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CHLORIDES AND BROMIDES OF NAPHTHALIN.

737

potash, which effects the removal of a certain portion of chlorine or of bromine, and the body which is left is one of those represented in the following table:

2. Compounds formed upon the type (Є10H ̧).

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101

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10H Br

Bronaphtose.

€10H Br

4

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101

Bromechlonaphtuse

3

H,Br,Cl,

Bronaphtise

10 5

eH Br

Chlonaphthalase.

eH CI

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6

HCl,

Chlonaphthalise . €10 Cl

From the results of this decomposition it appears to be probable that the formulæ given in the third column of the first table represent, more accurately than those of the second column, the true composition of the so-called chlorides and bromides of naphthalin, the names of which would require modification accordingly.

It must not, however, be supposed that the foregoing tables indicate all the combinations of chlorine with naphthalin which may be formed by substitution or otherwise. Many of these different compounds exist in several distinct modifications. There are, for example, no fewer than seven distinct forms of chlonaphtese, which Laurent has distinguished by the letters a, c, ad, e, f, x, and y; four of them, a, c, f, and x, are obtained by the distillation of the dichloride of naphthalin, and two of them, ad and e, by treating the same compound with potash, and y is the result of the action of chlorine upon dinitronaphthalin.

a and x are liquid at ordinary temperatures, c crystallizes in needles, which fuse at 122° (50° C.), ƒ crystallizes in tables, fusible at 214°, ad crystallizes in needles, which fuse at about 85°, e fuses at 88°; y fuses at 203° (95° C.), and may be sublimed in plates. Many of these bodies are also distinguished by differences in the degree of their solubility in alcohol and in ether, and by the different way in which they are attacked by chlorine and by bromine.

The existence of these remarkable modifications of chlonaphtese was accounted for by Laurent, on the supposition that in the com

substitution of 6 atoms of hydrogen by 6 of chlorine, the term chlonaphtalase is adopted. If bromine be the displacing body, the prefix bro is employed, and if both chlorine and bromine be present, the name employed indicates by the vowel in the concluding syllable the total number of atoms of hydrogen displaced, whilst the number of one of the halogens is indicated by a vowel attached to the prefix of the particular halogen to be represented. Thus chloribronaphtose indicates (Є,0,HCl, Br), or a compound in which 4 atoms of hydrogen have been displaced by 3 atoms of chlorine, and by 1 of bromine: the name bromechlonaphtose indicates that the 4 atoms of hydrogen displaced are represented by 2 atoms of bromine, and by 2 of chlorine.

738

CHLONAPHTESE-CHLONAPHTISE, ETC.

pound (H), or naphthalin, each of the 8 atoms of hydrogen has its distinct or allotted position in the compound molecule. In chlonaphtese 2 of these atoms of hydrogen are displaced by 2 atoms of chlorine, but it is not a matter of indifference which of I. 2. 3. 4.

the atoms are thus displaced. For example, ife, 10 5. 6. 7. 8.

represent the compound molecule of naphthalin, each numeral indicating a distinct atom of hydrogen, it is not a matter of indifference whether the displacement shall take place thus:

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€10 1, 2, 3, 105, 5, 6, 7, compounds which on

In all these cases we should still have analysis would exhibit a perfectly similar composition; and yet, from the different relative position of the atoms of chlorine in the compound, the properties of each might be different. It may be shown by calculation, upon the principle of permutation, that twenty-eight such varieties of chlonaphtese are possible; of these seven have been discovered. This idea of Laurent has been again handled in a very interesting way by Kekulé in his paper on the aromatic hydrocarbons (1550).

Chlonaphtise has also been obtained in seven different forms, all of which are crystallizable solids. Chlonaphtose is known under four different modifications. The compounds which contain both chlorine and bromine of the type naphtose, in which 4 atoms of hydrogen have been displaced, may be formed in three different ways, and yield three metameric modifications, viz. :— 1. Chloribronaphtose, which is obtained by exposing a mixture of bromine and chlonaphtise to the sun's rays; it forms six-sided prisms, which are fusible, and solidify at a temperature of about 221° (105 C.). 2. Bromachlonaphtose a, which is obtained by passing a current of chlorine over heated bronaphtese: it forms six-sided prisms of the consistence of wax, which after fusion solidify at 230° (110° C.). 3. Bromachlonaphtose ß, which is obtained by the distillation of dichloride of bronaphtese; it forms flattened oblique prisms. Several modifications of many of the other chlorides might be enumerated, but it is unnecessary to particularize further. This great variety of form admits of explanation upon the hypothesis already applied to account for the different forms of chlonaphtese. It is obvious that numerous as are the modifications of many of the forms of these derivatives of naphthalin, they constitute but a small number of the possible varieties which a permutation in the relative position of the elementary atoms of the compound would allow.

ANTHRACENE-METANAPHTHALIN-SHALE OILS.

739

(1564) Anthracene (EH1o; Anderson), formerly called Para14 10; naphthalin; Sp. gr. of vapour 6·741; Fusing pt. 416° (213° C.).— This substance accompanies naphthalin in the last stages of the distillation of coal tar. It may be purified from naphthalin by means of alcohol, which dissolves the naphthalin, but leaves almost all the anthracene untouched. Anthracene was supposed to be polymeric with naphthalin, but Anderson has lately shown that it possesses the formula given above: it is a white solid, which may be distilled without being decomposed, and it condenses in lamellar crystals. Its best solvent is oil of turpentine. Chlorine acts slowly upon anthracene, forming a substitution-compound (Є1H,Cl). Chlorine also combines directly with anthracene, forming the compound 1,H10Cl; with bromine its combination has the formula H1Br. Treated with nitric acid it yields oxanthracene H., which crystallizes in long needles.

14

8 2

(1565) Metanaphthalin, the Retisterene of Dumas [Fusing pt. 153° (67° C.); Boiling pt. 617° (325° C.)], is a compound polymeric with naphthalin: it was obtained by Pelletier and Walter during the distillation of resin. This body is sparingly soluble in cold alcohol, but is readily dissolved by boiling alcohol, as well as by ether, naphtha, and oil of turpentine. It does not appear to form any coupled acid when treated with oil of vitriol.

(1566) During the distillation of the bituminous shale of Dorsetshire, various products are obtained, which greatly resemble those contained in coal tar. The hydrocarbons approach in composition to (Han). A portion of the oil, which boils between 390° and 480°, furnishes a substance resembling kreasote, which Laurent termed ampelin: it is soluble to a considerable extent in water, but the addition of a few drops of an acid or of the solution of certain salts causes the separation of the ampelin. Ampelin is decomposed when the attempt to redistil it is made. By treating the oils of schist with nitric acid, Laurent obtained an acid metameric with the salicylic, and which he termed ampelic acid.

Shale tar is particularly rich in basic substances. G. Williams has detected in it, in addition to pyrrol, ammonia, pyridine, picoline, lutidine, collidine, and parvoline; besides two other bases as yet but imperfectly examined, which have been termed carmidine and vertidine. It is remarkable that aniline is not present amongst these bases. (Q. J. Chem. Soc., vii. 97.)

The destructive distillation of bones, and of azotised animal matters generally, yields a substance commonly known as Dippel's animal oil. This oil comes over accompanied by an aqueous liquid, charged with carbonate, sulphide, and cyanide of ammo

740

DIPPEL'S OIL-PYRROL.

nium. The oil itself is a complex mixture, consisting of a part which is soluble in acids, and of an insoluble portion; the latter constituting the larger part of the oil. In the portion soluble in acids, various volatile bases are present, including methylia, ethylia, tritylia, tetrylia, and amylia,―aniline, pyridine, picoline, lutidine, and the substance termed pyrrol by Runge. The portion insoluble in acids contains benzol, and a mixture of several nitriles.

