bluuebunny/crossref_metadata_2025 huggingface dataset:
FOrmation and reactivity of oxides and basic salts. I. Basic magnesium chlorides and sulphates
Authors: Glasson D. R. , O'Neill P. , Sheppard Margaret A.
Published: July 2010

Reactions of lime and magnesia with magnesium chloride and sulphate have been studied in relation to industrial processes, namely, extraction of magnesium from sea‐water and production of Sorel‐type cements. Variations in phase composition, surface area and crystallite and aggregate sizes of the products have been correlated with experimental conditions.

The solid limes react rapidly with the more dilute magnesium salt solutions, and the precipitated magnesium hydroxides are much more finely‐divided. Basic magnesium salts initially formed are decomposed subsequently to hydroxide as the pH becomes stabilised at higher values. Greater concentrations of magnesium chloride give more extensive basic salt formation and prevent all of the lime going quickly into solution. Similar products are given with solid magnesium hydroxide and magnesium chloride and sulphate solutions.

The Sorel‐type cements obtained from magnesium oxide and the more concentrated chloride solutions set appreciably, even before loss of surface through final ageing. They show two distinct phases: (a) irregular grains of 10–50 μm diameter, and (b) acicular or tabular crystals up to 20μm long, mainly in radiating growths. By contrast, the magnesium oxysulphate crystals are not so elongated and the cements set with considerable loss of surface area, giving interlocking structures in which 20–50 μm‐diameter grains are often ‘fused’ together as larger 400–500 μm aggregates.
Soot formation in ethylene and propane diffusion flames
Authors: Dearden P. , Long R.
Published: July 2010

Small samples of gas have been withdrawn from the luminous regions of the diffusion flames of ethylene and propane burning on a Wolfhard Parker burner and these have been analysed by gas chromatography.

In general, the parent hydrocarbon is rapidly decomposed on approaching and within the luminous region, acetylene being the major hydrocarbon product found. The concentration of acetylene falls rapidly near the interface with the oxidation zone suggesting that the main hydrocarbon oxidised in the latter is acetylene.

The rates of soot collection, the uncorrected temperatures in the flames and the concentration of stable hydrocarbon species have also been measured when oxygen, hydrogen and acetylene respectively were added to the fuel stream. Sooting rates and uncorrected flame temperatures have also been measured when the ‘oxygen index’ of the ‘air’ supply was varied, and it has been found that the sooting rate for both fuels increases with an increase in ‘oxygen index,’ the rate of increase falling off, however, at higher values.

Oxygen, when introduced into the fuel, leads to increased temperatures and sooting rates in the case of ethylene and to increased temperatures but decreased sooting rates in the case of propane. The sooting rates of flames of ethylene with acetylene or oxygen as additives increase linearly with the area under the acetylene concentration profile in the luminous zone (measured at a height of ∼ 5 mm above the burner). This area is proportional to the amount of acetylene present in the luminous zone at this height, which corresponds roughly with the onset of luminosity. Acetylene thus appears to be the major stable species via which soot is formed in such flames.

Propane flames with oxygen as additive to the fuel, however, behave differently in that although there is an increase in temperature and in the amount of acetylene in the luminous zone the sooting rate decreases. This discrepancy remains unexplained and requires further investigation.
Isothermal vapour–liquid equilibria for the binary system benzene–n‐octane
Authors: Elshayal I. M. , Lu B. C.‐Y.
Published: July 2010

Vapour–liquid equilibrium data were determined at three isothermal conditions for the binary system benzene–n‐octane using a modified Gillespie still. Non‐ideality of the vapour phase was evaluated and log γ values were correlated.
Studies on the preparation of calcium sulphate hemihydrate by an autoclave process
Authors: Combe E. C. , Smith D. C.
Published: July 2010

To enable further work to be carried out on the hydration of hemihydrate plasters, materials purer than the available commercial plasters and with reproducible properties were required. As a first stage in the attempted preparation of such materials, the process variables in the autoclave dehydration of gypsum were investigated. Methods of treating the gypsum to ensure reproducibility of particle size and for removing other hydrates of calcium sulphate from the prepared materials were developed. It was found possible to prepare samples of a purer hemihydrate, and the reproducibility of the properties of this material has been studied.
Effect of sample thickness on the formation of sodium trimetaphosphate
Authors: Lee J. D. , Bond A. H.
Published: July 2010

The conditions for preparing sodium trimetaphosphate by heating monosodium orthophosphate dihydrate have been studied. It has been found that the use of thicker samples allows a lower temperature and a shorter heating period to be used. Sodium trimetaphosphate of very high purity can be prepared by heating a sample 2·4 cm. thick for 1/2 hour at 500°.
Influence of amorphous silica on the hydration of tricalcium aluminate
Authors: de Jong J. G. M. , Stein H. N. , Stevels J. M.
Published: July 2010

Amorphous silica influences tricalcium aluminate (C3A) hydration both in pastes and in suspensions.

Two heat peaks are found by isothermal calorimetry during the paste hydration of C3A. The addition of amorphous silica causes the second heat peak to shift towards shorter reaction times and become more pronounced.

In suspensions, the change in ion concentration in the water phase is not influenced by the presence of amorphous silica except that the change in concentration occurs more quickly. Quantitative X‐ray analysis shows that more 3CaO.Al2O3.6H2O is present in suspensions containing amorphous silica than in silica‐free suspensions at equal hydration times.
The induced plasma torch as a high‐temperature chemical reactor. I. Oxidation of silicon tetrachloride
Authors: Audsley A. , Bayliss R. K.
Published: July 2010

Four torches of different design were constructed and evaluated. Injection of silicon tetrachloride vapour directly into the plasma resulted in instability and rapid extinction of the latter when the reagent flow rate exceeded 4 g/min. In the preferred design, the reagent was injected into the plasma tail flame through radial ports. With this system silicon tetrachloride was completely oxidised at a flow rate of at least 67 g/min.
Kinetics of the dissolution of uranium dioxide in nitric acid. II
Authors: Shabbir Muhammed , Robins R. G.
Published: July 2010

The kinetics of the dissolution of uranium dioxide in nitric acid were investigated at temperatures up to 150° and oxygen and argon gas pressures up to 1150 psig. A mechanism for the high‐pressure process is proposed which is consistent with experimental reaction rates and the mechanism proposed previously for temperatures below 100°.
Isothermal vapour–liquid equilibria for the ethanol–n‐octane system
Authors: Boublikova Ludmila , Lu B. C.‐Y.
Published: July 2010

A modified Dvorák & Boublík & recirculation still was used for the determination of isothermal vapour–liquid equilibrium data for the binary system ethanol–n‐octane at four temperatures. Liquid activity coefficients, γ, were evaluated, and log γ values were correlated by a three‐constant Redlich–Kister equation. Binary azeotrope exists at all four temperatures and the mole fraction of ethanol in the azeotrope increases with increasing temperature.
Anti‐fouling paints. I. Theoretical approach to leaching of soluble pigments from insoluble paint vehicles
Authors: Marson F.
Published: July 2010

A theoretical approach to the problem of how contact leaching anti‐fouling paints work is discussed; a possible mechanism is selected and applied to an idealised model of a paint film. A precise mathematical treatment is then attempted of the relationship between the leaching rate, the physical properties, and if applicable the chemical properties of the envisaged paint film and its environment. A mechanism previously proposed has been examined by this method. An equation is derived for an idealised paint film relating the leaching rate to the physical properties of the paint film and the leachate. It is assumed that the rate of solution of a soluble pigment from an insoluble vehicle is dependent only on the physical properties of the paint film and the diffusion of the solvated pigment through the exhausted matrix and the diffusion layer of leachate in direct contact with the surface of the paint. An equation is derived for an idealised paint film which relates the leaching rate to some physical properties of the paint film and of the leachate.

The equation is shown to predict qualitatively the effect of most variables known to affect the leaching of contact leaching paints. Some evidence is given to support the quantitative prediction of the relationship between the pigment volume content and the initial leaching rate, the effect of dissolved pigment in solution on the leaching rate, the increase in leaching rate for a given temperature increase, and the effect of velocity of flow past the surface of the paint film.

This method of approach would appear to be applicable to mechanisms and models bearing a closer resemblance to practical anti‐fouling paints. However, the mechanism proposed appears sufficiently well substantiated to be employed in the design of leaching experiments and their application to more practical problems, such as the formulation of anti‐fouling paints.

The need of a more rigorous approach to the design of leaching experiments is indicated.
Liquid extraction of metals from sulphate solutions by alkylphosphoric acids. I. Equilibrium distributions of copper, cobalt and nickel with di‐(2‐ethyl hexyl) phosphoric acid
Authors: Brisk M. L. , McManamey W. J.
Published: July 2010

Liquid‐liquid equilibrium data were obtained at 25° for the distribution of copper, cobalt and nickel between aqueous sulphate solutions and kerosene solutions of di‐(2‐ethyl hexyl) phosphoric acid (EHPA). Two mechanisms of extraction were observed. When the ratio (L) of organic phase equilibrium metal concentration to initial EHPA concentration was less than 0·1, the metals were extracted by the reaction:
equation image
and a correlation for the equilibrium distribution coefficients was obtained from the thermodynamic equilibrium relationship for this reaction, taking into account metal ion complexing in the aqueous phase. Ammonium hydroxide and sodium hydroxide were used as alkalis for pH adjustment and similar distribution coefficients were obtained with both when L was less than 0·1. For L greater than 0·1, metal‐EHPA polymers were also formed in the organic phase, a typical step in their formation being:
equation image
Equilibrium relationships were obtained from consideration of the equilibrium constants of the typical step and the reaction for monomer formation. The nature of the alkali used for pH adjustment influenced the distribution coefficients when L exceeded 0·1, higher distribution coefficients being obtained with sodium hydroxide than with ammonium hydroxide.
Formation of calcium plumbate: Kinetics and mechanism of reaction
Authors: Martini P. L. , Bianchini A.
Published: July 2010

In the presence of excess air the kinetics of reaction between CaO and PbO to form calcium plumbate are governed by the diffusion process described by Jander's kinetic model. The energy of activation of the process, as calculated from the Arrhenius equation, is 50 kcal/mol. In an air and nitrogen atmosphere (ratio 1:16) the reaction rate is 4–5 times slower.

It has been shown that formation of calcium plumbate from pure CaO and PbO takes place between 600–800° without formation of intermediate compounds.

From the results obtained it is deduced that the mechanism of formation consists of two main stages–diffusion between the CaO and PbO, substantially due to the more diffusible PbO, and chemical reaction in the presence of O2.
Flotation kinetics for calcite in a semi‐batch system
Authors: Tewari S. N. , Biswas A. K.
Published: July 2010

Flotation kinetics of calcite in a semi‐batch froth flotation system corresponds approximately to a second‐order rate equation, the order varying between 1·60 to 2·40 for different particle sizes and aeration conditions. Rate constant increases slightly with decrease in particle size and sharply with increase in air flow rate. It is postulated that flotation rate should depend on the magnitudes of solid/liquid and liquid/gas interfacial areas, besides other physico‐chemical parameters.
Precipitate flotation. V. Extractive solvent sublation
Authors: Pinfold T. A. , Mahne E. J.
Published: July 2010

The new technique of precipitate flotation of the second kind is unique amongst flotation processes in that it requires no surfactant. This does have the disadvantage that the floated material is not supported on the surface and tends to redisperse into the solution. A layer of immiscible organic solvent containing either a surfactant, a complexing agent, or the original precipitant, leads to solubilisation and retention of the floated material. As this is quantitative, spectrophotometric examination of the organic layer may provide a means of analysis for the ion originally precipitated. Complete removal from solutions as dilute as 10−5 M is possible.
Formation and surface properties of electron emissive coatings. II. Thermal decomposition and sintering of single alkaline‐earth carbonates
Authors: Judd M. D. , Pope M. I.
Published: July 2010

The thermal decomposition of ‘Spec‐Pure’ calcium, strontium and barium carbonates has been studied by preparing a calcination series up to 1200°. 0·6 g samples were placed in the bucket of a spiral silica spring balance and heated under vacuum, at a rate of rise of temperature of 200 deg c/h. After reaching a set temperature, the specific surface and total pore volume of the cooled residue were calculated, using data obtained from the sorption of nitrogen at 77°k. The results indicated that the extent of the activation which accompanies thermal decomposition depends on the amount by which the Tammann temperature of the resulting oxide exceeds the temperature at which the maximum rate of decomposition occurred.

Thermogravimetric and gas evolution studies on strontium and barium carbonates are also discussed in connexion with work reported in an earlier paper.
Factors responsible for the activity of precipitated iron fischer‐tropsch catalysts
Authors: Nandi S. P. , Saran T. , Mukherjee P. N.
Published: July 2010

Three precipitated iron Fischer‐Tropsch catalysts of identical chemical composition but prepared from different source materials were studied by gas adsorption. Of the Hofer ‘inducted’ catalysts, the most active one was found to combine greater surface area with a preponderance of narrower pores, compared with the other two. The greater activity was found to be reflected in the ‘a’ factor (Elovich Equation) which was very large. The limitation of the energy of activation as a parameter for the activity of solid heterogeneous catalyst was illustrated in terms of ‘compensation effect’. The complex nature of adsorption kinetics was shown by the anomalous temperature dependence of ‘a’ as well as changes in the slope of q versus log t curves.
Vapour‐liquid equilibria for the systems: Methylcyclohexane‐n‐butanol and toluene‐n‐butanol
Authors: Seetharamaswamy V. , Subrahmanyam V. , Chiranjivi C. , Dakshinamurty P.
Published: July 2010

Isobaric and isothermal vapour‐liquid equilibria have been determined for the binary systems: methylcyclohexane‐n‐butanol and toluene‐n‐butanol at 760 mm Hg total pressure and 90° using a modified Colburn still. The activity coefficients data were satisfactorily tested for their thermodynamic consistency by the method of Herington and a satisfactory correlation was also obtained through Wohl's three‐suffix Margules equations for both conditions of restraint in the case of both systems. Azeotropes were observed for both systems and both conditions of restraint.
Safe storage and transportation of some potentially hazardous materials
Authors: Lee P. R.
Published: July 2010

Many materials which are stored and transported in bulk undergo exothermic decomposition or oxidation reactions at elevated temperatures. Such reactions may render them liable to spontaneous ignition if they are in sufficient quantity and at such a temperature that the rate of heat production exceeds the rate at which heat is able to be transmitted to the surroundings.

Steady‐state thermal explosion theory has been used to predict safe storage and transportation (critical) masses at a series of temperatures for three representative types of self‐heating materials—baled wool, powdered ammonium nitrate and a solution of methylethyl ketone (2‐butanone) peroxide (40%) in dimethyl phthalate. The non‐steady‐state theory (reactant consumption admitted) has been used to estimate the time taken for these critical masses to reach the critical state at each temperature.

The critical masses have been shown to be consistent with safety requirements at present accepted for the storage and transportation of the materials discussed. The estimates of the times taken by the critical masses to reach the critical state bring an added dimension to the critical mass calculations, and together these results constitute an advance over the present situation where safe limits have been deduced on a trial and error basis.

