摘要:

Samples of butter from all the creameries in Manitoba were investigated as to mold content. The various species of molds isolated and their relative abundance are listed. A list of fungi recorded as occurring in butter is given. It is pointed out that fungi of various kinds may enter butter, and some of them may develop objectionable colonies when butter is held for some time in transportation or storage. Certain creameries are reported as producing butter practically free from fungi, and suggestions are given regarding methods of lessening the development of molds in butter.

ISSN:1923-4287    

DOI:10.1139/cjr33-071

出版商:NRC Research Press    

年代:1933

数据来源: NRC

摘要:

A parasitological survey of 236 gophers (Citellusspp.) in the province of Manitoba yielded five previously recorded ectoparasites, four species of Nematodes, three of which are regarded as new to science, an Acanthocephalan and two previously unrecorded species of Cestodes. No Trematodes or intracellular Protozoa were found.The importance of the Arthropod parasites as transmitters of disease, the pathogenicity of the enteric parasites and the correlation between the incidence of infestation and host abundance, are discussed.

ISSN:1923-4287    

DOI:10.1139/cjr33-072

出版商:NRC Research Press    

年代:1933

数据来源: NRC

摘要:

Vaccination trials and biological studies of B.C.G. have been carried on for a period of over eight years and are still continuing. Under conditions of continuous exposure to natural infection through cohabitation with tuberculous animals, trials varying in duration from two months to four and one-half years have been completed on 44 vaccinated cattle and 28 unvaccinated controls. In trials of short duration the percentage of cattle free from tuberculosis is slightly in favor of the vaccinated. In all cattle over two years of age tuberculosis was present to a greater or lesser degree. Judged by slight, moderate and extensive tuberculous involvement, there is some evidence of a greater resistance in the vaccinated cattle up to two and a half years of age, 26% of which showed extensive generalized tuberculosis, as compared with 53% of the unvaccinated. But in the age group ranging from two and a half to four and a half years no greater resistance is found in the vaccinated than in the unvaccinated cattle. It has not been possible to demonstrate a true lasting immunity by this method of vaccination, and such increased relative resistance as B.C.G. may confer during the early months of life declines and soon disappears, and fails to protect cattle exposed for two years to natural sources of infection from developing typical tuberculosis.The attenuated virulence and potential pathogenicity of B.C.G. have been studied for a period of over eight years in three original strains received in the years 1924, 1925 and 1927, and in the cultural descendants of each strain up to the year 1932. Each strain proved to possess an unfixed, potential virulence capable of exaltation on the one hand, and of complete attenuation or reduction on the other. This virulence, manifested but rarely and only in the earlier descendants, 1924–1928, declined under serial cultivation and periodic return to the special bile-potato media and apparently died out in the 1928–1929 generations, for none of the subsequent descendants tested proved capable of causing progressive reinoculable tuberculosis in laboratory animals.

ISSN:1923-4287    

DOI:10.1139/cjr33-073

出版商:NRC Research Press    

年代:1933

数据来源: NRC

摘要:

An investigation is described in which a determination was made of the length equation of a four-metre invar rule used as a basis for measuring tapes. A short description of the rule and its associated apparatus is given. The investigation demonstrated that different rules made at the same time from the same ingot of invar do not necessarily have identical thermal coefficients. It was also found that the temperatures of two rules of different cross section differed considerably even in a room where the air temperature was changing only at a very slow ratei.e., 1 °C. in two or three hours.

ISSN:1923-4287    

DOI:10.1139/cjr33-074

出版商:NRC Research Press    

年代:1933

数据来源: NRC

摘要:

The values for thermal conductivity of various common materials chiefly used in the walls of houses are given. By plotting the results obtained, as well as those obtained by other experimenters, on a density-conductivity diagram there is a general indication that at higher densities thermal conductivity increases with increase of density much more rapidly than it does at low densities.

ISSN:1923-4287    

DOI:10.1139/cjr33-075

出版商:NRC Research Press    

年代:1933

数据来源: NRC

摘要:

The sorption of water by asbestos fibre has been examined using two modifications of the static method. In the first method the sample was weighed in the absence of air by a quartz spring balance, after which the required vapor pressure of water was admitted. In the second method the samples were weighed in air in a room the temperature and humidity of which were controlled. The two methods have given identical results, producing the sigmoid isotherm similar to those found in the cases of cotton and wood, and exhibiting a marked inflexion in the region of the saturation point. The rate of sorption has been examined using the sorption balance and it has been shown that at humidities below 70% equilibrium is established in a few minutes; at higher humidities longer time is required. Because of this and other reasons it is suggested that in this region capillary condensation is taking place.

ISSN:1923-4287    

DOI:10.1139/cjr33-076

出版商:NRC Research Press    

年代:1933

数据来源: NRC

摘要:

A considerable variety of ketocyclopropanes has been submitted to the action of sulphuric acid, alone or in acetic acid. In general, the mode of reaction was similar to, though less drastic than, that of hydrogen bromide; this indicated a similar mechanism. When the cyclopropane ring was attacked, the product isolated was apparently formed by the addition of a molecule of water or acetic acid, or was the result of a secondary reaction dependent on a primary product so formed. The nitriles were hydrolyzed to amides without opening of the ring. A mechanism is suggested to account for the ring scission of cyclopropyl alcohols, which takes place in a different manner from most cyclopropane derivatives.

ISSN:1923-4287    

DOI:10.1139/cjr33-077

出版商:NRC Research Press    

年代:1933

数据来源: NRC

摘要:

In the condensation of acetaldehyde to crotonaldehyde, dihydro-p-tolualdehyde is obtained as a by-product. The determination of its structure, its properties and some of its reactions are described.

ISSN:1923-4287    

DOI:10.1139/cjr33-078

出版商:NRC Research Press    

年代:1933

数据来源: NRC

摘要:

The pyrolysis of the lower paraffins in externally heated quartz tubes has been studied under conditions of streamline and turbulent flow. It has been found possible to produce a high degree of turbulence in the flow of paraffin gases through tubes heated to a high temperature. It has been shown that when the pyrolysis is carried out under conditions of turbulent flow the yields of olefines obtained at a given temperature are greatly increased over those obtained in an open tube. It is further shown that under conditions of turbulent flow higher rates of conversion of the lower paraffins to olefines are possible since the temperatures at which side reactions begin to be noticeable are considerably higher under the above conditions than when the gas flow is streamline.

ISSN:1923-4287    

DOI:10.1139/cjr33-079

出版商:NRC Research Press    

年代:1933

数据来源: NRC