Cooley's Cyclopaedia of Practical Receipts Volume I Part 45

=Angostura, False.= See BRUCEA, CUSPARIA and STRYCHNOS.

=ANGOSTU"RINE=, =Angustu'rine= (-in). See CUSPARIN.

=ANHYDRIDE.= Most, if not all modern chemists, adopting GERHARDT'S practice of limiting the t.i.tle of acid to a particular cla.s.s of substances which contain hydrogen, now regard all true acids as salts of hydrogen.

Formerly many bodies, such as silica or white a.r.s.enic, were looked upon as acids, though if we adopt the foregoing definition they are not really so until they have combined with water. Such bodies, because they contain no hydrogen, are now distinguished as anhydrides; the substances, for example, familiarly known as carbonic, sulphurous, and phosphoric acids, must, upon the above principle, be designated carbonic, sulphurous, and phosphoric anhydrides. We may also define an anhydride to be an oxide which forms an acid on treatment with water.

=ANHY'DROUS= (-drus; _an'hydrous_, as marked by Brande, is less usual).

_Syn._ AN'HYDRUS, L.; ANHYDRe, Fr.; Wa.s.sERFREI, Ger. Free from water; dry.

In _chemistry_ and _mineralogy_, a term frequently applied to substances, as acids, alcohol, gases, salts, minerals, &c., which do not contain either free or combined water. GASES may generally be rendered anhydrous by pa.s.sing them through a tube containing fused chloride of calcium, or (_e.g._ AMMONIA and two or three others) quick-lime, in coa.r.s.e powder; and some of them, by pa.s.sing them through concentrated sulphuric acid. SALTS may generally be dried by cautiously submitting them to the action of heat, or by exposure to a very dry atmosphere; and alcohol, and many other volatile fluids, by careful distillation from chloride of calcium, or some other highly hygrometric substance.

=AN'IL.= [Fr., Sp., L.] The indigof'era anil of botanists--one of the plants yielding 'indigo'--a native of America, but now largely cultivated in the East Indies. See INDIGO (and _below_).

=AN'ILINE=[64] (-een). [Eng., Fr.] C_{6}H_{7}N. _Syn._ PHENYL'AMINE; ANILI'NA, ANILI'NUM, &c., L. A peculiar volatile organic base first noticed by Unverdorben in empyreumatic bone-oil, and afterwards obtained by Runge from coal-tar, and by Fritzsche, Zinin, A. W. Hofmann, and others, as a product of various reactions, processes, and decompositions, particularly those attending the destructive distillation of organic bodies.

[Footnote 64: For a detailed account of the methods of preparing aniline commercially, and of the dyes obtained therefrom, _see_ 'Dictionnaire de Chimie,' par A. Wurtz.]

PREP. Aniline is now almost invariably obtained, on the large scale, either directly or indirectly from coal-tar or indigo; and chiefly from the basic oil or naphtha, or the nitrobenzol, of which the former is the princ.i.p.al source. The following are the leading commercial and experimental processes:

1. From COAL-TAR or COAL-TAR NAPHTHA:--The basic oil or basic portion of coal-tar or coal-tar naphtha, forming the latter, denser, and least volatile products of the distillation or rectification of these substances, is strongly agitated, for some time, along with hydrochloric acid in slight excess, a gla.s.s globe, or, on the large scale, a suitable vessel of lead, or of enamelled iron, being employed for the purpose; the clear portion of the liquid (containing the hydrochlorates of the bases present) is then decanted and carefully evaporated over an open fire until acrid fumes begin to be disengaged, when it is again decanted or filtered; the clear liquor, or filtrate is next treated with potash or milk of lime in excess, by which the bases--chiefly aniline and chinoline--are liberated under the form of a brownish oil; the whole of the resulting mixture is now submitted to distillation, the portion which pa.s.ses over at or about 360 Fahr., and which consists chiefly of crude aniline, being collected separately; the product is purified by rectification and recollection, once or oftener, at the same temperature, and, lastly, by fresh treatment with hydrochloric acid and careful distillation with excess of potash, or milk of lime, as before.

