A microscopic theory of the kaolinite-water system is presented, based upon the assumption that the clay-water interaction may be envisioned as partly hydration of the exchangeable cations and partly adsorption by the oxygen and hydroxyl surfaces. The theory treats exchangeable cation hydration quantum-mechanically as an ion-dipole phenomenon and considers water adsorption by the mineral surface as a problem in hydrogen bonding. A statistical mechanical model incorporating the quantum-theoretical results is then invoked to find the contribution of each component interaction to the initial portion of the adsorption isotherm for homoionic kaolinite. Good agreement between the theoretical calculations and available experimental data is achieved for water vapor adsorption by Li-, Na-, K-, and Mg-kaolinite, without the use of ad hoc empirical parameters. The concordance, in turn, is used to suggest that the basis for adsorption hysteresis in kaolinite-water vapor systems is the irreversible transition: mineral surface water → cation hydration water.

The thermal decomposition of the kaolinite: N-methylformamide intercalate [Al2Si2O5(OH)4·HCONHCH3] has been studied by differential scanning calorimetry (DSC). The decomposition starts at 355 K, finishes at 450 K and follows Avrami-Erofeev kinetics for α = 0.04–0.96. ΔH for the loss of organic is 19 ± 2 kJ mol−1; the activation energy for the reaction is 30 ± 3 kJ mol−1.

High swelling bentonites cannot be analyzed for exchangeable cations with exactly the same technique as most soils. To resolve varied techniques used in the past and to establish a reliable procedure, the effects of sample size, the number of saturations, washes and extractions, and the volume of extracting solutions were determined on three high-swelling bentonites.

Small samples must be used to insure complete extraction of exchangeable cations, and the 0·5 g weight was the best size of those tested. Most exchangeable cations were removed in three extractions with 25 or 33 ml volumes of ammonium acetate. More extractions could result in excessive solubilization of minerals. Centrifugal force must be sufficient to prevent loss of sample during decantation. This varied from 4500 to 7500 g for 10–20 min, depending on particle size and sample dispersion.

The proposed CEC method requires little time, but still compared closely with Frink’s more extensive method and showed no significant difference between treatment means. The procedure was used to analyze high-swelling bentonites from fourteen locations in six Western States. Chemical properties changed within each deposit and with geographical location, but in general the bentonites contained high amounts of exchangeable Na, moderate amounts of exchangeable Ca and Mg, and low amounts of exchangeable K. Total exchangeable reliability of the proposed method.

I.R. absorption and X-ray diffraction data on butylammonium complexes of vermiculites show, when compared with the Wyoming montmorillonite complex, that the tetrahedral location of charge determines the keying of the -NH+3 groups into the ditrigonal cavities and that these groups have their C3 axes perpendicular to the layers. The aliphatic chains adopt different conformations depending on the area available per exchange position; they will either: (a) adopt an ’all-trans’ conformation with their axes inclined 55° to the silicate planes, when the area available is small; (b) rotate 120° around the C1-C2 bond to adopt a flat disposition relative to the layers, when the area available is larger than the area covered by the organic ion.

An electron microscope study was made to determine the effect of mechanical compaction method on the fabric produced in a compacted commercial kaolin. Direct platinum-shadowed carbon replicas were made from horizontal and vertical fracture surfaces within the middle third of cylindrical specimens compacted by static load, impact, and kneading compaction at optimum moisture content and at 3% above and below optimum. Replicas were studied in the electron microscope to arrive at a qualitative evaluation of fabric. No oriented fabric or edge-to-face random fabric of individual particles, as postulated by others, was found. Regardless of compaction method the fabric was found to consist of parallel and random arrangements of packets of kaolin flakes. Both impact and kneading compaction produced essentially the same fabric consisting of trajectories of parallel packets, probably the result of shearing deformation during compaction, within essentially randomly oriented zones of packets. Static load compaction produced a fabric in which some tendency of the packets to orient normal to the direction of loading was apparent. For all compaction methods some increase in parallel packet orientation was noted with increase in molding water content. The mode of parallel orientation differed between static load compacted specimens and those produced by either impact or kneading compaction. Results of the study indicate that some revision of concepts regarding particle orientation due to mechanical compaction should be made.

