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  • Cambridge University Press  (191)
  • 2010-2014
  • 1935-1939
  • 1925-1929  (191)
  • 1929  (191)
Collection
Publisher
Years
  • 2010-2014
  • 1935-1939
  • 1925-1929  (191)
Year
  • 1
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    Sugar-beet pulp as a source of pectin (1929)
    Cambridge University Press
    Details
    Publication Date: 1929-10-01
    Description: It has been shown that dried sugar-beet pulp contains a high percentage of pectose. A number of successive digestions of 1 hour each with 0·5 per cent. ammonium oxalate at 100° C. extracts an amount of pectin equal to 34·5 per cent. of the weight of dried beet pulp, basing the determination on the weight of crude pectin precipitated when the extracts are run into 95 per cent. alcohol. A single prolonged digestion gives a yield of crude pectin equal to 32·2 per cent. of the dried beet pulp.Digestion with acidic reagents, such as 0·5 per cent. oxalic acid, 0·6 per cent. tartaric acid, N/20 hydrochloric acid, etc., leads to a quicker extraction of pectin, owing to a speeding up of the pectose to pectin hydrolysis. The yield of pectin, however, is not thereby necessarily enhanced, since under such conditions the pectin undergoes a slow secondary hydrolysis during the extraction with the formation of reducing substances not precipitated by alcohol.Prolonged digestion at 100· C. of dried sugar-beet pulp with water alone also leads to a satisfactory extraction of pectin.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Cambridge University Press
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  • 2
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    A study in sampling technique: the effect of artificial fortilisers on the yield of potatoes (1929)
    Cambridge University Press
    Details
    Publication Date: 1929-10-01
    Description: (1) The desiderata of a sampling-method are outlined, and the particular case of sampling a large number of potato plots discussed.(2) An analysis is made of the yields of 54 sub-plots of the Rothamsted Potato Experiment of 1928, both as estimated by a sampling-method and as determined by large-scale lifting.(3) It is shown that most of the significant results of the experiment are obtained from the sample-yields, but that the higher standard error per plot obscures the effect of superphosphate.(4) It is concluded that at Rothamsted 102, and at Woburn 56, plants would have to be lifted to give a sampling-error as small as 4 per cent. It would then be profitable only to sample experimental plots of 1/20th acre or more in area.Finally it is a pleasure to record our indebtedness to Dr R. A. Fisher for much valuable advice and criticism: and to Mr H. J. G. Hines for assistance with the field work.
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    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 3
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    Note on the effect of sodium silicate in increasing the yield of barley:To the Editors of the Journal of Agricultural Science (1929)
    Cambridge University Press
    Details
    Publication Date: 1929-07-01
    Description: The last issue of this Journal (p. 132) contains a paper by Dr R. A. Fisher on the effect of Silica upon the growth of Barley at Rothamsted, which begins by stating that his data “show conclusively that the view previously rejected that the silicate acts by making available to the plant the actual reserves of soil phosphates must be regarded as strongly established.” Twice elsewhere Dr Fisher states that this erroneous conclusion of previous investigators is due to the fact that they had considered only the proportion of phosphoric acid in the ash and had overlooked the increase in the total phosphoric acid in the crop. As Mr Morison and I were the previous investigators in question I turned to our twenty-three-year-old paper with some curiosity to ascertain the grounds for this magisterial dismissal of our conclusions, for my remembrance of the subject did not tally with the opinion Dr Fisher attributes to us. Still less do I agree now that I have re-examined our original paper.
    Print ISSN: 0021-8596
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 4
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    The action of viscogen (calcium saccharate) on milk and cream (1929)
    Cambridge University Press
    Details
    Publication Date: 1929-07-01
    Description: The mechanism by which viscogen (calcium saccharate) brings about an increase in the viscosities of milk and cream has been investigated.The primary reaction appears to be the formation of a precipitate of insoluble (tri-calcium) phosphate. Considerable quantities of casein are carried down by the precipitate, and this co-precipitation of casein is probably the single factor which most influences the viscosity.Casein is not directly precipitated by viscogen, but the viscosity of its solutions is slightly increased as a result of their higher alkalinity due to this reagent. This action of viscogen is relatively unimportant in influencing the viscosity of milk or cream.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 5
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    The effect on lactation of the length of the preceding calving interval and its relation to milking capacity, to age and to other factors of influence (1929)
    Cambridge University Press
    Details
    Publication Date: 1929-07-01
    Description: Herd statistics of cattle in India suggest that for animals of about 3500 lb. yield capacity a calving interval of rather less than a year will give the best results in the following lactation. For cattle whose yield capacity is 6000 lb. an interval of 420 days is desirable while one of less than 335 days is seriously injurious.Study of individual cows and their recorded histories reinforces the above conclusions and also suggests that the interval should be longer in early lactations than in late and progressively longer as the milking capacity increases.It also indicates that unrestricted access to the bull may prevent the real yield capacity of a cow being discovered.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 6
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    The effect of fresh straw on the growth of certain legumes (1929)
    Cambridge University Press
    Details
    Publication Date: 1929-07-01
    Description: 1. In pot experiments with Glycine hispida and Vicia faba L., fresh chaff incorporated with the soil caused a significant increase in the number of nodules produced on inoculated plants, this increase being augmented by the further addition of phosphates.2. Fresh chaff, added at the time of sowing and inoculation, had more effect than chaff which was allowed to decompose in the soil for a month.3. Fresh chaff increases the multiplication of the nodule organism in sterilised soil.4. In soy beans without nodules, the chaff depressed the growth of the tops, but this depression did not occur either with soy or broad beans where nodules were present.5. In a field experiment made at Rothamsted, chaff, freshly ploughed in, increased the growth of broad beans and also of wheat sown the next season on the same ground.
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  • 7
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    ‘Single value’ soil properties: a study of the significance of certain soil constants: II. Studies on Natal soils (1929)
    Cambridge University Press
    Details
    Publication Date: 1929-04-01
    Description: In the first paper of this series (10)1, Keen and the present writer discussed work by earlier authors on the approximate specification of the nature of a soil by a single soil constant, in place of a detailed analysis, and described experimental work designed to show the significance of a number of simple physical measurements. The chief objects of the present paper are to describe the results obtained with such measurements as applied to a number of Natal soils, and to discuss the value of some other easily obtained physical data as a means of specifying the nature of a soil. Work of this type was discussed at the International Congress of Soil Science at Washington in 1927, and it was resolved that co-operative work on an international basis should be undertaken.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 8
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    The estimation of yield in cereal crops by sampling methods (1929)
    Cambridge University Press
    Details
    Publication Date: 1929-04-01
    Description: 1. Cereal plots were sampled by three different methods; two systematic, and one involving a random location of sampling units.2. The disadvantages of the systematic methods as compared with random sampling, emerged clearly.3. These disadvantages were further emphasised in an analysis of earlier data on sampling methods. For this purpose the methods and. results of certain recent contributions to statistical theory were used.4. By the use of a random sampling method, the variance due to sampling errors may be made a satisfactorily small fraction of the total variance of cereal plots one-fortieth of an acre in area.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 9
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    The properties of heavy alkaline soils containing different exchangeable bases (1929)
    Cambridge University Press
    Details
    Publication Date: 1929-01-01
    Description: 1. The nature of the replaceable base in a clay or soil exerts a profound effect on the physical properties. Clay-like properties are exhibited most strongly in the case of lithium, sodium, and magnesium.2. The proportion of fine material in a soil (i.e. that which remains in suspension in a column 10 cm. high after 14 days) cannot be correlated with other physical properties. Thus a soil of which over 50 per cent, was dispersed to this extent was the least plastic of those examined.3. A comparison of sodium, potassium, and calcium clays and soil showed that potassium resembles sodium in its chemical relationships as indicated by base exchange, but is very different from it in such physical properties as plasticity and permeability.4. Using mixtures of one-half normal chlorides of two bases, calcium and potassium are absorbed in equivalent amount while the sodium absorbed is only one-sixth of the amount of either of the other two.
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 10
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    The cobaltinitrite (volumetric) method of estimating potassium in soil-extracts (1929)
    Cambridge University Press
    Details
    Publication Date: 1929-07-01
    Description: The cobaltinitrite method, in the volumetric form here described in detail, enables known amounts of potassium to be accounted for quantitatively, independently of the presence of alkaline earth sulphates, or phosphates, provided that the amount of potassium is not varied over too great a range. The factor 0·000830 gm. K2O per c.c. N/10 KMnO4 suits the procedure described over a range of about 3 to 50 mg. K2O. Outside this range, or for highly accurate work within it, it may be desirable to calibrate the method.The method may be applied, in plant-ash analyses, indifferently to the original extracts containing other bases and phosphates, or to the mixed sulphates weighed for sodium and potassium together. It is applicable to small-quantity work upon soils with greater exactness and speed than is the perchlorate method. Citric acid extracts can be handled, with a relatively short manipulation, to give satisfactory results.Some analyses of ammonium chloride extracts have been unsatisfactory, and attention is called to the desirability of setting exchangeable potassium determinations upon a firmer analytical basis, by investigation of methods of freeing the extracts from ammonium salts.
    Print ISSN: 0021-8596
    Electronic ISSN: 1469-5146
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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