Number Of Negative Ions Research Articles

Dependence of solvation on particle shape

AbstractThe relationships which exist between the solvation and shape of colloid particles, as well as between solvation and viscosity, are discussed. From the most important experiments on these subjects the following conclusions may be drawn. Solvation is dependent on the size and shape of the particles and on the chemical relationship of the dispersion medium to the dispersed portion. True or chemical solvation is generally very small and there is no reason to speak of a thick and tightly bound solvent layer. The solvation of compactly formed particles of spherocolloids is greater, the smaller the particles (all other conditions being equal). Solvation is greater, the more loosely the particles are formed (for dispersion mediums having similar chemical properties and for similar dispersed or dissolved substances). Solvation increases when a corpuscular particle is transformed into a rodlike or threadlike particle; the viscosity also increases; if the threads are further broken down into smaller fragments, then the viscosity decreases, but a further increase in the chemical solvationis supposed to occur. The stability of many lyophilic sols, especially the proteins, depends very little on the solvation; it is mainly dependent on the chemical characteristics of the atomic groups which are found on the surfaces of the particles; the least stability is found for surfaces which contain heteropolar groups—that is, surfaces which have the same number of positive and negative ions.

Atmospheric‐electric observations at the Needham Laboratory for cosmic terrestrial research

In addition to the continuous measurement of field‐intensities in the broadcast and high‐frequency bands three instruments are regularly in use at the Laboratory for Cosmic Terrestrial Research at Needham, Massachusetts, for measuring atmospheric‐electric phenomena (Fig. 1): (1) A potential‐gradient apparatus; (2) an ion‐counter for determining the number of small negative ions of a given mobility; (3) a point‐discharge apparatus for determining atmospheric‐electric discharges between the Earth and the sky in either direction. The first of these at present is manually read, whereas the other two are automatically recording.

Holes in the Ionosphere and Magnetic Storms

THERE is good reason to attribute magnetic storms to neutral streams from the sun. These streams have equal numbers of positive and negative ions, because any excess would immediately be dissipated into the surrounding space.

ATMOSPHERIC ELECTRICITY AT THE COLLEGE‐FAIRBANKS POLAR YEAR STATION

The atmospheric‐electric program at College, Alaska, during the second International Polar Year extended from October 1, 1932, to August 31, 1933. (1) Continuous registration was made of air‐potential with a recording quadrant‐electrometer and a radioactive collector on a horizontal rod at the variation‐observatory and during most of the time also with a recording bifilar‐electrometer with radioactive collectors exposed by the stretched‐wire method for control at a standardization‐station. (2) Continuous registration was made of air‐conductivity due to both positive and negative ions, using semi‐portable apparatus in which the deflection is nearly proportional to the conductivity; in this apparatus the charge collected by the Gerdien condenser flows to earth through a resistance of about one electrostatic unit and the resulting voltage‐drop through this unit is recorded by a single‐fiber electrometer. (3) Determinations of the number of positive and negative small ions, usually made once each day, using a modified Ebert ion‐counter. (4) Determinations of the number of condensation‐nuclei, once daily from late in March through August, using an Aitken counter; during the cold weather the counter did not function satisfactorily.These data conform with those obtained in lower latitudes at stations on land that are relatively free from variable sources of pollution. The average gradient for all complete days for the eleven‐month period is 104 volts per meter with a maximum in January and a minimum in August. Harmonic analyses of the hourly values show that a 24‐hour component exists in gradient, in substantial agreement with Mauchly's findings. All complete days of positive and negative conductivity yield average values of 179 and 131 × 10−6 electrostatic unit, respectively. The variations are approximately the inverse of those in the gradient although their product—the electrical conduction current—shows regular daily and seasonal variations. The average number of positive small ions by months varied from a minimum of 620 per cc in July to a maximum of 980 in November. The number of negative small ions varied from 520 per cc in July to 660 in November and February. From the ion‐count and the corresponding values of conductivity a mean value of 1.56 cm2 volt−1 sec−1 for the mobility of both the positive and negative small ions was found, although different mobility‐groups are indicated by frequency‐curves. The average of 112 determinations of nuclei is 3760 per cc.The electrode‐effect appears to be quite important at this station. The ratio of positive to negative conductivity varies directly as the gradient, both in long‐period and short‐period changes. This and other features of the results are explicable on the basis of conditions as they would exist in quiet air. At times turbulence is effective in complicating the relations between the elements and so for a complete explanation of these results the effect of mixing must be considered in addition to conditions as they would exist in quiet air.

