Edward Frankland (1825-1899)

On a New Series of Organic Bodies Containing Metals

Under the above title I described, more than three years ago, some preliminary experiments[1] which proved the existence of certain organic compounds highly analogous to cacodyl, and, like that body, consisting of a metal, or in some cases phosphorus, associated with the groups C₂H₃, C₄H₅, C₆H₇, &c., and possessing, in most instances, highly remarkable powers of combination. I fixed the composition and studied some of the reactions of two of these bodies, to which the names Zincmethyl (C₂H₃Zn) and Zincethyl (C₄H₅Zn) were provisionally assigned, besides giving methods for procuring similar compounds containing tin, arsenic and phosphorus, by acting upon the iodides of the alcohol radicals with these elements, and expressing a belief, founded upon the similarity of functions existing between hydrogen and the groups of the form C_nH_(n+1), that most, if not the whole, of the compounds contained in the following series might be formed; those marked thus * being at that time already known.

Hydrogen series.	Methyl series.	Ethyl series.	Butyl series.	Valyl series	Amyl series.	Phenyl series.
ZnH	ZnC2H3*	ZnC4H5*	ZnC6H7	ZnC8H9	ZnC10H11	ZnC12H5
AsH2*	As(C2H3)2*	As(C4H5)2	As(C6H7)2	As(C8H9)2	As(C10H11)2	As(C12H5)2
SbH3*	Sb(C2H3)3	Sb(C4H5)3	Sb(C6H7)3	Sb(C8H9)3	Sb(C10H11)3	Sb(C12H5)3
PH3*	P(C2H3)3*	P(C4H5)3	P(C6H7)3	P(C8H9)3	P(C10H11)3	P(C12H5)3

More recently Löwig and Schweitzer[2] have commenced labouring in the same field, and have filled up one of the gaps in the foregoing table by the formation of stibethyl (Sb(C₄H₅)), in acting upon iodide of ethyl with an alloy of antimony and potassium; the same chemists state also the probable formation of similar compounds containing methyl and amyl in place of ethyl, and bismuth and phosphorus instead of antimony.

I have continued my researches upon the organo-metallic bodies formed as above described, and having succeeded in increasing the list by the addition of several new members, I propose, in a series of papers, of which this is the first, to lay before the Royal Society the results of my experiments on the formation of bodies of this class.

The agents which I have hitherto employed in the formation of these organo-metallic compounds are two, viz. heat and light; in many cases either of these can be used, in others only one can be made to effect the desired combination, whilst more rarely the assistance of both appears to be essential. In those experiments in which heat was employed the materials were subjected to its action in sealed glass tubes, about 12 inches long, and varying in diameter from half an inch to 1 inch, the thickness of the glass being about one-eighth of an inch[3]. To preserve the gaseous products of the operation in a state of perfect purity for subsequent investigation, the tubes were well exhausted before being sealed; they were then immersed to about half their depth in an oil-bath, and heated to the required temperature. In cases where the influence of light was employed, the materials, confined in tubes of precisely similar dimensions, were exposed to the sun's rays, concentrated in most cases by an 18-inch parabolic reflector, near the focus of which the tubes were placed, either naked or surrounded by a solution of sulphate of copper to absorb the calorific rays. By this arrangement the light and heat could be increased, diminished or modified at pleasure, which was found very convenient in several of the operations.

Action of Tin upon Iodide of Ethyl.

Examination of Solid Products.

I. 1.6806 grm., treated with aqueous solution of ammonia, was immediately decomposed, iodide of ammonium being formed, whilst the iodine in the original compound became, as I shall show below, replaced by oxygen; this oxide, which is almost absolutely insoluble in ammonia, collected on a filter and dried at 100° C., weighed .7263 grm.; decomposed by boiling nitric acid it gave .5811 grm. peroxide of tin. The ammoniacal solution, acidulated with nitric acid and precipitated by nitrate of silver, yielded 1.8418 grm. iodide of silver. After precipitation of the excess of nitrate of silver by hydrochloric acid, sulphuretted hydrogen was passed through the solution, and the slight precipitate formed was washed, dried, ignited and added to the above peroxide of tin, in the weight of which it is included.

II. 1.4254 grm., burnt with oxide of copper, 2 inches of metallic copper being placed in front of the combustion-tube, gave .5858 grm. carbonic acid and .2975 grm. water.

III. 1.2209 grm. gave 0.5008 grm. carbonic acid and .2580 grm. water.

IV. 2.0980 grms., treated as described in No. I., yielded .9218 grm. of the body produced by the action of solution of ammonia, which yielded .7239 grm. peroxide of tin. The ammoniacal solution, precipitated by nitrate of silver as in No. I., produced 2.2883 grms. iodide of silver.

V. .9113 grm. gave .3735 grm. carbonic acid and .1908 grm. water.[5]

These numbers show that the crystalline body is a compound of one atom of ethyl, one atom of tin, and one atom of iodine. The formula --

	Calculated.[6]		Found.
			I.	II.	III.	IV.	V.
C4	24	11.18	----	11.21	11.19	----	11.18
H5	5	2.33	----	2.32	2.35	----	2.33
Sn	58.82	27.40	27.18	----	----	27.12
I	126.84	59.09	59.21	----	----	58.76
		100.00

For reasons described below, I propose to call this compound iodide of stanethylium.

Iodide of stanethylium crystallizes in transparent, slightly straw-coloured needles, which are right rectangular prisms, frequently one-twelfth of an inch broad and 2 or 3 inches in length. They are very soluble in ether and in boiling alcohol; less so in cold alcohol and in water; the watery solution is decomposed on boiling, oxide of stanethylium being precipitated and hydriodic acid formed. Iodide of stanethylium fuses at 42° C., and boils at 240° C., undergoing at the same time partial decomposition: it possesses, at common temperatures, a peculiar pungent odour, somewhat resembling the volatile oil of mustard, and which irritates the eyes and lining membrane of the nose, causing a discharge which continues for several hours or even days, especially if the vapour from the heated iodide of stanethylium be inhaled; yet this compound can scarcely be said to be volatile at common temperatures, since a few grains may be exposed to the air for several weeks without any appreciable loss of weight.

Oxide of Stanethylium.

I. .3497 grm., burnt with oxide of copper, gave .3218 grm. carbonic acid and .1630 grm. water.

II. .7296 grm., decomposed by nitric acid and ignited, gave .5778 grm. peroxide of tin.

III. .9218 grm. gave, when similarly treated, .7239 grm. peroxide of tin.

These numbers agree closely with the formula --

	Calculated.		Found.
			I.	II.	III.
C4	24	25.05	25.09	----	----
H5	5	5.22	5.18	----	----
Sn	58.82	61.39	----	62.25	61.73
O	8	8.34	----	----	----
		100.00

Analyses nos. I. and IV. of iodide of stanethylium also clearly show the transformation of the iodide into the oxide of stanethylium by ammonia; in analysis No. I. 1.6806 grm. of iodide of stanethylium gave .7263 grm. of oxide of stanethylium, and in analysis No. IV. 2.0980 grms. of the iodide yielded .9218 grm. of the oxide of stanethylium. Hence

	Calculated.	Found.
		I.	II.
100 parts of iodide of stanethylium yield of oxide of stanethylium	44.64	43.22	43.93

The numbers obtained by experiment correspond sufficiently well with the theoretical one, when it is considered that oxide of stanethylium is not absolutely insoluble in excess of ammonia.

Oxide of stanethylium presents the appearance of a somewhat cream-white amorphous powder, closely resembling peroxide of tin, but less heavy than that oxide; it has a peculiar though slight ethereal odour and a bitter taste; it is insoluble in water, alcohol and ether, but readily dissolves in solutions of acids and of the fixed alkalies; with acids it forms salts, which are, however, for the most part difficultly crystallizable; those with strong acids exhibit an acid reaction. The nitrate deflagrates when heated to about 120 °C., and on the application of a higher heat becomes pure peroxide of tin. The salts of oxide of stanethylium behave with reagents so nearly like the salts of peroxide of tin, that the two are very difficult to distinguish from each other.

Sulphide of Stanethylium.

Sulphide of stanethylium presents the appearance of an amorphous cream-coloured powder, having a pungent and very nauseous smell, resembling decayed horse-radish: when heated it fuses, froths up and decomposes, emitting vapours of a most insupportable odour. Heated with nitric acid it is decomposed with the formation of peroxide of tin.

Chloride of Stanethylium.

This salt is best prepared by dissolving oxide of stanethylium in dilute hydrochloric acid: on evaporation at a gentle heat or over sulphuric acid in vacuo, the chloride crystallizes out in long colourless needles, isomorphous with the iodide, which salt it also closely resembles in all its properties; it is however more volatile, and therefore emits a more intensely pungent and irritating odour than the iodide.

Stanethylium.

I. .3150 grm., burnt with oxide of copper and oxygen gas, gave .3498 grm. carbonic acid and .1757 grm. water.

These numbers correspond sufficiently with the formula

		Calculated.	Found.
C4	24	27.32	26.95
H5	5	5.69	5.51
Sn	58.82	66.99	----
		100.00

The isolation of stanethylium from its chloride by zinc, is therefore expressed by the following simple equation: --

Stanethylium exists at the ordinary atmospheric temperature, as a thick, heavy, oily liquid, of a yellow or brownish-yellow colour, and an exceedingly pungent odour, resembling that of its compounds, but much more powerful. It is insoluble in water, but soluble in alcohol and ether. At about 150 °C. it enters into ebullition, a quantity of metallic tin is deposited, and a colourless liquid distils over, having a peculiar odour, containing a considerable quantity of tin, and exhibiting no tendency to combine with iodine or bromine: the composition and properties of this liquid I have not further ascertained; it possibly consists of or contains binethide of tin (Sn(C₄H₅)₂). In contact with the air stanethylium rapidly attracts oxygen and is converted into a white powder, which has all the properties of oxide of stanethylium. Chloride, bromide and iodide of stanethylium are immediately formed by the action of chlorine, bromine and iodine, or their hydrogen acids respectively, upon stanethylium; the first and third are in every respect identical with the salts above described. I have analytically examined the bromide prepared by adding an alcoholic solution of bromine to an alcoholic solution of stanethylium until the colour of the bromine no longer disappears; by spontaneous evaporation the bromide of stanethylium is deposited in long white needles, which closely resemble, both in appearance and properties, the chloride of stanethylium. These crystals, pressed between folds of bibulous paper, and dried over sulphuric acid in vacuo, gave the following analytical results: --

.9730 grm., burnt with oxide of copper, yielded .5108 grm. carbonic acid and .2582 grm. water.

These numbers agree very closely with the formula-

	Equivs.		Calculated.	Found.
Carbon	4	24	14.30	14.32
Hydrogen	5	5	2.98	2.95
Tin	1	58.82	35.05	----
Bromine	1	80.00	47.67	----
		167.82	100.00

These results show that stanethylium perfectly resembles cacodyl in its reactions, combining directly with the electro-negative elements and regenerating the compounds from which it has been derived.

Examination of Gases.

Weight of flask filled with gas	35.4712 grms.
Temperature of room	20.8° C
Height of barometer	761.2 mm
Height of internal column of mercury	15.2 mm
Temperature in balance case	22.6° C
Weight of flask filled with dry air	35.4703 grms.
Temperature in balance case	22.8° C
Capacity of flask	140.50 cubic centimetres

From these data the specific gravity was calculated to be 1.0384.