2. From NITROBENZOL:--_a._ (Zinin.) An alcoholic solution of nitrobenzol, after saturation with ammonia, is treated with sulphuretted hydrogen, until, after some hours, a precipitation of sulphur takes place; the brown liquid is then repeatedly saturated with fresh sulphuretted hydrogen, until no more sulphur separates, the reaction being aided by occasionally heating or distilling the mixture; an excess of acid is next added, and, after filtering the liquid, and the removal of the alcohol and unaltered nitrobenzol by ebullition or distillation, the residuum is lastly distilled with caustic potash, in excess. The ANILINE found in the receiver may be rendered quite pure by forming it into oxalate of aniline, repeatedly crystallising the salt from alcohol, and finally distilling it with excess of caustic pota.s.sa, as before.

The following is a cheaper and more convenient process; and probably the best, or one of the best, that has yet been invented for obtaining aniline:--

_b._ (M. Bechamps.) From nitrobenzol distilled along with basic protacetate of iron; or, what is better, by distilling a mixture of iron-filings, 2 parts, and acetic acid, 1 part, with about an equal volume of nitrobenzol, the reaction being a.s.sisted, whenever the effervescence flags, by the application of a gentle heat. The liquor found in the receiver consists of aniline and water, from which the first, forming the lower portion, is obtained, after sufficient repose in a separator; or more easily, by adding a very little ether, which by dissolving in the aniline, causes it to rise to the surface, when it is at once decanted. A very s.p.a.cious gla.s.s or earthenware retort must be employed in the process, as the ma.s.s swells up violently; and it must be connected with the receiver, on the small scale, by means of a Liebig's condenser, and, on the large scale, by an ordinary worm-pipe and tub, kept in good action by a sufficient flow of cold water.

The apparatus for carrying out Bechamp's method was devised by Nicholson, and is exhibited in the subjoined plate.

"It consists essentially of a cast-iron cylinder (A) of 10 hectolitres (220 cubic gallons) capacity. A stout iron tube is fitted to this vessel, reaching nearly to the bottom of the cylinder. The upper part of this tube is connected with the machinery (G), while the surface of the tube is fitted with steel projections. The tube serves to admit steam, as well as acting as a stirring apparatus. Sometimes, instead of this tube, a solid iron axle is employed, and in this case there is a separate steampipe (D).

Through the opening at K the materials for making aniline are put into the apparatus, while the volatile products are carried off through E. H serves for emptying and cleaning the apparatus. The S-shaped tube connected with the vessel B acts as a safety valve. When it is intended to work with this apparatus there is poured into it through K 10 parts of acetic acid at 8 B. (sp. gr. 1060), previously diluted with six times its weight of water; next there are added 30 parts of iron filings, or cast-iron borings, and 125 parts of nitrobenzol, and immediately after the stirring apparatus is set in motion. The reaction ensues directly, and is attended by a considerable evolution of heat and vapours. Gradually more iron is added until the quant.i.ty amounts to 180 parts. The escaping vapours are condensed in F, and the liquid condensed in R is from time to time poured back into the cylinder A. The reduction is finished after a few hours."

[Ill.u.s.tration]

3. From INDIGO:--Powdered indigo is added to a boiling and highly concentrated solution of caustic potash, as long as it dissolves and hydrogen gas is liberated; the resulting brownish-red liquid is evaporated to dryness, and the residuum is submitted to destructive distillation in a retort, which, owing to the intumesence of the ma.s.s, should be strong and s.p.a.cious. The ANILINE is found in the receiver under the form of a brownish oil mixed with ammoniacal liquor, and by separation from the latter, and subsequent rectification, is obtained nearly colourless. It may be further purified, as in the preceding processes.--_Prod._ 18 to 20% of the indigo employed.