Secondary Processes of Ionization in Mercury Vapor

The ionization occurring in mercury vapor as the result of the impact of electrons of energy less than 10.4 volts was studied by use of a tube containing a small filament, the emission of which was limited by space-charge. The ionization produced has been studied as a function of electron velocity, bombarding current and pressure of the mercury vapor. For electron velocities above 7 volts the data are in agreement with the assumption that the larger part of the ionization is the result of ionization of metastable atoms by electron impact. Critical potentials at 8.4 and 8.6 volts are identified with the configurations $5{d}^{9}6{s}^{2}6p^{3}{P}_{1}^{0}$ and $5{d}^{10}6s7p^{3}{P}_{1}^{0}$, respectively. Another critical potential at 6.9 volts is tentatively identified as the difference between the lower metastable level, $6s6p^{3}{P}_{0}^{0}$, and a negative energy level, $6{p}^{2}^{3}P_{1}$. Large numbers of negative ions were found in the neighborhood of 4.9 volts. It is suggested that ionization observed in this region is due to the simultaneous formation of a positive ion and a negative ion upon the collision of a $2^{3}P_{0}$ atom with a $2^{3}P_{1}$ atom.

Variation with Temperature of the Electrification Produced in Air by the Disruption of Water Drops and Its Bearing on the Prevalence of Lightning

The total charge carried by the negative ions which are produced in the air when a water drop is disrupted by falling through a horizontal stream of air was measured for different stream velocities at temperatures between 1\ifmmode^\circ\else\textdegree\fi{}C and 63\ifmmode^\circ\else\textdegree\fi{}C. The dependence of this charge upon the size of the drop was found from observations made with drops differing in volume between 0.076 cc and 0.092 cc. For blasts exceeding that necessary just to disrupt the drops, the charge obtained per drop disrupted increases rapidly both with the velocity of the blast and with increase of temperature. The rate at which the charge changes with increase of temperature of the drop depends upon the magnitude of the air stream employed for producing the disruption. For drops of 5.8 mm diameter falling from a height of 2 cm through a horizontal cylindrical stream of 1 cm diameter and having an average velocity of 20 m/sec., the relation between the numbers of negative ions produced per drop disrupted at the temperatures 1.3\ifmmode^\circ\else\textdegree\fi{}C, 24.2\ifmmode^\circ\else\textdegree\fi{}C, 42.1\ifmmode^\circ\else\textdegree\fi{}C and 62.5\ifmmode^\circ\else\textdegree\fi{}C, respectively, was found to be 1: 3: 6.4: 11. In the range of temperatures found in the atmosphere at different times the amount of electrification produced in the air when raindrops are disrupted by air currents of a given magnitude may be at least three times as large when the rain-water is warm as when it is cold. Rain temperature is therefore an important factor in determining the frequency and the intensity of lightning discharges.

The Limiting Polarization of Downcoming Radio Waves Traveling Obliquely to the Earth's Magnetic Field

The paper is a theoretical discussion of the limiting polarization of downcoming electromagnetic waves propagated at oblique angles to the earth's magnetic field. The main conclusions arrived at are: (a). The polarization of the downcoming wave tends to a definite limit on leaving the Kennelly-Heaviside layer. The limiting polarization has been shown to be very nearly independent, for conditions that are likely to hold in practice, of the presence of large numbers of heavy negative ions in addition to the electrons, and of the occurrence of collisions between electrons and gas molecules. (b). The shape of the ellipse of polarization is determined by the frequency of the wave relative to the critical frequency, and by the angle between the direction of propagation and the lines of force of the earth's magnetic field. (c). The orientation of the ellipse is such that the principal axes are perpendicular to the direction of propagation, the major axis being in the plane containing the direction of the earth's magnetic field and the direction of propagation. (d). The sense of rotation of the electric vector contained by the ellipse is left-handed when the direction of propagation of the ordinary downcoming ray makes an acute angle with the earth's field; the rotation is right-handed when the angle is obtuse.

Relation between the Potential Gradient and the Number of Large Ions in the Atmosphere

IN making some tests recently with an apparatus designed for the observation of large ions in the atmosphere, I have found evidence of a close connexion between the concentration of large ions and the magnitude of the atmospheric potential gradient. When conditions are not quite steady the two quantities frequently vary simultaneously in the same fashion, large values of one being accompanied by large values of the other. The curves in Figs. 1 and 2, each representing about one hour's observations, show examples of this correspondence. The connexion is not always so well marked, as large and irregular fluctuations in the potential gradient are often unaccompanied by any notable change in the concentration of large ions. There is nearly always, however, a general resemblance be tween the curves obtained, and in a number of cases, peaks even more sharply defined than those of Fig. 2 have been found to coincide. The figures for the concentration of large ions refer to ions of one sign only. No great difference has so far been found between the numbers of positive and negative ions, except on one occasion during heavy rain, when the potential gradient was negative and negative ions were present in considerable excess. The values given for the potential gradient are not absolute values with reference to a plane surface.

Atmospheric ionization and its variations

The atmospheric electricity elements dealt with include the potential gradient, the numbers of positive and negative ions and the charges carried by them, the conductivity of the air and the vertical air-earth current. For instantaneous values it suffices to know the potential gradient and either the conductivity or the current. But in the case of mean values, depending on a number of individual observations, a knowledge of all three elements is necessary. Particulars are given of the annual variations observed at various stations. Information as to diurnal variation is very scanty, except in the case of potential gradient. The monthly values in the annual variation, and the hourly values in the daily variation, are expressed as percentages of their arithmetic means. This is done partly because less uncertainty attaches to relative than to absolute values in the case of all the electrical elements. Reference is made to some conclusions as to the diurnal variation of potential gradient and the existence of a sun-spot period recently arrived at by Dr. Bauer and Dr. Mauchly, of the Carnegie Institution of Washington.

The atmospheric potential gradient, and a theory as to the cause of its connection with other phenomena in atmospheric electricity, together with certain conclusions as to the expression for the electric force between two parallel charged plates

The primary purpose of the following paper is to show that the theory of conduction of electricity in gases, combined with the assumption of an atmospheric potential gradient of such a sign that the potential increases with the height, leads us to expect:1(1) That the ratio of the number of positive ions per c. c. at the Earth's surface, to the number of negative ions shall be greater than unity.

On the recombination of the ions produced by Röntgen rays in gases and vapours

In a space containing both positive and negative ions the concentration of tends ions tends to diminish as a result of the union of ions of opposite sign. The number of ions of each sign which disappear in unit time is proportional to the number of collisions between ions of opposite sign. This is proportional to the product of the concentrations of the two kinds of ions and it is customary to express the change in the form of the equation dn 1 / dt = —α n 1 n 2 = dn 2 / dt , where n 1 and n 2 are the numbers of positive and negative ions respectively in unit volume, and α is a constant for a gas at a given temperature and pressure; α is called the coefficient of recombination of the ions. When the concentrations of the two kinds of ions are equal the equation takes the simple form dn / dt = —α n 2 , the solution of which is n 0 being the concentration of the ions initially, and n the concentration after an interval of time t . In what has been said above the effect of diffusion is supposed to be negligible.

Notes on the Behaviour of Incandescent Lime Kathodes

Wehnelt has shown that incandescent lime emits a large number of negative ions; if, therefore, hot lime is used as the kathode, a discharge may be obtained in a vacuum tube with P.D.s as low as 30 volts. The alteration with time of these kathodes, under continued use, has been investigated and the following results obtained: (1) When lime is heated on platinum foil, so far from showing fatigue, it actually increases in activity. With P.D.s greater than the saturation voltage this increase may be ninefold. At lower voltages a slow but steady increase up to 100 per cent. has been found. The steady activity falls when the lime is cold, the initial activity may greatly increase. (2) When the lime is heated on nickel foil, if the tube carries a heavy discharge, the current increases to a maximum and then decreases. A greatly increased activity is frequently shown after the lime has been cold for some hours. At the lower voltages the same general variations are shown as with platinum. (3) Great irregularity is frequently shown when the current is first started; at this stage other causes than temperature, such as mechanical vibrations, greatly influence the emission of ions.