摘要:

Another and more direct experimental method for determining the reflection from and transmission through parallel-faced partitions of sound energy of short wave-length was studied. Measurements were taken of the energy transmitted through obstructing plates by means of a torsion pendulum placed in the "ultrasonic shadow", the incidence of the energy being normal. The theoretical and experimental results obtained in previous researches by taking reflection measurements only were confirmed, and again it was shown necessary to employ the bulk modulus of elasticity for computations of velocity instead of Young's.

ISSN:1923-4287    

DOI:10.1139/cjr30-001

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The half-value time of absorption from meta-stable electronic atomic states is calculated on the hypothesis that the whole decay is due to collision phenomena. Definite assumptions, which include the atomic energy level scheme, are made as to the efficiency of collisions and the interaction of two meta-stable states in these processes. The assumption adopted as the only one producing an approximation to experimental facts shows that the probability of an exchange is dependent on theabsolute valueof the energy difference between the states concerned. The results calculated from the final formula, for helium, neon and argon at normal and very low temperatures depend on one arbitrary constant, which is the same for all states and gases considered, and show fair agreement with any experimental values so far published. An estimate is made of the energy tolerance of a quantum transition.

ISSN:1923-4287    

DOI:10.1139/cjr30-002

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The properties of the zone plate are worked out theoretically, using the method developed by Voigt for diffraction problems. The case treated is the one for which the plate is illuminated by monochromatic plane waves at normal incidence. The various approximations made are clearly indicated and the results obtained are compared with experimental data.

ISSN:1923-4287    

DOI:10.1139/cjr30-003

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

In the preparation of o-benzoylbenzoic acid from benzene and phthalic anhydride, ferric chloride is a much poorer catalyst than aluminum chloride, but an equimolecular mixture of ferric and aluminum chlorides, although less active than aluminum chloride itself, possesses an activity greater than the sum of the activities of its components separately. Ferric chloride is not a catalyst for the combination of benzene and ethylene. Amalgamated aluminum is a better catalyst than aluminum chloride for both of the reactions mentioned.

ISSN:1923-4287    

DOI:10.1139/cjr30-004

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The condensation of acetone with glycerol has been carried out in a neutral medium, at a low temperature, and the product shown to consist entirely of the five-membered isopropylidene-glycerol ketal. Based on this fact, the use of the substance for the determination of the structure of fats is therefore warranted. Isopropylidene-glycerol and its acetate readily hydrolyse on heating with water.No satisfactory explanation can, as yet, be offered for the non-formation of the six-membered ketal under the conditions outlined.Acetone, as previously shown by other workers, is capable of forming a six-membered cyclic ketal with glycerol-β-methyl ether, dihydroxy acetone, pentaerythritol and certain carbohydrates.

ISSN:1923-4287    

DOI:10.1139/cjr30-005

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The investigation described deals with the equilibria existing in a water solution of sulphur dioxide. The vapor pressures and conductivities of solutions of sulphur dioxide were measured over the temperature range 23° to 135 °C. at various concentrations up to 8%. The densities of the aqueous solutions up to 15% were also measured. A discussion of the various equilibria in the light of these data leads to the conclusion that sulphurous acid is one of considerable strength, its apparent weakness being due to the small amount of H2SO3actually present. With rise in temperature the free sulphur dioxide increases and the hydrogen-ion concentration of the sulphite liquor used in current practice is so low that it seems highly improbable that the cooking reaction is due essentially to this factor. Apart from the bearing this work may have on the theory of sulphite cooking and the theory of the equilibria existing in the SO2−H2O system, it fills a considerable gap in the data regarding sulphur dioxide.

ISSN:1923-4287    

DOI:10.1139/cjr30-006

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Studies were conducted on heat-treated samples of unbleached straight-grade flour milled from Western Canadian hard red spring wheat with the purpose of determining the influence of time and temperature of heating flour with normal moisture content on certain biochemical properties related to "strength". Samples were selected which showed a progressive range in baking quality including some which revealed improvement as a result of heat treatment, when baked by the basic procedure. Gluten quality was impaired in all heat-treated samples, as evidenced by decreased viscosity of leached, acidulated flour suspensions, a decreased rate and extent of imbibition of the washed out gluten, and decreased gas retention of the dough. High positive correlations between viscosity, gas retention, and loaf volume were obtained. The somewhat higher correlations between these measures of gluten quality and loaf volume when determined with potassium bromate added to the formula suggest that the bromate method gives a better measure of gluten quality than the basic procedure. Decrease in viscosity was approximately a linear function of the temperature, for constant time of heating. Ease of peptization of the flour proteins by N. magnesium sulphate, N. potassium iodide, and 5% potassium sulphate solutions showed a marked and progressive decrease with increasing severity of heat treatment. The high positive correlations between the percentage of protein extractable by these salts indicate that the magnitude of these fractions is influenced by the same inherent qualities of the flour proteins. The high positive correlations between the percentage of protein peptized by these salts and viscosity, suggest that these "qualities" are the colloidal properties of the flour proteins. High positive correlations were obtained between loaf volume and percentage of protein peptized. Increasing the moisture content of the flour, with fixed time and temperature of heating, resulted in decreased peptization indicating more extensive heat denaturation of the gluten proteins. Fractionation of the flour proteins showed that the decrease in the potassium sulphate fraction with increasing severity of heat treatment contributed to both the gliadin and glutenin fraction (as determined by the direct barium hydroxide method). Diastatic activity, as determined by the modified Rumsey method and by the rate of gas production in doughs without added sugar, revealed only slight decreases with those flours which showed improvement in baking quality due to heat treatment. Marked decreases were observed with the more severe heat treatments. Susceptibility of the starch to diastatic action was unaltered until marked damage to baking quality resulted, when significant decreases were noted. Heat inactivation of diastase evidently occurred before changes in amyloclastic susceptibility. Proteolytic activity markedly decreased with heat treatment, significant decreases being noted before diastatic activity was appreciably altered. The hydrogen ion concentration of flour extracts revealed no particular trend due to heat treatment, but the buffer value was somewhat increased. The biochemical changes investigated were, for the most part, in a direction associated with decreased baking quality, and provided no adequate explanation for the improvement in baking quality observed in certain samples when baked by the basic procedure.

ISSN:1923-4287    

DOI:10.1139/cjr30-007

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The effect of various representative hæmotoxins on human and rabbit red blood cellsin vitrowas studied. It was found that as a result of the action ofB.welchiitoxins produced from a variety of strains of the organism a definite anisocytosis was produced and that the change in size of the cells followed a regular sequence. The first change to be noted was a development of cells having an average diameter less than the normal (microcyte stage). Further action of the toxin resulted in the replacement of these microcytes by cells having an average diameter greater than the normal (macrocyte stage). Following this macrocyte stage it was found that there was a return of the cells to a diameter very closely approximating the normal. This change in the size of the cells did not appear as a result of the action of any of the other hæmotoxins worked with viz.,B.tetani,V.septique,Strepto.scarlatinœ,Staph.aureus.

ISSN:1923-4287    

DOI:10.1139/cjr30-008

出版商:NRC Research Press    

年代:1930

数据来源: NRC