal, lac-dye, and madder, which, under proper treatment, yield permanent colours of considerable brilliancy, the first and third more particularly so. Extremely beautiful but fugitive colours are also obtained from Brazil wood, safflower, archil, and some other substances.

For purple-red or crimsons (magenta, fuchsine, &c.), on silk or wool, the aniline reds (salts of rosaniline) are now extensively used. (See TAR-COLOURS.) The mode of applying them is noticed under PURPLE DYE. SILK is usually dyed of a permanent red or scarlet with cochineal, safflower, or lac dye; wool, with cochineal and, still more frequently, with madder; and cotton, with madder (chiefly), Brazil wood, &c. The leading properties of these substances are given under their respective names, and the methods of employing them are generally referred to in the articles DYEING, MORDANTS, &c., and, therefore, need not be repeated here. The following may, however, be useful to the reader:--

1. First, give the 'goods' a mordant of alum, or of alum-and-tartar, rinse, dry, and boil them in a bath of madder. If acetate of iron be used instead of alum, the colour will be purple, and by combining the two, as mordants, any intermediate shade may be produced.

2. The yarn or cloth is put into a very weak alkaline bath at the boiling temperature, then washed, dried, and 'galled' (or, when the calico is to be printed, for this bath may be subst.i.tuted one of cow-dung, subsequent exposure to the air for a day or two, and immersion in very dilute sulphuric acid. In this way the stuff gets opened, and takes and retains the colour better). After the 'galling' the goods are dried, and alumed twice; then dried, rinsed, and pa.s.sed through a madder bath, composed of 3/4 lb. of good madder for every lb. weight of the goods; this bath is slowly raised to the boiling point in the course of 50 or 60 minutes, more or less, according to the shade of colour required; after a few minutes the stuff is taken out, and slightly washed; the operation is then repeated, in the same manner, with fresh madder; it is, lastly, washed and dried, or pa.s.sed through a hot soap bath, which carries off the fawn-coloured particles.

3. (ADRIANOPLE RED, TURKEY R.) This commences with cleansing or scouring the goods by alkaline baths, after which they are steeped in oily liquors brought to a creamy state by a little carbonate of soda; a bath of sheep's dung is next often used as an intermediate or secondary steep; the oleaginous bath, and the operation of removing the superfluous or loosely adhering oil with an alkaline bath, is repeated two or three times, due care being taken to dry the goods thoroughly after each distinct process; then follow the distinct operations of galling, aluming, maddering, and brightening, the last for removing the dun-coloured principle, by boiling at an elevated temperature with alkaline liquids and soap; the whole is generally concluded with treatment by spirit of tin. In this way are given the most brilliant reds on cotton.

_Obs._ Wool takes from half its weight of madder to an equal weight to dye it red; cotton and linen take rather less. On account of the comparative insolubility of the colouring matter of madder, this dye-stuff must be boiled along with the goods to be dyed, and not removed from the decoction, as is the practice in using many other articles. Other dye-stuffs are frequently added to the madder bath, to vary the shades of colour. Decoction of fustic, weld, logwood, quercitron, &c., are often thus employed, the mordants being modified accordingly. By adding bran to the madder bath the colour is said to be rendered much lighter, and of a more agreeable tint.

=RED GUM.= A slight eruptive disease of infancy, occasioned by teething, and, less frequently, by irritation from rough flannel worn next to the skin. See STROPHULUS.

=RED LAV'ENDER.= See TINCTURE OF LAVENDER (Compound).

=RED LIQ'UOR.= The crude solution of acetate or sulpho-acetate of alumina employed in calico printing. It is generally prepared by mixing crude sulphate of alumina with about an equal weight of crude pyrolignite of lime, both being in the state of solution.

=RED PIG'MENTS.= The preparation of the princ.i.p.al red pigments are described under their respective names. The following list includes most of the reds in use:--

=Arme'nian Bole.= _Syn._ BOLE ARMENIAN; BOLUS ARMENIae, L. Formerly imported from Armenia, Portugal, Tuscany, &c.; now generally made by grinding together a mixture of whiting, red oxide of iron, and red ochre, in nearly equal proportions.

=Red, Brown.= A fact.i.tious mixture of red oxide of iron and red ochre, in variable proportions.

=Car'mine.=

=Carmina'ted Lake.=

=Red Chrome.= _Syn._ DICHROMATE OF LEAD, RED CHROMATE OF L.; PLUMBI DICHROMAS, P. CHROMUS RUBRUM, L. _Prep._ 1. Boil pure carbonate of lead with chromate of pota.s.sa, in excess, until it a.s.sumes a proper colour; then wash it well with pure water, and dry it in the shade.

2. Boil neutral chromate of lead with a little water of ammonia or lime water.

3. (Liebig and Wohler.) Fuse saltpetre at a low red heat in a Hessian crucible, and throw in chromate of lead (pure chrome yellow), by small portions at a time, as long as a strong ebullition follows upon each addition of the pigment, observing to stir the mixture frequently with a gla.s.s rod; after repose for a minute or two, pour off the fluid part, and, as soon as the solid residuum is cold, wash it with water, and dry it by a gentle heat.

_Obs._ Great care must be taken, in conducting the last process, not to employ too much heat, nor to allow the saline matter to stand long over the newly formed chrome-red, as the colour is thus apt to change to a brown or orange. When well managed the product has a crystalline texture, and so beautiful a red colour that it vies with native cinnabar. The liquid poured from the crucible is reserved for manufacturing chrome yellow.

=Red, In'dian.= _Syn._ PURPLE OCHRE; OCHRA PURPUREA PERSICA, TERRA PERSICA, L. This is a native production, brought from Ormus. A fact.i.tious article is prepared by calcining a mixture of colcothar and red ochre.

=Lakes= (Various).

=Red, Light.= From yellow ochre, by careful calcination. It works well with both oil and water, and produces an admirable flesh-colour by admixture with pure white. All the ochres, both red and yellow, are darkened by heat.

=Red Or'ange.= _Syn._ SANDIX. Obtained from white lead by calcination.

Very bright.

=Real'gar.= Bisulphide of a.r.s.enic.

=Red Bole.= See ARMENIAN and VENETIAN BOLE. (Ochres.)

=Red Chalk.= A clay iron ore, much used for pencils and crayons, and, when ground, also for paints.

=Red Lead.= _Syn._ MINIUM. The finest red lead is prepared by exposing ground and elutriated ma.s.sicott, or dross of lend, in shallow iron trays (about 12 inches square, and about 4 or 5 inches deep), piled up on the hearth of a reverberatory furnace, to a heat of about 600 to 650 Fahr., with occasional stirring, until it acquires the proper colour. The furnace employed for the preparation of ma.s.sicot during the day usually possesses sufficient residuary heat during the night for this process, by which fuel is saved. Lead for the above purpose should be quite free from copper and iron.

=Red O'chre.= A natural product abounding on the Mendip hills.

=Red Or'piment.= _Syn._ RED a.r.s.eNIC. Tersulphide of a.r.s.enic.

=Red Vene'tian.= _Syn._ BOLUS VENETA, L. A species of ochre, brought from Italy.

=Rose Pink.= This is whiting coloured with a decoction of Brazil wood to which a little pearlash has been added. A very pretty colour, but it does not stand. It is always kept in a damp state. The colour may be varied by subst.i.tuting alum for pearlash, or by the addition of a little spirits of tin.

=Vermil'ion.= (See under that word.)

=REDUC'TION.= _Syn._ REVIVIFICATION. A term in its fullest sense applied to any operation by which a substance is restored to its neutral state; but now generally restricted, in chemistry, to the abstraction of oxygen, and hence frequently termed deoxidation or deoxidis.e.m.e.nt. This change is operated by either heating the substance in contact with carbon or hydrogen, or in exposing it to the action of some other body having a powerful affinity for oxygen. See POTa.s.sIUM, &c.

=REFI"NING.= A term employed in commercial chemistry and metallurgy synonymously with purification. The separation of the precious metals from those of less value, as in the operation of parting, const.i.tutes the business of the 'refiner.' See GOLD, SILVER, &c.

=REFRAC'TION (of Light).= The deviation of a ray of light from its original path on entering a medium of a different density or power. For the practical application of this property, see GEMS.

=REFRI"GERANTS.= Medicines or agents which tend to lessen the animal temperature without causing any marked diminution of sensibility or nervous energy. Among internal refrigerants cold water, weak acidulous drinks, and saline aperients, are those which are probably the best known and the most useful. Among external refrigerants are cold water, evaporating lotions, weak solutions of subacetate of lead, &c.

=REFRIGERA'TION.= The abatement of heat; the act or operation of cooling.

