2nd. If we act upon this chloride ethyl, or, more conveniently, upon the bromide or iodide of ethyl, with acetate of silver, we obtain acetate of ethyl, thus :

:

3rd. If we treat acetate of ethyl with potash, we reproduce alcohol, thus :

K

H,

C2Ho}0+}0=CF;}0+CHOO

519.-1st. Parallel reactions are produced if, in place of the vinic alcohol, which is monatomic, we operate upon glycol, which is a biatomic alcohol. Thus, if we act upon glycol with pentachloride of phosphorus, we obtain Dutch liquid :

Glycol.

Dutch liquid.

(CH)0,+2 PCI, 2 PC, O+ 2HCl + C, H, Cl2 H2 S

2nd. If we treat Dutch liquid, or the corresponding iodine or bromine compound, with acetate of silver, we obtain acetic glycol ether (diacetate of glycol), thus:

3rd. If we treat diacetate of glycol with potash, we regenerate the biatomic alcohol glycol, thus:

520. From comparison of these facts, it is proved that Dutch liquid is to glycol that which chloride of ethyl is to vinic alcohol; and that, by consequence, Dutch liquid is the ether chloride of glycol, or chloride of ethylene, which is the chemical name by which it is now known.

521. The following is a list of the radicals, C, H2n, which have been produced from the vinic alcohol series :

·-

522. Preparation of these hydrocarbons.-These bodies are produced by the action of an excess of concentrated sulphuric acid, or chloride of zinc, or other bodies which have a strong affinity for water, on the corresponding alcohols (alcohols of the vinic series) at a high temperature; the alcohols become converted, by the abstraction of the elements of water, into these hydrocarbons, thus :Ethylene.

Vinic alcohol.

-

523. These hydrocarbons are also formed along with the alcohol radicals when the iodides of the alcohol radicals are acted upon by zine (195). These hydrocarbons are also formed in the destructive distillation of organic substances; several of them being found among the products of the distillation of coal.

524. In some cases the hydrocarbon, C2 H2n, which is obtained, appears to be coupled, for it has a vapour-density double of that which it ought to possess. For example, the vapour of the hydrocarbon obtained in distilling amylic alcohol, (SO) O2, has a density

C, Hu
H

O, with

H2

exactly double of that obtained by distilling the same alcohol with chloride of zine; therefore, if the equivalent of the latter be represented by C, Ho, the equivalent of the hydrocarbon obtained by the action of sulphuric acid must be C10 H20: the hydrocarbon in this case has therefore suffered condensation, and has been converted into the polymeric paramylene.

525. Properties.-These bodies combine readily with sulphuric anhydride, and with pentachloride of antimony. They are also absorbed by oil of vitriol, and the solution, when diluted with water and distilled, yields the corresponding monatomic alcohol in the vinic series. They also combine, as we have already noticed, with two equivalents of chlorine, bromine, or iodine, forming compounds, the best known of which is Dutch liquid. They are especially distinguished by this property of combining with two equivalents of these metalloids. The property of being dissolved by sulphuric acid, and of forming liquid compounds with chlorine and bromine, is made available for separating olefiant gas, and the other more volatile hydrocarbons of the series, from other gaseous bodies (see exercise 92, page 73). If, after these chlorine compounds, Ca H2n+ Cl2, have been obtained, we continue to act upon the body with chlorine, we can finally remove all the hydrogen, replacing it by chlorine. Olefiant gas is distinguished from the other gaseous members of the group by solidifying into a solid crystalline mass on being exposed to a freezing mixture.

21

526. The hydrides of the alcohol radicals, C, H2n + 19 and also the hydrides of the other alcohol radicals, are capable of furnishing, by the fixation of one equivalent of oxygen, a corresponding series of monatomic alcohols. These hydrocarbons, which we have represented by the formula Č2 H2, also furnish, by the fixation of one atom of oxygen, a corresponding series of monatomic alcohols. But these hydrocarbons of the formula C, H2n furnish, by the fixation of one atom of water, another series of monatomic alcohols. This fixation of water has not yet been accomplished with the marsh gas series. Olefiant gas and its homologues furnish these two series of monatomic alcohols, whilst marsh gas and its homologues have only yet furnished one series, thus:

MARSH GAS SERIES.

OLEFIANT GAS SERIES. By the fixation of one equivalent of oxygen.

MARSH GAS SERIES.

OLEFIANT GAS SERIES.

By the fixation of one equivalent of oxygen.

Hydride of ethyl. Vinic alcohol.

527. The fixation of the one equivalent of oxygen cannot yet be effected directly, but is accomplished by a series of substitution processes. The fixation of water by olefiant gas and its homologues is accomplished by absorbing them by sulphuric acid, adding water and then distilling.

528. These hydrocarbons, C, H2n, are striking examples that the same body can have more than one rational formula; we have already noticed that they can be looked upon as the hydrides of the aldehyde radicals, if we represent the aldehydes on the water type. As they behave in every respect like the marsh gas series with oxygen, giving rise to alcohols of the allylic series, they may be looked upon as the hydrides of the alcohol radicals of this series of alcohols. By their conversion into the vinic series of alcohols by the fixation of water they play the part of monatomic hydrocarbons of the general formula C, H2n. And, lastly, they play the part of diatomic radicals in the diatomic alcohols.*

The chemical atom of these bodies occupies two volumes, and it is also evident, from many of their chemical reactions, as, for instance, their uniting directly with chlorine, &c., that their atoms in the free state are not united in pairs. See foot-note, p. 232.

(3.) COMPOUNDS OF METALS WITH MONATOMIC RADICALS.

529. We have already very frequently pressed on the attention of the student that the formula of bodies, according to the new views, are regulated by their vapourdensities; it is assumed that the molecules of all bodies occupy two volumes in the gaseous state. Now, all the volatile compounds of metals with the monatomic radicals, contain an even number of equivalents of metal in two volumes of vapour, with the exception of those in which biatomic metals occur. Therefore, the formulæ of zincethyl, zinc-methyl, mercury-methyl, mercury-ethyl, cannot be C, H, Zn, &c., as these formulæ only correspond to one volume of vapour, but they must be the double of that, thus:

530. Now, if we contrast the two-volume formulæ of the hydrides and oxides of these alcohol radicals, we shall see that the metals which have hitherto been considered as the strict representatives of hydrogen, do not, as regards their state of condensation in these organometallic bodies, represent hydrogen; mercury and zinc represent oxygen.

531. Nor is this difference between the condensation of hydrogen and the metals confined to organic compounds. Deville and others have recently taken the vapour-density of various metallic chlorides, and have found that these likewise are present in a more condensed form than their hydrogen representative. Whereas the formula of hydrochloric acid is, the formula of an equal volume of M2 M metallic choride is CLS

or

&c.

532. From these considerations, Wanklyn and Wurtz have suggested that the equivalents of zinc, mercury, tin,