This article reconsiders the classed and gendered construction of the Author in the Roman Mediterranean, a construction that generates the intertwined notions of authorship and authenticity. Modern scholarly conversations about authorship and pseudepigraphy in the Roman Mediterranean often proceed from the uninterrogated assumptions that (a) ancient texts (including early Christian texts) were the monographic products of solitary authors and (b) everyone in antiquity, regardless of gender or class, had access to the status of being an ‘Author’. While conversations about (in)authentic textual production extend beyond the works that become part of the New Testament, these twin assumptions form the basis for modern debates about ‘forgery’ in New Testament literature. This article challenges both assumptions by first surveying the role of uncredited collaboration in Roman literary culture and then analysing ancient Christian discourses surrounding (a) illicit textual meddling and (b) inappropriate textual ascription. These two discursive categories reveal how the categories of class and gender are entangled with early Christian ideas of the Author. Ancient discourses of authenticity and authorship were not simply about who produced texts but about policing which acts of textual production count as ‘authoring’.

For a partially multiplicative quandle (PMQ) ${\mathcal {Q}}$ we consider the topological monoid $\mathring {\mathrm {HM}}({\mathcal {Q}})$ of Hurwitz spaces of configurations in the plane with local monodromies in ${\mathcal {Q}}$. We compute the group completion of $\mathring {\mathrm {HM}}({\mathcal {Q}})$: it is the product of the (discrete) enveloping group ${\mathcal {G}}({\mathcal {Q}})$ with a component of the double loop space of the relative Hurwitz space $\mathrm {Hur}_+([0,1]^2,\partial [0,1]^2;{\mathcal {Q}},G)_{\mathbb {1}}$; here $G$ is any group giving rise, together with ${\mathcal {Q}}$, to a PMQ–group pair. Under the additional assumption that ${\mathcal {Q}}$ is finite and rationally Poincaré and that $G$ is finite, we compute the rational cohomology ring of $\mathrm {Hur}_+([0,1]^2,\partial [0,1]^2;{\mathcal {Q}},G)_{\mathbb {1}}$.

The different types of iron oxide phases associated with the surfaces of two suites of kaolins from Georgia, U.S.A., and from the Southwest Peninsula of England, have been identified using electron spin resonance (ESR) spectroscopy combined with magnetic-filtration, thermal, and chemical treatments. It has been shown that the English kaolins are coated with a lepidocrocitelike phase, which is readily removed by de Endredy's method of deferrification, while the Georgia kaolins are coated with a hematite- or goethitelike phase, which is not removed by this treatment. Throughout the course of this study, the effects of the various physical and chemical treatments on the brightness values of the kaolins were examined.

Gravitational settling and centrifuge techniques have been criticized in the preparation of X-ray specimen mounts for quantitative clay petrology because of the marked mineral segregations that can occur. Although the same factors can operate to produce error in the separation of the traditional less-than-2-μm fraction, this potentially more important source of bias is seldom taken into consideration. A fair representation of the bulk sample deserves at least as much attention as a representative X-ray mount. The most accurate and precise X-ray analyses may be geologically misleading or meaningless otherwise and translate as exercises in precision for its own sake.

Scan electron micrographs (SEM) show the textures of ball clay, plastic refractory clay, flint clay, and of kaolins from Cornwall, U.K., and Brittany, France. The texture of ball clay is a swirl and ragged-flake pattern. Plastic refractory clay shows a transition in texture from ball clay to plastic, semi-plastic, to semi-flint, and flint-clay. Flint-clay texture exhibits a matrix of tiny, compactly interlocked clay grains in which may be interspersed small, tight books and sheaves of kaolinite. The plastic to flint clays are interpreted to be sequential components of the flint-clay facies. In one sense they represent elements in clay diagenesis.

Kaolins from the Cornwall district, U.K., and Brittany, France, show more similarity than dissimilarity in texture. Evidence from texture suggests that while hydrothermal action at Cornwall initiated alteration of the granite, the last significant process of kaolinization there was weathering.

This paper reports the measured distribution of major cations in interstitial, exchangeable and non-exchangeable phases of estuarine sediments. The observed changes in ionic ratios result from the valence and dilution effects in the Donnan equilibrium concept according to which the ion exchanger favors the sorption of divalent ions at the expense of monovalent cations and cations migrate to the outer solution. The above findings have direct application to an interpretation of diagenetic changes in clay minerals.