The methods outlined may be used to estimate critical masses and induction periods for any other self‐heating material and may be relied upon to give results of the correct order of magnitude.
Dehydration of ethyl alcohol on alumina‐coated silica
Authors: Fahim R. B.
Published: July 2010

Catalysts were prepared by precipitation of aluminium hydroxide on a wet silica gel. The dehydration of ethyl alcohol on catalysts varying in alumina content was studied at 307° using a flow system. The products of dehydration were ethylene, ether and water. The kinetics of the formation of ethylene followed the Langmuir‐Hinshelwood mechanism, while the formation of ether occurred according to the Langmuir‐Hinshelwood mechanism and the Rideal‐Eley mechanism simultaneously. The catalytic activity was controlled by the amount of aluminium on the surface. The rate constants were correlated with the surface nature of the catalysts.
Mechanical behaviour of bituminous waterproofing membrane systems
Authors: Marijs P. D. , Bonafont R. L.
Published: July 2010

The mechanical behaviour of waterproofing membrane systems composed of one or more layers of bituminous sheeting fully bonded together to form an integral layer has been studied and a theory has been evolved which allows membrane stresses and strains to be calculated as a function of the mechanical properties of the constituent materials and of the associated substrate movement. Allowance is made for the visco‐elastic effects of bitumen.

It is concluded that the ability of membranes to accommodate substrate movement largely depends on the mechanical properties of the base fabrics used to reinforce bituminous sheetings, and this has been confirmed in controlled experimental work.

The order of substrate movement that may be tolerated by a single‐layer fully bonded system was calculated for a number of conditions. The improved mechanical performance afforded by partial bonding was considered to be worthwhile.
An oscillating baffle column fitted with stator rings III. Hold‐up and drop distribution
Authors: Thomas W. J. , Weng P. K. J.
Published: July 2010

A study of drop sizes and their distribution in a new extractor shows the distribution to obey a log‐normal law. Hold‐up of dispersed phase obtained manometrically is related to oscillation speed (N), relative flow‐rate (Qt) and phase flow ratio. Equations are proposed for prediction of d32 and Ψ from N and Qt. The incipient flood point can be established either from the graphs or equations.

An equation proposed by Misek to correlate the relative flow‐rate of the phases, the interdroplet collision rate, and coalescence has been examined. Values of U0, the free fall velocity obtained indirectly by experiment from the Misek‐type equation, are compared with free fall velocities for single drops obtained by other workers. The system examined was water‐acetic acid (solute)‐carbon tetrachloride (disperse phase).
An oscillating baffle column fitted with stator rings IV. interfacial area and mass‐transfer coefficients
Authors: Thomas W. J. , Weng P. K. J.
Published: July 2010

Studies are reported on an oscillating baffle column fitted with stator rings with special reference to interfacial area.

Pseudo point values of interfacial area are given along the extractor which together with values of mass‐transfer coefficient, Ka, enable pseudo point values of the coefficient for continuous and disperse phases, Kc and Kd, to be evaluated. The dependence of point and overall values of Kc, Ka and a (the overall interfacial area) on operating parameters are considered.
Degree of hydration of portland cement pastes with low water/cement ratios as influenced by curing conditions
Authors: Hanna K. M. , El‐Hemaly S. A.
Published: July 2010

Measurements of chemically combined water contents were made on Portland cement pastes made with water/cement ratios of 0.20 to 0.30 by weight. In addition to the factors involving water/cement ratio, curing medium, curing history and curing period, the degree of hydration of cement pastes cured at room temperature was significantly influenced by the availability of adequate water supply during the first 24 hours of the curing process.
Catalysis of graphitisation
Authors: Marsh H. , Warburton A. P.
Published: July 2010

The demand for graphites with specific properties and for an improvement in the economics of graphite production in recent years has led to an increased interest in catalytic graphitisation. At the present time, however, there is no review available of published studies and this paper attempts to make good this deficiency. Mechanisms whereby inorganic additives can catalyse graphitisation are considered, followed by a discussion of the mechanisms by which inorganic additives promote the graphitisation process. A comprehensive survey of the relevant literature to date is presented which describes in more detail the type of carbon used, the experimental techniques employed and the improvement obtained in graphite quality.
Vapour‐liquid equilibria of the carbon tetrachloride‐toluene system
Authors: Wang J. L. H. , Boublikova L. , Lu B. C.‐Y.
Published: July 2010

The vapour‐liquid equilibria of the system: carbon tetrachloride‐toluene were studied at five isothermal conditions by use of a modified Dvorak & Boublik circulation still. Liquid activity coefficients, γ, were evaluated. The values of γ were close to unity. The In γ values were correlated by a three‐constant Redlich‐Kister equation.
Reaction of isoprene with phenols catalysed by nickelocene and phenylmagnesium bromide
Authors: Suga K. , Watanabe S. , Kikuchi H. , Hijikata K.
Published: July 2010

The reaction of isoprene with phenol, catalysed by nickelocene and phenylmagnesium bromide, yields 2,2‐dimethylchroman, 2‐(3′‐methyl‐2′‐buten‐1′‐yl)phenol, 4‐(3′‐methyl‐2′‐buten‐1′‐yl)phenol, 2,2‐dimethyl‐8‐(3′‐methyl‐2′‐buten‐1′‐yl)chroman and 2,2‐dimethyl‐6‐(3′‐methyl‐2′‐buten‐1′‐yl)chroman. Reactions with other phenols were examined.
Fischer‐tropsch waxes v. Study of branching and its effect on crystallinity using an improved infra‐red method
Authors: Le Roux J. H.
Published: July 2010

A method for the determination of degree of branching, much faster than the one previously used, is described. A sample cell designed for fast introduction and removal of samples is used and the method for measuring band intensities has been adapted to computer use.

