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Interaction of exchangeable copper(II) with montmorillonite was studied by means of infrared and electron spin resonance spectroscopy supported by X‐ray diffraction, magnetic susceptibility measurements, and determination of CEC values. The solvation properties of the clays after heat treatment are found to be much different with ethanol than with water. Dehydration of exchangeable Cu(II) allows these ions to become imbedded in hexagonal cavities of the silicate structure, or penetrate into the empty octahedral positions and lower the layer charge. Resolvation allow the Cu(II) ions to move out of the hexagonal holes; however, Cu(II) ions that have migrated to the octahedral layer are not exchangeable. No evidence for specific adsorption was found. The results indicate that the properties of Cu(II) on clay surfaces are dependent largely on its strongly held ligand water, and the ion behaves much like other divalent ions on clays.

When benzene or phenol are adsorbed on smectite containing Fe(III) or Cu(II) on the exchange complex, higher molecular weight products are formed. Evidence for these products is provided by mass spectroscopy. In the case of benzene most of the reaction products cannot be attributed to coupled benzene rings, while extensive coupling occurs for phenol. Electron spin resonance spectroscopy provides evidence for radical cation formation of the aromatic molecules. The involvement of these radical cations is thus proposed in the formation of the higher molecular weight species. The relevance of these reactions to the natural systems of soils and sediments is suggested.

A large quantity, up to 560 kg/ha, of elemental K fertilizer was required to obtain optimum yields and quality of tomatoes (Lycopersicon esculentumMill.) in a fertility trial. The fertility trial was on a low well‐drained terrace of the St. Joseph River at Sodus Horticultural Experiment Farm located in Berrien County, Michigan. The surface layer of the soil contained 15% clay with a Ca/Mg cation exchange capacity of 115 meq/100 g. This clay was capable of fixing about 94% of the applied K fertilizer. A study of the glacial geology and more recent geomorphology in the area was done in order to determine the distribution and possible origin of the vermicultic soil clay at the study site. The geomorphic study showed that the oldest land surface had acid leached soils with the surface layer containing considerable chloritized vermiculitic clays but little or no vermiculite. In contrast the younger well‐ and moderately well‐drained river terraces had soils that were higher in pH, and the surface layers contained vermiculitic clay but very little chloritized vermiculite. Analysis of the soils on the river terraces showed a relationship of vermiculitic clay content to soil pH. If the soil pH was > 7.5 or < about 6.3 the vermiculite content of the surface layer dropped sharply. The vermiculite in the river terrace soils is apparently derived from chloritized vermiculitic soil clays that were eroded from the older upland soils. The change in pH of the environment from acid to neutral or mildly alkaline plus abundant organic matter, under suitable conditions, evidently triggers a dechloritization reaction involving an aluminate or organic complexing mechanism.

The comparative rates of removal of the ions from Wyoming bentonite‐quartz sand systems during electroosmosis were as follows: Na+> K+> Mg++> Ca++. The differential movement of ions tends to separate the cations as they move through the media. The percentage of an ion removed by a given amount of electricity was increased by the addition of a complementary ion. The rate of Na+and K+removal was proportional to the amount of these ions remaining in the system and decreased steadily as electroosmosis proceeded. The rate of Ca++removal tended to remain more or less constant until the Ca++concentration in the cell had been reduced to about 0.5 symmetry. In the early stages of electroosmosis the transference numbers of Na+and K+in systems containing no free salt were very near unity. Under similar circumstances the transference number for Ca++was greater than in some salt solutions but did not approach unity. The amount of water flow per milliequivalent of cation removed was greatest for Ca++, intermediate for K+, and least for Na+.

Ketone adsorption by montmorillonite was found to be greatly influenced by the nature of the exchangeable cation. Mechanisms of bonding included (i) direct ion‐dipole interaction of the carbonyl with the ion in cases where the ion had a low hydration energy or where special treatments were used to dehydrate the ion; (ii) outer sphere coordination to the metal ion by bridging through directly coordinated water molecules; (iii) formation of electrovalent bonds through proton donation by 2,4 pentanedione to the clay saturated with Al or Cu ions to form the acetylacetonates of these ions.

Models of homogeneous and heterogeneous cationic diffusion systems were applied to clay minerals. The diffusion of Na and Cs ions in expanded Na‐vermiculite, which has both internal and external surface available for cationic diffusion, decreased with increasing diffusion time, a characteristic of heterogeneous systems. Diffusion of those ions remained essentially constant in collapsed K‐vermiculite which has only external surface available for diffusion and can thus be described as homogeneous. The property of homogeneity was further confirmed with cationic diffusion in the vermiculite whose exchange sites were clogged by p‐phenylenediamine cation, and in Na‐ and K‐kaolinite; while the heterogeneous property was observed for Na‐ and K‐bentonite. The diffusion of Na ion in Na‐vermiculite was related to a model originally derived for mathematical analysis of grain boundary problems. The evaluation of diffusion coefficients of external surface (De) and of interlayer surface (Di) was made, and Deof Na ion in Na‐vermiculite was found to be about 5 times larger than that of Di. The importance of considering the homo‐ and heterogeneity of the system in the study of cationic diffusion in clay minerals is suggested.

Nitric oxide was found to be chemically adsorbed on mont‐morillonite and nontronite when the exchange complex was saturated with certain transition metal ions. Infrared data showed a number of reactions depending on the nature of the saturating ion including: (i) coordination of NO as the mono or dinitrosyl complex; (ii) formation of N2O; (iii) formation of (NO)+. The NO molecule was able to penetrate the interlamellar regions of Co‐montmorillonite or Co‐nontronite. On all other systems, apparently only surface adsorption occurred. When air was admitted, all surface‐adsorbed NO was immediately oxidized, but interlamellar NO decreased at a rate apparently dependent upon the diffusion of NO to the clay mineral surface. A produce of oxidation was found to be coordinated nitrite.

The diffusion of five ions into three different homoionic bentonite gels obeyed Fick's law with the special boundary conditions for diffusion into solids. The diffusion coefficients of the ions followed the sequence SO4> Na > Rb > Ca > Cs for all three homoionic bentonite gels. The effect of exchangeable cation on the diffusion coefficient of the diffusing ion in bentonite gels followed the sequence K > Na > Li. The effect of exchangeable cation on the activation energy and distance between successive absorption sites of the diffusing cation followed the sequence Li > Na > K. Cs ion diffused into Csvermiculite but not into Na‐vermiculite. SO4=ion mobility was higher at low clay concentrations than in pure water. As clay concentration increased, SO4=ion diffusion rate decreased more rapidly than that of exchangeable Na+ion. The factors affecting diffusion of ions in clay gels are discussed.

A tertiary amalgam electrode was utilized in the measurement of CaCl2and Ca++activities. Activity coefficients from electromotive force data compared favorably with those in the literature. The relative influence of various metal ion salts on the CaCl2and Ca++activities followed the sequence Rb ≥ Mg > K > Na > Li for both kaolinite and Wyoming bentonite. The activities of CaCl2and Ca++in bentonite‐kaolinite mixtures differed from predicted activity values based on pure clay systems.

Field and laboratory studies show that the nonlimy, more reddish, finer textured layers (Bt) found in the subsoils of three coarse‐textured soil profiles in Michigan contain a considerably higher concentration of silicate clay minerals and “free iron oxide” than the adjoining sandier layers. These layers also have slightly more organic matter than the adjoining sandier layers, and considerably less organic matter than the Bhirhorizons in the same or associated profiles. These textural bands may or may not be from the same initial material as the horizons immediately above or below them. They are wholly or in part the result of pedogenetic processes. Both physical and chemical mechanisms are probably involved in the textural band formation. The existence of complexes of “free iron oxide”‐silicate clay‐organic matter in the soil and their ability to move through artificial columns containing natural nonlimy soil material was demonstrated in the laboratory. In addition, the movement of silicate clay and iron‐organic matter complexes simultaneously or at different times can be postulated. The deposition of the individual complexes or a combination of them may be caused by a chemical interaction between them, physical factors such as wetting and drying of the soil, or the activity of a third agency on one or both of the mobile constituents, e.g., free lime flocculating clay and/or organic‐iron complexes. Results indicate that a combination of the above mentioned factors is needed to explain the physical, chemical, and micropedological observations.

Interlayer removal experiments using a chloritized vermiculitic soil clay showed its dynamic character by rapid alteration to vermiculite. The Ca/Mg cation exchange capacity of one sample dispersed ultrasonically and treated with dilute NaOH at pH 10 increased from 33 to 169 meq/100 g while the K/NH4CEC remained in a range of 25 to 35. This particular sample contained all of the organic matter and the natural surface oxides. On standing for 12 days at lower pH, interlayer material was redeposited as indicated by Ca/Mg CEC reduction. Another sample of the same soil clay was pretreated in a conventional manner. The Ca/Mg CEC also increased from 24 to 113 and the K/NH4CEC increased from 20 to 31 meq/100 g when treated with NaOH in the same manner. A standard prochlorite showed small but equal upward increases of both kinds of CEC. Deuteration experiments using a chloritized vermiculitic soil clay, a vermiculitic soil clay, and a standard prochlorite showed the easy accessibility of interlayer OH groups to deuteration at moderate temperatures. The interlayer OH groups of chloritized vermiculite showed deuteration at 68C, while the OH groups in the 2:1 structure of the vermiculitic soil clay started deuteration at 150C and those of the prochlorite at 200C.

The transfer of protons from a protonated species to an uncharged molecule at the surface of clay minerals is an important process. NH+4, pyridinium, ethylammonium, methylammonium, and protonated‐urea montmorillonite and nontronite complexes were equilibrated over NH4OH, pyridine, methylamine, or with 3‐aminotriazole, and the status of the adsorbed molecule determined using infrared spectroscopy. Proton transfer or retention by a species depends on two factors: (i) the relative basicities of the two interacting compounds and (ii) the relative concentration or activities of the reactants and products. Indications were that the clay mineral altered the basicity of some compounds compared to the others. The relative order of basicity of the compounds studied here were found to be 3‐aminotriazole > ammonia > methylamine = ethyamine > pyridine > urea. Such proton transfer reactions as have been demonstrated here to occur in model clay‐organic complexes are undoubtedly processes of importance in natural systems.

X‐ray diffraction analysis of the < 2 µ fraction of the main horizons of a Deer Park sand, a Podzol soil in northern Michigan, shows that montmorillonite is the dominant layer silicate in the A2 horizon of this soil. This montmorillonite appears to have weathered from illite and mica and chlorite interstratified with vermiculite and montmorillonite which are present in the underlying horizons. Chemical and X‐ray data indicate that the montmorillonite in the fine fraction (< 0.2 µ) of the A2 horizon contains some randomly interstratified mica. The Greene‐Kelly test, X‐ray powder diffraction, differential thermal, infrared, and chemical data show that the expanding component of this fine fraction is a beidellite of formula [Al1.62Fe0.18Mg0.28][Al0.45Si2.55]O10[OH]2with exchange capacity = 0.49 M+per half unit cell. This beidellite has a high layer charge, most of which arises from tetrahedral substitution, and shows a strong tendency to fix potassium.

Soil fractions from six soils known to vary in ability to supply K to field crops were cropped intensively in greenhouse experiments. All soils and soil fractions were Mg‐saturated prior to conducting the experiments. The K content of the clay and of the silt was linearly correlated with the logarithm of the K uptake for each fraction, except for the silt fraction of one soil. No correlation was noted between the uptake of K and the K content of the entire soil. In equilibrium experiments, K in solution in 1.0nMgOAc after 90 days was linearly correlated to the K content of the clay. A similar correlation was obtained with the entire soil. The different pattern of K release during cropping tests as compared to the equilibrium studies is attributed to rate processes which would govern release during cropping, but which would not be a factor in the equilibrium experiment. X‐ray analyses indicated the formation of expanding lattice clays upon the removal of interlayer K by cropping. Large amounts of K were removed from the coarse clay (2.0–0.2µ), intermediate amounts from the medium clay (0.2–0.08µ), and small amounts from the fine fraction (<0.08µ). This differential release of K by the different size clay fractions can be explained by a decrease in the activity of interlayer K when the K content of the clay is decreased.

