volatilises. Treated with acid it gives salts, and by long heating the anhydrous oxide [Sn(CH3)3]2O.

Of the dimethyl compounds distan-tetramethyl has been prepared, but requires further investigation. Stan-dimethyl diiodide, Sn(CH3)2I2, crystallises in prisms, melting at 22°, boiling at 228°, and pretty readily soluble in water. Ammonia precipitates from it amorphous stan-dimethyl oxide, insoluble in water, soluble in potassic hydrate, and yielding crystalline salts with the acids.

Compounds containing both ethyl and methyl are also known. Their formation is represented by the equations:

Sn(C2H5)2Cl2 + Zn(CH3)2 = ZnCl2 + Sn(C2H5)2(CH3)2 and 2Sn(CH3)3Cl + Zn(C2H5)2 = ZnCl2 + 2Sn(CH3)3(C2H5).

355. Of normal propyl and isobutyl derivatives there have been prepared Sn(C3H7),I as a liquid boiling at 269°-270°, and Sn(C,H)3I as an oil boiling at 292°-296°. Stan-triisobutyl hydrate is solid, amorphous, volatile, and of strongly alkaline reaction.

LEAD COMPOUNDS OF THE ALCOHOL RADICALS.

356. In most of its inorganic compounds lead acts as a diad element, but in its compounds with the alcohol radicals, as far as they are yet known, it behaves as a tetrad.

The compounds Pb(CnH2n+1) are prepared by action of alcoholic iodides upon an alloy of lead and sodium, or better by treatment of plumbic chloride with organo-zinc compounds, followed by distillation. Probably the diad compounds or the double molecule of the latter are first formed:

PbNa2

PbNa2

PbCl 2

Ръс

PbCl2

+ 2Zn(CnH2n+1)2 = 2ZnCl2 + Pb2(CnH2n+1)4

which yield lead and the tetrad compound at a far lower temperature than in the case of distan-tetrethyl:

By halogens the latter are converted into alkylic haloids and monohaloid derivatives:

Pb(CnH2n+1)4 + I2 = CnH2n+1I + Pb(CnH2n+1)зI ;

by acids into paraffins and salts:

Pb(CnH2n+1)+ HCl = CnH2n+2 + Pb(CnH2n+1)3Cl 2Pb(CnH2n+1)4 + H2SO4 = 2CnH2n+2 + [Pb(CnH2n+1)3]2SO4. From these salts the strongly basic hydrates, Pb(CnH2n+1)3OH, can be obtained. Methyl, ethyl, and isoamyl compounds are known.

R

357. Lead Methyl Compounds.-On adding to perfectly dry plumbic chloride, contained in a distillation apparatus, filled with dried carbonic anhydride, a quantity of zinc methyl insufficient for complete decomposition, metallic lead separates, and on distillation plumb-tetramethyl, Pb(CH3)4, passes over as a colourless, mobile liquid, boiling at 110°. The sp. gr. is 2.034 at 0°, its found vapour density at 130° 9.52 (theoretical 9-25). It is insoluble in pure water, but readily in alcohol and ether; it is not affected by atmospheric oxygen. If plumbic tetramethyl be boiled for some time with hydrochloric acid there separates, on cooling, long silky needles of plumb-trimethyl chloride, Pb(CH3)3C1, which can, when dry, be sublimed in a small glass tube.

=

By the decomposition of plumb-tetramethyl by careful addition of iodine, plumb-trimethyl iodide, Pb(CH3)3I, is obtained in colourless needles, little soluble in water, readily in boiling alcohol. If this be distilled with solid potassic hydrate, an oil smelling like mustard passes over, which solidifies to strongly alkaline prisms, probably of plumb-trimethyl hydrate, Pb(CH3)3.OH.

358. Lead Ethyl Compounds. Plumb-tetrethyl, Pb(C2H5)4, is usually prepared by decomposition of plumbic chloride with zinc ethyl, and distillation in vacuo of the liquid poured off the precipitated lead. It is a colourless liquid of 1.62 sp. gr., boiling with partial decomposition at above 200°. When heated in the air it burns with an orangecoloured, green-mantled flame. Boiled with hydrochloric acid, it gives plumb-triethyl chloride, Pb(C2H5)3Cl, with evolution of ethane, and reacts with iodine to form the respective iodides :

Pb(C2H5) + I2 = Pb(C2H5)3I + C2H¿I.

Both haloid compounds crystallise in needles, are volatile, and smell like mustard oil. When distilled with solid potassic hydrate, plumbtriethyl hydrate, Pb(C2H5)3.OH, passes over as an oily, strongly alkaline liquid, of powerful odour, which solidifies on cooling to a mass of interlaced needles. Plumb-triethyl sulphate, [Pb(C2H5)3]2SO4, separates, on neutralisation of an aqueous solution of the hydrate with sulphuric acid, in difficultly soluble, hard, brilliant octahedra.

359. Plumb-tetrisoamyl, Pb(C,H11), is obtained, by action of isoamylic iodide upon lead-sodium alloy, extraction of the product with ether, and evaporation of the filtered solution, as a yellow oily liquid which cannot be distilled unaltered. Plumbic triisoamyl iodide, Pb(CH)I, prepared from this, crystallises in colourless needles. The hydrate and chloride are also known.

ALUMINIUM COMPOUNDS OF THE ALCOHOL RADICALS.

360. On heating aluminium filings with ethylic iodide in sealed glass tubes to 130°-150°, there is obtained a thick liquid, spontaneously inflammable in air, and decomposed by water with explosive violence. This results from the direct union of the metals with the components of the ethylic iodide, and without doubt has the composition Al2(C2H5)313. Pure aluminium ethyl cannot be obtained by distillation from this, the liquid distilling over invariably containing some iodine.

Organo-aluminium bodies can be obtained in a state of purity by

digesting the corresponding mercury compounds with thin aluminium foil, this method serving especially for the preparation of the methyl and ethyl compounds. From the determinations of their vapour densities these bodies immediately above their boiling points must be expressed by the formula Al(CnH2n+1)6, being analogous to that of aluminic chloride; on increasing the temperature, however, the vapour density decreases and approaches to nearly half its former value, i.e. corresponds to the molecular formula Al(CnH2n+1)3. The organoaluminium compounds fume in the air, readily inflame spontaneously, and then burn with evolution of thick fumes of alumina. Water decomposes them with explosive violence into paraffins and aluminic hydrate:

Al2(CnH2n+1)6 + 6H2O = Al2(OH)6 + 6CnH2n+2

Aluminium methyl, Al,(CH3), or Al(CH3)3, is obtained by digesting mercury dimethyl with aluminium foil and then distilling. It is liquid at ordinary temperatures, crystalline at 0°, and boils at 130°. Immediately above this temperature the vapour density is 4:35, at 160° only 3.9-4.1, and finally at 240° only 2·8. The theoretical density for Al,(CH3)6 is 4.98; for Al(CH3)3, 2:49.

Aluminium ethyl, Al2(C2H5), or Al(C2H5)3, obtained in similar manner to the methyl compound, is still liquid at -18° and boils at 194°. At 230° its vapour density is found to be 45. The vapour would therefore appear to be a mixture of a little Al2(C2H5)6 (theoretical density 7-88) with much Al(CH3)3 (theoretical density 3.94).

MERCURY COMPOUNDS OF THE ALCOHOL RADICALS.

361. Mercury forms saturated compounds with two alcohol radicals, Hg(CnH2n+1)2. They can be prepared by the action of organo-zinc compounds with mercuric chloride :

HgCl2 + Zn(CnH2n+1)2 = ZnCl2 + Hg(CnH2n+1)2 ;

and directly by the action of sodium amalgam, diluted with much mercury upon the alcoholic iodides, some ethylic acetate being generally also added:

HgNa2+2ICnH2n+1 = 2NaI + Hg(CnH2n+1)2.

By careful addition of halogens to these compounds one alcohol radical is removed and replaced by the halogen:

Hg(CnH2n+1)2 + I2 = Hg(CnH2n+1)I + CnH2n+1I;

but excess of halogen converts these into mercuric haloids:

Hg(CnH2n+1)I + I2 = HgI2 + CnH2n+1.I.

Halogen hydro-acids even in excess only cause the replacement of one alcohol radical:

Hg(CnH2n+1)2 + HCl = Hg(CnH2n+1)Cl + CnH2n+2

The oxy-acids act similarly and form corresponding salts.

The iodides can be prepared directly from the alcoholic iodides and mercury in presence of sunlight:

Hg + CnH2n+1I

CnH2n+1

= Hg<I
HgCnH2n

and can be converted into the diorgano-compound by heating with potassic cyanide :

2

2Hg(CnH2n+1)I + 2KCN = 2KI + Hg + C2N2+ Hg(CnH2n+1) 2. If the haloid compounds be brought into contact with moist argentic oxide, the caustic basic hydrates are formed: CnH2n+1

Hg<CnH2n+1 + AgOH= AgCl + Hg OH

which yield salts with acids. All these compounds are extremely poisonous, especially when the vapours of the volatile ones are breathed. Strong dilution with air does not prevent this action, long breathing of such a mixture producing chronic poisoning of the most fearful description.