The remainder of the gas was submitted to eudiometrical analysis: the following numbers were obtained:--

I. In Short Eudiometer
	Observed volume	Temp.	Difference of mercury level. mm	Barom. mm	Corrected vol. at 0° C. and 1 metre press.
Volume of gas used (dry)	143.4	21.0° C	16.3	760.5	99.09
Volume after action of fuming SO3 (dry)	122.5	18.2	37.0	754.7	82.42
II. In Combustion Eudiometer
Volume of gas used (moist)	110.3	18.1° C	570.7	755.2	17.48
Volume after admission of O (moist)	383.6	18.3	274.7	755.7	167.31
Volume after explosion (moist)	326.9	18.4	332.4	755.8	124.86
Volume after absorption of CO2 (dry)	264.5	17.0	398.3	760.7	90.23
Volume after admission of H (dry)	592.5	17.0	77.9	761.6	381.33
Volume afterexplosion (moist)	303.5	17.7	355.9	762.7	111.64

As the gas, left unabsorbed by fuming sulphuric acid, was soluble in about its own volume of alcohol, with the exception of a very small per-centage due to the nitrogen introduced by diffusion through the sulphuretted water, it could not contain either hydrogen or hydride of methyl; and the result of the above combustion proves that it is hydride of ethyl, for I have shown that 1 vol. of hydride of ethyl consumes 3.5 vols. oxygen, and generates 2 vols. carbonic acid, numbers which almost exactly correspond with those obtained.

17.48 vols. of the gas, containing 17.15 vols. of combustible gas and .33 vol. of nitrogen, consumed 59.93 vols. oxygen and generated 34.63 vols. carbonic acid; hence

Volume of combustible gas.		Oxygen consumed.		Carbonic acid generated.
17.15		59.93		34.63
1	:	3.49	:	2.01

Further, the gas agrees in all its chemical and physical properties, with the hydride of ethyl prepared by the action of zinc upon iodide of ethyl in presence of water.

The composition of the gas absorbed by fuming sulphuric acid was determined by exploding a known volume of the original gas with excess of oxygen, and determining the quantities of oxygen consumed, and carbonic acid generated.

This determination gave the following number:--

III.
	Observed volume	Temp.	Difference of mercury level. mm	Barom. mm	Corrected vol. at 0° C. and 1 metre press.
Volume of gas used (moist)	122.0	19.7° C	563.0	764.2	20.95
Volume after admission of O (moist)	424.5	20.0	240.4	764.3	200.33
Volume after explosion (moist)	363.5	20.4	301.0	763.5	150.40
Volume after absorption of CO2 (dry)	296.7	19.7	366.4	760.4	109.03
Volume after admission of H (dry)	683.1	21.7	4.0	760.8	478.89
Volume after explosion (moist)	368.6	21.8	293.3	761.2	153.09

Hence 20.95 vols. containing 20.62 vols. combustible gas, consumed 70.78 vols. oxygen, and generated 41.37 vols. carbonic acid: now as 20.62 vols. of this gas must contain, according to analyses Nos. I. and II., 17.10 vols. hydride of ethyl, which would consume 59.85 vols. oxygen and generate 34.20 vols. carbonic acid, it is evident that the volumes of oxygen consumed, and carbonic acid generated, by the gas absorbed by fuming sulphuric acid, must bear the following relation to each other:--

Volume of gas absorbable by fuming SO3		Oxygen consumed.		Carbonic acid generated.
3.52		10.93		7.17
1	:	3.10	:	2.03

The body removed by fuming sulphuric acid is therefore olefiant gas, 1 vol. of which consumes 3 vols. oxygen , and generates 2 vols. carbonic acid, numbers which correspond sufficiently with those obtained in the above determination.

The last analysis can also be employed to control Nos. I. And II.; for if we represent the volume of nitrogen, contained in the original gas, by x, that of hydride of ethyl by y, and that of olefiant gas by z; and further, the volume of mixed gases, oxygen consumed, and carbonic acid generated, respectively by A, B and C, we have the following equations:--

x + y + z = A
(7/2)y + 3z = B
2y + 2z = C,

x = .27
y = 17.06
z = 3.62
     20.92

The per-centage composition of the gases evolved by the action of heat upon iodide of ethyl and tin is therefore the following:--

	I. and II.	III.
Hydride of ethyl	81.61	81.43
Olefiant gas	16.82	17.28
Nitrogen	1.57	1.29
	100.00	100.00

This result is also confirmed by the determination of the specific gravity of the gaseous mixture, as is seen from the following calculation:--

C4H5H	81.61 x	1.03652	= 84.590
C4H4	16.82 x	.96742	= 16.272
N	1.57 x	.96740	=  1.519
	100.00		102.381	/ 100 = 1.02381
Specific gravity found by experiment . . .				= 1.0384

The presence of hydride of ethyl and olefiant gas amongst the products of the action of heat upon iodide of ethyl and tin, shows that the combination of tin with iodide of ethyl is not the only reaction which takes place, but that a portion of the iodide of ethyl is also decomposed by the tin, with the production of iodide of tin and ethyl; the latter body being transformed at the moment of its liberation into hydride of ethyl and olefiant gas, a catalysis to which this radical is so prone,

It was ascertained that protoiodide of tin was present amongst the solid products of the reaction.

The large excess of hydride of ethyl exhibited in the above analysis, may have been caused, either by the greater solubility of olefiant gas in iodide of ethyl (a further and considerable amount of gas being expelled from the tube by the application of a gentle heat), or by the presence of moisture in the materials, which would give rise to the formation of oxyiodide of tin and hydride of ethyl,

Both these causes probably contribute to produce the excess of hydride of ethyl; but the very small amount of gaseous products, compared with the solid ones, convinced me that the production of the former is only an accidental circumstance, which, however it may be interpreted, does not at all affect the principal reaction, viz. the formation of iodide of stanethylium. The gases, evolved by the action of light upon iodide of ethyl and tin, are perfectly similar to those obtained by the action of heat.

Stanmethylium and stanamylium are formed when the iodides of methyl and amyl respectively are exposed to the action of light in contact with tin; their salts are isomorphous with those of stanethylium; but I have not yet completed the investigation of these bodies.

Action of Zinc upon Iodide of Methyl.

Zincmethylium.

A is the decomposition tube bent at an obtuse angle at a, and connected with the receiver B by the doubly perforated cork c, which also contains the small tube b, open at both ends. The receiver B is drawn out at f until its internal diameter is diminished to about 1/20th of an inch, and this drawn out extremity is connected, by means of a caoutchouc joint, with the chloride of calcium tube C, which at its opposite extremity is in connection with a hydrogen gas apparatus D. d, e are two small glass bulbs for preserving the condensed liquid. The apparatus being thus arranged, hydrogen is evolved in D, and becoming perfectly desiccated in passing through the chloride of calcium tube C, enters the receiver B at f, expelling the atmospheric air through the tube b. When the gas has thus streamed through the apparatus for at least a quarter of an hour, and every trace of air has been expelled from B and from the bulbs d, e by diffusion, the extremity of the tube b is hermetically sealed, at the same moment that the evolution of gas from D is interrupted. The drawn out extremity of the receiver B being then quickly sealed at f; B, d and e remain filled with pure dry hydrogen, and A with a mixture of gases free from oxygen, as any trace of this element, which might have penetrated there, would be instantaneously absorbed by its contents. B is then immersed to its neck in cold water, and a gentle heat cautiously applied to the whole length of A by mean of a spirit lamp. The mobile fluid in A soon enters into ebullition, and distils over into the receiver B; as soon as the distillation is finished and A become cold, its capillary extremity is fused off at a by means of a blowpipe, a remaining hermetically sealed. The receiver B is then removed from the water and dried; heat is applied to the side adjacent to the bulbs d, e, so as to expel a portion of the enclosed gas from their open ends at f; on subsequent cooling, a certain quantity of the liquid rises into these bulbs, which are alternately heated and cooled, until every trace of the liquid has not only entered them but passed entirely into their expanded portion, so as to leave the capillary limbs filled with hydrogen. It is of importance that the whole of the liquid should be forced to enter these bulbs, otherwise, on subsequently opening the mouth of the receiver, it inflames, causing the expulsion of the liquid from the bulbs, and thus rendering the experiment abortive. The cork c is then removed, and the bulbs d, e extracted as quickly as possible, the open capillary extremities being immediately sealed before the blowpipe. The bulbs, having been previously weighted, the increase denotes the weight of the included liquid. The residue in A was found scarcely to effervesce with water, and consisted of iodide of zinc mixed with the excess of metallic zinc employed.

I have fixed the composition of the liquid obtained as above described, and proved it to be a compound of one atom of zinc and one atom of methyl, by the following experiments:--

I. One of the bulbs above mentioned was opened beneath an inverted receiver filled with recently boiled distilled water; its contents were rapidly resolved into hydrated oxide of zinc and a permanent gas, which last was submitted to eudiometrical examination; the following results were obtained:--

The action of fuming sulphuric acid did not produce any diminution of volume.

The gas was nearly insoluble in absolute alcohol.

A eudiometrical combustion yielded the following results:--

	Observed volume	Temp.	Difference of mercury level. mm	Barom. mm	Corrected vol. at 0° C. and 1 metre press.
Volume of gas used (moist)	122.5	18.7° C	602.2	747.8	14.86
Volume after admission of O (moist)	287.9	18.7	418.4	747.6	84.39
Volume after explosion (moist)	232.1	18.6	479.7	747.4	54.71
Volume after absorption of CO2 (dry)	188.2	18.6	519.4	747.5	40.19
Volume after admission of H (dry)	549.4	18.4	162.7	747.6	301.04
Volume after explosion (moist)	425.7	18.4	279.0	747.6	180.62

Volume of comb. gas		Oxygen consumed.		CO2 generated
14.86		29.39		14.52
1	:	1.98	:	.98

I. In Diffusion Eudiometer
	Observed volume	Temp.	Difference of mercury level. mm	Barom. mm	Corrected vol. at 0° C. and 1 metre press.
Volume of gas used (dry)	173.0	19.0° C	20.1	741.1	116.61
Volume after diffusion (dry)	144.3	19.2	46.3	740.8	93.63
II. Estimation of Oxygen in residual gas.
Volume of gas used (moist)	117.5	19.3° C	53.1	740.6	75.44
Volume after absorption of O (moist)	101.2	17.0	69.3	742.8	64.16
III. Combustion of Gas remaining after absorption of Oxygen
	Observed volume	Temp.	Difference of mercury level. mm	Barom. mm	Corrected vol. at 0° C. and 1 metre press.
Volume of gas used (moist)	155.9	17.3° C	558.7	743.3	24.91
Volume after admission of O (moist)	302.7	17.7	399.0	744.0	93.78
Volume after explosion (moist)	270.2	17.6	433.2	744.2	75.13
Volume after absorption of CO2 (dry)	246.3	17.8	458.7	744.7	66.13
Volume after admission of H (dry)	522.3	17.9	182.4	745.1	275.80
Volume after explosion (moist)	349.5	18.0	350.5	745.0	124.30

The gas, remaining after diffusion and subsequent absorption of oxygen, therefore contained in 24.91 vols. 15.63 vols. nitrogen and 9.28 vols. combustible gas, which last was a single gas and not a mixture, since it consumed the same amount of oxygen and generated the same amount of carbonic acid after as before diffusion:--

Volume of combustible gas		Oxygen consumed.		CO2 generated
9.28		18.37		9.00
1	:	1.98	:	.97

Experiments Nos. I., II. and III., taken together, enable us to ascertain the volume of the gas which escaped and that of the air which entered during the diffusion experiment; these volumes are as follow:--

Volume of gas escaped	86.95
Volume of air entered	63.97

Hence, according to the well-known law of diffusion, the specific gravity of the gas must be .5413.

The gas is therefore hydride of methyl (light carburetted hydrogen), 1 vol. of which consumes 2 vols. oxygen and generates 1 vol. carbonic acid, and the specific gravity of which is .5528, numbers which correspond almost exactly with those obtained by experiment.

II. A glass jar, graduated in cubic centimetres, was filled with recently boiled distilled water, to which about twenty drops of sulphuric acid had been added, and inverted in a shallow glass dish containing the same liquid; the other bulb was then introduced into the inverted jar, and its capillary extremity broken off against the side of the vessel; the water now slowly gained access to the liquid in the bulb and steady decomposition ensued, the oxide of zinc dissolving as fast as formed, in the dilute sulphuric acid, and the hydride of methyl collecting in the inverted jar. When the decomposition was quite complete, the volume of gas was read off with the usual corrections for temperature and pressure, the graduated jar rinsed out and removed, and the solution of sulphate of zinc in the glass dish, after being evaporated to a smaller bulk, was treated with carbonate of potash and the zinc precipitated as basic carbonate, and weighed as oxide with usual precautions: the following results were obtained:--

.3109 grm. gave .2660 grm. oxide of zinc, and 138.15 cubic centimetres dry hydride of methyl, at 0° C. and 760 mm. pressure, equivalent to .0930 grm.

These numbers agree sufficiently with those calculated from the formula

	Calculated.		Found.
1 equiv. of Methyl	15	31.56	29.91
1 equiv. of Zinc	32.52	68.44	68.67
	47.52	100.00	98.58

This compound, for which I propose the name Zincmethylium, possesses the following properties:--It is a colourless, transparent and very mobile liquid, refracting light strongly, and possessing a peculiar penetrating and insupportable odour; it is very volatile, but I have not yet been able to determine its boiling-point with accuracy.

Zincmethylium combines directly with oxygen, chlorine, iodine, &c., forming somewhat unstable compounds, a description of which I reserve for a future communication. Its affinity for oxygen is even more intense than that of potassium; in contact with atmospheric air it instantaneously ignites, burning with a beautiful greenish-blue flame, and forming white clouds of oxide of zinc; in contact with pure oxygen it burns with explosion, and the presence of a small quantity of its vapour in combustible gases gives them the property of spontaneous inflammability in oxygen. Thrown into water, zincmethylium decomposes that liquid with explosive violence and with the evolution of heat and light; when this action is moderated, so as to prevent any great rise of temperature, the sole products of the decomposition are oxide of zinc and hydride of methyl,

The extraordinary affinity of zincmethylium for oxygen, its peculiar composition, and the facility with which it can be procured cannot fail to cause its employment for a great variety of transformations in organic compounds; by its agency there is every probability that we shall be able to replace oxygen, chlorine, &c., atom for atom, by methyl, and thus produce entirely new series of organic compounds, and obtain clearer views of the rational constitution of others. I intend to pursue this branch of the subject whilst studying the compounds of zincmethylium and the corresponding bodies containing ethyl and amyl.

Examination of the Gas a.

Temperature of room	18.6° C
Height of barometer	754.2 mm.
Height of inner column of mercury	15.2 mm.
Weight of flask and gas	35.4161 grms.
Temperature in balance base	19.6° C
Weight of flask and dry air	35.4500 grms.
Temperature in balance case	20.2° C
Capacity of flask	140.51 cubic centimetres

From these data the specific gravity was calculated to be .79598.

The eudiometrical analysis of the gas gave the following results:--

I. In Short Eudiometer
	Observed volume	Temp.	Difference of mercury level. mm	Barom. mm	Corrected vol. at 0° C. and 1 metre press.
Volume of gas used (dry)	194.7	18.6° C	2.1	754.2	137.06
Volume after action of fuming SO3 (dry)	194.8	18.7	2.2	753.5	137.03
Volume after removal of specimen for combustion (dry)	153.8	19.0	22.0	741.0	103.38
Volume after action of alcohol	82.0	18.7	7.0	741.4	53.72
II. In Combustion Eudiometer
	Observed volume	Temp.	Difference of mercury level. mm	Barom. mm	Corrected vol. at 0° C. and 1 metre press.
Volume of gas used (moist)	101.5	18.9° C	621.7	752.4	10.86
Volume after admission of O (moist)	388.1	18.6	311.7	752.0	154.20
Volume after explosion (moist)	354.6	18.5	345.8	752.2	129.71
Volume after absorption of CO2 (dry)	321.1	18.3	376.9	752.0	112.88
Volume after admission of H (dry)	745.1	18.7	.8	751.1	523.19
Volume after explosion (moist)	428.3	18.7	274.1	750.5	184.54
III.
	Observed volume	Temp.	Difference of mercury level. mm	Barom. mm	Corrected vol. at 0° C. and 1 metre press.
Volume of gas used (moist)	104.2	18.8° C	619.2	750.5	11.23
Volume after admission of O (moist)	371.2	18.9	330.6	750.2	140.04
Volume after explosion (moist)	335.0	18.9	367.7	750.2	114.76
Volume after absorption of CO2 (dry)	299.0	18.2	401.3	750.3	97.83
Volume after admission of H (dry)	707.0	18.4	26.9	750.6	479.33
Volume after explosion (moist)	431.6	18.7	273.4	749.8	185.96

Analysis No. I. proves the absence of all the members of the olefiant gas family, and also that the mixture consists of--

Gas absorbable by alcohol	48.04
Gas unabsorbable by alcohol	51.96
	100.00

The behaviour of the iodides of ethyl and amyl in contact with zinc[8], led me to expect that the gaseous products of the decomposition of iodide of methyl by the same metal would consist of methyl, hydride of methyl, and the first member of the olefiant gas series, methylene; but in addition to the proof of the absence of this latter body afforded by the absence of all absorption by fuming sulphuric acid, analyses Nos. II. and III. demonstrate the impossibility of methylene being a constituent of the gaseous mixture; for on constructing three equations in which the volumes of methyl, hydride of methyl, and methylene are expressed, the value obtained for the last gas is invariably a small negative quantity. The volumes of methyl and hydride of methyl are readily found by the two following equations, in which the volume of combustible gas is represented by A, the contraction produced by explosion with excess of oxygen by B, and the volumes of methyl and hydride of methyl respectively, by x and y, the contraction produced by the explosion of methyl and excess of oxygen being 2.5 times its own volume, and that produced by the explosion of hydride of methyl twice its own volume:--

According to analysis No. II., 10.88 vols. of combustible gas produced a contraction, on explosion with oxygen, equal to 24.49 vols.; and in analysis No. III., 11.23 vols. of combustible gas produced a contraction on explosion, equal to 25.28 vols. Hence, by the application of the foregoing equations, the per-centage composition of the gaseous mixture may be expressed as follows:--

	II.	III.	Mean.
Methyl	50.18	50.22	50.20
Hydride of Methyl	49.82	49.78	49.80
	100.00	100.00	100.00

This result is confirmed by the action of alcohol in analysis No. I., and also by the determination of the specific gravity of the mixed gases, which agrees very closely with that deduced from the above numbers, as is seen from the following comparison:--

Methyl	50.20	x 1.0365 = 52.0323
Hydride of Methyl	49.80	x  .5528 = 27.5294
	100.00		79.5617	/100 = .795617
Specific gravity found by experiment				= .79598

The origin of the hydride of methyl in the above gaseous mixture is readily perceived, when the volatility of zincmethylium and the method of collecting the gas are taken into consideration; on opening the decomposition-tube beneath water, a copious effervescence was observed wherever the evolved gas came in contact with water; and as this effervescence was accompanied by the formation of a flocculent precipitate of oxide of zinc, it could only be caused by the presence of the vapour of zincmethylium, which, on coming in contact with water, would be instantaneously decomposed into oxide of zinc and hydride of methyl.

I have not yet endeavoured to procure the methyl free from admixture with hydride of methyl, but have no doubt that, by collecting the gas as evolved from the decomposition-tube over mercury, and absorbing the zincmethylium vapour by dry iodine, the methyl would be left in a state of purity. It perfectly resembles in its properties, chemical and physical, the methyl procured by KOLBE from the electrolysis of acetic acid.[9]

Examination of the Gas b.

I. In Short Eudiometer
	Observed volume	Temp.	Difference of mercury level. mm	Barom. mm	Corrected vol. at 0° C. and 1 metre press.
Volume of gas used (dry)	168.9	18.6° C	3.6	750.2	118.05
Volume after action of fuming SO3 (dry)	169.5	18.7	3.7	749.8	118.35

One volume of absolute alcohol, at 19° C. and 732.6 mm. pressure, absorbed .175 vol. of this gas.

II. In Combustion Eudiometer
	Observed volume	Temp.	Difference of mercury level. mm	Barom. mm	Corrected vol. at 0° C. and 1 metre press.
Volume of gas used (moist)	126.7	18.9° C	595.1	744.9	15.83
Volume after admission of O (moist)	344.9	18.9	357.7	744.8	119.64
Volume after explosion (moist)	295.9	18.9	408.7	744.5	88.44
Volume after absorption of CO2 (dry)	260.7	18.6	446.1	744.3	72.78
Volume after admission of H (dry)	705.7	18.5	24.6	741.3	473.66
Volume after explosion (moist)	513.0	18.6	193.6	741.1	255.35

These results correspond almost exactly with those yielded by hydride of methyl, 1 vol. of which requires 2 vols. of oxygen for combustion, and generates 1 vol. of carbonic acid.

Volume of combustible gas		Oxygen consumed.		CO2 generated
15.83		31.04		15.66
1	:	1.96	:	.99

By the action of zinc upon iodide of methyl, therefore, two distinct decompositions take place, viz. 1st, the decomposition of iodide of methyl by zinc with the production of iodide of zinc and methyl,

Zincethylium.

Its formula must therefore be

Zincamylium.

From this circumstance, and its analogy with zincmethylium, there can be no doubt that its formula is

Action of Mercury upon Iodide of Methyl in presence of Light.

I. .3170 grm. dissolved in alcohol and treated with nitrate of silver, gave .2142 grm. iodide of silver.

II. .6205 grm. burnt with oxide of copper, gave .0813 grm. carbonic acid, .0505 grm. water, and .5960 grm. protoiodide of mercury. The iodide of mercury, a small portion of which was decomposed into metallic mercury and periodide, collected as an incrustation at the front end of the combustion-tube, about a couple of inches of which had been left empty for this purpose, and projected from the furnace, the heat being so regulated that none of the watery vapour condensed in the combustion-tube. When the analysis was concluded, the weight of the protoiodide of mercury, mixed with traces of periodide and metallic mercury, was determined by cutting off the part of the combustion-tube containing it, and ascertaining its weight before and after the iodide was removed. The numbers obtained agree very closely with the formula

	Calculated		Found
			I		II
2 equivs. Carbon	12	3.51	-------		3.57
3 equivs. Hydrogen	3	.88	-------		.90
1 equiv. Mercury	200	58.51	-------	}	96.05 ______
1 equiv. Iodine	126.84	37.10	36.56
	341.84	100.00			100.52

This compound is therefore evidently the iodide of a new organo-metallic body, consisting of one atom of methyl and one atom of mercury, and for which I propose the name hydrargyromethylium: it is formed by the direct union of one atom of mercury with one atom of iodide of methyl, under the influence of light,

Iodide of hydrargyromethylium is a white solid, crystallizing in minute nacreous scales, which are insoluble in water, moderately soluble in alcohol, and very soluble in ether and iodide of methyl; by the spontaneous evaporation of these solutions the crystals are again deposited unchanged. Iodide of hydrargyromethylium is slightly volatile at ordinary temperatures, and exhales a weak but peculiarly unpleasant odour, which leaves a nauseous taste upon the palate for several days; at 100° C. the volatility is much greater, and the crystals are rapidly dissipated at this temperature when exposed to a current of air. At 143° C. it fuses and sublimes without decomposition, condensing in brilliant and extremely thin crystalline plates. In contact with the fixed alkalies and ammonia, it is converted into oxide of hydrargyromethylium as a slightly yellow flocculent precipitate of a peculiar and most insupportable odour. I have not yet further examined the reactions of this remarkable body, nor have I attempted the isolation of the hydrargyromethylium.

A corresponding compound containing amyl is formed, though with difficulty, under similar circumstances, but I have not yet succeeded in producing one containing ethyl, the iodide of this radical yielding, as I have shown,[10] when exposed to sunlight in contact with mercury, iodide of mercury, and a mixture of ethyl, hydride of ethyl and olefiant gases.

I have also made some preliminary experiments with other metals, and find that most of them are capable of thus entering into combination with the organic groups, methyl, ethyl, and amyl; amongst those which thus combine under the influence of light most readily, and seem to promise the most interesting results, I may mention arsenic, antimony, chromium, iron, manganese and cadmium. I hope to have to honour of laying before the Royal Society, at an early period, the results of my experiments upon these compounds.

Imperfect as our knowledge of the organo-metallic bodies may yet appear, I am unwilling to close this memoir without directing attention to some peculiarities in the habits of these compounds, which promise to throw light upon their rational constitution, if they do not lead to extensive modifications of our views respecting chemical compounds in general, and especially that interesting class termed conjugate compounds.

That stanethylium, zincmethylium, hydrargyromethylium, &c. are perfectly analogous to cacodyl there can be no reasonable doubt, inasmuch as, like that body, they combine directly with the electro-negative metalloids, forming true salts; from which, in most cases, and probably in all, the original group can be again separated unaltered; and therefore any view which may be taken of the new bodies must necessarily be extended to cacodyl. The discovery and isolation of this so-called organic radical by Bunsen was certainly one of the most important steps in the development of organic chemistry, and one, the influence of which upon our theoretical views of the constitution of certain classes of organic compounds, can scarcely be too highly estimated. It was impossible to consider the striking features in the behaviour of this body, without finding in them a most remarkable confirmation of the theory of organic radicals, as propounded by Berzelius and Liebig.

The formation of cacodyl, its habits, and the products of its decomposition, have for some time left no doubt of the existence of methyl ready formed in this body; and Kolbe[11], in developing his views on the so-called conjugate compounds, has proposed to regard it as arsenic conjugated with two atoms of methyl ((C₂H₃)₂As). So long as cacodyl was an isolated example of an organo-metallic body, this view of its rational composition, harmonizing as it did with the facts elicited during the route of cacodyl through its various combinations and decompositions, could scarcely be contested; but now, since we have become acquainted with the properties and reactions of a considerable number of analogous bodies, circumstances arise which I consider militate greatly against this view, if they do not render it absolutely untenable. According to the theory of conjugate radicals just alluded to, cacodyl and its congeners, so far as they are at present known, would be thus represented:--

Cacodyl	(C2H3)2As
Oxide of cacodyl	(C2H3)2AsO
Cacodylic acid	(C2H3)2AsO3
Stanmethylium	(C2H3)Sn
Stanethylium	(C4H5)Sn
Oxide of stanethylium	(C4H5)SnO
Stanamylium	(C10H11)Sn
Zincmethylium	(C2H3)Zn
Zincethylium	(C4H5)Zn
Zincamylium	(C10H11)Zn
Stibethine (Stibethyl)	(C4H5)3Sb
Binoxide of stibethine	(C4H5)3SbO2
Oxide of stibmethylium	(C2H3)4SbO
Hydrargyromethylium	(C2H3)Hg
Iodide of hydrargyromethylium	(C2H3)HgI

When the formulae of inorganic chemical compounds are considered, even a superficial observer is impressed with the general symmetry of their construction. The compounds of nitrogen, phosphorus, antimony and arsenic especially exhibit the tendency of these elements to form compounds containing 3 to 5 equivs. of other elements, and it is in these proportions that their affinities are best satisfied; thus in the ternal group we have NO₃, NH₃, NI₃, NS₃, PO₃, PH₃, PCl₃, SbO₃, SbH₃, SbCl₃, AsO₃, AsH₃, AsCl₃, &c.; and in the five-atom group, NO₅, NH₄O, NH₄I, PO₅, PH₄I, &c. Without offering any hypothesis regarding the cause of this symmetrical grouping of atoms, it is sufficiently evident, from the examples just given, that such a tendency or law prevails, and that, no matter what the character of the uniting atoms may be, the combining-power of the attracting element, if I may be allowed the term, is always satisfied by the same number of these atoms.[13] It was probably a glimpse of the operation of the law amongst the more complex organic groups, which led Laurent and Dumas to the enunciation of the theory of types; and had not those distinguished chemists extended their views beyond the point to which they were well supported by then existing facts,--had they not assumed, that the properties of an organic compound are dependent upon the position and not upon the nature of its single atoms, that theory would undoubtedly have contributed to the development of the science to a still greater extent than it has already done; such an assumption could only have been made at a time when the data upon which it was founded were few and imperfect, and, as the study of the phenomena of substitution progressed, it gradually became untenable, and the fundamental principles of the electro-chemical theory again assumed their sway. The formation and examination of the organo-metallic bodies promise to assist in effecting a fusion of the two theories which have so long divided the opinions of chemists, and which have too hastily been considered irreconcilable; for, whilst it is evident that certain types of series of compounds exist, it is equally clear that the nature of the body derived from the original type is essentially dependent upon the electro-chemical character of its single atoms, and not merely upon the relative position of those atoms. Let us take, for instance, the compounds formed by zinc and antimony; by combination with 1 equiv. of oxygen the electro-positive quality of the zinc is nearly annihilated; it is only by the action of the highly oxidizing peroxide of hydrogen that the metal can be made to form a very unstable peroxide; but when zinc combines with 1 equiv. of methyl or ethyl, its positive quality, so far from being neutralized, is exalted by the addition of the positive group; and the compound now exhibits such intense affinity for the electro-negative elements as to give it the property of spontaneous inflammability. Teroxide of antimony has also little tendency to pass into a higher state of oxidation; but when its three atoms of oxygen are replaced by electro-positive ethyl, as in stibethine, that affinity is elevated to the intense degree which is so remarkable in this body.

