摘要:

AbstractFactory data collected at Cape Town and Port Elizabeth are used to demonstrate variations in the oil and vitaminAcontents of the liver of the Cape hake. In addition to seasonal changes related to the sexual cycle, there are marked fluctuations from year to year, probably connected with variations in the food supply, which ultimately are related to oceanographic factors, such as sea temperatures, Migratory phenomena have an important bearing on the average size and physiological condition of the fish caught, and size of fish also markedly influences the oil and vitamin A content of the Users.

ISSN:0368-4075    

DOI:10.1002/jctb.5000651001

出版商:John Wiley&Sons, Ltd    

年代:1946

数据来源: WILEY

摘要:

AbstractFrom 16 to 44 μg./g. of nicotinic acid were found in samples of raw coffee beans. Nicotinic acid in produced during the roasting of coffee by the decomposition of trigonelline present in the raw beans. The production of nicotinic acid is dependent on the extent of roasting, a dark roast coffee containing more than a light roast coffee. Normal samples of roasted coffee contained from 95 to 263 μg./g. of nicotinic acid. The nicotinic acid content of coffee is not dependent on the variety of bean. The nicotinic acid is almost completely extracted in the preparation of the beverage for drinking, the amount in a cup of white coffee (200 ml, half 10% coffee decoction and half milk) being between 1 and 2 mg. The pyridine in coffee also originates from the decomposition of trigonellin

ISSN:0368-4075    

DOI:10.1002/jctb.5000651002

出版商:John Wiley&Sons, Ltd    

年代:1946

数据来源: WILEY

摘要:

AbstractFactors which influence the determination of peroxide values by the iodimetric method have been investigated. These include dissolved oxygen and moisture in the reagent, time and temperature of reaction, and amount of fat taken. The necessity for adequate de‐aëration of the reagent before admixture with the fat had been demonstrated for this, as previously for the photometric ferrous salt method, but the ratio between the “aërobic” and “anaërobic” values is much smaller for the iodimetric than for the ferrous salt method. Alternative procedures for determination of iodimetric peroxide values are recommended by (a) a “cold” method involving standing at laboratory temperature for one hour, or (b) a rapid “hot” method involving heating at the boiling point of the solvent for two minutes.The increase in apparent peroxide value observed in earlier iodimetric procedures when the quantity of fat taken for the determination was reduced, has been shown to be due to an increasing error reuniting from further oxidation of the fat by dissolved oxygen during the determination, rather than to a decreasing error due to loss of iodine by re‐absorption. In both the procedures now recommended, exclusion of atmospheric oxygen is adequate and the results, within reasonable limits, are independent of the size of t

ISSN:0368-4075    

DOI:10.1002/jctb.5000651003

出版商:John Wiley&Sons, Ltd    

年代:1946

数据来源: WILEY

摘要:

AbstractThe use of iron as the variable internal standard for the determination of trace elements in the cathode layer are, when the iron varies from two to one hundred per cent of ferric oxide, is discussed. Davidson and Mitchell's method, which requires one trace element working curve of fixed iron content and a correction curve for variation of iron content, is examined. Straight line working curves, of slope approximately unity up to at least five hundred parts per million, are obtained for most of the trace element lines when log intensity ratio, corrected for background, is plotted against log concentration, the curves for different iron contents being parallel but vertically displaced. Straight line correction curves are obtained by plotting this separation of the working curve, due to variation in iron content, against log concentration of iron. Two shortened methods for the derivation of the curves are proposed: in the first, the working and correction curves fan be prepared from a standard material by a single determination of the log intensity ratio of the trace element and internal standard lines, corrected for background; the second employs an observed working curve and an arbitrary correction curve. In the concentration ratio method, in which the working curve itself makes allowance for the variation in internal standard content, the log intensity ratio is plotted against the log concentration ratio and this method has similar limitations to the first shortened method.

ISSN:0368-4075    

DOI:10.1002/jctb.5000651004

出版商:John Wiley&Sons, Ltd    

年代:1946

数据来源: WILEY

摘要:

AbstractA method is described for the detection and estimation of the montmorillonite group minerals by X‐rays, which completely eliminates difficulties due to the change of basal spacing with hydration, allowing a vacuum camera to be used if desired. The method is based on the formation of a montmorillonite‐glycerol complex. It may be combined with either the powder or the oriented aggregate techniques. With the former, and with a vacuum camera, 1% montmorillonite has been detected with ease. A table of data of the main basal reflections of the glycerol‐montmorillonite, in their relation to the basal reflections of other minerals likely to occur in clays, is given. The extension of the method to rough quantitative analysis of montmorillonite clays is described. A discussion is given of the question of distinguishing between montmorillunite and hydrous

ISSN:0368-4075    

DOI:10.1002/jctb.5000651005

出版商:John Wiley&Sons, Ltd    

年代:1946

数据来源: WILEY

摘要:

AbstractThis paper discusses the results of electron microscope examination of a number of pigments commonly used in paints, lacquers etc. A table summarises the information available as to particle size and shape as obtained from electron microscopy, optical microscopy and adsorption experiments.

ISSN:0368-4075    

DOI:10.1002/jctb.5000651006

出版商:John Wiley&Sons, Ltd    

年代:1946

数据来源: WILEY

摘要:

AbstractSeveral pilot and production units for penicillin were erected in Britain during the war, mostly employing milk bottles or special flasks. The successive operations, washing, filling, autoclaving, inoculating, incubating and harvesting were usually mechanised. Surface culture methods could not compete with submerged culture processes developed in U.S. and now installed in two large British factories, since a single tank may be equivalent to half a million milk bottles. The penicillin is concentrated and purified by adsorption or partition processes and the final penicillin solution is freeze‐dried to increase its stabilit

ISSN:0368-4075    

DOI:10.1002/jctb.5000651007

出版商:John Wiley&Sons, Ltd    

年代:1946

数据来源: WILEY

摘要:

AbstractThe usual particle size analysis gives data on particle size distribution by weight or by values of a function related to it,e.g., the surface area of particles of the same weight. There are three methods for the determination of particle size in the sub‐sieve range1Measuring the settling velocity, assuming Stokes' law.2Counting particles of the same weight.3Measuring the size of the observed or projected images of the particles in their most stable positions. The results gained by two of these methods have been compared,e.g., by Andreasen,2by Bishop4and by Jones,14but it seems that hitherto no attempt has been made to compare systematically the results of all three, methods. This comparison, originally used merely for verifying purposes, has led to a method of measuring the mean particle shape. This measurement is executed in the following way: a fraction of hearly equal‐sized particles is isolated, their mean volume determined by the counting of particles of the same weight and the mean of their greatest cross sections (i.e., of the images of the particles in their most stable positions) is measured. The mean thickness is then calculated as a quotient of the mean volume and mean cross section, a prismoidal form of the particles being assu

ISSN:0368-4075    

DOI:10.1002/jctb.5000651008

出版商:John Wiley&Sons, Ltd    

年代:1946

数据来源: WILEY

摘要:

AbstractThe determination of the moisture content of a material by the measurement of its specific inductive capacity is now well established, and several commercial instruments are available using this principle, generally in conjunction with electrical conductivity. An instrument easily constructed in the laboratory is described in this paper, which it is hoped will enable the principle to be more widely used. The method employed in the determination of the moisture content of various cereals is described, together with the degree of accuracy to be expected and the limitations of the method.

ISSN:0368-4075    

DOI:10.1002/jctb.5000651009

出版商:John Wiley&Sons, Ltd    

年代:1946

数据来源: WILEY

摘要:

AbstractIn Part I of this paper reference was made to the occurrence of up to 2·20 p.p.m. of bromine, combined as bromide, in some underground water supplies of Southern England. The effect of traces of bromide in tests for free chlorine is now discussed. Bacteriological experiments also indicate that when waters containing free ammonia are being chlorinated, the presence of small amounts of bromide leads to a considerable acceleration of the rate of sterilisation: it appears that this effect is marked with 1 p.p.m. of combined bromine but as little as 0·25 p.p.m. may be significant under some conditions. The experiments were mainly confined to the case where the organic content of the water was very small, but this frequently applies in underground supplie

ISSN:0368-4075    

DOI:10.1002/jctb.5000651010

出版商:John Wiley&Sons, Ltd    

年代:1946

数据来源: WILEY