Among the purposes to which refrigeratory processes are applied in the arts, the princ.i.p.al are--the condensation of vapours--the cooling of liquids--the congelation of water, and--the production of extreme degrees of cold in chemical operations. The first of these is referred to under the heads DISTILLATION, STILL, &c., and the second under WORT. It is, therefore, only necessary to notice here the third and fourth applications of cold, artificially produced, above referred to.

The refrigeratory processes at present employed depend upon the greater capacity for heat which the same body possesses as its density lessens, or its attenuation increases; as exhibited in the sudden liquefaction of solids, the rapid evaporation of liquids, and the almost instantaneous return of atmospheric air, or other gaseous body, from a highly condensed state to its normal condition. The loss of sensible heat in the first example is the basis of the various processes of producing cold by what are commonly called 'FREEZING-' or 'FRIGORIFIC-MIXTURES,' all of which act upon the principle of liquefying solid substances without supplying heat.

The caloric of liquidity being in these cases derived from that previously existing in the solid itself in a sensible state, the temperature must necessarily fall. The degree of cold produced depends upon the quant.i.ty of heat which is thus diffused through a larger ma.s.s, or which, as it were, disappears; and this is dependent on the quant.i.ty of solid matter liquefied, and the rapidity of the liquefaction. Saline compounds are the substances most frequently employed for this purpose, and those which have the greatest affinity for water, and thus liquefy the most rapidly, produce the greatest degree of cold. Similar changes occur during the evaporation of liquids. When heat pa.s.ses from the sensible to the insensible state, as in the formation of vapour, cold is generated. This may be shown by pouring a few drops of ether or rectified spirit on the palm of the hand, when a strong sensation of cold is experienced. A still more familiar ill.u.s.tration of this fact is exhibited in the rapidity with which the animal body loses heat when enveloped in damp or wet clothing.

The evaporation of water produces a degree of cold which is greater than that of other liquids, in exact proportion as the insensible or latent heat of its vapour exceeds theirs. In the attenuation or rarefaction of gases similar phenomena occur.

It has been found that evaporation proceeds much more rapidly from the surface of fluids in a vacuum than in the atmosphere. Water may be easily frozen by introducing a surface of sulphuric acid under the receiver of an air-pump, over which is placed a capsule filled with water, so that the vapour arising from the latter may be immediately absorbed by the former.

After a few strokes of the piston the water is converted into a solid cake of ice. The acid operates by absorbing the aqueous vapours as soon as generated, and thus maintaining the integrity of the vacuum. Professor Leslie found that, when air is thus rarified 250 times, the surface of evaporation was cooled down 120 in winter; and when only 50 times, a depression of 80 or even 100 took place. "Sulphuric acid is capable of congealing more than 20 times its weight of water before it has imbibed nearly its own bulk of that liquid, or has lost about 1/8th of its refrigerating power." (Ure.) Sulphuric acid, which has become diluted in this way, may be reconcentrated by heat. Any substance having a great tendency to absorb moisture may be subst.i.tuted for the sulphuric acid.

Fused chloride of calcium, quicklime, nitrate of magnesium, chloride of zinc, and oatmeal (dried nearly to brownness before a common fire), have been used for this purpose. Again, instead of employing an air-pump, a vacuum may be produced by the agency of steam, afterwards condensed by the affusion of cold water.

A pleasing philosophical toy, ill.u.s.trative of the evaporative power of a vacuum, is the 'CRYOPHORUS,' or 'FROST-BEARER,' of Dr Wollaston. This instrument consists of two small gla.s.s globes, united by a tube, one of which is partly filled with water. The whole apparatus is perfectly free from air, and is, consequently, filled with attenuated aqueous vapours. No sooner is the pressure removed as by plunging the empty ball into a freezing mixture (which condenses the vapour), than rapid evaporation commences, and the water in the other ball is frozen in two or three minutes.

[Ill.u.s.tration]

Even in hot climates ice may be produced under favorable circ.u.mstances by evaporation. On the open plains, near Calcutta, this is effected by exposing a thin stratum of water to the atmosphere, during the fine clear nights of December, January, and February. The pans are made of porous earthenware, and water is poured in to the depth of about 1-1/2 inch. A large number of these vessels are arranged in an excavation in the ground, 30 or 40 feet square and 2 feet deep, the bottom of which is covered, to the depth of 10 or 12 inches, with sugar canes or the stalks of Indian corn. At sunrise the pans are visited, the ice separated from the water, and packed as tight as possible in a deep cavity or pit, well screened from the heat.