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Nitrogen adsorption isotherms have been determined on a microporous rutile sample before and after preadsorption of nonane. Analysis of the isotherms by the αs method, using different standard adsorption data, shows that the experimental phenomena can only be explained rationally using a standard isotherm based on a material of the same chemical composition as the material under study, rather than one with the same BET C constant.

Die Cadmiumapatite Cd5(PO4)3OH und Cd5(PO4)3F sowie der bisher nicht bekannte Jodapatit Cd5(VO4)3J wurden in Form von Kristallen erhalten. Die Substanzen wurden mit rontgenographischen Pulver- und Einkristallmethoden untersucht. Alle Ein-kristalldiagramme weisen hexagonale Symmetrie auf. Die Jodverbindung hat eine so niedrige c-Konstante (etwa 6,5 A), das eine Diskussion der Halogenidlagen in der Struktur notwendig erscheint. Die Reflexe von C5(PO4)3F zeigen Aufspaltungen, die fur eine trikline Verzerrung der Apatitstruktur und fur Zwillingsbildung sprechen. Im Temperaturbereich von etwa 150 bis 350°C verschwindet die Deformation reversibel. Cd5(AsO4)3F und Cd5(VO4)3F sowie die entsprechenden OH-Verbindungen konnten nicht erhalten werden. Dagegen wurden die neuen isotypen Verbindungen Cd2XO4F (X = P, As, V) auf thermischem und hydrothermalem Wege dargestellt. Einkristalluntersuchungen und die Morphologie von Cd2PO4F ergaben die Raumgruppe C2/c. Es bestehen strukturelle Beziehungen zu den Mineralen der Wagnerit-Gruppe. Im Zusammenhang mit der Synthese von Cd2XO4F wird die relative Stabilitat verschiedener Apatite diskutiert. The Cadmiumapatites Cd5(PO4)3OH und Cd5(PO4)3F as well as the yet unknown iodoapatite Cd5(VO4)3I were synthesized and investigated by X-ray powder and single crystal methods. All single crystal diagrams exhibit hexagonal symmetry. The iodine compound has such a low c constant (about 6.5 A) that is seems essential to discuss the halide positions in the structure. The reflexions of Cd5(PO4)3F show splitting which is indicative of a triclinic distortion of the apatite structure and of twinning. At about 150–350°C the deformation disappears reversibly. Cd5(AsO4)3F, Cd5(VO4)3F and the corresponding OH-compounds could not be prepared, but the new isotypic compounds Cd2XO4F (X = P, As, V) were synthesized by thermal and hydrothermal reactions. Single crystal investigations and the morphology of Cd2PO4F proved the space group C2/c. There are structural relations to the minerals of the wagnerite group. In connexion with the synthesis of Cd2XO4F a discussion of the relative stabilities of different apatites is given.

From previous results and from 16 additional trials relating Bray acid-soluble plus adsorbed phosphorus to the phosphorus fertilizer requirement of the tomato crop in Prince Edward County, Ontario, the mean c1 constant for 66 trials was 0.00410, and the mean c constant for 40 comparisons was 0.00428. The standard error was ± 0.00027 for the mean c1 value and ± 0.00031 for the mean c value. The mean c1 value for trials conducted in a single year differed from the mean for all trials in only one of six years. The mean c value for each of three years did not deviate significantly from the general mean.The use of the established constants in estimating the amounts of phosphorus required for 95 per cent of maximum yield in the area is illustrated for a range of soil test values. When recommended amounts of phosphorus for 95 per cent of maximum yield were used in the 16 trials, the mean value obtained for percentage of maximum yield was 96. With less than the recommended amounts, the values for percentage yield tended to decrease, the mean value for three-quarters of that recommended being 89 per cent.

In an isentropic expansion of a real gas, the relationship pvγ = C (γ, C constant) is not exact. A development is given for an accurate exponent ᾱ (the effective ``gamma''), related to the ratio of specific heats, which permits the use of the relationship p0v0ᾱ = p1v1ᾱ for an isentropic expansion between any two pressures. The exponent may be computed from the initial conditions of the gas, the expansion ratio, equation of state data, and data on the variation of specific heat with temperature.

1. Acicular crystals of FeB and Fe2B formed on borided iron show preferred orientation. The axis of FeB crystals is parallel to the [001] and [100] directions. The axis of the Fe2B crystals is parallel to the [111] direction. 2. The preferred orientation is due to the easier diffusion of boron into the boride through the channel in the lattice. 3. In places of conjuction of the lattices of FeB and Fe2B the c constant of the Fe2B lattice decreases significantly, which apparently is associated with the adaptation of the Fe−Fe spacings in the nucleation of the FeB phase.

Consider the linear purely dynamic system described by the mathematical model $$ \underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{\dot x} = A\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{x} + B\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{u} $$ (2.1.1) (2.1.2) , where x ∈ Rn is the state vector, u ∈ Rm the input vector, y ∈ Rs the output vector; A, B, C constant n×n, n×m and s×m matrices.

The l -type doubling transitions of PF 3 in the ν 4 state are reanalyzed by taking into account the third-order terms, while keeping the centrifugal distortion constants the same as those in the ground state. An equally good fitting is obtained, and other parameters are not influenced very much, except for the C constant.

In a recent paper (publis hed in Nachr. T echn. Zeitschr.) Volland proposes an analyti cal model of the earth· ionos phe re waveguid e which is claimed to be in basic agreeme nt with the predictions of t he semi e mpirical transmission formula of L W. Austin for frequ e ncies less than 300 kc/s. In this note, the Rat·earth ass umptions made by Volland are question e d an d any agreement of hi s res u lt with Austin's formula is a ttribut ed to a fortuitou s cancell ation of e rrors. It is rathe r interestin g to n ote that H . Volland [1964] has r ecently publi shed a pa per under th e title "Bemer­ kungen zur Aus tin'schen Forme]" (Re marks on Austin' s formula). This basic radio transmission formula was proposed b y L. W. Austin and pub]jshe d in the Bulletin of th e Bureau of Standards over 50 ye ars ago [Aus tin , 191 5]_ Volland proposes an analyti­ cal model of th e earth-ionospher e waveguid e whi c h i s claimed to be in basic agreement with the predictions of the semi-empirical A us tin formula for frequ en cies less than 300 kc /s. At the same time, Volland sta tes that a fl at-earth ass umption is adequate and he asserts that the curvature of th e earth leads onl y to second­ order correc tion s and, thus, may be neglected. Sin ce this latter state ment is in violent co ntradi c ti on to most of the r ecent th eoreti cal work on VLF and LF mode theory of propagati on, so me comments on Volland's paper are call ed for. To pro perly orient the reader , a bri ef survey of Vol­ land's formulation is giv e n. His model consists of a flat homoge neo us earth with a di electri c constant Ee and conductivity (Te. The ionos phere is r e presented by a reflecting level at a height h above the earth's surface_ His formula, in cylindrical coordinates (p, cp , z), for the vector potential of a vertical dipole source of moment II is given by