to 0°, whereupon it solidifies in the crystalline state; removing the red mother-liquor; and lastly, fusing and again rectifying the product."

953. It is a colourless, neutral liquid, having a not unpleasant odour; specific gravity 2:436 at 23° C.; solidifies below 10° (by slow cooling it yields shining prisms, which melt at 16°); boils between 217° and 218°. It is called isotribromhydrine by Berthelet and De Luca.

954. Terbromide of allyl is isomeric with_terbromhydrine and bibromide of bromopropylene. It is distinguished from terbromhydrine, C, H, Br,, by its boiling point. It is distinguished from bibromide of bromopropylene, C, H, Br Br, by its boiling point, its specific gravity, by solidifying above 0°, and by its behaviour with alcoholic potash, with ammonia, with oxide of silver, and with sodium. Terbromide of allyl is converted, by alcoholic potash, into an etherial liquid which boils at 135°. Ammonia converts it into bibromally lamine, N (C, H, Br), H, and bromide of ammonium. Bromide of bromopropylene, on the other hand, is converted by ammonia into bromide of ammonium, and a compound whose empirical formula is C. H, Br. With moist oxide of silver, terbromide of allyl yields bromide of silver and glycerine, whereas bromide of bromopropylene does not yield glycerine when treated with silver salts. Terbromide of allyl is decomposed by sodium, yielding allyl and bromide of sodium; but it is difficult to remove the whole of the bromine. Bromide of bromopropylene, treated with sodium, yields, not allyl, but bibromopropylene, C, H, Br,.

955. Terbromhydrine is obtained by acting upon bibromhydrine or epibromhydrine (bodies whose acquaintance the student made when studying the decompositions of glycerine) with pentabromide of phosphorus.

956. Perchloride of vinyl or acetyl (C, H, Cl,).—“ If chlorine gas is passed to saturation through chloride of ethylene, covered with a layer of water, and placed in a dark situation; the yellow liquid then brought into the light, where it loses its colour, becomes heated, and gives off hydrochloric acid, which dissolves in the water;

This experiment ought to be repeated, varying the conditions, as the bromide of the bromopropylene ought by analogy to yield glycerine.

chlorine gas continuously passed through it for two days in the light; the watery stratum decanted, and the oil distilled, rejecting the first portion, which passes over below 115° C., and the last portion, which distils above 115° C. The portion obtained in the middle of the process at 115° C., and amounting to three-fourths of the whole, is a pure product."

957. Mixed with alcoholic potash, it immediately be. comes heated, and forms a precipitate of chloride of potassium, and afterwards yields to distillation the liquid C, H, Cl, without any evolution of gas. Exposed to daylight in a bottle filled with chlorine, it is converted, in the course of twenty-four hours, into sesquichloride of carbon and hydrochloric acid,

C, H, Cl, + 6 Cl⇒ C, Cl, + 3 H Cl.

958. Chloroform (CHCl,).-This substance is best prepared by distilling alcohol, wood spirit, or acetone, with a solution of chloride of lime. Bromoform, C H Br,, and iodoform, CHI,, are obtained in a similar manner. Hofmann has clearly proved, in his researches on the compound ammonias, that the radical, C H, in these bodies is triatomic.

NEGATIVE OR ACID CHLORIDES.

Chlorides of triatomic inorganic acids, or negative
chlorides:-

959. Antimony and phosphorus form also pentachlorides. These pentachlorides are sometimes viewed as the trichlorides of a compound chloride radical. Example:

Chloride of chlorophosphoryl chloride of phosphorus)

Chloride of triatomic cyanogen

(penta

(P Cl,)” Cl, ([(CN),]′′ Cl)

The hydrogen compounds of the triatomic radicals, ferricyanogen and cobalticyanogen :

(H, [Fe, (CN),]"); (H ̧ [Co, (C N).]”).

These radicals, ferricyanogen and cobalticyanogen, are triatomic. They may be considered as replacing the three equivalents of chlorine in the treble molecule of hydrochloric acid. The general formula of their salts is therefore,

(M, [Fe, (CN)."); (M, [Co, (CN).]").

QUADRUPLE MOLECULE.

H1CL.

POSITIVE CHLORIDES.