4. By fusing, with proper precautions, a mixture of isatine and hydrate of pota.s.sium (both in powder); a retort connected with a well-cooled receiver, being employed as the apparatus. Said by Profs A. W. Hofmann and Muspratt to be "the most eligible process for isolating" aniline.[65]

[Footnote 65: Muspratt's 'Chemistry,' i, 599.]

5. From anthranilic acid mixed with powdered gla.s.s or sand, and rapidly heated in a retort.

6. By treating an alcoholic solution of benzine with a little zinc and hydrochloric acid.

7. By heating phenyl-alcohol with ammonia in sealed tubes.

In Zinin's process the nitrobenzol is dissolved in alcohol, and the solution, after the addition of ammonia, is saturated with sulphuretted hydrogen. After standing some time the solution deposits a large quant.i.ty of sulphur, and the liquid yields aniline.

Many other reducing agents have been proposed for the conversion of nitrobenzol into aniline, such as a.r.s.enite of sodium, powdered zinc, &c., but on the large scale they have all been found inferior to the process of Bechamp. Kremer's process consists in heating one part of nitrobenzol in a proper apparatus with five of water and two and a half of zinc dust. When the reaction is completed the aniline, amounting to about 65% of the weight of the benzol, is distilled off in a current of steam.

_Prop., &c._ A thin, oily, colourless liquid, with a faintly vinous odour, and a hot and aromatic taste; very volatile in the air; miscible in all proportions with alcohol and ether; very slightly soluble in water; neutral to ordinary test-paper, but exhibiting an alkaline reaction to dahlia-petal infusion and paper; dissolves camphor, sulphur, and phosphorus, and coagulates alb.u.men; possesses a high refractive power; and precipitates the oxides of iron, zinc, and alumina, from solutions of their salts, and neutralises the acids, like ammonia. With the acids it forms numerous crystallisable compounds of great beauty, and which are easily formed, and are precisely a.n.a.logous to the corresponding salts of ammonia. These, on exposure to the air, acquired a rose colour, in many cases gradually pa.s.sing into brown. Its boiling-point is 359 to 360 Fahr.; sp. gr. 1028.

_Tests._--1. Chromic acid gives a deep greenish or bluish-black precipitate with aniline and its salts:--2. Hypochlorite of lime strikes an extremely beautiful violet colour, which is soon destroyed:--3. The addition of two or three drops of nitric acid to anhydrous aniline produces a fine blue colour, which, on the application of heat, pa.s.ses into yellow, and a violent reaction ensues, sometimes followed by explosion:--4. With b.i.+.c.hloride of platinum it yields a double salt (platino-chloride of aniline) a.n.a.logous to the like salt of ammonia.

These reactions distinguish it from all other substances.

Commercial aniline is a mixture consisting in great part of aniline, paratoluidine (solid), and orthotoluidine in variable proportions. In addition it contains small amounts of metatoluidine, nitrobenzol, odorine, &c., but for all practical purposes it may be regarded as a mixture of aniline and toluidine. These anilines are obtained from a portion of the light coal-tar naphtha boiling between certain temperatures, by treating it first with nitric acid to convert it into the nitro-compounds, and then reducing these with iron and acetic acid, as already described under Bechamp's process. It is very plain that as the coal-tar naphtha contains variable proportions of benzol and toluidine, the resulting product must also vary in the quant.i.ties of aniline and toluidine it will contain. In order to distinguish between various samples of commercial aniline, Reimann submits them to fractional distillation and compares the results.

He places 100 c. c. of the sample to be tested in a retort fitted with a thermometer and heated by means of an oil bath. The liquid as it distils is received in a narrow graduated cylinder, and the amount that pa.s.ses over between every 5 C. (9 F.) is noted.

In order to obtain standards for comparison he first distilled a sample of light aniline, or kuphaniline, as he terms it, then one of heavy aniline or baraniline; afterwards mixtures of the two in varying proportions. In the accompanying table the results are given.

