摘要:

AbstractNitroaminoguanidine on diazotization yields nitroguanidine and nitroguanyl‐azide which may be isomerized to 5‐nitramine‐teuazole. Nitroguanyl azide acts as a dibasic acid when titrated with alkalis, as it is quantitatively isomerized to the dibasic nitramine‐tetrazole. Volumetric procedures for the estimation of the azide and its isomer are de

ISSN:0368-4075    

DOI:10.1002/jctb.5000681101

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractA method is described for determining the amount of DDT in foodstuffs, using monoethanolamine to dehydrochlorinate the DDT, followed by electrometric titration of the free chloride with silver nitrate; the monocthanolamine does not hydrolyse the fats and oils. The method has been used to determine the quantities of DDT transferred from DDT‐impregnated sacking to wheat, wheat flour, soya flour, decorticated groundnuts, and cocoa beans. Relatively large quantities of DDT may be transferred in B few months, particularly to finely divided and fatty foodstuffs, and much caution must be exercised in making recommendations for the use of DDT‐impregnated sacks 10 prevent or control insect infestation in stored foodstuffs. The importance of vapour‐phase transfer of DDT is disc

ISSN:0368-4075    

DOI:10.1002/jctb.5000681102

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractCompressed mixtures of iron and barium peroxide or iron and potassium dichromate are examples of systems capable of undergoing self‐propagating incandescent reaction when ignited. It has been found that in both of these systems a non‐incandescent reaction, called the pre‐ignition reaction, sets in at a measurable rate below the ignition temperature. This reaction has been shown to be a genuine solid‐solid reaction. Its kinetics have been investigated, and the part it plays in the propagation of the incandescent reaction is di

ISSN:0368-4075    

DOI:10.1002/jctb.5000681103

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractA brief review of cytological studies of bacterial cell division is followed by a description of preliminary investigations of the chemical nature of factors which, in complex media, influence the division process. In these, magnesium is shown to be essential for the normal cell division of both Gram positive and Gram negative rod‐shaped eubacteria, but in significantly different amounts.In simple synthetic media, magnesium is also essential for the synthesis of bacterial protoplasm, and in the complete absence of this ion, eubacteria fail to grow. The magnesium requirements of Gram positive organisms are about ten times as great as the requirements of Gram negatives. This difference is attributed to the fact that the former also incorporate magnesium into their structure.The significance of these findings and the observed differences in cell division of the cocci and rod‐shaped organisms arc discus

ISSN:0368-4075    

DOI:10.1002/jctb.5000681104

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractIn an investigation into the production of aroma in roasted coffee, some of the principal volatile constituents have been determined. In the staling of coffee only small losses of aldehydes, acetone, and volatile phenols occurred and there was no loss of pyridine or of furfural, despite the volatility of these constituents. Apart from a conversion of diacetyl to acetyl‐methyl carbinol, no change indicating a loss of aroma was discovered. When coffee was prepared for drinking, some losses of volatile constituents were detected. The substance, or substances, giving the characteristic aroma to roasted coffee is as yet unidentified. It is probable that other less volatile substances, that are soluble in light petroleum and are readily oxidizable, are involved in the flavour of roasted coffe

ISSN:0368-4075    

DOI:10.1002/jctb.5000681105

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractWhen a vertical rod is rotated in certain over‐aged samples of sweetened condensed milk, the milk climbs up the rod. When a disc is rotated near the bottom of the beaker containing the sample, the liquid is drawn radially towards the centre.It is suggested that these phenomena, commonly called “Weissen‐berg Effects,” are caused, in the case of condensed milk, by an uncoiling of globular protein molecules as a result of denaturation.Samples showing Weissenberg effects arc sometimes also thix

ISSN:0368-4075    

DOI:10.1002/jctb.5000681106

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractIn the course of related preparative work onp‐aminosalicylic acid derivatives, it was brought to our notice by certain workers on the bacteriological side that samples of the acid itself, obtained by them from different sources and used by them, did not always appear to be uniform, either physically, or in theirin vitrobacteriology. It was decided therefore to explore the possibilities of a convenient laboratory synthesis which would yield consistentp‐aminosalicylic acid in working quantities, and involve only ordinary bench equipm

ISSN:0368-4075    

DOI:10.1002/jctb.5000681107

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY

摘要:

AbstractAn account is given of some of the more purely physical aspects of the process of drying sensitive materialsin vacuoat a low temperature. A relation is established on theoretical and experimental grounds, between the mean air pressure in the desiccator, the rate of drying, and the difference between the vapour pressures at the evaporator and condenser. Considerations arising from the shape and size of the desiccator, evaporator and condenser ate discussed.The process whereby sensitive materials are dried in the frozen state in a moderately high vacuum is now well established and has been used on a commercial scale for the preparation of dried blood plasma and penicillin.1,2,3,4In view of its high cost it has not been applied to foodstuffs to any considerable extent, although the results are in most cases superior to those of any other method of drying, and rival those of quick‐freezing.5,6,7However, good results have been obtained with foodstuffs at higher temperatures and pressures than those usually considered necessary; this paper describes some experiments and observations on the process under such conditions which are independent of the material being dried; a second paper will describe the results obtained with green peas.The process, as it will be considered here, consists essentially in the sublimation of the ice contained in the frozen material (the “evaporator”) and its condensation as a layer of ice upon a cold surface (the “condenser”); it takes place in a vessel known as the “desiccator,”, the pressure in which is wry considerably reduced. The rate of drying is controlled almost entirely by the rate at which the evaporator is heated, since apart from losses due to radiation and conduction, which arc very small until the concluding stage is reached, all the heat applied must be used as latent heat of sublimation.In order that the final product shall be of satisfactory quality, an upper limit must be fixed to the temperature of the material at each stage of the process. Since the principal factor influencing the temperature of the evaporator is the vapour pressure around it, one requirement of a satisfactory plant is that the desired rate of drying may take place with a sufficiently low vapour pressure at t

ISSN:0368-4075    

DOI:10.1002/jctb.5000681108

出版商:John Wiley&Sons, Ltd    

年代:1949

数据来源: WILEY