ISSN:0022-5142    

DOI:10.1002/jsfa.2740011102

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractA colorimetric procedure is described for the determination of small amounts of potassium. The soil is extracted with Bray's extracting reagent and the available potassium is precipitated as cobaltinitrite. The determination of potassium precipitated involves the diazotization of sulphanilic acid, using the nitrite groups, of the cobaltinitrite precipitate, and subsequent coupling with dimethylaniline to give methyl orange. The colour is measured with a Spekker absorptiometer. The method is applicable to the routine determination of potassium in soil extracts.

ISSN:0022-5142    

DOI:10.1002/jsfa.2740011103

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractChanges in the sugar content of the water of the coconut have been followed during ripening and germination. From the most immature fruit in which the cavity has just formed to about the seven‐month‐old fruit when it is full size but still unripe, the sugars present, which are almost entirely reducing sugars, increase to a maximum of about 5% concentration. Thereafter non‐reducing sugars appear, but the total concentration of sugars fall to about 2% in the fully ripe nut, 12 to 13 months old.The results were much the same in the three varieties ofCoos nuciferaL. studied—the ordinary tall palm, a dwarf variety, and a variety with orange‐coloured fruit, known in Sinhalese as Rath‐Thembili—expect that in the water of dwarf nuts small amounts of non‐reducing sugars were present in the earlier stages.During the early stages of germination the concentraion of reducing sugars continues to fall, but that of total sugars remains fairly constant until the fourth month of germination, whe

ISSN:0022-5142    

DOI:10.1002/jsfa.2740011104

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractApparatus for testing strength is reviewed, attention being drawn to the different physical principles involved. The American definition of pectin jelly grade has been adapted to conform with English jam‐manufacturing practice, and the effect of different conditions of gel preparation is described. Rate of cooling and Ph are more important factors than type or quantity of buffer, and temperature of ageing and soluble‐solids content both exert considerable influence above Ph 3.0. Points are listed for consideration when formulating a laboratory procedure for jelly sideration when formulating a laboratory procedure for jelly grading. Methods of determining the rate of set are briefly descri

ISSN:0022-5142    

DOI:10.1002/jsfa.2740011105

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractA method is described for the determination of the soluble carbohydrate content of dried samples of grass silage, using the anthrone reaction. The procedure described below is substantially similar to that of Morris except that modifications required for stabilization of the colour developed were used and a Hilger Spekker absorptiometer was the instrument selected for making the determinations. The silage extracts used were partial hydro‐lysates obtained by heating the dried material with o‐25N‐H2SO4for a short p

ISSN:0022-5142    

DOI:10.1002/jsfa.2740011106

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractThe use ofAspergillus niger(Mulder's M strain) as a test organism for determining Mg, Cu, Zn and Mo in soils, and the last‐named in tissue extracts and the ash of plants, is described. Special chemical methods are used to remove the ‘test’ nutrient from the basal culture solution. A standard growth series is prepared for each element in turn by adding increasing amounts of the ‘test’ nutrient to 50 ml. portions of the purified basal culture solution containing all the other essential elements at adequate levels. After sterilization, the solution is inoculated with a spore suspension ofAspergillus nigerand then incubated at 25° C. for 6 days. The material for test is put into a culture solution containing all the essential mineral elements other than the one to be determined, so that under condition of test, the growth of the fungus depends on the amount of ‘test’ nutrient it derives from the material added.The bioassay results for soil samples have shown Mg deficiency in the presence of a shortage of K, a point not shown by the chemical analysis of the crops : Cu deficiency in certain alkaline fen soils and in sandy soils where fruit trees showed ‘dieback’ symptoms; Zn deficiency in soil where apple and pear trees showed ‘little leaf ’ symptoms; Mo deficiency in soils from areas where brassica crops showed ‘whiptail’ effects. Because of the extreme sensitivity of the biological method for Mo, it has been used to determine the element in tissue extracts and ash of normal plants and those deficient in molybdenum. Some aspects of the physiology of micronutrient elements in relation to nitrogen metabolism o

ISSN:0022-5142    

DOI:10.1002/jsfa.2740011107

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

摘要:

AbstractIn view of the widespread interest in insecticidal formulations based on parathion, the vapour pressures of the pure material and a number of related compounds likely to be encountered in the commercial product have been measured at various temperatures within the range 25–92° C. The materials examined include : (a) pure parathion, O,O′‐diethyl O‐P‐nitrophenyl thiophosphate, (b) S‐ethyl isomer of (a), O,S‐diethyl 0‐P‐nitrophenyl phosphate, (c) S‐phenyl isomer of (a), O,O′‐diethyl S‐p‐nitrophenyl phosphate, (d) commercial parathion, which contains mainly pure parathion together with small quantities of various related compounds, (e) O,O′,O″‐triethyl thiophosphate, (f) O,O′‐diethyl S‐ethyl phosphate, (g) O‐ethyl O,O′‐bis‐P‐nitrophenyl thiophosphate. Compounds (a) to (d) and (g) were examined by an effusion technique. Compounds (e) and (/) were examined in a liquid U‐tube manometer. Details of the preparation of the materials are given. The vapour pressures have been shown to be low at ordinary temperatures (generally of the order of 10−4mm. mercury, or lower, at 20° C).The data provided will be of use in assessing the toxic hazards of exposure to the vapour of parathion and related compounds, and

ISSN:0022-5142    

DOI:10.1002/jsfa.2740011108

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY

ISSN:0022-5142    

DOI:10.1002/jsfa.2740011101

出版商:John Wiley&Sons, Ltd    

年代:1950

数据来源: WILEY