摘要:

AbstractA description is given of the development and performance of a variable foam‐generator for use in laboratory experiments with mechanical foams for fire‐fighting.The generator is designed to provide accurate control of the character of the foam as measured by its expansion factor and its ultimate shear strength.The apparatus has been called a mechanical foam‐generator to distinguish it from equipment in which the disperse phase of the foam is generated chemically; air is the gas most commonly used for the disperse phase, but other gases may be used if req

ISSN:0021-8871    

DOI:10.1002/jctb.5010011001

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractA description is given of apparatus for comparing the efficiencies of different, mechanically‐produced, fire‐fighting foams by measuring a ‘figure of merit.’ The figure of merit used is a dimensionless index intended to take into account the ability of the foam to flow over the surface of an inflammable liquid, its resistance to destruction by contact with the liquid and its resistance to destruction by fire. Examination of the foam is carried out under standard conditions and the figure of merit is then defined as the ratio between the rate of coverage of the liquid surface by the foam and the rate of destruction of the foam when the liquid is allowed to burn.Figures of merit have been obtained for a number of different fire‐fighting foams

ISSN:0021-8871    

DOI:10.1002/jctb.5010011002

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractPrevious application of surface‐tension rules to dilution of coal tars is criticized and it is considered that the surface tension of the mixture of diluent with the oils of the tar must be considered rather than the surface tension of the diluent alone. Maximum insolubles in a tar‐diluent system occur at lower ratios of diluent to tar for both horizontal‐ and vertical‐retort tars. The relation of maximum insolubles to the surface tension of the diluents has been examined and generally it is shown that diluents with surface tensions above that of the tar behave quite differently from those of lower surface tension. The results are interpreted to mean that flocculation and precipitation, followed by solution or redis‐persion, occur when diluent of surface tension lower than the tar is added in increasin

ISSN:0021-8871    

DOI:10.1002/jctb.5010011003

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractA new method for identifying alcohols by the determination of the melting points of thep‐nitro‐phenylhydrazones of their acetoacetates is described and shown to be of fairly general application. The method may also be used to give an approximate estimate of the homogencity of commercial alcohols.A selection of melting points of the derivatives of purified alcohols normally used in commerce is given and some results for the ordinary commercial products are shown for compari

ISSN:0021-8871    

DOI:10.1002/jctb.5010011004

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe sedimentation curves for suspension of kaolins from Central Europe, Italian bentonites and clays have been obtained by using a hydrostatic balance provided with a normal plunger. Investigations undertaken to establish the accuracy of the method and the theoretical calculation of the sedimentation curves are briefly described. The possibility of applying Stokes' law to the mass settling of kaolins is also discussed. The authors wish to emphasize (a) the possibility of determining the average diameter of powder particles by means of the tangent to the curve at zero time, and (b) the possibility of deducing from experimental sedimentation curves both the curves relating to size distribution (the number of particles as a function of equivalent diameter) and the cumulative curves (the percentage by weight of particles having dimensions smaller than one determined equivalent diameter).When carrying out sedimentation measurements, particularly with kaolins, it is possible to obtain regular curves only when conditions are such as to avoid flocculation. This result is achieved by adding suitable electrolytes in quantities which determine the smallest sedimentation volume.The average equivalent diameters of the powders examined were deduced from such sedimentation curves.Statistical measurements of dimensions made by direct microscopic observations have been carried out on two kaolins from Central Europe, resulting in average values which agree very closely with those calculated from the sedimentation curves.Cumulative curves of the usual type have been obtained from the densimetric curves of sedimentation.

ISSN:0021-8871    

DOI:10.1002/jctb.5010011005

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe homogeneous alkaline hydrolysis of the acetates, caprylates and palmitates ofn‐octadecanol and cholesterol in the four lowest normal alcohols has been studied. It is shown that the various constants for the reactions are within the range recorded for similar reactions of low molecular weight esters, no anomalies of any sort being observe

ISSN:0021-8871    

DOI:10.1002/jctb.5010011006

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe aqueous alkaline hydrolysis of wool wax,n‐octadecyl caprylate and palmitate and cholesteryl acetate and caprylate as oil‐in‐water emulsions stabilized by various agents, has been examined. It is shown that the extent of reaction in a given time is not related to the quality of the emulsion, but is probably limited by the rate of penetration of the inte

ISSN:0021-8871    

DOI:10.1002/jctb.5010011007

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractMeasurements on unfractionated and fractionated polystyrenes have provided data from which several fundamental conclusions can be drawn: (i) for a large class of mechanical properties, the value of the property is zero at low molecular weights, increases with increasing molecular weight, and finally approaches an asymptote; (ii) the details of the molecular weight distribution curve are immaterial in determining the value of the measured mechanical property as long as the number‐ and weight‐average molecular weights are above their respective limiting values; (iii) polystyrene contains a quasi‐permanent molecular network whose parameters determine the visco‐elastic response of the macroscopic s

ISSN:0021-8871    

DOI:10.1002/jctb.5010011008

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractThe preparation of several amino‐alkanols by the reduction with lithium aluminium hydride of certain ‘amic’ acids and their esters, aromatic keto‐acid amides and nitriles is de

ISSN:0021-8871    

DOI:10.1002/jctb.5010011009

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY