摘要:

AbstractThe paper draws attention to the importance of the part played by peroxidic bodies or active oxygen in the weathering of coal; comparative investigations have been made with both coal and carbon, which are shown to behave similarly.The initial reaction appears to involve chemisorption, which, in the presence of water, is followed by the formation of a coal‐or carbon‐oxygen‐water complex. The normal inherent wafer content of coals is a function of their internal surface; this is a minimum with coals containing c. 89 per cent carbon. The peroxygen content of coals shows a similar variation with carbon content.The peroxygen complex is markedly unstable above approximately 70° c., a temperature long known to be critical in regard to spontaneous combustion of coal. Below it the complex is formed easily and remains relatively stable, little oxygen entering the coal substance; also the amount of ulmification remains very small. The small quantity of gaseous oxidation products consists chiefly of carbon monoxide with a less amount of CO2. Above 7°D c. the complex starts to break down, although with carbon it does not appear to be completely destroyed until 350°c. is reached. Oxidation above 70°C. is also marked by a big increase in the oxygen content of a coal, its general ulmification and in the yield of gaseous oxidation products; also carbon dioxide then preponderates over the monoxide. These observations were substantiated by means of gravimetric balances for the coal‐oxygen reaction at 50° and 90° c. The pressure changes at these two temperatures were also different; whereas a gradual fall in pressure was recorded at 50° c., at 90° c. a temporary rise in pressure occurred. The remarkable difference in the behaviour above and below this critical temperature is common to both coal and carbon, and in view of the ability of carbon to form a carbon‐oxygen‐water complex, it is evident that with both materials the overall oxidation is controlled by the rate of breakdown of the complex. Of paramount importance is the necessity for the presence of water; indeed, an explanation is now forthcoming of the classical experiments of C. J. Baker and H. B. Baker in 1887‐88, which demonstrated that dry carbon cannot be readily oxid

ISSN:0368-4075    

DOI:10.1002/jctb.5000680701

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractAlthough the properties of polymethyl methncrylate have been widely reported in the scientific and technical literature, few1references appear to studies of the properties of the higher‐polyalkyl methacrylates.The present paper deals with examination or re‐examination of a number of polymeric higher methacrylic esters undertaken with a view to obtaining information on the influence of thee alcohol alkyl chain length, and of branching in this chain on the properties of the polymer.Polymers have been examined of all the alkyl methacrylates up to the butyl series. Of the amyl hexyl and octyl series a selection has been prepared out of the many possible isomers, the choice having been indicated by the results of work on the lower homologues.Attempts have been made to explain differences in the properties of the polymers mainly on the basis of induction due to methyl groups in the alcohol alkyl radicals. This would be only one of numerous causes of differences in properties, but the assumption that it is important has led to results which appear to be of sufficient interest to discuss in the present pa

ISSN:0368-4075    

DOI:10.1002/jctb.5000680702

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractThe machine has been designed for work on the partition chromatography of amino acids and of purine and pyrimidine nucleosides to facilitate the collection of successive fractions of small volumes of the percolate from the chromatographic column. Each fraction (of up to 50 ml.) is collected for a pre‐determined time and sixty such fractions in all may be obtained without resetting the machin

ISSN:0368-4075    

DOI:10.1002/jctb.5000680704

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractThe effect of mixing various inhibitors with sodium nitrite is described, the efliciency and probable mode of action of phosphates including mctaphosphnte, carbonate, sulphates and zinc salts being discussed. In general the radicals studied were those having insoluble ferric salts and reasonably soluble calcium and magnesium salts. Zinc salts were considered owing to the possibility that their cathodic action might rcinforcc the anodic action of nitrite. Sulphites were included in the experiments owing to their ready reaction with dissolved oxygen.

ISSN:0368-4075    

DOI:10.1002/jctb.5000680705

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractIn 1936, Britton and one of the authors,1in a review of the outdoor exposure rests organized from Cambridge, expressed the view that “An invisible film of condensed moisture is prejudicial to nearly all types of paints; therefore painting should not be commenced too early in the day.” In an earlier statement,2reference was made to the danger of “extra moisture entrapped when the painting was early.” On the other hand, certain other experiments had suggested that, when paint was applied to a steel surface carrying large visible drops of water, the water was generally not entrapped below the coat, hut was either expelled or emulsified; indeed, when a deliberate attempt was made to shut in water below paint, it was found difficult to do this, except at re‐entrant angles.In 1940, fresh experiments were started, designed (I) to compare the behaviour of paint‐coats applied to deliberately wetted surfaces with that of similar coats applied to dry steel, and (2) to ascertain whether any troubles encountered in painting wet steel could be overcome by use of emulsion paints‐‐‐such as were being developed about that time

ISSN:0368-4075    

DOI:10.1002/jctb.5000680706

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractThe extinction point of acetylene was determined by burning a vertical he under constant pressure and in an atmosphere consisting of O2and N2of constant composition which could be altered at will. The length of flame, the diameter of the combustion chamber, the velocity of the gas mixture through the combustion chamber, and the percentage excess air all affect the extinction point. The results under specific conditions are given in the conclusions. The presence of CO2in the inlet gas mixture increases the value of the extinction point but to a lesser extent then that previously found for other hydrocarbon gases, e.g., methane.

ISSN:0368-4075    

DOI:10.1002/jctb.5000680707

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

Abstract(1) Field experiments have shown that varying manurial treatment combined with proper irrigation does not increase the oil and protein content of Palestine olives up to the standard of other Mediterranean brands.(2) Careful picking, selecting, washing and pressing of the olives under hygienic conditions produces an oil of low acidity.(3) Dark colouring may be avoided by employing a suitable pressing process whereby the crushing of olives and maceration of cells containing the colouring matter is prevented. A lower yield is thus obtained, which may, however, be increased by employing a corresponding higher pressure.(4) Rancidity can be avoided by storage of the oil in air‐tight containers filled to capacity and kept in a dark, cool plac

ISSN:0368-4075    

DOI:10.1002/jctb.5000680708

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY