摘要:

An experimental research showing how corrections in the value of velocity of phase propagation may be made to take into account lateral inertia, and how the law (Rayleigh's) will break down at higher frequencies because of other types of vibration intervening. When the ratio of radius to length, multiplied by the mode of vibrationexceeds a certain figure (in the case of duralumin, 0.55) the law breaks down, and it appears that radial longitudinal vibrations intervene. From the research a simple method emerges to determine Poisson's ratio, which in the case of duralumin is found to be 0.35.An application of this ultrasonic method is made to determine Young's modulus for ice, in order to find more consistent values than those generally quoted. The value of this modulus for ice at about 0 °C. is found to be about 9 × 1010dynes/cm2. corresponding to a velocity of sound in it of 3.15 × 105 cm. per sec.

ISSN:1923-4287    

DOI:10.1139/cjr31-098

出版商:NRC Research Press    

年代:1931

数据来源: NRC

摘要:

The experimental knowledge so far available of the velocity of longitudinal waves in cylindrical rods is reviewed, and it is shown that a close analogy most probably exists between waves in cylinders of liquid and in solid rods. The theory for rods due to Pochhammer is considered with reference to a specific case for which experimental velocities have been determined, and it is shown that the agreement at low frequencies is good. At higher frequencies, however, theory and experiment differ widely.

ISSN:1923-4287    

DOI:10.1139/cjr31-099

出版商:NRC Research Press    

年代:1931

数据来源: NRC

摘要:

The Gerdian type of atmospheric ionization measuring apparatus was attached to a cabin aeroplane so that the state of ionization of the atmosphere could be studied. The limitations of the apparatus for aeroplane use are discussed. Measurements were taken from ground level to heights of 15000 ft. The results are plotted in number of ions per cc. (separate curves for positive and negative) at different altitudes.The results indicate that at the cloud level there is an abnormal excess of small positive ions and a minimum in the excess of positive ions over negative ions from 4000–6000 ft. higher. This does not include large ions such as charged water drops or dust particles. The observations were taken in regions free from clouds, the cloud level being determined by observation on clouds in the sky, and by relative humidity measurements taken at the same time.

ISSN:1923-4287    

DOI:10.1139/cjr31-100

出版商:NRC Research Press    

年代:1931

数据来源: NRC

摘要:

The decomposition represented by the general equationhas been found to take place according to the monomolecular law. In the case of the several homologous esters already investigated at pressures above 10 cm. of mercury the reaction is entirely homogeneous, is uninfluenced by the presence of inert gases and obeys the Arrhenius equation. This paper describes the experimental method and deals with the decomposition of ethylidene diacetate to acetaldehyde and acetic anhydride at temperatures of 220° to 268 °C. and at initial pressures of 11 to 46 cm. of mercury. The heat of activation is 32900 cal./mol and the velocity constants (sec−1) are given by the equation, ln. The theoretical significance of the data is discussed.

ISSN:1923-4287    

DOI:10.1139/cjr31-101

出版商:NRC Research Press    

年代:1931

数据来源: NRC

摘要:

Acetaldehyde, when freshly distilled, suffers immediate oxidation on coming into contact with oxygen or air. A compound is produced which in aqueous solution behaves as an organic peracid. This has a pronounced effect upon the subsequent gas-phase oxidation of the acetaldehyde.

ISSN:1923-4287    

DOI:10.1139/cjr31-102

出版商:NRC Research Press    

年代:1931

数据来源: NRC

摘要:

A new alkaloid,retrorsine, has been isolated fromSenecio retrorsusof South African origin. Analysis of the free base and its methiodide together with its hydrolytic products point to the empirical formula, C18H25O6N. Hydrolysis yields a new base, C8H13O2N, termedretronecinetogether with an acid,retronecic acid, isolated as the monolactone, C10H14O5. The base is tertiary, contains one hydroxyl (benzoyl derivative) and probably a ketonic group. The preparation of the di-p-phenylphenacyl derivative of the acid proves its dibasicity. The alkaloid, jacobine, fromS.jacobaeahas been isolated in a state of purity and probably has the empirical formula C18H23O5N, although this is only partly confirmed by analysis of the hydrolytic fragments. The necine derived from jacobine is shown to be identical with retronecine.An examination ofS.aureusfailed to show the presence of an alkaloid in tractable amounts. A system of simplified nomenclature to designate theSenecioalkaloids and their hydrolytic products is suggested.