THE CHLORIDES OF THE POSITIVE METALS. 960. Tin and titanium form chlorides on the type of the quadruple atom; the following are therefore the symbols of the molecules of these chlorides, Sn" Cl1; Ti”” ̊C1⁄4 ̧. NEGATIVE GROUP.

Chlorides of tetratomic elements.

961. "Each tetrachloride has a corresponding bichloride, and the general behaviour of the tetrachlorides shows that two of the chlorine atoms are held less forcibly than are the other two."

CHAPTER X.

AMMONIA TYPE.

962. Ammonia, chloride of ammonium, and hydrated oxide of ammonium, although they are all members of the ammonia family, are, nevertheless, constructed on

H

}

different types. Ammonia, HN, is the prototype of a

H

large class of bodies; chloride of ammonium, N H., Cl, is constructed on the type of hydrochloric acid; and

hydrated oxide of ammonium, HO, is constructed on the type of water. One, or even all the atoms of hydrogen in ammonia, in chloride of ammonium, and the atoms in the ammonium in hydrated oxide of ammonium, can be replaced by an equivalent number of simple or compound radicals; these derivatives belong, of course, to the same type as the ammonia, the chloride of ammonium, or the hydrated oxide of ammonium, from which they are derived.

H

963. Phosphoretted hydrogen, HP, arsenetted hydro

H

H

H

H

gen, H As, and antimonetted hydrogen, HSb, are conH) structed on the ammonia type; the hydrogen in these bodies can be replaced, as the hydrogen in the prototype, by other radicals. These derived bodies belong, of course, to the same type, ammonia, as the bodies from which they are derived. Bodies containing phosphorus, antimony, and arsenic, have been produced, resembling chloride of ammonium and hydrated oxide of ammonium in their constitution; these, therefore, necessarily belong to the hydrochloric acid type and the water type, respectively.

964. By means of polyatomic radicals, two, three, four, or even five atoms of ammonia or phosphide, arsenide or antimonide, of hydrogen, can be made to coalesce, the polyatomic radical replacing its equivalent number of hydrogen atoms in the ammonia, &c. We can, in this way, even bind together ammonia with its phosphoretted, antimonetted, or arsenetted analogue.

965. There are, therefore, mon-ammonias and poly-ammonias, and mon-ammoniums and poly-ammoniums. The mon and poly-ammonias are constructed on the type of one, two, or more, atoms of ammonia; they will, therefore, be considered under this type. The mon and poly. oniums come under the type hydrochloric acid, or the type water; if the onium body is combined with any of the halogen elements, or with cyanogen, it comes under the type hydrochloric acid; the other onium compounds come under the type water.

966. We shall now specially consider the bodies which are constructed on the type of a single molecule of

ammonia.

SIMPLE MOLecule.

H

HN
H

967. This group embraces (1) Monamines. (2) The phosphines, arsines, and stibines. (3) The metalamides. (4) The organo-amides.

968. The derivatives of ammonia can be formed by replacing the hydrogen of the ammonia either by alcohol radicals, or by acid radicals, or by metals. When it is replaced by the alcohol radicals, the basic character of the ammonia is more or less preserved; but when it is replaced by the acid radicals, it is lost; but there is such a gradual transition from one group to the other, as regards whether they can, or cannot, combine with acids, that it is frequently difficult to decide from this test to which class an ammonia derivative belongs. But the bodies belonging to the basic class do not yield up, when boiled with potash, ammonia and the radicals whose introduction into ammonia has produced them; indeed, hitherto, very few processes are known in which these bodies yield up their radicals. The bodies belonging to the neutral class, on the other hand, are readily decomposed into ammonia and the hydrated oxides of their radicals. The simplest manner, therefore, of distinguishing to which class any ammonia derivative belongs, consists in boiling the compound under examination with potash;-if it belongs to the basic class, it will remain unaltered; if it belongs to the neutral class, ammonia will be evolved, and a potassium salt formed.

969. The bodies belonging to the basic class are designated by the general terms-amines, phosphines, arsines, stibines, according as they contain nitrogen, phosphorus, arsenic, or antimony.

970. The bodies in which the basic character is extinct are distinguished by the termination ide, as amides, &c. 971. The amine class embraces that large number of compounds known as organic bases, many of which are