摘要:

AbstractA study was made of the effects of some additives of different types on the water requirement of samples of calcined gypsum prepared in different ways. Accelerating salts and variations in the pH had little effect on the water requirement but some inhibitors of the set and surface‐active materials produced appreciable changes. The samples of calcined gypsum studied varied amongst themselves in their response to the action of additives.The effects of additives are of interest as they act only by modifying the surface condition of the grains of calcium sulphate hemihydrate, and the theory of this is discusse

ISSN:0021-8871    

DOI:10.1002/jctb.5010121201

出版商:John Wiley&Sons, Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractA further examination has been made of the crude paraldehyde filtrate obtained in the preparation of metaldehyde.The second form of paraldehyde has now been isolated and examined. The second form of metaldehyde has again been isolated, and there has also been found what is almost certainly a third metaldehyde.The probable structures of the various isomers are discussed and related to their infra‐red spectra. A new infra‐red group frequency at 1170 cm.−1for 1,3‐dioxans and 1,3,5‐trioxans is

ISSN:0021-8871    

DOI:10.1002/jctb.5010121202

出版商:John Wiley&Sons, Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractResults of heating five lime‐alumina mixtures for 3–120 h. at temperatures from 1045° to 1405° are presented. The mixtures were prepared from mixtures of CaCO3(calcite) and α‐Al2O3and also from co‐precipitated hydroxide gels. Significant departures from equilibrium were noted. In general the gel mixtures approached the equilibrium state more rapidly. Unstable 5CaO,3Al2O3was not detected. Previous interpretations ofX‐ray diffraction patterns of heated lime‐alumina mixtures are shown to be in error. The mechanism of the reaction cannot be uniquely determined from a study of the bulk rea

ISSN:0021-8871    

DOI:10.1002/jctb.5010121203

出版商:John Wiley&Sons, Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractA hydrophobic surface has been produced on condenser tube surfaces by injection of montan wax and related chemicals into the‐condensing steam. The extent and duration of the increase in the overall heat‐transfer coefficient of the condenser, that results from the condensation of steam in discrete drops on the hydrophobic surface, have been measured. It is shown that the most successful dropwise condensation promoters are those waxes with the highest proportion of acidic groups, and that these are most effective when used with copper or copper alloy condenser tu

ISSN:0021-8871    

DOI:10.1002/jctb.5010121204

出版商:John Wiley&Sons, Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractVisual observations and heat‐transfer data on the promotion of dropwise condensation by montan wax and its fractions, together with analytical data, led to the following conclusions:(1)Promotion is primarily due to normal fatty acids C22–C32occurring uncombined in the wax, C26, C28and C30being predominant. The longer the hydrocarbon chain, the less easily is the acid desorbed. Hydrocarbons and esters may participate in promotion.(2)Promotion by adsorption from solution is very rapid (<1 min.). Promotion by injection depends on distribution by the steam, and probably requires melting of the wax.(3)Wax fatty acids clean copper condenser tubes by corrosion; the resultant cupric soap is probably inactive in promotion.(4)Degradation experiments show that chemical changes and foaming are unlikely to prevent the use of montan wax in boiler systems involving temperatures up to 3

ISSN:0021-8871    

DOI:10.1002/jctb.5010121205

出版商:John Wiley&Sons, Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractThe thermal transformation of bayerite (alumina trihydrate) to α‐alumina has been studied byX‐ray diffraction and infra‐red spectra. The bayerite was prepared by treatment of sodium aluminate solution with carbon dioxide.It is concluded that the thermal transformation of bayerite proceeds in the following seq

ISSN:0021-8871    

DOI:10.1002/jctb.5010121206

出版商:John Wiley&Sons, Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractA method of studying the coagulation of dilute mineral suspensions with aluminium sulphate is described, which substantially reduces pH variation with coagulant dose, but which allows the pH to be varied independently of the coagulant dose. The method is applied to the study of 50‐p.p.m. suspensions of various pure minerals likely to be present in river water and to samples of suspended solids isolated from rivers. The concentration of aluminium sulphate required for coagulation is markedly pH‐dependent and is least close to neutrality. The behaviour of both the pure minerals and the samples isolated from rivers is almost identical, but montmorillonite behaves anomalously at acid pH val

ISSN:0021-8871    

DOI:10.1002/jctb.5010121207

出版商:John Wiley&Sons, Ltd    

年代:1962

数据来源: WILEY

摘要:

AbstractThe precipitation of aluminium hydroxide following the addition of aluminium sulphate to solutions containing sodium bicarbonate, sodium hydroxide and sodium chloride was investigated. The degree of precipitation was determined both by measuring the amount of residual soluble aluminium and the change of turbidity.The optimum pH for the coagulation of dilute clay suspensions with aluminium sulphate corresponds to that at which aluminium hydroxide is most rapidly precipitated and coagulated in the absence of clay. It is concluded that mutual coagulation of aluminium hydroxide and clay must be insignificant. The clay particles are probably removed by enmeshment in the mass of flocculating aluminium hydroxide.

ISSN:0021-8871    

DOI:10.1002/jctb.5010121208

出版商:John Wiley&Sons, Ltd    

年代:1962

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010121209

出版商:John Wiley&Sons, Ltd    

年代:1962

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010121210

出版商:John Wiley&Sons, Ltd    

年代:1962

数据来源: WILEY