When the result of this reaction is distilled with caustic potash, ethylia is liberated, whilst water and potassic iodide are formed. Now, if ethylia be submitted in a sealed tube to a fresh portion of ethyl iodide, a second atom of hydrogen will be removed, and an additional equivalent of ethyl will be substituted for it, whilst the hydriodate of a new base (diethylia) is formed :— and if diethylia hydriodate be submitted to distillation with caustic potash, diethylia itself will be liberated. This base may in its turn be treated with a fresh portion of ethyl iodide, and so the third atom of hydrogen may be displaced by a third equivalent of ethyl, yielding a salt which, when distilled with potash, furnishes a third base, triethylia (Є,H),N. Each of the alcohols may be made to furnish bases corresponding to each of the foregoing ethyl bases; for instance, by similar methods, a mixture of methyl iodide and ammonia can easily be made to yield methylia, dimethylia, and trimethylia; and from amyl iodide, amylia, diamylia, and triamylia may be formed. These bases are all homologous with ammonia, which they closely resemble in properties. But the action of ethyl iodide does not stop even here, for it is possible, by its means, to obtain a fourth series of bases homologous with the hypothetical body ammonium. (Hofmann, Phil. Trans., 1851.) If, for example, a quantity 5/4 of triethylia be heated in a tube with an additional quantity of ethyl iodide, the two bodies enter into combination, and a compound [(Є2H.), N,I], analogous to ammonium iodide (H ̧N,I), is formed; all the 4 atoms of hydrogen in the ammonium having been displaced by a corresponding number of equivalents of ethyl: Triethylia. Ethyl iodide. Tetrethylium iodide. (¤ ̧Н¿) ̧N + ¤‚Í‚I = (¤ ̧H¿) ̧Ñ‚I. The iodide thus obtained is a crystalline substance. It is not possible to obtain the base tetrethylium (E,H,), N, in a separate form; since, like ammonium, it immediately undergoes decomposition; nor can the base be liberated by the action of a solution 518 ARTIFICIAL BASES DERIVED FROM THE ALCOHOLS. of caustic potash; but if a solution of the iodide be treated with freshly precipitated oxide of silver, double decomposition ensues, iodide of silver is formed, and the hydrated oxide of tetrethylium is liberated: : Tetrethylium iodide. (Є2H,),N,I + AgHO = Hydrated tetrethylium oxide. AgI + (Є2H),NHO. It might have been anticipated that, under these circumstances, tetrethylium oxide would have been resolved into triethylia and alcohol, just as ammonium oxide becomes broken up into ammonia and water when similarly treated: thus, since H Tetrethylium H Ꮎ (¤‚H ̧), NI + AgH✪ should become AgI + H+(¤‚H ̧) ̧Ñ; but such is not the case; the new compound is very stable, and on evaporation of the solution, the hydrate of the new base may be obtained in crystals, which, like those of caustic potash, absorb water and carbonic acid from the atmosphere, and possess the caustic action of potash, combined with a bitter taste like that of quinia. This base forms the type of a numerous class, which are analogous to it both in composition and in properties. Hydrated tetrethylium oxide in common with many others like it, such as the hydrated tetramethylium oxide [(ЄH ̧),NH→], is sufficiently powerful to saponify the oils, and to precipitate the metallic oxides from their salts, just as potash does. It forms crystallizable salts. These bases differ in a marked manner from such bases as ethylia, diethylia, and triethylia, all of which, like ammonia, are volatile without decomposition. The hydrated tetrethylium oxide, and others which resemble it, however, cannot be volatilized without undergoing decomposition, in which case they are converted into water, a hydrocarbon homologous with olefiant gas, and a volatile alkali corresponding to triethylia; for example : Hydrated tetrethylium oxide. Olefiant Triethylia. (Є2H ̧) ̧NH‡ = H ̧0 + ¤‚H ̧ + (Є¿H¿) ̧N. Ammonia is thus capable of originating two classes of bases, one set being volatile, and corresponding in properties to ammonia itself, and hence termed ammonia bases; the other set fixed, resembling caustic potash in properties, and corresponding to ARTIFICIAL BASES DERIVED FROM THE ALCOHOLS. 519 hydrated ammonium oxide, and hence distinguished as ammonium bases. The ammonia bases in the free state precipitate many of the metallic oxides from solutions of their salts, and like the organic bases generally, furnish sparingly soluble crystalline double salts when their chlorides are mixed with platinic chloride. If in the preparation of these bases, by substitution from the iodides of the alcohol radicles, phenylia (EH,,H,N), or aniline, as it is commonly termed, be employed instead of ammonia, a corresponding series of bases may be obtained from it, in which the two remaining typical atoms of hydrogen in aniline may be successively displaced by one equivalent of one of the alcoholic radicles; and finally, the compound may be converted into an ammonium base by the action of another atom of ethyl iodide; 6 for example, aniline (or phenylia) HN, becomes, when treated with ethyl iodide, successively, 1. ethyl-phenylia, H, N; 2. diethyl-phenylia, Є,H. N; 3. and finally, hydrated triethyl 5 €2H2 2 5 Hofmann, in the further investigation of this remarkable method of preparing artificial bases, found that each of the three atoms of hydrogen in ammonia may be displaced by a different alcohol radicle. For instance, it is possible to obtain, first, * The successive stages of these reactions are usually less distinct than the foregoing statement would make it appear. Even during the first operation of the iodide of the alcohol radicle upon ammonia, a mixture of the secondary and tertiary bases, or even of the ammonium base, is observed; so that the isolation of a single base is not easy. The ammonium base may always be obtained pure with certainty by decomposing the product of the first operation with potash, and treating the mixed bases which come over on distillation, with fresh iodide, and repeating these operations successively two or three times. The whole of the distilled bases finally become converted into the ammonium base. The tertiary bases, like triethylia, may also easily be obtained pure, since, if the ammonium base be liberated from the iodide by means of oxide of silver, and be then distilled, the distillate furnishes the tertiary base in a pure state. The primary bases, such as ethylia, are best obtained pure by distilling the cyanic ether of the alcohol with caustic potash; but the secondary bases, like diethylia, are less readily procured in a pure form. 520 ARTIFICIAL BASES DERIVED FROM ANILINE. methylia, by the action of methyl iodide upon ammonia; then by acting upon methylia with ethyl iodide, the compound methylethylia (corresponding to diethylia) is formed :— and on distilling this hydriodate of methyl-ethylia with caustic potash, the new base is liberated. Now, if methyl-ethylia be treated with amyl iodide, a compound corresponding to triethylia is formed, but containing, in the place of the three atoms of ethyl, three different alcohol radicles; for example : : Methyl-ethyl-amylia Amyl iodide. hydriodate. ен Hofmann even succeeded in obtaining an ammonium base, derived from aniline, containing 4 different hydrocarbon radicles, and to which the unwieldy name of hydrated methyl-ethylamylo-phenylium oxide must be assigned : It, of course, will not be overlooked that if the ordinary salts of ammonia are supposed to be compounds of ammonia, the salts of all the bases derived from ammonia ought to be considered from the same point of view :-If ammonia hydriodate be regarded as ammonium iodide, ethylia hydriodate should be ethylium iodide, and the composition and nomenclature of the ethyl bases would be simply translated thus (no hydriodates of the ammonium bases are known) : : In this work, however, for the sake of marking the distinction between the volatile and the fixed bases, the termination ium will be reserved for such bases as are formed upon the type of hydrated ammonium oxide. (1374) Isomeric Bases. - An important circumstance, in relation to the molecular constitution of ammonia, was elicited in the course of these investigations. Let the three atoms of hydrogen in ammonia be represented by the letters h, H and H; and h let HN ammonia :-it might be supposed that the three different H = atoms of hydrogen h, H, and H, in the molecule of ammonia, might each have a different function to perform in the alkaline group. Suppose, then, that a derivative base were formed, in which the atom of hydrogen h were replaced by a radicle called X X, forming a new base HN; the other atoms of hydrogen, H H and H, admit of being displaced respectively by other radicles, Y and Z. Suppose, for example, that X represents phenyl (EH), Y, amyl, and Z, ethyl; the question is, whether the same compound will be formed indifferently when amyl is substituted for H, and ethyl for H, or when ethyl supplies the place of H, and amyl of H. Whether, in fact, there will be any perceptible difX X ference if the compound be obtained in the form of Y N; or of Z N. To decide this point Hofmann carefully compared the properties of phenyl-amyl-ethylia (Є1HN), prepared by acting upon phenyl€1H;) amylia, HN, by ethyl bromide (E,H,Br), which would yield ЄHN, with the compound phenyl-ethyl-amylia, Є,H, N, 5 formed by decomposing phenyl-ethylia, EH, N, with amyl bro H 5 mide (ЄH1Br); but the two substances comported themselves alike in all respects. The two bodies thus obtained are, there |