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Data from two flights of a new superconducting magnetic spectrometer are reported. This instrument was capable of a direct matter-antimatter separation in the cosmic rays. Antimatter events would appear in the spectrometer as trajectories which curve in the opposite direction to common matter, because of their negative charge. A brief description of the equipment and of the characteristics of the instrument is presented, along with the data processing techniques used. A new upper limit on the amount of antimatter in primary cosmic rays has been established. The limits are considerably lower than those for any previous experiment.

The specific adsorption of anions depends on the pK values of the anion acids. The adsorbed anions confer a negative charge on the surface displacing the zero point of charge to lower pH values.

IN his recent presidential address to the Royal Meteorological Society, under the above title, Sir George Simpson1 has given a full account of experimental results on the processes giving rise to electrical charges on raindrops and in clouds. Due largely to work in which Sir George has himself taken a big part, a fairly clear picture is now available of the electrical structure of a thunder-cloud, showing a positive charge above and a negative charge below, with a localized concentration of positive charge at a still lower level. There must be two processes of separation of charge: an upper one, in a region where the temperature is below freezing-point, and where the separation has been ascribed by Simpson and Serase2 to a process of friction between ice-particles, giving a negative charge to the larger particles and a positive charge to the air ; and a lower one, where the precipitation is entirely in liquid form, and where the separation of charge is ascribed to the breaking of drops, giving positive drops and a negative charge to the air.

THE surface of filter paper, in contact with water, has a slight negative charge1, and this may account for the non-adsorption of certain colloidal electrolytes such as dyes of the ‘acid’ type, when developed with water, as these also carry a net negative charge in aqueous solution. By the application of principles similar to those described by Weiss2, a ‘primary adsorbate’ may be applied to paper, in this case being so arranged that the paper now has a net positive charge in contact with water. A suitable compound for this purpose is cetyl trimethyl ammonium bromide, the paper being soaked in 0.03 per cent aqueous solution and dried before use.

COMPLEXES of vermiculite with straight-chain, amine cations have been investigated in considerable detail1–3; complexes with cyclic amine cations have been neglected. In the present study, complexes were made using anilinium, cyclohexylammonium, 2,6-lutidinium, N, N-dimethylanilum, piperazinium, piperidinium, p-toluidinium, and 2,6-xylidinium ions. The vermiculite, from Llano County, Texas, has the very high negative charge of l.96/O20(OH)4 unit, equivalent to approximately one charge per two oxygen surface holes. The interlayer Mg2+ ions were replaced by Li1+ to facilitate forming the complex, then small flakes were soaked at 80° C in 0.1 N solutions of the amine hydrochlorides for 50 to 140 h.

IT has often been observed that snowstorms are accompanied by pronounced electrical effects; blown snowflakes and the air in their vicinity become highly charged. No explanation has been offered for the mechanism involved in snowstorm electrification, but analysis1 shows that, despite the erratic and often contradictory results, it is possible to discern a pattern in the electrification which is explicable qualitatively in terms of the theory of charge transfer associated with temperature gradients in ice2. According to the theory, which was verified experimentally, charge is separated when temperature gradients are applied along ice specimens, or when two pieces of ice of different temperature are momentarily brought into contact; the colder ice acquires positive charge and the warmer ice negative charge.

PROF. ARMSTRONG holds that Simpson's theory of the thunderstorm is invalid because its physical basis is unsound. He believes that it is not possible for water-drops to become electrically charged by simple rupture in air. If Simpson's paper (Phil. Trans., A, vol. 209, p. 379, 1909) is consulted, it will be found that the author of the theory has established quite definitely that when water-drops in contact with air only are broken by an air-current, the resulting smaller drops are positively charged, the corresponding negative charge going to the air as an excess of negative ions. The present writer is all the more confident of the reality of this effect, as in subsequent experiments (Proc. Roy. Soc., A, vol. 90, p. 531, 1914), with a form, of apparatus quite different from that used by Simpson, he obtained the same results. Thus, whatever be the grounds on which Prof. Armstrong declines to believe in the possibility of an electrical separation as the result of a “mere division of water-drops against an air-current”, there is no doubt that such a separation does occur: !

A CO-ORDINATE union between a bivalent atom, for example, of oxygen, and an atom or group X may be regarded as having resulted from the attachment of a neutral atom of the bivalent element to X, and its mode of formation frequently corresponds to this, although the transference of an already co-ordinated bivalent atom from another atom to X is a frequent variant of it. In any compound, therefore, the combination may be expected to behave as a composite atom or group, so that electronic effects, which in the original group would assert themselves at X, will assert themselves similarly in a qualitative, though possibly not quantitative, manner at the bivalent atom in the combination. For example, the composite thiosulphate ion, which is formed from the sulphite ion and sulphur, is stable only so long as it preserves its double negative charge, and breaks down into its components on partial or complete neutralisation. This, however, can occur in two ways, because there are two alternatively possible effective seats of the negative charge to which a cation may attach itself—the original ionic group or the attached sulphur atom

A CONSIDERABLE volume of experimental data concerning the problems of high field conductivity and the electrical breakdown in liquid dielectrics is now in existence, and many theories have been proposed to explain these results. Nevertheless it is rather doubtful whether it will be possible to choose the right one without an understanding of the negative charge carriers and their high field mobility. With the exception of the measurements of Chong1, there are no mobility data at high field strengths. On the contrary, a number of papers concerning the mobility of ions in low fields have been published2–5. The most systematic investigations concerning this problem were carried out by I. Adamczewski.

IN a letter to NATURE of April 13 (vol. lxxxvi., p. 213) I gave reasons for the view that at least some of the forms of aurora borealis are caused by a type of rays which, as regards absorption by matter, follow the same law as α rays from radio-active substances. In the letter I also mentioned that the diurnal distribution of aurora apparently would require a negative charge of the rays.

ARISING from an investigation of the variation in positive and negative charge with pH in a number of ferruginous tropical soils1, it appeared that the use of alcohol washings in the determination of cation exchange capacity (CEC) on such soils might lead to serious errors.

No special difficulty has been experienced in showing that the β particles (electrons), expelled from radium, carry with them a negative charge of electricity. The positive charge left behind on the vessel containing the radio-active material is simply and strikingly illustrated in the arrangement devised by Strutt, which is now popularly known as the “radium clock.”

PARTICLES of colloidal graphitic oxide dispersed in water have a negative charge, and under a potential gradient move relatively rapidly towards the anode1. Under certain conditions, however, reduction of the oxide occurs at the cathode, with the formation of long carbon dendrites. This phenomenon was shown in striking manner under the following conditions.

IT is well known that petrols flowing down a tube acquire a quite considerable electrostatic charge, and it is perhaps less well known that the addition of a reasonable quantity of alcohol reduces this charge to insignificant proportions1. Some recent experiments on the effect of small quantities of alcohol reveal, however, very puzzling results. The pure petrol always acquires a positive charge and the addition of slightly more than 1 per cent of alcohol reduces the charge to zero; but what is remarkable is that the addition of a little more alcohol produces a negative charge until about 8 per cent, after which the charge is negligible.

IT has been suggested that one of the characteristics of embryonal1, proliferating2, or neoplastic3 mammalian cells is the presence of a high surface negative charge, as measured by cell electrophoresis. Data on fresh human tumour cells have not been available, however, except for studies of leukaemic cells4,5. The present investigation was designed to accumulate cell electrophoretic mobilities from a variety of fresh human tumour tissues.

THE mesoionic 1,3,4-thiadiazoles, I, were first reported by Busch1, who assigned a bicyclic structure to the compounds. Schoenberg2 later re-examined the structure of Busch and offered a resonance hybrid structure, now accepted as being typical of a large group of heterocycles described as being mesoionic3. We became interested in the mesoionic 1,3,4-thiadiazoles as a natural extension of our interest in the pharmacology and pharmaceutical chemistry of the sydnones II4–7. It occurred to us that since the two ring systems are isoelectronic (that is, being mesoionic they both possess an aromatic, positively charged, 5-membered ring, and a balancing negative charge on an exocyclic atom) the possibility might exist that the two ring systems could also be bioisosteric. That is, the ring itself may behave as a pharmacologically active functional group and that this already expressde similarity between the ring systems may impart similar pharmacological activity. A more conservative speculation would be that perhaps the mesoionic 1,3,4-thiadiazole ring system would have some prominent pharmacological activity.