The differential thermal analysis apparatus was used as a means of determining the heats of desorption of NH3, methylamine, and ethylamine from bentonite clay. A method was developed using nitrogen gas to prevent oxidation of the sample during analysis. The average heat of desorption of NH3and methylamine for the temperature range of 200° to 450°C. was found to be 35.3 and 40.9 kcal. per mole, respectively. In each case the desorption was accompanied by loss of equal moles of water. It is postulated that the water loss arises from decomposition of Al(OH)3. The average heat of desorption of ethylamine for the same temperature range was 157 kcal. per mole; however, the simultaneous loss of large quantities of water accounted for most of the heat change.

The relationships of particle size of biotite to K release, oxidation state of iron, cation‐exchange capacity, and total charge of the mineral were studied. The first stage of alteration, accomplished by leaching 15 minutes with 0.1NNaCl, showed a marked relationship to particle size. At this point, the only K removed was that on the external surfaces of the particles, and consequently the fine particles lost a larger percentage of their total K at this stage than did the larger particles. However, by the last stage where 50% of the total K had been removed, the large particles generally had lost as much as the fine. Once the initially exchangeable K has been removed, the release of matrix K from the particles is suggested to be controlled by the concentration gradient and the geometry of the diffusion path available for the exchanging ions, Na and K. The equilibrium concentration of K in 0.1NNaCl was shown to be proportional to the total K content of biotite which had been altered to different levels of total K. The oxidation state of iron in the biotite was shown to be a function of particle size and extent of alteration.

Data presented suggest that the rate of K release from biotite by leaching with NaCl is independent of the amount of K in the mineral during the depletion of a large proportion of the total K content. Optical and X‐ray diffraction data show that weathering of biotite to vermiculite proceeds from the outside edge in toward the center of the particle. The 14Å. layers were found to have about 4 times the diffraction intensity of the 10Å. layers. Observation was made of the actual weathering front. The dependence of rate of K release on leaching rate, NaCl concentration, temperature, time, and particle size was evaluated and an empirical equation derived relating these variables. A theory is presented that the apparent zero‐order type of reaction results from the maintenance of a constant concentration of reactive K similar to the principle of a saturated solution of a material in equilibrium with its solid phase. The logarithmic portion of the curve is suggested as the place where a “saturated solution” of reactive K can no longer be maintained and rate of release becomes dependent on the amount of unreacted K.

Release of potassium from fixed forms in an illite, montmorillonite, and vermiculite and from the native forms of an illite, biotite, and muscovite was investigated. Methods used in studying potassium release were chemical, electrochemical, and biological. Changes in minerals following potassium release were followed with X‐ray diffraction and chemical techniques. Results of the study indicated the potassium “fixed” by vermiculite and montmorillonite to be available for plant growth. The native potassium of biotite was a great deal more available for plant growth than that of an illite or muscovite.

The effects of particle size of various clay minerals on the properties of cation exchange capacity, ethylene glycol retention, and gas adsorption were determined. The particle size of the clays was varied by limited ball‐milling procedures. Kind of exchangeable cation did not greatly affect the ethylene glycol retention by non‐expanding clays, but cations capable of undergoing fixation did affect the retention by montmorillonite. This indicated the effect of exchangeable cations, capable of fixation reactions, was to prevent solvation of the inner‐layer spaces of montmorillonite rather than a differential association between the cations and ethylene glycol. Ethylene glycol retention was not found to be a function of cation exchange capacity. Specific surface figures determined by ethylene glycol retention and by B.E.T. analysis, using ammonia adsorption, agreed fairly well for non‐expanding clay minerals but differed considerably for montmorillonite.