-------------+------------------------------------------------------------------------ Centigrade { K. 100 90 85 80 75 60 50 25 0 { B. 0 10 15 20 25 40 50 75 100 -------------+------------------------------------------------------------------------ Below 180 8-1/2 7 2-1/2 5-1/2 7 ... 7 5-1/2 ...

180--185 54 50 29-1/2 22 5-1/2 7 4-1/2 2-1/2 2 185--190 34 34 56-1/2 55-1/2 55-1/2 37 7-1/2 4-1/2 1-1/2 190--195 ... 5 7-1/2 8-1/2 15 33 42 17 8 195--200 ... ... ... ... 9 ... 19 36 18 200--205 ... ... ... ... 4-1/2 16 10 16 39 205--210 ... ... ... ... ... ... 3-1/2 8 19 210--215 ... ... ... ... ... ... ... 4-1/2 7 Residue 3-1/2 4 4 8-1/2 3-1/2 7 6-1/2 5 5-1/2 -------------+------------------------------------------------------------------------

To ascertain the quality of any sample it is only necessary to distil it in the manner already described, and compare the results with those in the above table.

(For further information consult Wagner's 'Chemical Technology,' Calvert's 'Dyeing and Calico Printing,' edited by Stenhouse and Groves; Crooke's 'Practical Handbook of Dyeing and Calico Printing,' Ure's Dictionary, edited by Hunt.)

_Uses_, _&c_. Chiefly in dyeing, for the production of colouring matter of various rich shades of purple and violet, some approaching pink, by the action of chromic acid; and of a splendid crimson, by the action of various oxidising agents. It forms the basis of the celebrated new dyes for silks lately patented by Mr W. H. Perkin, and others, and which are not only more delicate and gorgeous in tint, but also more permanent, than any produced by other substances.

Besides numerous salts, various subst.i.tution compounds of aniline have been formed, all of which possess vast scientific interest, and several are likely to prove of importance in the arts. See DYEING, INDIGO, TAR COLOURS, &c. (also _below_.)

=Aniline, Chro'mates of=. _Prep_. 1. (NEUTRAL CHROMATE.) From sulphate or oxalate of aniline and chromate of potash, by double decomposition.

2. (b.i.+.c.hRO'MATE:--Mr W. H. Perkin.) Sulphate of aniline and b.i.+.c.hromate of potash, in equivalent quant.i.ties, are separately dissolved in water, and the solutions, after being mixed, are allowed to stand for several hours.

The whole is then thrown upon a filter, and the black precipitate which forms is washed and dried. It is next digested in coal-tar naphtha (--?

benzol), to extract a brown resinous substance; after which it is digested in alcohol, to dissolve out the colouring matter (b.i.+.c.hROMATE OF ANILINE), which is left behind on distilling off the spirit, as a coppery friable ma.s.s. Patented.

=Aniline, Cy'anide of=. Benzonitrile.

=Aniline, Ox'alate of=. (C_{6}H_{7}N)_{2}C_{2}O_{4}. Obtained by saturating an alcoholic solution of oxalic acid with aniline; the salt separating as a crystalline ma.s.s. It is very soluble in hot water; much less so in cold water; only slightly soluble in alcohol; and insoluble in ether. It may be crystallised from hot water or boiling alcohol. Used chiefly to form other salts.

=Aniline, Sul'phate of=. (C_{6}H_{7}N)_{2}SO_{4}. Prepared by saturating aniline with dilute sulphuric acid, and gently evaporating the liquid until the salt separates. By re-solution in boiling alcohol, it crystallises out, as the liquor cools, under the form of very beautiful colourless plates, of a silvery l.u.s.tre. It is freely soluble in water, and in hot alcohol; scarcely soluble in cold alcohol; and insoluble in ether.

It is chiefly employed in the preparation of the new aniline dyes.

=ANIMAL'CULE= (-kule). [Eng., Fr.; pl. animal'cules.] _Syn._ ANIMAL'CULUM (pl., animal'cula[66]), L.; THIERCHEN, Ger. In _zoology_ and _physiology_, a microscopic animal, or one so extremely small, that it is either invisible, or not distinctly discernible, without the aid of a lens or microscope; more especially one that is not perceptible to the naked eye.

"A mite was anciently thought the limit of littleness; but there are animals 27,000,000 of times smaller than a mite." A thousand millions of some of the animalcula found in common water are said to be collectively of less bulk than a single grain of sand; yet their numbers are so prodigious as sometimes to give the fluid they inhabit a pale red or yellow tinge. The milt of a single codfish is said to contain more of these minute animals than there are people in the whole earth. Animalcula were first scientifically observed by Leuwenhoek about the year 1677.

a.s.sisted by the microscope he unveiled, as it were, he created a new world for future naturalists and microscopists to explore.

[Footnote 66: Animalculae for the plural, sometimes heard and met with, is a barbarism; yet one not wholly confined to the vulgar, for we find it in Vincent's edition of Haydn's admirable 'Dict. of Dates,' not merely twice, or oftener, in the text, but as a 't.i.tle-word,' and also in some other works where we might least expect it.]

"Take any drop of water," says Professor Rymer Jones, "from our rivers, from our lakes, or from the vast ocean itself, and place it under the microscope; you will find therein countless living beings moving therein in all directions with considerable swiftness, apparently gifted with sagacity, for they readily elude each other in the active dance they keep up.... Increase the power of your gla.s.ses, and you will soon perceive inhabiting the same drop, other animals compared to which the former were elephantine in their dimensions, equally vivacious and equally gifted.

Exhaust the art of the optician, strain your eyes to the utmost, until the aching sense refuses to perceive the little quivering movement that indicates the presence of life, and you will find that you have not exhausted nature in the descending scale."

Amongst the most remarkable discoveries of modern science must be reckoned that of fossil animalcules in such abundance as to form the princ.i.p.al part of extensive strata. This discovery is due to Ehrenberg, who found the Polierschiefer (the polis.h.i.+ng slate or tripoli) of Bilin to be almost entirely made up of the siliceous s.h.i.+elds of a minute fossil animalcule, the length of one of which is about 1/288th of a line, so that about 23,000,000 of animalcules must have gone to form a cubic line, and 41,000,000,000 to form a cubic inch of the rock. Ehrenberg succeeded in discovering the formation of similar strata in deposits of mud at the bottom of lakes and marshes, the mud swarming with living animalcules, probably in their turn to be fossilised. The bergmehl, or mountain meal of Sweden and other parts of Europe, which is sometimes used as an article of food, is entirely composed of the remains of animalcules; not merely, however, of their siliceous s.h.i.+elds, for it contains a considerable per-centage of dry animal matter. Some animalcules prefer waters impregnated with iron, and their death gives rise to an ochreous substance in which iron is a princ.i.p.al ingredient.

=AN'IME= (an'-im-e). [Eng., L., Sp.] _Syn._ GUM-AN'IME, A.-RES'IN; ANIMe, Fr.; ANIMEHARZ, KOURBARILLHARZ, Ger.; COURBARIL, JUTAIBA, Nat. A pale brownish-yellow, transparent, brittle resin, which exudes from the _hymenaea courbaril_ (Linn.) or locust-tree, the _h. martiana_, and other species of hymenaea growing in tropical America. It contains about 2% of volatile oil, which gives it an agreeable odour; melts without decomposition; is (nearly) insoluble in alcohol and in caoutchoucine, but forms a gelatinous ma.s.s in a mixture of the two. (Ure.) It burns readily, emitting a very fragrant smell. Sp. gr. 1054 to 1057.

_Uses, &c._ As a fumigation in spasmodic asthma; in solution as an embrocation; and in powder as a subst.i.tute for gum guaiac.u.m. In this country it is chiefly employed to make varnishes and pastilles (which _see_).