Crude sedimentary kaolin clay from central Georgia, U.S.A., which had a wide distribution of particle size, was divided into several size fractions by repeated sedimentation in water. The resulting fractions had approximately a 2:1 ratio in dia. between their upper and lower limits. Each fraction was then studied by transmission and scanning electron microscopy and characterized in terms of surface area (both geometric and by gas adsorption), particle shape and impurity analysis.

Particle diameter determined from measurements made on electron micrographs showed considerable deviation from the diameter obtained by Stokes sedimentation. This deviation was especially large for the coarser particles and could be explained by the microscopically observed porosity of the kaolinite booklets. Imperfect stacking of the crystallites within a kaolinite booklet leads to a moderately regular array of slit-like voids. Effective particle densities as low as about 1·6 have been observed. The pore structure was also investigated by use of mercury intrusion porosimetry.

Boron adsorption by Ca forms of montmorillonite, illite, and kaolinite was determined as a function of pH and boron concentration in solution. Data from batch experiments were compared with results computed for each clay according to fitted adsorption coefficients (maximum boron adsorption and affinity constants related to the binding energy). The agreement between calculated values and experimental results indicates that a phenomenological equation can be used to predict boron adsorption on clays as a function of both of these variables. For the solution-to-clay ratios examined, the water content does not affect the boron-surface interaction as expressed by the above adsorption parameters. Because the affinity of clays for B(OH)4− is much stronger than for B(OH)3 , the adsorption maximum was obtained only under alkaline conditions at approximately pH 9.0 to 9.7. It is suggested that the pH of maximum adsorption is a function of the ratios of affinity coefficients of the three species B(OH)3, B(OH)4−, and OH− competing for the same adsorption sites. The adsorption coefficients indicate that in some cases the difference in the amount of adsorbed boron between montmorillonite and kaolinite could be either small or large, depending on the circumstances. The main factor that would affect this difference is the total amount of boron in the suspension. Estimated value of the adsorption maximum was 2.94, 11.8 and 15.1 µmole/g for Ca-kaolinite, Ca-montmorillonite, and Ca-illite, respectively.

The electrical conductivity of Na-montmorillonite suspensions in various salt and clay concentrations was measured. The weight conductance of the clay suspension was found to decrease with increase in clay concentration between 0 and approximately 0·5 g clay/100 ml, then rose to a plateau at 6–10 g clay/100 ml. The weight conductance of the clay suspensions also increased with an increase in the salt solution concentration. If the model of two resistors in parallel is used in interpreting the experimental data, these changes can be attributed to an increase in the mobility of the adsorbed Na ions. It is proposed that the two resistors in series model is more realistic in describing the conductivity of the suspensions. This model predicts the observed weight conductance changes of the suspensions, while the mobility of the adsorbed ions remains constant. A constant mobility of the adsorbed Na ions in clay-water systems of low to medium salt and clay concentrations also is predicted by the diffuse double layer.

Mica particles approximately 10 or 25 mm square and 0.5 mm thick were placed in NaCl-NaTPB solutions to make visual observations of the changes that occur in micas when the interlayer K is replaced by Na. Samples of muscovite, biotite, phlogopite, lepidolite, and lepidomelane were used, and the effects of different degradation periods were photographed.

An increase in the thickness of the particles due to basal planes splitting apart was observed with all micas. This exfoliation released interlayer K and in some cases caused the particles to cleave into separate flakes. Lepidomelane particles remained intact despite a 20-fold increase in thickness in 7 days. Even muscovite and lepidolite exfoliated and cleaved, but much longer degradation periods were needed.

There was a distinct change in the color of the dark biotite, phlogopite and lepidomelane particles when K was removed. Therefore, the initial stages of K depletion at holes, scratches, and edges of the particles were easily followed. As the degradation of the mica particles progressed, however, the color of the mica became a less reliable index of the stage of K depletion. Visual evidence of K depletion at the edges of particles was also obtained with muscovite, but not with lepidolite.

Transverse sections of 25-mm particles of K-depleted biotite were photographed to show the edge expansion that occurred when interlayer K was replaced by Na.

The hypothesis tested was that macroscopic swelling of montmorillonitic clays is reduced by the presence of interlayer minerals. Fine and coarse clay fractions of Camargo and Panther Greek bentonite samples were artificially interlayered by reaction of Al2(SO4)3 and NaOH in 0∙5% suspensions of the clays. All four clay fractions reacted similarly to artificial interlayering. At an Al:clay ratio of 16 meq Al/g clay the CEC was completely lost, surface area was reduced and X-ray basal spacings were altered. No macroscopic swelling occurred in samples treated with 16 meq of Al/g of clay. At smaller concentrations of hydroxy-aluminum 8 and 2 meq Al/g clay, the clay properties were less drastically altered. Extraction of interlayered clays with Na citrate restored the original C.E.C., surface area, and basal spacings of all samples and resulted in some slight enhancement of C.E.C. and surface areas of the coarse fractions. Treatment with hot Na citrate resulted in an increase in swelling ability but only slight increases in C.E.C. and surface area. Evidence presented supports the hypothesis that macroscopic swelling of montmorillonitic clays is greatly reduced by interlayer materials. Reduced swelling due to interlayering occurs even when other clay properties may be slightly different from those of nontreated samples. Indications are that interlayer material occurs naturally in the clays studied and this may apply to other bentonite deposits.

Karakorum, in present-day Mongolia, was the first capital of Mongol empire and has often been portrayed as the cosmopolitan city par excellence of its era. This portrayal is primarily based on the description of the city as a multicultural community in a travelogue written by the Franciscan monk William of Rubruck, who spent some time there in 1254. This understanding of cosmopolitanism stems from a colloquial sense of the term and does not take into account its history and layered meanings. Based on a discussion of the term, this article presents an approach to cosmopolitanism suitable for archaeology, namely by examining the practices of ‘lived cosmopolitanism’. Taking the archaeological evidence from Karakorum as a case study, the author explores the cultural fields of city layout and architecture, cuisine, religion, and funerary rites to answer the question of whether and how the people of Karakorum were cosmopolitan. The discussion shows that it is of the utmost importance to distinguish between social groups and their status. While the Great Khans can be viewed as cosmopolitans of their time, the commoner population of Karakorum appears rather to have been segregated into different groups. The material evidence so far points to low degrees of engagement among different groups within the city. Yet, the discussion of cosmopolitanism reveals deeper insights into the social realities of the city’s inhabitants and unresolved questions in the study of this important city.

On 7 December 2022, the United Nations General Assembly adopted a treaty known as the Beijing Convention governing the recognition abroad of the international effects of judicial sales of ships. This article explores the rationale for a specific Convention on this issue, and its interaction with other relevant international conventions. It then analyses the recognition approach adopted by the Convention and evaluates its potential strengths and weaknesses. While some provisions might need further consideration, the overall conclusion is that the Beijing Convention has the potential to strengthen the legal certainty of the purchaser's title obtained via this sale mechanism and thus help debt recovery. Although common law jurisdictions might find it at odds with some of their features, the expected benefits from ratifying it seem to outweigh these issues and are already prompting a steady number of signatures, including those of China, the European Union and Singapore.

The sequence of mineral reactions involving zeolites and other authigenic phases in tuffaceous sedimentary rocks can be explained by growth- and dissolution-reaction kinetics. Kinetic factors may determine the specific authigenic phases which form and the temporal and spatial constraints on the solution composition during irreversible dissolution and growth reactions in glass-bearing rocks. The glass phase generates a high level of supersaturation with respect to a variety of aluminosilicates in the pore fluid. The sequence of assemblages formed during a series of metastable reactions resembles an Ostwald step sequence. Metastable reactions occur because formation of less stable phases such as gels, clays, and disordered zeolites may lower the total free energy of the glass-bearing system faster than the growth of the stable assemblage including ordered feldspars, quartz, and micas. Eventually, after a series of steps, the most stable silicate assemblage for the bulk composition, temperature, and pressure may form. However, the formation of intermediate metastable phases can delay the attainment of equilibrium by as much as tens of millions of years.

An aluminian smectite with about one Al3+/Si4+ replacement per unit cell was batch- synthesized on a large scale (100-gal autoclave) at 3 00°C and 1240 psig with reaction times of several hours rather than days. This rapid crystallization was related to the use of NH4+ as the charge-balancing cation and to partial F/OH substitution. The short synthesis time prompted a study of continuous crystallization. Either of two techniques, flow through a stirred autoclave and through a multi-staged reactor column, produced crystalline product; neither gave the crystallinity of the batch process.