ISSN:1923-4287    

DOI:10.1139/cjr31-103

出版商:NRC Research Press    

年代:1931

数据来源: NRC

摘要:

The chief determining factor in spontaneous self-fertilization in white sweet clover (Melilotus alba) appears to be the distribution of pollen within the unopened flowers. This in turn depends on (1) length of stamens, (2) length of style, (3) amount of pollen, and (4) size of cavity within the upper part of the keel. When the flower structure and quantity of pollen is such as to insure the deposition of pollen grains on the stigma before the blossom is likely to be disturbed by insects, the plant will be normally self-fertilized. In the yellow flowered species of sweet clover (Melilotus officinalis) spontaneous self-fertilization is effectively prevented, except in certain varieties, by a characteristic of the stigma which makes it unreceptive. Scarification of the stigmatic surface appears to be necessary before fertilization can take place. Variation occurs also, as inM.alba, in the length of stamens and style, size of keel cavity, and the amount of pollen.There is a high correlation inM.albabetween the percentage of flowers which are naturally self-pollinated and the percentage of flowers which produce pods when the plants are caged to exclude insects. Selection of plants which are normally self-fertilized can be made by examining the early flowers, thus obviating the necessity of bagging or caging plants which do not possess this character.A strain ofM.albawhich is normally self-fertilized was found to produce almost twice as much seed as another strain which is normally cross-pollinated under comparable conditions in the field.

ISSN:1923-4287    

DOI:10.1139/cjr31-104

出版商:NRC Research Press    

年代:1931

数据来源: NRC

摘要:

A study of the predominant sugar-tolerant yeasts infecting 163 samples of normal Canadian honey led to the recognition of eight different species, comprising the generaZygosaccharomyces,SchizosaccharomycesandTorula. The frequency of their occurrence varied greatly, one type,Z.richteri, being by far the most commonly encountered. The yeast predominating originally is not necessarily the most abundant type after fermentation. Analysis of samples fermenting within 14 months showed species ofZygosaccharomycesonly to be most abundant, whileZ.richteri, in addition to being the predominant type infecting a large majority of samples, was able, even in certain cases where it was originally outnumbered, to develop and apparently assume the leading role in fermentation.

ISSN:1923-4287    

DOI:10.1139/cjr31-105

出版商:NRC Research Press    

年代:1931

数据来源: NRC

摘要:

An enquiry was made by the Hudson's Bay Company into the origin and spread of a serious disease resembling epidemic encephalitis of silver foxes which periodically destroys large numbers of sledge dogs in the arctic and subarctic regions of Canada. A similar disease occurs in the arctic fox, and is associated with an important four-year cycle in the numbers of the fox, which may thus form a permanent reservoir for the disease organism, or organisms. General forecasting of this fox cycle is possible, and is dependent on knowledge of the lemming cycle in the arctic, and associated climatic phenomena.

ISSN:1923-4287    

DOI:10.1139/cjr31-106

出版商:NRC Research Press    

年代:1931

数据来源: NRC

摘要:

A high degree of consistency was secured in retests of five groups of birds from various sources and tested from 2 to 22 times. The results of repeated agglutination tests were, except in a few cases, confirmed by the macroscopic appearance of the ovary and by bacteriological examination.Data show that positive reactors consistently react positive to the test, and that they seldom recover from pullorum infection. This is especially true of birds that have completed the first laying year. With these very little variation can be expected in retests at short intervals. In the case of pullets that are just starting to lay, a small percentage of reactors may throw off the infection and subsequently react negatively.Non-reactors from an infected flock when left in contact with reactors in presence or absence of males, may in later tests react positively. This is generally due to infection through contact with infected birds, contaminated droppings, feed, water or litter. These non-reactors, if kept isolated from reactors, as a rule remain negative. When such birds become reactors at subsequent tests, the possibility of recent infection taking place just before or after the first test is not excluded. Hence, non-reactors from infected flocks should be retested at short intervals.Suspicious reactors as a rule do not show marked variations in titre from month to month. It is impossible to predict whether a suspicious reactor will in course of time become a distinctly positive or negative reactor. With these birds therefore diagnosis must be done with care and the general condition of the flock taken into consideration. In an eradication program the bird has to be sacrificed unless it is very valuable, in which case several retests would need to be conducted before a final diagnosis is made.Male birds do not as a rule react in as high dilutions as females, consequently fluctuations in reaction from test to test are not uncommon. Therefore, particular care must be exercised in diagnosis in the case of male birds.

ISSN:1923-4287    

DOI:10.1139/cjr31-107

出版商:NRC Research Press    

年代:1931

数据来源: NRC