摘要:

AbstractChrysotile fibres were treated hydrothermally with aqueous suspensions or pastes of MgO, SiO2, Al2O3, Fe2O3, Ca(OH)2, Ca3SiO5and β‐Ca2SiO4. Partial or complete reaction often occurred, but the fibres persisted as pseudomorphs which were studied byX‐ray fibre rotation photographs. Those of the products which did not contain calcium, such as Mg2SiO4, Mg3Si4O12H2and Mg(OH)2, were usually formed with a definite crystallographic orientation relative to that of the chrysotile. A mechanism is proposed to explain this, based on the assumption that reaction occurs by migration of cations (Mg2+, Si4+, Al3+, Fe3+, H+) through a relatively unaffected oxygen framework. Products containing calcium, such as CaMgSiO4, were unoriented. This is attributed to the fact that their oxygen frameworks are more open than those of the compounds not containing calcium; because of this, their formation requires destruction and rebuilding of the crystal structure. The significance of these results for the manufacture of autoclaved asbestos cement products is briefly indic

ISSN:0021-8871    

DOI:10.1002/jctb.5010130401

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractDetails are given for the production of rigid porous bodies (compacts) made by compacting under high pressure fine powders in the particle range of 10—0·01μ of silica, calcium carbonate, plaster of Paris and molecular sieves. These compacts were used as samples to study sorption and related dimensional changes. The results were used to compute spreading pressure by applying the Gibbs adsorption equation and allowed derivation of the Δl/lvs φ plots using the Bangham relation.With compacts made from molecular sieves, it was possible to study the forces imposed on the particles by water entering or leaving the micropore s

ISSN:0021-8871    

DOI:10.1002/jctb.5010130402

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractCompacts made from powdered material are used in an effort to explain anomalous results obtained from the isothermal uptake of water vapour by various types of dehydrated gypsum. In the sorption isotherms, a sharp discontinuity occurred at R.H. between 0·25 and 0·40 and a secondary hysteresis was observed. Sorption of methanol on these materials was also measured, and results were compared with those obtained with water.The determination of the expansion isotherm enabled an application of the Gibbs adsorption equation to be made, which led to a method by which it was possible to differentiate between hemihydrate and adsorbed water and thus allow a calculation of a B.E.T. surface area from the water isotherm for the material.From this calculation and others obtained by use of a modified Kelvin equation, it was concluded that the anomalies noted above were due to sites on the surface of the plaster that required an activation energy for ‘sorption’ to occur. The generation of these sites was considered dependent on the method of preparation of the anhydrous calcium sulphate. The water attached to these sites would thus be termed ‘chemisorbed

ISSN:0021-8871    

DOI:10.1002/jctb.5010130403

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractThe preparation of n‐alkyl methacrylates by trans‐esterification has been studied. An optimum procedure for the synthesis of n‐butyl methacrylate was developed by examining the suitability of quinol as polymerisation inhibitor and the effects of catalyst concentration and of the mole ratios of the reactants used. The mole ratio of alkanol to acid was particularly important, the optimum being much lower than that previously reported. The conclusions where they can be compared are in agreement with the results of similar work reported by Dvořkák in 1958.By the method proposed, the reaction period and the time to recover the ester were reduced, and the yield was greatly increased. The general applicability of the method was established by the preparation of a series of n‐alkyl meth

ISSN:0021-8871    

DOI:10.1002/jctb.5010130404

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractSolubilities and equilibria at 20° in the system phenol,o‐cresol, water, sodium hydroxide have been determined: solubilities up to rather more than 3% of sodium hydroxide (complete miscibility), and equilibria to a lower value. The measurements indicate that the separation factor of the phenols between aqueous and phenolic phases is not sensitive to the alkali content of the soluti

ISSN:0021-8871    

DOI:10.1002/jctb.5010130405

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractA study has been made of the thermal hydrocracking of n‐pentane and n‐heptane at 10 atmospheres pressure over the temperature range 550–700°, with particular reference to the formation of aromatics. The n‐paraffins are converted largely to gaseous products; C2and C3hydrocarbons are important intermediates in the gasification and methane is found in increasing amounts with increase in temperature. As the temperature rises, aromatics are formed and there is a concomitant decline in the amount of olefins; traces of butadiene are also found.The formation of aromatics during thermal hydrocracking of n‐paraffins parallels the thermal aromatisation well known to occur in thermal cracking in the absence of added hydrogen. The acetylene and butadiene hypotheses of aromatic formation are considered. Neither is considered to be satisfactory in explaining the results and it appears more likely that a free‐radical mechanism

ISSN:0021-8871    

DOI:10.1002/jctb.5010130406

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractUse of aqueous ammonium chloride instead of dilute hydrochloric acid for extraction of highly ferruginous soils removes insignificant amounts of sesquioxides, so that the extract can be used for determination of calcium without further treatment (as is necessary for the acid extract).

ISSN:0021-8871    

DOI:10.1002/jctb.5010130407

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractA flow sheet is given for the separation process described. The lanthanons are isolated as sulphates and converted to hydroxides. Thorium and cerium are insoluble in hydrochloric acid at pH 3·5. The other lanthanons are adsorbed on Dowex‐50 ion‐exchanger, samarium, neodymium and praseodymium being eluted with a 0·025M solution of the diammonium salt of EDTA, and lanthanum with N‐ammonium c

ISSN:0021-8871    

DOI:10.1002/jctb.5010130408

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010130409

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY