ISSN:0021-8871    

DOI:10.1002/jctb.5010150809

出版商:John Wiley&Sons, Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractThe theories of crystal nucleation from solution and the experimental techniques which have been used to study this phenomenon, are reviewed. A more detailed review of nucleation from aqueous solution follows in which attention is drawn to the two types of nucleation, primary and secondary, which characterise the crystallisation of electrolytes from aqueous solution.

ISSN:0021-8871    

DOI:10.1002/jctb.5010150801

出版商:John Wiley&Sons, Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractPrecipitates of ‘hydrous’ cobalt oxide have been prepared by reacting cobaltous chloride and sodium hydroxide under controlled conditions of pH, concentration and flow rate. The samples were washed and dried at room temperature and small portions heated at controlled temperatures up to 900°.X‐Ray analysis of the unheated precipitate indicated that it was possibly a basic chloride of indefinite composition, rather than Co(OH)2. Heat treatment over the range 400°—900° gave Co3O4, the crystallinity increasing with temperature; some CoO was also detected in the 900° sample. The unheated material had an appreciable specific surface area (>110 m.2/g.), but this decreased rapidly with the temperature of heat treatment and became very low (<1 m.2/g.) at 900°. The shape of the nitrogen adsorption isotherm changed after heat treatment and the preliminary results suggest that the oxide surface became either more uniform or covered with a chemisorbed lay

ISSN:0021-8871    

DOI:10.1002/jctb.5010150802

出版商:John Wiley&Sons, Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractStorage of liquid ozone or pure gaseous ozone has practical disadvantages and a study has been carried out on the storage of oxygen containing 10% ozone. It has been shown that this mixture can be compressed to and handled at 70 atm. The slow thermal decomposition of ozone can be minimised by cooling to −78°, when the gas can be stored in suitable vessels for long periods with negligible loss of ozone.Results suggest that, when stored at ambient temperature and elevated or normal pressures, the predominant reaction is a simple monomolecular decomposition of ozone, with an energy of activation of 3.9 kcal./mo

ISSN:0021-8871    

DOI:10.1002/jctb.5010150803

出版商:John Wiley&Sons, Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractIn continuation of previous work on the setting of gypsum plasters,1study has been made of the effects of tartaric acid and potassium and calcium tartrates on this reaction.Tartaric acid (like acetic acid) has little retarding power, except in the higher concentrations. The marked accelerating effect of the potassium salt is attributed to precipitation of tartrate ions as calcium tartrate, with the formation of potassium sulphate; this is supported by several similarities between the effects of potassium tartrate and those of potassium sulphate, as determined by Smithet al.2Calcium tartrate has negligible effect on the reaction.

ISSN:0021-8871    

DOI:10.1002/jctb.5010150804

出版商:John Wiley&Sons, Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractIn the continued search for useful inorganic polymers, boron‐containing monomers having the vinyl group attached to boron and/or phosphorus were prepared.B‐trimethyl‐borazines (MeBNAr)3(Ar =o‐ orp‐EtC6H4) were α‐brominated byN‐bromosuccinimide; but dehydrobromination to introduce the vinyl group was of limited success. Vinylboron dichloride reacted with ethyl phosphate or bis‐(2‐chloroethyl) vinylphosphonate to give the alkyl chloride (EtCl or Cl2C2H4) and polycondensates containing presumably P‐O‐B linkages. Similar results were obtained with the vinylphosphonate andB‐trichloroborazine, orB‐trichloro‐N‐tri‐o‐ethylphenylborazine oro‐ethyl‐phenylboron dichloride. Interaction ofB‐trichloro‐N‐triallylborazine and tri‐n‐butyl phosphate similarly gave n‐butyl chloride and the B‐O‐P compound.Reduction of functionality of boron and/or phosphorus by attachment of the vinyl group did not lead to a marked improvement in the properties of the condensates. Prospects of incorporating vinyl polymerisation are not promising; nevertheless further knowledge of the factors relating to P‐O

ISSN:0021-8871    

DOI:10.1002/jctb.5010150805

出版商:John Wiley&Sons, Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractSamples of quicklime and hydrated lime have been sulphated by sulphuric acid and by sodium sulphate solutions at 22°. Rates of sulphating, changes in surface area and phase composition and crystallite size have been correlated with the surface properties of the initial limes. The products have been compared with calcium sulphate dihydrate directly precipitated from solution by double decomposition, and subsequently aged.In acid sulphating, the gypsum from the quicklime has approximately the same specific surface (and average crystallite size) as that directly precipitated from 0.5 M‐calcium nitrate andN‐sulphuric acid. The more active intermediate hydrated lime dissolves more readily and does not impede the sulphating so seriously as the less active initial hydrated lime samples. The latter give products with larger specific surface (smaller average crystallite size) from the more concentrated acid solutions, where the rapid separation of gypsum ultimately impedes the sulphating of the remaining lime.Sulphating with 0.5 M‐soldium sulphate produces increasing alkalinity until about 16% of both the quicklime and the hydrated lime have been converted to gypsum. The sulphate initially separating, probably as a gel, impedes the reaction. The surface decreases until the gypsum begins to crystallise, but its crystallinity remains inferior to that of the acid‐sulphated lime of much lower specific

ISSN:0021-8871    

DOI:10.1002/jctb.5010150806

出版商:John Wiley&Sons, Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractSamples of carbonated lime (calcitic and vateritic) have been sulphated byN‐H2SO4and by 0.5M‐Na2SO4at 22°. Rates of sulphating, changes in surface area and phase composition and crystallite size have been correlated with the surface properties of the initial carbonates. The products have been compared with gypsums obtained by (1) dissolving ground dolomite inN‐H2SO4, and (2) directly precipitating from solution by double decomposition and subsequently ageing.The acid sulphatings are not seriously impeded by the newly formed gypsum; evolution of carbon dioxide evidently prevents the layers becoming impervious. The less active calcium carbonates yield gypsum of surface activity (and average crystallite size) similar to that directly precipitated from 0.5M‐Ca(NO3)2and N‐H2SO4. The more active calcitic and vateritic samples initially give gelatinous products, before the gypsum crystallises and ages similarly.Sulphating with 0.5M‐Na2SO4slowly produces increasing alkalinity until about 10% of the calcium carbonate has been converted to gypsum; its crystallinity remains ill‐defined and inferior even to gypsum from

ISSN:0021-8871    

DOI:10.1002/jctb.5010150807

出版商:John Wiley&Sons, Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractBenzotriazole (B.T.A.) is shown to be a satisfactory corrosion inhibitor for copper in closed‐circuit, water‐cooled stators. Laboratory and plant tests indicate that conductivity increase and copper pick‐up are significantly reduced at concentration levels greater than 20 p.p.m. of

ISSN:0021-8871    

DOI:10.1002/jctb.5010150808

出版商:John Wiley&Sons, Ltd    

年代:1965

数据来源: WILEY