ELECTROKINETIC methods can be used with great advantage in the study of the adsorption of electrolytes or potential-determining ions on crystalline substances. One of us1 determined the streaming potentials in diaphragms of precipitated and aged barium sulphate, as a function of the composition of the bathing electrolyte solution. Reyerson, Kolthoff and Kieth Coad2 have recently confirmed in a general way these results, With the exception that they found a constant negative charge in hydro-alcoholic (50 per cent) solution of potassium chloride (10-5 M). Ruyssen1 had found that by the replacement of the aqueous potassium chloride solution by a hydroalcoholic one the initial negative charge was reversed.

PROF. ARMSTRONG'S friendly criticism (NATURE, October 13, p. 537) of my theory of the origin of electricity in thunderstorms seems to neglect the fact that my explanation of thunderstorms is based entirely upon experimental and observational evidence. If experiments can be said to prove anything, then my work and the work of others has shown conclusively that: (a) if there are ascending currents exceeding 8 metres per second in the atmosphere, there must be a great deal of breaking of rain drops; (b) every time a water drop breaks there is a separation of electricity; (c) the broken water drops retain a positive charge; (d) the air attains a negative charge. On the other hand, observations have shown that there is a considerable excess of positive electricity brought down by rain. These are all tangible facts which any one can test by making the suitable experiments, and I have done nothing more than arrange them into such a form that a reasonable account of the phenomena of thunderstorms results.

THE electroscope which Prof. Lodge proposes to use to indicate positive and negative potentials by different movements of the leaves (see p. 320), has the disadvantage that (assuming the case to be charged negatively), if too large a negative charge be given to the gold leaves they will diverge, and the inference will be that the potential is zero or positive, neither of which is the truth. For the purpose Prof. Lodge has in view, a Bohnenberger's electroscope would indicate more clearly positive, negative, or zero potential. Instead of the two dry piles, the inner and outer coatings of a charged insulated Leyden jar connected to two knobs, one on each side of the single gold leaf, might be substituted.

I THINK that the difficulty which Mr. Burbury expresses on p. 439 (March 12), under the above heading, probably rests on a misapprehension. He says: “When zinc is isolated, a negative charge is on it, and therefore at an outside point there is a positive slope of potential upwards from the zinc.” My statement, on the contrary, is that a piece of zinc immersed in an oxidizing medium possesses no charge so long as it is isolated, but experiences a lowering of potential by reason of the chemical tendencies of its surface-film—i.e. the contiguity of a number of negatively charged oxygenations. In this film, indeed, there is an electrical double-layer, consisting of equal opposite charges, the negative facing the zinc, the positive facing outwards; but there is no charge such as will produce the slightest effect at an external point. Contact with copper of course changes all this; displacing negative electricity from zinc to copper across the junction, from copper to zinc through the air. It is this displacement which affects all external points; and it is this which electroscopic experiments have displayed. There is nothing whatever to be detected in the neighbourhood of a piece of isolated zinc, unless its surface-film itself be explored. The range of its effect is sharply bounded by the thickness of its infinitesimal air-film, on which the whole of the molecular strain is thrown: much as is expressed by Mr. Chattock in the latter half of his letter on p. 367.

PERHAPS the following slight elaboration of Dr. Lodge's views on the electrical condition of air films in contact with metals will commend itself to Mr. Burbury. It seems to me that by its means the difficulty of realizing the source of the negative charge on the oxygen atoms is to a certain extent got over without thereby forfeiting any of the essential features of the air film theory.

SYNTHETIC zeolites1, especially those with the same structure as natural faujasite, have recently come into prominence as industrial catalysts. Pickert, Rabo, Dempsey, Schomaker and references2 have convincingly demonstrated the importance of the positions of the exchangeable cations which compensate for the effective negative charge of aluminium atoms in the aluminosilicate framework. ‘Linde’ 13X normally has Na+ in all the cation positions. Very little attention has been given to the effect of dehydration qf the zeolites on the position of the cations, or the position of individual ions when more than one type of cation is present.