ISSN:0021-8871    

DOI:10.1002/jctb.5010050913

出版商:John Wiley&Sons, Ltd    

年代:1955

数据来源: WILEY

摘要:

AbstractThe atmospheric corrosion of a few common metals has been studied at more than twenty sites in Nigeria and at some others under various conditions of atmospheric humidity and salinity. Contrary to general belief, corrosion is not generally higher under tropical conditions than in temperate climates. Where there is no industrial pollution, the governing factor is airborne salt and while in very saline atmospheres steel may corrode as much as 8 g./dm.2/month, in very humid areas free from high salinity the rate may be less than 0.1. The rate of corrosion of ferrous metals varies little between wet and dry seasons or between day and night. Atmospheric salinity has been measured by various methods and at many places; the corrosion of ferrous metals and zinc is proportional to the rate of deposit of salt on a damp textile surface. The corrosion of steel in tropical tidal waters is twice as fast in tidal as in continuous immersion, and in the former case can be as high as 12 g. dm.2/ month.

ISSN:0021-8871    

DOI:10.1002/jctb.5010050901

出版商:John Wiley&Sons, Ltd    

年代:1955

数据来源: WILEY

摘要:

AbstractThe bomb‐combustion method for determining sulphur in coal, recently modified by Strambi,3has been further improved in respect of both accuracy and time of determination. The technique evolved has been applied to the determination of chlorine and shown to provide a method which, in time and accuracy, compares favourably with the B.C.R.A. Rapid Eschka Metho

ISSN:0021-8871    

DOI:10.1002/jctb.5010050902

出版商:John Wiley&Sons, Ltd    

年代:1955

数据来源: WILEY

摘要:

AbstractA method is developed in which barium is precipitated from aqueous solution by addition of sodium lauryl sulphate; excess of the latter is then titrated with a suitable quaternary ammonium compound. Contrary to expectation, a number of cations interfere.

ISSN:0021-8871    

DOI:10.1002/jctb.5010050903

出版商:John Wiley&Sons, Ltd    

年代:1955

数据来源: WILEY

摘要:

AbstractThe literature on the ethylenediaminetetra‐acetate method for determination of sulphate is reviewed and the limitations of the method are discussed. In the procedure now described, after precipitation of sulphate as barium sulphate, excess barium is precipitated with sodium lauryl sulphate and excess of the latter titrated with a suitable quaternary ammonium salt as described in Part I of this serie

ISSN:0021-8871    

DOI:10.1002/jctb.5010050904

出版商:John Wiley&Sons, Ltd    

年代:1955

数据来源: WILEY

摘要:

AbstractThe iodate oxidation of 2 : 4‐dinitrophenylhydrazine has been investigated and procedures, based on this reaction, are now suggested for the semi‐micro volumetric determination of carbonyl compounds. Some observations on the completeness of precipitation of 2 : 4‐dinitrophenylhydrazones are inc

ISSN:0021-8871    

DOI:10.1002/jctb.5010050905

出版商:John Wiley&Sons, Ltd    

年代:1955

数据来源: WILEY

摘要:

AbstractA method is described whereby the tantalum content of ‘Specpure’ niobium pentoxide can be reduced to a few parts per million without simultaneous contamination of the sam

ISSN:0021-8871    

DOI:10.1002/jctb.5010050906

出版商:John Wiley&Sons, Ltd    

年代:1955

数据来源: WILEY

摘要:

AbstractSphagnum, heather (Calluna vulgaris) and peat samples have been analysed for total ash, crude fats, Kjeldahl nitrogen, cellulose, total reducing substances, reducing sugars and the individual sugars glucose, galactose, arabinose and xylose. Xylose, mannose, fucose and ribose were isolated from a peat hydrolysate and characterised. Fructose and fructose‐containing oligosaccharides were found chromatographically in the freshSphagnum.A polysaccharide has been isolated from peat in which glucose is the principal sugar along with mannose, galactose, xylose, an unidentified uronic acid and a trace of rhamnose. The free amino‐acids ofSphagnumand peat, and the amino‐acids in the hydrolysates have been examined chromatographically. Chloroform extraction ofSphagnumgave a sterol fraction resembling ‘β’

ISSN:0021-8871    

DOI:10.1002/jctb.5010050907

出版商:John Wiley&Sons, Ltd    

年代:1955

数据来源: WILEY

摘要:

AbstractPure dry caprolactam (CL) does not polymerize on heating at 250°, but does so readily in presence of small quantities of water to yield an equilibrium polymerizate consisting of a linear polymer fraction (including some monomeric ϵ‐aminocaproic acid), unconverted lactam and higher cyclic oligomers. This equilibrium was studied in closed vessels at two temperatures and over a range of water contents from 0.05 to 2.5 mole per mole CL (number average degree of polymerization, D.P., of chain fraction varying from ∼ 100 to 10). The analyses comprised quantitative determination of unconverted CL, cyclic oligomers, monomeric ϵ‐aminocaproic acid, total chain fraction and end groups (—NH2and —COOH).The results were evaluated in terms of two equilibrium constants for the reversible formation and hydrolysis of the amide bond in CL (K1) and in linear molecules (K2). From these results it was concluded that the latter is independent of chain length, in conformity with the assumption introduced by Flory and Schulz in their general theory of polycondensation reactions.The value ofK2is in conformity with that derived from measurements on the polycondensation equilibrium of ω‐aminoheptanoic acid (where lactam formation is so small that it may be neglected). In both casesK2is found to decrease proportionally with increasing water content (decreasing D.P.) of the system. This effect of the medium remains to be explained.Kinetic study of the CL‐water system reveals that amide‐bond formation and hydrolysis alone cannot account for the rate of lactam conversion but that at least one other predominating reaction, probably addition of lactam to chain ends, play

ISSN:0021-8871    

DOI:10.1002/jctb.5010050908

出版商:John Wiley&Sons, Ltd    

年代:1955

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010050909

出版商:John Wiley&Sons, Ltd    

年代:1955

数据来源: WILEY