Taking this view of the so-called conjugate organic radicals, and regarding the oxygen, sulphur, or chlorine compounds of each metal as the true molecular types of the organo-metallic bodies derived from them by the substitution of an organic group for sulphur, oxygen, &c., the anomalies above mentioned entirely disappear, and we have the following inorganic types and organo-metallic derivatives:--

Inorganic types.				Organo-metallic derivatives.
As		S			As		C2H3		Cacodyl.
		S					C2H3
As		O			As		C2H3		Oxide of Cacodyl.
		O					C2H3
		O					O
As		O			As		C2H3		Cacodylic acid [14].
		O					C2H3
		O					O
		O					O
		O					O
ZnO					Zn(C2H3)				Zincmethylium.
Zn		O			Zn		C2H3		Oxide of Zincmethylium.
		Ox					Ox
Sb		O			Sb		C4H5		Stibethine.
		O					C4H5
		O					C4H5
Sb		O			Sb		C4H5		Binoxide of Stibethine.
		O					C4H5
		O					C4H5
		O					O
		O					O
Sb		O			Sb		C4H5		Oxide of Stibethylium.
		O					C4H5
		O					C4H5
		O					C4H5
		O					O
SnO					Sn(C4H5)				Stanethylium.
Sn		O			Sn		C4H5		Oxide of Stanethylium.
		O					O
Hg		I			Hg		C2H3		Iodide of Hydrargyromethylium.
		I					I

The only compound which does not harmonize with this view is ethostibylic acid, to which Löwig assigns the formula C₄H₅SbO₅; but as that chemist has not yet fully investigated this compound, it is possible that further research may satisfactorily elucidate its apparently anomalous composition.

It is obvious that the establishment of this view of the constitution of the organo-metallic bodies will remove them from the class of organic radicals, and place them in the most intimate relation with ammonia and the bases of Wurtz, Hofmann, and Paul Thenard; indeed, the close analogy existing between stibethine and ammonia, first suggested by Gerhardt, has been most satisfactorily demonstrated by the behaviour of stibethine with the haloid compounds of methyl and ethyl. Stibethine furnishes us, therefore, with a remarkable example of the operation of the law of symmetrical combination above alluded to, and shows, that the formation of a five-atom group from one containing three atoms, can be effected by the assimilation of two atoms, either of the same or of opposite electro-chemical character; this remarkable circumstance suggests the following question:-- Is this behaviour common also to the corresponding compounds of arsenic, phosphorus and nitrogen; and can the position of each of the five atoms, with which these elements respectively combine, be occupied indifferently by an electro-negative or electro-positive element? This question, so important for the advance of our knowledge of the organic bases and their congeners, connote now long remain unanswered.

If the views I have just ventured to suggest should be as well borne out by future researches as they are by the facts already known, they must occasion a profound change in the nomenclature of the extensive series of compounds affected by them: I have not, however, ventured to introduce this new system of nomenclature, even in the case of the new bodies described in this memoir, since hasty changes of this kind, unless absolutely necessary, are always to be deplored. In accordance with the suggested view of the constitution of the organo-metallic compounds, the following plan of nomenclature would probably be found most convenient.

Arsenic Compounds.
(C2H3)2As	Bimethide of arsenic.
(C2H3)2AsO	Bimethoxide of arsenic.
(C2H3)2AsO3	Bimetharsenic acid.
(C2H3)2AsO3+KO	Bimetharseniate of potash.
Zinc Compounds.
(C2H3)Zn	Methide of zinc.
(C4H5)Zn	Ethide of zinc.
(C10H11)Zn	Amylide of zinc.
Tin Compounds.
(C2H3)Sn	Methide of tin.
(C2H3)SnI	Methiodide of tin.
(C4H5)Sn	Ethide of tin.
(C4H5)SnO	Ethoxide of tin.
(C4H5)SnCl	Ethochloride of tin.
(C4H5)SnOSO3	Sulphate of ethoxide of tin.
(C10H11)Sn	Amylide of tin.
(C10H11)SnO	Amyloxide of tin.
Antimony Compounds.
(C2H3)3As	Termethide of antimony.
(C2H3)4AsO	Quadromethoxide of antimony.
(C4H5)3As	Terethide of antimony.
(C4H5)3AsO2	Terethobinoxide of antimony.
Mercury Compounds.
(C2H3)Hg	Methide of mercury.
(C2H3)HgI	Methiodide of mercury.

[2]Annalen der Chemie und Pharmacie, Bd. LXXV. s. 315. [Frankland's note--CJG]

[3]A minute account of the construction and use of these tubes is given in the Journal of the Chemical Society, vol. ii. p. 265. [Frankland's note--CJG]

[4]Journal of Chemical Society, vol. ii. p. 267. [Frankland's note--CJG]

[5]The substance used in Nos. IV. and V. was produced by the action of light, that used in the other analyses by the agency of heat. [Frankland's note--CJG]

[6]N.B. Frankland is using C = 6, H = 1, O = 8, Sn = 58.82, I = 126.84. --John Park

[7]Quarterly Journal of Chemical Society, vol. ii. p. 283. [Frankland's note--CJG]

[8]Journal of Chemical Society, vol. ii. p. 265, and vol. iii. p. 30. [Frankland's note--CJG]

[9]Journal of Chemical Society, vol. ii. p. 173. [Frankland's note--CJG]

[10]Journal of Chemical Society, vol. iii. p. 331. [Frankland's note--CJG]

[11]Journal of the Chemical Society, vol. iii, p. 372. [Frankland's note--CJG]

[12]In a later edition of this paper, the words arsenious anhydride follow italicized in parentheses. --CJG

[13]In a later edition of this paper, most of this sentence is italicized. It is certainly a clear statement of the concept of valence. --CJG

[14]In a later edition of this paper, the word anhydrous follows italicized in parentheses. --CJG