It is shown how the degree of branching decreases from the first member of a series of extract waxes to the residue, because of the higher solubility of isoparaffins compared with that of n‐paraffins. A linear relationship between crystallinity and degree of branching was found to exist for the series. Fischer‐Tropsch ‘medium wax’ exhibits an abnormally low crystallinity. Possible causes for this are the fact that it has a much lower average molecular weight than the extract waxes, which were derived from ‘hard wax’, and that there can be differences in chain‐length distribution.

The extract waxes were found to contain 4–6% more amorphous material than isoparaffins, as determined by urea adduction. This difference is explained in terms of the tendency of the urea method to give too low values, the fact that some normal molecules can be present in amorphous regions and the uncertainty of the significance of infra‐red crystallinity in absolute terms.
High‐temperature oxidation of aluminium in various gases
Authors: Breakspere R. J.
Published: July 2010

The oxidation of high‐purity aluminium sheet in dry oxygen, moist oxygen, carbon dioxide and carbon monoxide (at total pressure 1.333 × 103 Nm−2) was studied in the range 673–923°K, using a vacuum microbalance to follow weight gains. 14CO2 and 14CO were used to elucidate the mechanism of the oxidation in these gases and to estimate the extent of carbon deposition in the oxide layer.

The rate of oxidation in moist oxygen was similar to that in dry oxygen, the principle reaction being 2Al + 3H2O ← Al2O3 + 3H2.

It is suggested that there are three steps in the reaction in CO2, viz. 2Al+3CO2 ← Al2O3 + 3CO, followed by 2Al + 3CO ← Al2O3 + 3C, and about 10% of the deposited carbon reacting further by 4Al + 3C ← Al4C3. Only the last two reactions are operative in carbon monoxide.

The Arrhenius plots show a distinct break in the region 773–823°K for both carbon monoxide and carbon dioxide, but not for dry or moist oxygen. This is tentatively explained by a change in the rate‐determining process from diffusion via grain boundaries or cracks in the oxide, to lattice diffusion. It is suggested that carbon may become mobile in the oxide film between 773 and 823°K and may tend to congregate in the grain boundaries and cracks.

The oxide film remained protective throughout the duration of the experiments in all the gases.
Effects of additives on graphitisability of carbons and graphite
Authors: Richards B. P. , Kellett E. A.
Published: July 2010

The effect of additives to the green mix on the subsequent graphitisability of various carbons and graphites has been studied using X‐ray diffraction techniques. The carbons have been characterised in terms of the structural parameters, La, Lc, d0002 and p.

It is concluded that metallic iron (or sometimes other catalysing additives) produces little enhancement of graphitisability in materials which are known to be intrinsically graphitising on the Franklin scale (for example chars from PVC, petroleum and pitch).

The cooking of petroleum, prior to mixing with a binder, is shown to predetermine the form that the coke will assume as the grist in the graphitised artefact. It is suggested as a consequence that it should be possible to investigate the effect that the grist and binder components have separately on the various physical properties of a heat‐treated artefact.

It is shown that the addition of metallic impurities substantially enhances the degree of graphitisation and crystallinity attainable in a given heat treatment of classical non‐graphitising carbons (furan coke and cellulose). By contrast, for an archetypical graphitising material (PVC char), the crystallinity and structural perfection potentially attainable on heat treatment are considerably decreased as a result of the addition of sulphur.
Residence time distribution in continuous crystallisers
Authors: Hill S.
Published: July 2010

The theory of continuous crystallisation (especially of sucrose) in crystallisers connected in series, in which a suspension of growing crystals is fed forward through the system without backmixing, is presented, and the calculation of the minimum coefficient of variation that can be attained under stated conditions is described. Two cases specifically considered are: (1) stirred reactors of equal mean residence times connected in series, and (2) tubular reactors in which the residence time distribution is given by a Gaussian error function. Reduction of coefficients of variation either by connecting reactors in series or by extending a tubular reactor in the axial direction is considered. Series connexion is always superior to extension because it prevents backmixing at the points of connexion.
Kinetics of oxidation of butadiene to crotonaldehyde
Authors: Hotanahalli S. S. , Chandalia S. B.
Published: July 2010

The oxidation of butadiene to crotonaldehyde has been investigated using an aqueous catalyst solution containing palladium chloride–cupric chloride in dilute hydrochloric acid. Unlike the oxidation of ethylene, propylene, etc., this oxidation was found to be a zero‐order reaction with respect to butadiene. The effects of temperature and the concentration of Pd2+, Cu2+, Cl− and H+ ions on the reaction rate were studied. The order of reaction with respect to Cl− and H+ ions in this case (approximately 1.5 and −0.25, respectively) is different from that observed in the case of lower alkenes.
Hydration of dibarium silicate I. Stoicheiometry of hydration
Authors: Hanna K. M. , Cook R. L. , Kantro D. L.
Published: July 2010

Dibarium silicate, Ba2SiO4, was hydrated in two ways: in paste form at 25° using a water/solid weight ratio of 0.7:1, and in a polyethylene bottle rotated on a wheel at 5°, 25° and 50°, using a water/solid weight ratio of 9.0:1. When Ba2SiO4 is hydrated in paste form, the stoicheiometry of the reaction at 25° is the same as in bottle‐hydration at 50°: 2BaO.SiO2+2.2H2O = 1.2BaO.SiO2.1.4H2O+0.8Ba(OH)2. The stoicheiometry of bottle‐hydration at 5° and 25° is represented by the equation: 2BaO.SiO2+2.2H2O = BaO.SiO.1.2H2O+Ba(OH)2. Barium silicate hydrate, 1.2BaO.SiO2.1.4H2O, is well crystallised and has a specific surface area of ˜ 3m2/g. The crystals are plate‐like and have a tendency to form clusters. The low‐baria hydrate, BaO.SiO2.1.2H2O, is poorly crystallised and consists of thin platelets. It has a specific surface area of ˜ 35m2/g. The thermal dehydration of fully hydrated barium silicate and of the barium silicate hydrates was investigated by thermogravimetric and differential thermal analysis techniques.

