two negative edges in each atom, so that when such a bond opens into a single bond it may do so at any edge.

Here the double bond is not formed on the faces of the cube, which lie at right angles to the nuclear poles, but on any of the four faces, which are parallel with the poles as a consequence of this there cannot be more than four such double bonds operating from any atom, which has an undistorted octet.

In double bonds one or more electron may be displaced and may occupy different corners of the octet from those which they normally occupy in the atom: the samic thing will also occur in a treble bond.

Distortion of the octet will be considered here only as from the cube to the tetrahedral form, either partly or wholly as a shrinkage, but it is possible that the octet may exhibit other forms of distortion in shrinkage or expansion, as, for instance, to the octohedron. In shrinking from the cube to the tetrahedron, one or more corners of the cube disappear, leaving triangles which will constitute tetrahedral faces.

weakness. Copper is one of those elements, which may have varying numbers of electrons in its octet, see Bury (J. Amer. Chem. Soc., 1921, XLIII., 1602), so that its three oxides will be constituted differently. Cu,O will conform with Fig. 2 where it has only one electron in its octet: CuO with Fig. 3 with two electrons, and CuO, with Fig. 5 with four electrons its chlorides and other salts will likewise have normal structures.

Gold has similar properties to copper with respect to its octet, so that AuO will conform with Fig. 3, and Au,O, with Fig. 4. The reasons for the instability of the cuprous salts and also of most of the salts of gold do not seem clear; it is possible that the cause may be due to the change in the numbers of electrons in the octets of these elements, which brings about stable or unstable arrangements in their atoms. Silver peroxide, Ag2O,, will probably have a composition similar to that of sodium or hydrogen peroxides, since when Ag2O2 is

Group II.-General types, BeO, MgO, CaO, ZnO, etc., are represented by Fig. 3.

In the octet of the metal the electron at (b) has travelled from its normal position (a) and a similar action has occurred in the Oxygen octet.

The stability of these oxides to heat is very great, but the bond is only stable to heat and not to the electricity of other atoms, for it is weak enough to be attacked by such a neutral substance as water, which fact is a good demonstration of the difference between the actions of these two forces.

The peroxides of the types CaO2, BaO2, etc., will have a somewhat analagous constitution to that of hydrogen peroxide, since they can be formed by its action upon the hydroxides of these metals: their instability is thus accounted for. They will be constituted as follows:

atom, say, of oxygen, came in contact with the carbon under suitable conditions for union; the result would be as shown in Fig. 5, in which the dotted lines represent the new lines of force brought into play; these pass out through the middle of the two tetrahedral faces. The tetrahedron has been retained in Fig. 5, in order to show its bearing on the whole thing. The new lines. of force may be taken to be halves of the old lines of force running to the electrons (c) and (d) in Fig. 8.

When lines of force run out to the corners of the octet of an atom to positions where there are no electrons, and when no union occurs with another atom, the first atom will be in the activated or nascent condition; if union occurs, these lines of force remain in position, but when union does not take place they may shrink into the nucleus or they may coalesce with the lines of force running to neighbouring electrons, in which case distortion would occur.

This view of the matter may seem, at first sight, a little bizarre, but when it is remembered that a transition of this kind is only a passage from hemihedral to holohedral types, well known in crystallography, there seems no reason why it should not occur in such cases as this, the only difference being that it might take place in stages. It explains both the possibility of the existence of carbon mon oxide, as well as its instability to certain reagents such as oxygen, chlorine, etc. (see rule 7), since the opening up of the second cube face in the carbon atom will take place more readily after the first has been formed. At the same time the double bond in CO is a normal one, and this, together with the likelihood that a small quantity of electrical energy or effort would be necessary to open up the distorted carbon octet, gives CO enough stability to exist, although only half of the normal valencies of the carbon are saturated. This substance is another instance of great stability to heat but not to the electricity of other atoms. CO2 will be normally formed like CO2, thus:

+

0 = C = C = C = 0

Each double bond is composed of both negative and positive edges, as shown in Fig. 1.

As analagous cases to CO, in this group, might be cited those of the stannous and plumbous salts. The example of stannous

This configuration explains the readiness with which the compound absorbs oxygen, since the second half of the cube is easily opened.

The tendency of the octets of the elements of this group towards distortion seems to be greater than those of most of the other groups: also quadrivalence seems to become less pronounced with increase of atomic weight, the greater number of internal electrons in the atoms of the members of higher atomic weight evidently weaken the lines of force to the electrons of their octets, thus encouraging distortion.

It cannot be thought that every atom has a full cube octet; as examples, hydrogen, the alkali metals, the alkaline earths, and the boron group have not enough electrons in their outer layers to warrant us in supposing that an imaginary cube, having only one or two corners occupied by electrons, surrounds the nucleus; these elements must naturally have distorted octets, and it is therefore more than likely that those elements, having larger numbers of electrons in their octets, may also exhibit distortion, even in the combined state.

Chemical Research Laboratory,
School Gardens,
Shrewsbury.

GENERAL NOTES.

THE STRUCTURE OF THE ATOM. The issue of Nature for July 7 contains a special 16-page supplement, in which Prof. Niels Bohr, professor of physics in the University of Copenhagen, gives a comprehensive and striking account of the present state of knowledge of the structure of the atom.

Prof. Bohr has taken a leading part in the development of modern conceptions of atomic structure; and he devotes particular attention in his paper to the interpretation of spectra, and the main features of the properties of atomical elements on considerations of the manner in which an atom can be imagined to be built up by the capture and binding of electrons to the nucleus, one by one.

NEED FOR SETTLEMENT OF

EUROPEAN SITUATION.

In the course of his speech at the Bradford meeting of the Federation of British Industries, Sir Eric Geddes said:—

fair

"The general upward trend of trade which goes on through the centuries is, therefore, checked because of the disturbed condition of Europe, and while I see reason to hope for an upward trend in the cycle of trade, I can at present see nothing but blackness when I look for a resumption of the upward progression in the general level of trade shown during the last century. Therefore, as first and foremost of all measures which can be taken for the improvement of trade, and the reduction of unemployment in this country, I would put the settlement of the European situation. We, as a great exporting country, are worst hit of all by the present state of affairs in Europe. Our unemployment is caused by that, and I do not think that the working, trading, and banking community of the country can too insistently bring before His Majesty's Government the conviction which I feel-and which I believe is generally felt that the great problems of this country would melt as mist melts before the sun, if a stabilised condition could be brought about in Europe. It is not only the direct influence on trade that is felt; but it has an influence on taxation, and taxation is one of the great burdens against trade to-day."

In a pamphlet issued by the United States Geological Survey* some interesting particulars are given of the occurrence of diamonds in Arkansas.

Stones found within the exposures of peredotite and have been mined to a depth of 20 feet, and the deposit is thought to extend to great depths. Dr. G. F. Kunz con

siders that the peridotite is the source of the diamonds. The production so far does not appear to be very great, although it is stated that it is difficult to obtain complete figures of production, some 5,300 stones are known to have been obtained.

The method of separating the stones is the same as is now practised in Kimberley, viz., working the material in circular pans having a revolving vertical shaft to which radiating arms are attached, at stated intervals the concentrates are removed and passed over grease tables to which the diamonds adhere while the other minerals are washed off. The stones are said to be mostly small, and to vary in colour from white to yellow and brown, some very fine crystals have been found.

*Diamond-bearing Peridotite in Pike County, Arkansas, by Hugh D. Miser and Clarence S. Ross. Bulletin 735, I.

The current number of the Analyst contains a paper by H. Droop Richmond on the action of potassium carbonate upon lead glass. It was found that the apparently dry dry salt had an appreciable action on the glass, and that the action increased rapidly as moisture was absorbed. Both lead and arsenic were found in potassium carbonate that had been stored in bottles containing these substances, and the danger of the use of such bottles as containers for this salt is pointed out.

LABORATORY EQUIPMENT.

The Council of the Society of Chemical Industry have received from the Department of Scientific and Industrial Research a request to nominate three or four members to furnish information with regard to the quality and technical range of British production of optical glass and instruments, laboratory glass and porcelain, synthetic organic chemicals, analytical reagents, and other fine chemicals. The Department had already sought the opinions of a large number of professors of chemistry, physicists, and others, but appeared to have addressed enquiries to very few practitioners in chemistry. The Council suggested, therefore, that useful opinions might be obtained from such practitioners,