The b-dimensions of the unit cells of six different Na-saturated montmorillonites were determined by X-ray diffraction at water contents ranging from 0 to 20 g per g of montmorillonite. In every case, the b-dimension increased progressively with water content from its initial value, which was characteristic of each dry montmorillonite, to a final value of ~9•0Å, which was common to all montmorillonites. The latter value was reached when the water contents of the respective montmorillonites were equal to those at maximal swelling. When these water contents were plotted against the corresponding changes in b-dimension, a straight line that passed through the origin was obtained.

Different structure-sensitive properties of the water in montmorillonite-water systems (i.e. the partial specific volume, the amount remaining unfrozen at −5°C and the activation energy required for ions to move through it) were available, as functions of the species of exchangeable cation, from previous studies. Relevant b-dimensions were determined in the present study. It was found that all of these water properties were correlated with the b-dimension of the associated montmorillonite.

Our results indicate that epitaxy exists between the crystal lattices of montmorillonite and adsorbed water and that these lattices undergo mutual adjustment with each increment of water. The resulting loss of free energy causes water adsorption, i.e. swelling, to occur spontaneously. Swelling stops when no further adjustment takes place. This does not happen until the adsorbed water is several hundred angstroms thick and has achieved a preferred configuration.

Differences were found in the differential thermal analysis curves and in the temperatures of new-phase development between allophanes of high (1.91–1.99) and low (1.47–1.53) SiO2/Al2O3 ratios. The endothermic peak due to continuous dehydration and dehydroxylation was at higher temperatures (153°-185°C) for allophanes with high SiO2/Al2O3 ratios and at lower temperatures (148°–165°C) for those with low SiO2/Al2O3 ratios. The temperature of the exothermic peak was lower and the height affected more by the exchangeable cation content for allophanes with high ratios than for those with low ratios. New phases did not develop in allophanes having high Si02/Al2O3 ratios even after they were heated to 1000°C, above the temperature of the exothermic peak. In contrast, a symptomatic development of new phases was noted in allophanes with low SiO2/Al2O3 ratios at 900°C, below the temperature of the exothermic peak. The effect of SiO2/Al2O3 ratio in the thermal behavior of allophane strongly suggests that differences in the structure are closely associated with the chemical composition of this material.

Effects of particle size, crystallinity and the amount of the structural water in kaolinites on their infrared spectra, were studied. The samples were ground in a vibrating ball-mill, and infrared and X-ray spectra, as well as thermal and specific surface area measurements, were taken on the initial and ground samples. Changes of the 3705-cm−1 infrared band intensity and of the absorbance ratio of the A 3630/A 3705-cm−1 bands were determined as a function of the grinding time. Correlation functions between the absorption ratio, calculated from the infrared spectra, and the average particle size, as well as between the amorphism, calculated from the X-ray spectra, and the average particle size, were obtained.

In the contemporary maritime industry, characterised by intense competition, reduced visibility due to heavy fog is a primary cause of accidents, significantly impairing maritime operational efficiency. Consequently, investigating foggy weather navigation safety holds crucial practical significance. This paper, through an analysis and synthesis of various aspects of foggy navigation technology, including foggy navigation regulations at different ports, fog warnings, foggy vessel environmental perception and foggy auxiliary navigation systems, explores the key issues concerning vessel navigation during foggy conditions from a scientific perspective. This discussion encompasses the aspects of regulatory frameworks, standardisation, and the development of intelligent and responsive onboard equipment. Finally, the paper offers a glimpse into potential strategies for fog navigation.

The morphology of synthetic montmorillonite and hectorite was studied using electron microscopy and X-ray diffraction techniques. Interstratified montmorillonite-mica particles may be identified in these specimens by electron microscopy and electron diffraction techniques. Magnesium-substituted samples were found to exhibit an increasing amount of curling with increasing magnesium content except for the end-member magnesium clay. Synthetic hectorite clays do not necessarily have the same morphology as natural hectorite clays. A study was made also of the morphology of a series of samples obtained from a study of kinetics of crystallization. Boehmite and montmorillonite were the basic components of the system. It was found that the montmorillonite clay particles curled around the boehmite which had been adsorbed on the basal surfaces on the montmorillonite.