The similarities and differences between the barium silicate hydrates obtained in the hydration of barium silicate and the calcium silicate hydrates obtained in the hydration of β‐dicalcium silicate and Ca3SiO5 are discussed. A mechanism of hydration of barium silicate is proposed which involves solution, precipitation and crystallisation steps.
Hydration of dibarium silicate II. rate of hydration
Authors: Hanna K. M. , Cook R. L. , Kantro D. L.
Published: July 2010

The rate of hydration of dibarium silicate (Ba2SiO4) in paste form at room temperature was investigated. The uncombined barium hydroxide produced in the reaction, determined by a modified Franke method, was used as a measure of the extent of hydration. The linear relationship obtained between the uncombined barium hydroxide and the chemically combined water confirms that similar hydration products are formed at all stages of hydration, and either may be used as a measure of the degree of hydration. The rate of hydration of dibarium silicate was found to be lower than that of tricalcium aluminate, but higher than those of alite, tricalcium silicate and β‐dicalcium silicate. The effect of water/solid ratio on the rate of hydration was also investigated. Dibarium silicate was completely hydrated after 30 days when it was mixed with a water/solid weight ratio > 0.7:1.
Optical studies of surface impurities on titanium dioxide
Authors: Clark W. C. , Broadhead P.
Published: July 2010

Titanium dioxide powders, prepared by the hydrolysis of titanyl sulphate, discolour in a vacuum. The discoloration is stable in dry oxygen or dry air, but it bleaches in the presence of water vapour. Infra‐red and thermogravimetric measurements show that the discoloration and bleaching cycle is associated with the state of adsorption of hydrogen‐bonded water by sulphate impurities on the titanium surface.
Solubility of carbon in sodium
Authors: Longson B. , Thorley A. W.
Published: July 2010

The solubility of carbon in sodium over the range 600‐950° may be expressed by the equation: log sol. = 7.20‐5465/T where solubility is in ppm and T in °K.

From plots of carbon activity versus concentration, and from observations that oxygen does not affect carbon solubility, it is proposed that carbon dissolves in sodium as single atoms.
Supply and demand for road aggregates
Authors: Please A. , Pike D. C.
Published: July 2010

Estimates have been made of the production and use of the various materials used as road aggregates for 1966–67, and the regional distribution was also calculated. Future demand for road aggregates is considered, and it is estimated that the total demand by 1977 will be ∼ 85 × 106 tonnes per annum, the overall growth rate until then being ∼ 6% compound per annum.
Kinetics of dissolution of copper(II) sulphide in aqueous sulphuric acid solutions
Authors: Biswas A. K. , Mohan N. P.
Published: July 2010

The rate of dissolution of synthetic cupric sulphide (CuS) which is the analogue of the naturally occurring sulphide mineral covellite, in sulphuric acid solutions of concentration range 5 × 10−3 to 3 mole/l over the temperature range 20–65°c at atmospheric pressure was studied.

Thermodynamic considerations suggested that the primary reaction taking place during the leaching is: CuS+1/2O2 + H2SO4 → CuSO4 + S+H2O.

It is proposed that up to an initial sulphuric acid concentration of 1 mole/l, the reaction rate is controlled by the diffusion of H+ ions through the sulphur film to the CuS/S interface. For higher sulphuric acid concentrations the oxygen dissolved in the acid decreases and the rate‐determining step is believed to be diffusion of dissolved oxygen through the sulphur film to the CuS/S interface. A parabolic model is suggested for the dissolution reaction, and this model is supported by the experimental data.

The activation energy for the dissolution reaction was found to be 8000±2000 cal/mole and this was independent of the H+ concentration and hence the nature of the diffusing species.
Gas‐phase catalytic alkylation of aromatic hydrocarbons
Authors: Hojabri F.
Published: July 2010

The gas‐phase alkylation of aromatic hydrocarbons was studied using various solid catalysts. The alkylation of xylenes with propylene produced tetra‐alkylbenzenes whose structures suggest that these products will be suitable for the preparation of pyromellitic acid.
Discoloration at anatase titanium dioxide surfaces by organic contamination
Authors: Clark W. , Broadhead P.
Published: July 2010

A major cause of vacuum discoloration of some anatase titanium dioxide powders at 5 × 10−2 torr has been identified as contamination by rotary pump oil. The discoloration is stable in dry air but fades on exposure to moist air.
Barium aluminate hydrates III. BaO.Al2O3.2H2o and BaO.Al2O3.0.5H2O
Authors: Ahmed A. H. M. , Dent Glasser L. S.
Published: July 2010

Two compounds of formula BaO.Al2O3.2H2O have been synthesised and studied by infra‐red, X‐ray and thermal analytical techniques. One form yielded another crystalline product, BaO.Al2O3.0.5H2O, as an intermediate during dehydration. The results are interpreted in terms of the known crystal structure of one of the forms of the dihydrate.
Drying of sodium silicate solutions
Authors: Dent Glasser L. S. , Lee C. K.
Published: July 2010

Sodium silicate solutions with a silicon dioxide:sodium monoxide mole ratio of 3.41:1 were dried gently to give amorphous solids. These solids, together with the products obtained by heating them at various temperatures up to ∼ 200°c, were studied by differential thermal analysis, solubility tests and other techniques. The resultant data give some insight into the structural changes which occur in the solid during the drying process.
Characterisation of waxes by differential scanning calorimetry
Authors: Flaherty B.
Published: July 2010

The characterisation of hydrocarbon and natural waxes by differential scanning calorimetry is described. It is shown that the determination of the melting, cooling and remelting curves of a wax, and comparison with the corresponding curves of authenticated waxes, affords a rapid and valuable method for the identification of many waxes. Heats of transition of many waxes are also given.
Adsorption of sulphite, oleate and manganese(II) ions by β‐manganese dioxide and its activation in flotation
Authors: Yousef A. A. , Arafa M. A. , Malati M. A.
Published: July 2010

A high‐grade ore sample A and a synthetic sample B of β‐MnO2 were characterised by a number of physical methods. The points of zero zeta potential were found at pH4.4 and 4.6 for A and B, respectively. Below the critical micellar concentration and at pH 7, the adsorption isotherms of oleate on to sample B followed the Freundlich equation, the adsorption density decreasing with rising temperature. Over a wider concentration range, the isotherm had a Langmuir shape and was displaced to higher adsorption densities in presence of NaCl. The adsorption density was slightly affected by pH, but it gradually decreased beyond pH 9. From a comparison of the adsorption and ζ potential results, the adsorption mechanism could not be electrostatic only but may also involve van der Waals and π interactions.

The adsorption isotherm of sulphite ions exhibited a broad maximum and was shifted to lower adsorption densities in presence of oleate. The amount of Mn2+ ions released on conditioning sample A in sulphite solutions increased with increasing sulphite concentration. It could be assumed that sulphite ions were adsorbed prior to reaction with MnO2 producing Mn2+ ions, which were the activating species in flotation. Although there was an adsorption competition between sulphite and oleate ions, the adsorption of the latter was enhanced in presence of sulphites.

The adsorption density of Mn2+ ions on to sample B increased linearly with increase in their equilibrium concentration. Assuming the low‐coverage form of the Langmuir isotherm, the heat of adsorption was found to be 51.9 kJ/mole.

The adsorption density of Mn2+ ions increased with increasing the pH of the medium from 5 to 6.5, in agreement with the more negative surface charge on the MnO2 particles. Above a certain Mn2+ concentration, the charge was reversed. The adsorption of Mn2+ ions is interpreted in terms of an Na+/Mn2+ exchange mechanism. Tentatively, the cations are assumed to be in the outer Helmholtz layer of the electric double layer of MnO2.

The activating effect of Mn2+ cations was demonstrated by the increased adsorption density of oleate in presence of Mn2+ ions and by the corresponding increase in flotation recovery. Oleate adsorption was exothermic, i.e. similar to its adsorption in absence of activating cations. It is assumed that activation involves electrostatic attraction between the activating Mn2+ and the oleate ions.
Reversible phase transformation in the system calcium oxide‐chromium sesquioxide‐oxygen
Authors: El‐Rafei E. A.
Published: July 2010

Further studies were carried out on the reversible phase transformation of the low melting (1228°c) calcium chromate chromite (941) into the high melting (2170°c) monocalcium chromite (CK) with the liberation of free CaO and oxygen.

The investigation of specimens of synthesised 941, calcium chomate (CK1), and 941‐bearing samples with a high content of periclase (as in dolomitic magnesite chrome refractories) cooled from different temperatures showed the presence of transformation products of 941 phase under different conditions of its formation, and thermogravimetric analysis and complex differential thermal analysis confirmed the reversible nature of this phase transformation.

Irrespective to the method of formation of 941 or the existence of a high periclase content and a solid solution of 2CaO.SiO2 with it, 941, at its melting point, starts to undergo a reversible phase transformation according to the equation: 9CaO.4CrO3.Cr2O3.3CaO.Cr2O3+6CaO+3 O2.

The presence of 941 phase in basic refractories produced from raw materials with a high CaO content, should be considered to be a secondary phase, re‐formed during the cooling process.

Beta‐alpha polymorphism of the liberated CK was exhibited above 1600°c during this phase transformation.
Apparatus for sampling of liquid oxygen, nitrogen and argon in the plant
Authors: Malan E. , Van Merwe P. Der
Published: July 2010

A simple sampling system was developed to enable the sampling of liquid oxygen, nitrogen and argon in the plant, which can then be analysed at any remote laboratory. The procedure is described for the operation of the high pressure system to avoid contamination by air. Analyses have shown that repetitive sampling of the same product tank gave repeatable results.
The shapes and applications of enthalpic curves
Authors: Davidson Fay C. , Sloan John P. , Williams David R.
Published: July 2010

A computer programme, RWCRVE, is reported that plots both the formation and enthalpic curves from ΔH° and ΔS° of complexing. RWCRVE (i) permits a detailed analysis of the factors dictating the shapes of enthalpic curves, and (ii) suggests new conclusions that may be drawn from experimental enthalpic curves; such conclusions concern symbiosis effects of a complexed ligand upon the next ligand‐metal bond being formed, ion‐pair effects and extrapolations of these discussions to industrial and biological systems where all the details of complexing may not be clearly established.
On the thermochemistry of gypsum
Authors: Khalil A. A. , Hussein A. T. , Gad G. M.
Published: July 2010

Heating gypsum below 100°c gives rise to limiting values of weight loss around that of the hemihydrate formation whatever is the time of heating. Calcination at 100°c and above, on the other hand, causes a continuous loss in weight as the time is prolonged, leading to γ‐anhydrite when adequate time is given. In most of the examined samples a resistant state, with trace amounts of residual water, is reached towards the end of the dehydration process. Such residual water is driven off completely below the transformation temperature of γ‐ to β‐CaSO4.
Production of cyclodextrin glycosyltransferase by Bacillus macerans in batch cultures
Authors: Lane A. G. , Pirt S. J.
Published: July 2010

Satisfactory growth of Bacillus macerans and high activities of cyclodextrin glycosyltransferase (CGT) were obtained in media containing potato extract. The appearance of CGT in culture supernatant fluids during the stationary phase of growth was not due to autolysis, since intracellular levels of the enzyme were very low throughout the cultivation. When cell growth was limited by the starch concentration in the medium, CGT activity remained low during the logarithmic phase of growth but high activities appeared suddenly in the supernatant fluid when growth ceased. Negligible activities were produced by cultures growing in a nitrogen‐deficient medium in which starch was present in excess. CGT therefore appears to be a true extracellular enzyme, produced in response to exhaustion of the starch from the medium. A simple fractionaltion procedure was developed for concentrating the CGT from culture supernatant fluids. This enzyme preparation was used to convert 20% (w/v) starch solutions to cyclodextrins in 24 h and the cyclodextrins recovered were equivalent to 55% of the original starch.
Isolation of glucose oxidase with the use of DEAE‐cellulose
Authors: Kučera J. , Hanus J.
Published: July 2010

A method is described for the isolation of glucose oxidase from the bacteria Aspergillus niger using sorption on DEAE‐cellulose. The method is rapid by comparison with precipitation methods and results in a preparation having a specific activity of 87‐5 e.u./mg. The preparation contains no detectable catalase or amylase activity and appears to be suitable for most purposes without further treatment.
Falling‐film evaporators and their applications in the food industry
Authors: Wiegand J.
Published: July 2010

A general survey is given of the history of the falling‐film evaporator and its uses in the food industry. An explanation of the reasons for its production is given and is followed by details of operation and an examination advantages and disadvantages met in its use. Examples of specific design‐types are discussed and illustrated.
The plate evaporator
Authors: Gray R. M.
Published: July 2010

A description of the plate evaporator is given with particular reference to the A.P.V. products. The difference between the plate evaporator and plate heat exchanger is pointed out. The advantages and disadvantages of this method of evaporation are discussed. The specific requirements of the plate evaporator in dealing with heat sensitive materials are considered.
Reactions of cyclohexane in a microwave discharge reactor
Authors: Brooks B. W. , Sambrook R. M.
Published: July 2010

A study has been made of the reactions of cyclohexane in a continuous‐flow microwave discharge reactor. Butene‐1 and propylene were the major reaction products; ethylene and hydrogen were produced in smaller amounts. The distribution of reaction products was found to depend on the reactor pressure and flow‐rate. The results show that the fragmentation of cyclohexane is not the sole source of butene‐1.

The insertion of nickel wire into the reactor enhanced the production of ethylene and propylene; yields of butene‐1 were diminished. In the presence of nickel the production of ethylene and propylene became independent of pressure. When carbon dioxide was added to the cyclohexane feed the major reaction product was acetylene. The carbon dioxide did not react chemically. The yields of acetylene per unit energy input were found to be fairly high.
The catalytic activity and electronic property of cupric oxide semiconductor
Authors: Bhattacharya D. P. , Mukherjee P. N.
Published: July 2010

The correlation between catalytic and electronic properties has been experimentally verified for cupric oxide semiconductor. The catalytic activity of cupric oxide for CO oxidation was measured in terms of energy of activation for CO chemisorption whereas the electronic property was measured in terms of the electrical conductivity. The semiconducting properties of cupric oxide were varied by doping with different proportions of altervalent ions such as lithium and gallium.
The acid‐catalysed condensation of xylene and styrene
Authors: Malan E.
Published: July 2010

During the plant process of acid‐refining of crude xylene with concentrated sulphuric acid, a considerable amount of residue remains after fractionation. The main constituents of this residue were identified as α‐phenyl‐α(dimethy1‐pheny1)ethanes. Mass spectrometry, n.m.r., infra‐red, gas chromatography and synthesis were used for structure elucidation.
Reconsideration of a theory of the setting of gypsum plaster
Authors: Ridge M. J. , King G. A. , Molony B.
Published: July 2010

The rates of hydration of eight samples of calcium sulphate hemihydrate, six of which were commercial calcined gypsum, were determined from the accompanying increases in temperature. The compositions of the samples and the areas of their surfaces were determined, and the sizes of the microcrystals in the hydrated and hardened systems were studied. The results strongly support the applicability of a theory of hydration of calcium sulphate hemihydrate developed earlier.

The possibilities of calculating periods of induction are described, and some of the implications of the theory discussed.