摘要:

Light waves are too short and ordinary sound waves generally too long to permit experimental work on diffraction and scattering by a single small obstacle. An opportunity for such work however is presented in the case of ultrasonic waves.This paper describes an experimental investigation on the factors which determine the diffractive reflection and scattering of an ultrasonic wave train by plane circular opaque discs, and discusses the results. These are of special importance in the measurement of sound energy intensity by the torsion-pendulum method, for such measurements should always be corrected to allow for the effect of diffractive scattering of the energy by the measuring-pendulum vane. The correction factor will depend on the size and form of the pendula vanes employed and for circular vanes can be obtained directly from such curves as are shown in this paper as results of the investigation.

ISSN:1923-4287    

DOI:10.1139/cjr30-075

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Certain peculiar variations in the radiated energy from a five-metre triode oscillator observed by a previous experimenter, have been investigated. The factors influencing the output appear to be changes in input and in the surrounding temperature. With tubes employing oxide-coated filaments, these changes are sometimes of considerable importance, while in other cases such variations have a negligible effect. Several curves of output plotted against various input values are given.

ISSN:1923-4287    

DOI:10.1139/cjr30-076

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Several methods of measuring the wave-length of electric waves on wires have been investigated. It was found that incorrect results were obtained when neon glow-tubes were moved along the wires to indicate the voltage nodes. By placing the neon lamp at the far end of the wires, however, and using shorting bridges to indicate the nodes, it was found possible to obtain quite consistent results. A thermogalvanometer, used in a similar manner, proved to be a somewhat better indicator and gave results which were more precise.

ISSN:1923-4287    

DOI:10.1139/cjr30-077

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Experiments on the detection of rock salt deposits by electrical methods are described. It is shown that these methods give definite indications of the depth of the deposit when the latter is as much as 600 ft. below the surface.The interpretation of results obtained by the "single electrode probe" method is discussed.

ISSN:1923-4287    

DOI:10.1139/cjr30-078

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The reactions between hydrogen chloride and α-, β-, and γ-butylene have been investigated in both the liquid and gaseous states. The effect of temperature and concentration of the reactants on the reaction velocities was studied and the reaction products were examined. In the liquid state the γ-isomer reacts rapidly, the α- much more slowly and the β- slowest of all. In the gaseous state at atmospheric pressure only γ-butylene shows a measurable reaction which is bimolecular and probably heterogeneous. The liquid reactions were found to be homogeneous. Where possible the freezing-point curves of the systems were determined in order to ascertain the extent of molecular compound formation. The results obtained bear out the conclusions arrived at from previous work on the effect of molecular attraction upon reaction velocity, and indicate the existence of a catalytic factor peculiar to the liquid state. Suggestions as to the mechanism of such a catalysis are offered.

ISSN:1923-4287    

DOI:10.1139/cjr30-079

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Ammonia and carbon dioxide were subjected to intensive drying, with subsequent inhibition of reaction when the gases mixed. Liquefaction of the non-reactive mixture resulted in immediate reaction taking place and the hypothesis is put forward that the "liquid condition" may be looked upon as a catalytic influence.

ISSN:1923-4287    

DOI:10.1139/cjr30-080

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Honey was substituted for commercial sucrose in various straight-dough bread baking formulae, the doughs fermented for varying times and proofed and baked in the usual manner. No significant difference in loaf volume, flavor, or other bread characteristics could be detected, indicating that honey possesses no superiority over sucrose but is of equal value when compared on the basis of equivalent sugar content. The baking tests were supplemented by studies on the rate of gas production in doughs and also by determinations of the reducing-sugar content of the doughs at the end of the proof period. Rate of gas production was similar and the reducing-sugar content of the doughs were of the same order. A comparison of the results obtained by the different baking formulae indicate the importance of considering the formula in relation to the apparent fermentation tolerance of a flour. No difference was observed in the rate of gas production in partially buffered yeast-honey and yeast-sucrose suspensions of equivalent sugar content prepared in a manner to simulate conditions in fermenting bread doughs. Studies on the rate of inversion of sucrose by yeast showed that the rate of invertase action exceeds the speed of zymase action and indicate that sucrose inversion is not a limiting factor in the rate of gas production in bread doughs. An extension of the market for honey in the baking industry would seem to lie in the direction of increasing its use in sweet goods where its flavor, higher sweetening power and greater hygroscopicity are particularly advantageous—the last in relation to checking. In bread manufacture these properties do not come into play since the relatively low percentage of sugar used is to a large extent removed by fermentation.

ISSN:1923-4287    

DOI:10.1139/cjr30-081

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The bound-water method was modified for use with flour suspensions and provided a simple means for the direct measurement of the approximate hydration of the colloidal constituents in dilute lactic acid. The average hydration of the dry matter in 15% suspensions was in the region of 40 to 50%, the value being slightly higher in washed suspensions. Starch maintained a hydration close to 30%, under all conditions investigated. The prepared proteins, in dilute lactic acid, were hydrated about 85%. The calculated hydration of the proteins as they occurred in the flour was about 100% in unwashed and 200% in washed suspensions.No significant differences were found by this method in the hydration of strong and weak flours, and it is thought that such differences as may exist are too small to be of major importance as factors in baking quality. The experimental results are harmonized with the facts concerning viscosity and the behavior of bread dough by assuming micellar aggregation of the gluten.

ISSN:1923-4287    

DOI:10.1139/cjr30-082

出版商:NRC Research Press    

年代:1930

数据来源: NRC