4

(1567) Pyrrol (ЄH ̧N); Sp. gr. of liquid 1'077; of vapour 2'47; Boiling pt. 271° (133° C.).—This body has been carefully examined by Anderson (Edin. Phil. Trans., xxi. 586). Its purification is attended with considerable difficulties. During the distillation of the acid solution of the crude pyridine bases (1368) from Dippel's oil, a peculiar fœtid oil is obtained, which is colourless at first, but it becomes in a few days of a reddish colour, and ultimately nearly black. On subjecting this oil to fractionated distillation, a considerable portion is obtained between 270° and 290°. If agitated with dilute sulphuric acid and dried over sticks of potash, it may be obtained nearly pure by repeated rectification. In order to purify it perfectly, it should be digested in a copper flask with 5 or 6 times its weight of caustic potash, allowing the liquid as it distils to fall back into the flask. Gradually the pyrrol enters into combination with the potash, and the heat may be raised nearly to redness without expelling any portion of the pyrrol. The residue thus obtained in the retort, after any traces of picoline have been expelled by heat, when thrown into water is decomposed, and pure colourless pyrrol rises to the surface.* This liquid has an odour faintly resembling that of chloroform, and a hot pungent taste. It becomes brown when exposed to the air. It is insoluble in alkaline solutions, but is slowly dissolved by acids. Its most remarkable reaction is the production of a pale pink colour, which gradually deepens to an intense carmine when a splinter of fir-wood moistened with hydrochloric acid is exposed to the vapour of pyrrol. When a solution of pyrrol in a dilute acid is heated, a red flocculent substance is deposited, and the liquid, if not extremely dilute, becomes of a gelatinous consistence; a similar change occurs in the acid

* Schwanert finds pyrrol among the products of the dry distillation of ammonium pyromucate (H,NE,H,,), accompanied by a substance which he terms carbo-pyrrolamide HN,, the amidated compound of an unstable acid, the carbo-pyrrolic, which readily breaks up into pyrrol and carbonic anhydride :

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BITUMEN, ASPHALT, AND PETROLEUM.

741

solutions at ordinary temperatures if left for a few days. Alcoholic solutions of pyrrol precipitate solutions of corrosive sublimate, and of cadmic chloride, but not those of the metals in general.

4

12 14

12 14 2

The red substance obtained by the action of acids is supposed by Anderson to have the composition of 12HNO, being formed from pyrrol by the elimination of the elements of ammonia and the assimilation of water, thus: 3 H ̧N+H2O=H2N=Є12H12N2O. (1568) Bitumen, Asphalt, and Petroleum.-Closely connected with the products of destructive distillation are the different forms of bitumen, asphalt, and petroleum. Deposits of these substances are found in various localities, as, for example, at Trinidad, at Zante, and in some parts of the north of Italy, and also on the borders of the Caspian Sea, where petroleum occurs in beds of marl above coal measures. Petroleum is likewise abundant at Rangoon, and in several other localities of the kingdom of Burmah, where the naphtha is obtained from a pale blue clay, soaked with oil, which rests upon roofing slate, beneath which is coal containing much pyrites. The petroleum (petri oleum, rock oil) from the lastnamed locality has been made the subject of examination by De la Rue and H. Müller (Proceed. Roy. Soc., viii. 221). It is obtained by sinking wells about sixty feet deep, in which the liquid is collected as it oozes from the soil. At common temperatures it has the consistence of goose fat; it is lighter than water, and has usually a greenish-brown colour; it has also a slight, peculiar, but not unpleasant odour. It is composed almost entirely of volatile constituents, about 11 per cent. of which come off below 212°. The fixed residue does not amount to more than 4 per cent. if it be distilled in a current of superheated steam. About 10 or 11 per cent. of the volatile matters consist of a body fusible at 149° (65° C.), but which is solid at ordinary temperatures (paraffin). When the liquid portion is agitated with oil of vitriol, some of its constituents enter into combination with the acid, but the greater part remains unaltered by this agent. In the portion which combines with the acid, benzol, toluol, xylol, and cumol have been identified, and there are several basic substances which have not as yet been completely examined. The liquid from which the hydrocarbons of the benzol series have been removed by the action of oil of vitriol, after being rectified, constitutes rock oil, or mineral naphtha; it is a mixture of several hydrocarbons, and is the liquid in which potassium and sodium are preserved. In order to purify it for this purpose, the crude distillate must be agitated several times with a fifth of its bulk of oil of vitriol; after which the undecomposed hydrocarbon is to be well washed

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