No compounds of mercury with alcohol radicals of the formula Hg2(CnH2n+1)2, corresponding to mercurous chloride, have been

obtained.

362. Methyl Compounds.-In order to prepare mercury dimethyl one per cent. sodium amalgam is slowly added with constant shaking to a mixture of methylic iodide with one-tenth of its volume of ethylic acetate. The mixture becomes hot, while mercury and sodic iodide separate. If the proportion of the latter becomes so large that the liquid becomes pulpy, all volatile matters must be distilled off and treated anew with sodium amalgam. This treatment is continued until one atom of sodium has been added for every molecule of methylic iodide, and a small quantity of the liquid no longer yields iodine on boiling with nitric acid. The distillate, after addition of water, is shaken with potassic hydrate to remove ethylic acetate, and the separated heavy oil dried by calcic chloride and rectified.

3

Mercury dimethyl, Hg<CH;, is a colourless refractive liquid not miscible with water, boiling at 95°, and has sp. gr. 3.069 at ordinary temperatures. It has a faint, somewhat sweet odour, does not alter in air, is, however, readily inflammable, and burns with a luminous flame with evolution of mercury vapours. It dissolves caoutchouc, resin, and phosphorus.

Mercury methyl-iodide, Hg<CH3, is prepared from the preceding

by addition of iodine to its aqueous solution. It separates in crystals, and is obtained pure on recrystallisation from hot alcohol in white nacreous plates. It melts at 143°, sublimes readily, is insoluble in water, but is readily soluble in alcohol and ether.

CH3

Mercury methyl-chloride, Hg, completely resembles the

iodide.

An alcoholic solution of the iodide gives, on addition of argentic nitrate, a precipitate of argentic iodide, and the filtrate on evaporation in vacuo yields colourless, transparent prisms of mercury methylnitrate:

CH3
Hg

CH,

+ AgO.NO2 = AgI+Hg O.NO2

AgI+Hg<0.NO2

readily soluble in water, but difficultly in alcohol. It melts at

100°, and on cooling becomes crystalline again. From its aqueous solution metallic chlorides precipitate mercury ethyl-chloride; alkalies produce no precipitate.

363. Ethyl Compounds.-Mercury diethyl, Hg(C2H5)2, is prepared like the methyl compound, and shows similar properties. It is a liquid of sp. gr. 2:44 and boiling at 159°. The vapour density is 9.97. At 200° its vapour decomposes into mercury and butane.

Mercury ethyl-chloride, HgC2H5, , prepared, amongst other me

thods, by mixing solutions of mercury diethyl and mercuric chloride : Hg(C2H5)2 + HgCl2 = 2Hg(C2H¿)Cl,

forms white silvery needles.

Mercury ethyl-iodide, HgCH, obtained from mercury and

ethylic iodide in diffused daylight. By direct sunlight it is decomposed into mercury and butane (together with some ethane and ethylene).

C2H5

By treatment of the haloid compounds with moist argentic oxide, mercury ethyl-hydrate, Hg, goes into solution, and is left on evaporation as a strongly caustic alkaline liquid, which precipitates most metals from their salts as hydrates and yields crystalline salts with acids.

364. Mercury dipropyl, Hg(CH2.CH2.CH3)2, boils at 189°-191° and has sp. gr. 2·124 at 16°.

Mercury diisobutyl, Hg(C4H9)2, distils between 205°-207°; sp. gr. 1.835 at 15°.

Mercury diisoamyl, Hg(C5H11)2, is readily obtained from a mixture of isoamylic iodide, acetic ether, and sodium amalgam. It is a colourless liquid, cannot be distilled unchanged, is insoluble in water, has sp. gr. 166, and gives with iodine crystalline plates of mercury isoamyl iodide, Hg(C¿H11)I.

ZINC COMPOUNDS OF THE ALCOHOL RADICALS.

365. On submitting granulated zinc for a long time to the action of alkylic iodides with exposure to light, then, as with other metals, bodies of the formula Zn(CnH2n+1)I result. The same change occurs on heating, only goes further, so that in sealed tubes zinc and paraffins (as di-radicals) are formed (§ 150), some zinc compound of the alcohol radical being formed at the same time. The zinc compound is obtained in larger quantity when anhydrous ether is mixed with the alkylic iodide and the mixture heated with zinc in sealed tubes to 130°-150°.

After cooling the tube is carefully opened, when gaseous products (paraffins, &c.) escape. By gentle warming the ether is expelled, and the residue, consisting mainly of the iodo-zinc compound, distilled in a stream of carbonic anhydride, decomposition occurring as shown by the equation:

2Zn(CnH2n+1)I = ZnI2 + Zn(C2H2n+1)2

Organo-zinc compounds may also be obtained by heating the alkyl