BRITISH INDUSTRIES FAIR. PROMISING TRADE PROSPECTS FOR 1924.

It is expected that 1924 will prove the most momentous and beneficial year for British trade since the war. In addition to the great exhibition at Wembley, the British Industries Fair at the White City is already assured of such support from overseas buyers as will probably establish a record.

In previous years the Fair has been held in February. This year, to meet the convenience of the many buyers who will be attending the opening weeks of the British Empire Exhibition, it has been decided to hold it in London, from April 28 to May 9, and at Castle Bromwich Aerodrome, BirIningham, from May 12 to 23. As a result it is expected that the number of buyers visiting the Fair will be far ahead of past

years.

A quarter of a million invitations are annually issued by the organisers, the DeOf these, a partment of Overseas Trade. considerable quantity have already been issued to buyers in the more distant parts of the world. Of the acknowledgments so far received, over sixty per cent. state that the writers have definitely arranged to attend. A feature of these replies is the large proportion received from far away countries which have not been represented at previous fairs. Iceland, Ecuador, Chili, Siam, Peru, China and Siberia will be among those represented, in addition to the better known commercial centres from which buyers attend the Fair each year as part of their regular business. Reports from Constantinople show that great interest in the Fair is being shown in Turkey, and reports from the remainder of the Near East are also encouraging.

Each of these buyers will receive a copy of the Fair catalogue immediately on his arrival. Classified by trades, this catalogue is so valuable as a permanent directory of British trades that applications for it are received throughout the year from buyers in all parts of the world.

Unlike the British Empire Exhibition, the British Industries Fair is not open to the public. From the point of view of the

trade buyer this is of the greatest value in facilitating actual business. Another important factor for the doing of business in comfort and with despatch is that in both London and Birmingham all the exhibits are under one roof.

The national importance of increased export trade is now generally understood, and a great number of the exhibitors at the Fair have shown their appreciation of this fact by devoting the past year to a study of the needs of overseas markets. Prices, too, are lower as a whole than at any time since the

war.

It has, during recent years, become a widely adopted rule for exhibitors to make the Fair their first opportunity of marketing their new lines for overseas consumption. There are indications that the coming Fair will be particularly valuable to buyers in this connection.

As in past years, there will be an information bureau, where trade inquiries of all kinds can be satisfied, and representatives of the Department of Overseas Trade in constant touch with every trade will be able to introduce buyers to exhibitors able to satisfy their requirements. A corps of interpreters will also be in attendance and prepared to meet every possible requirement.

Naturally the great mass of exhibitors at the Fair are manufacturers who have exhibited for years past, but space can usually be found for new firms by extending the area of the Fair, provided that applications are received in good time. Such applications should be made to the Secretary, British Industries Fair, 35, Old Queen Street, Westminster, S.W.1, from whom full information as to the most suitable way of organising contemplated exhibition displays can also be obtained.

made up of a massive positively electrified centre surrounded by electrons. The number of electrons increasing from one in the atom of hydrogen to a hundred or more in the heavier elements. The positive charge of the centre and the negative charges on the electrons will produce a field of electriIcal force which will be determinable when the position of the electrons can be specified. Thus the force exerted by the atom, and therefore its chemical properties, will depend upon the configuration of the electrons, and to determine this is one of the most important problems in the electron theory of chemistry. This problem is that of determining the way the electrons will arrange themselves under the action of their mutual repulsions and the forces exerted upon them by the positive charge. In the first place, we observe that if these forces were to vary strictly as the inverse square of the distance, we know by Earnshaw's theorem that no stable configuration in which the electrons are at rest or oscillating about positions of equilibrium is possible, the electrons must describe orbits, and further, they must describe different orbits; for such a system as that in Saturn's rings where several units follow each other round the same orbit, it is not possible when the units, as the electrons would do, repei each other instead of attracting one another like the constituents of Saturn's rings. When there are several electrons in the atom the orbits described by the electrons would be of great complexity, and the mental picture conveyed by this multitude of crbits would be too blurred and complicated to be of much assistance in helping us to get readily a clear idea of what is going on in chemical processes.

"I have therefore adopted the plan of supposing that the law of force between the positive part and the electrons is, at the distances with which we have to deal in the atom, not strictly that of the inverse square, but a more complex one which changes from attraction to repulsion as the distance between the positive charge and the electron diminishes. This hypothesis leads to a simple mental picture of the structure of the atom, and its consequences are in close agreement with the facts of chemistry. I suppose that the repulsive force between two electrons is always inversely proportional to the square of the distance. With regard to this point I may point out that we have no direct evidence as to what may be

the law of force between electrical charges at distances comparable to 10-8 cm., which is a distance which we have reason to believe is comparable with that which separates the positive charge from the electron in the atom. The direct experimental verification of this law has been, of course. made at incomparably greater distances. while the direct experiments, such as those on the scattering of the alpha particles, only give information as to the law at distances very small compared with 10-8

I shall assume that the law of force between a positive charge and an electron is expressed by the equation:

F= (Ee) [1-(cr)],

where F is the attraction between the charge, E, e, the positive and negative charges on the core and the electrons, respectively, r the distance between them, and c is a constant varying from one kind of atom to another, it is the distance at which the force changes from attraction to repulsion and is of the order of 10-8 cm.

"We may remark, in passing, that the introduction of some new physical law, involving directly or indirectly a length of this order, is necessary for any theory of the structure of atoms. We could not form a theory at all if all we knew about the action of electric charges was that they repelled or attracted inversely as the square of the distance, for this would put at our disposal only two quantities, the mass of an electron and its charge, and so could not furnish the three units of space, mass and time required for any physical theory. The discovery of the induction of currents, or, what is equivalent, the magnetic effect due to electric charges, introduced another fundamental unit, the velocity of light; the unit of length to which this system leads is the radius of the electron, about 10-2 13 cm., a quantity of quite different order from 10-8 cm., which which corresponds to atomic dimensions. The size of atoms being what it is, is a proof that there is some law of physics not recognised in the older science which is all-important in connection with the theory of the atom, and must form the basis of that theory. If the law of force is that just given, then a number of electrons can be in stable equilibrium around a posi tive charge without necessarily describing orbits around it,"-Pages 3 to 5.

STUDIES IN THE REACTIONS OF THE AMINO GROUP IN 4' AMINO 1 PHENYL 5 METHYLBENZOTHIAZOLE.

PART VI. DIAZONIUM COMPOUNDS OF
DEHYDROTHIOPARATOLUIDINE.

BY R. F. HUNTER, F.C.S.

(Continued from Page 104.) Dehydrothioparatoluidine, on dissolving. in hydrochloric acid, or in the form of a suspension in the latter, is diazotized to a mixture of syn and anti forms of the diazonium chloride (1), by means of amyl, ethyl, sodium nitrite, under suitable conditions. The syn and anti forms of (1) were isolated by Morgan (J.C.S., 1922). It was decided to prepare from the diazonium salt, therefore, firstly, a typical azodye, the one formed by coupling with resorcinol was chosen (2); secondly, to repeat the work on the phenolic derivative, 4' hydroxy 1 phenyl 5 methylbenzothiazole (3); and lastly, to prepare the diazoamino derivative of dehydrothiotoluidine.

thiotoluidine are made into a fine suspension with 30 ccs. of concentrated hydrochloric acid in a 250 cc. beaker. The same volume of ice water is then added, and the beaker placed in and kept in a freezing mixture until its temperature is 0° C.

The theoretical sodium nitrite in 30 ccs. of ice water, previously cooled in a freezing mixture, is then slowly run in from a tap funnel without constant stirring. A minute or two after the addition the solution clears to a dark brown liquid. There should be no smell of nitrous acid after the addition. The theoretical resorcinol dissolved in 30 ccs. of 2N caustic soda is now added from a tap funnel, after having been cooled in a freezing mixture. The addition of the first drop of coupler produces an immediate bright red precipitate. Approximately uniform stirring should be maintained during the addition. When the addi tion of coupler is complete, the beaker is allowed to stand for half an hour. Salt is then stirred in (50 gms.), and the beaker left for another hour. The red precipitate is then filtered and washed free from salts with hot water, finally with a small quantity of dilute alcohol, and the product dried on the steam and weighed. The yield is nearly theoretical for normal coupling.

4' Hydroxy 1 phenyl 5 methylbenzothiazole:

The preparation of this on a small scale has already been described by the author (loc. cit.). In this case 5 gms. of dehydrothiotoluidine were worked up after the method described, the diazo solution being boiled for four hours. The product, after purification by means of alkali and hydrochloric acid, was dried, and a portion recrystallised from hot alcohol in the form of pale yellow crystals. The crystals were nearly white. The yield was about 50 per

cent.

Diazoamino compound of dehydrothistoluidine.

The preparation was as for the azo colour, only the diazotization was carried out in sulphuric acid solution. The proportions used were theoretical. The product was obtained as a brown solid in good yield.

The Imperial College of Science and Technology.

South Kensington, S.W.7.

January, 1924.