摘要:

In the absence of air, a linear relation, independent of temperature, was observed between moisture loss and colour change. The change was mainly one of intensity, and was reversible. In air, irrespective of its humidity, changes in both intensity and quality of colour occurred, but no definite relation was found between changes in humidity and colour quality for different samples. In saturated air, intensity changes became complete in the early part of the storage period, but the enhanced changes in air of lower humidity continued to increase. No influence of temperature on the rate of colour change was observed in dry air or in air of 60% relative humidity.

ISSN:1923-4287    

DOI:10.1139/cjr39d-004

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

An apparatus is described in which provision for slow cooling of a metal mirror by circulating over it liquid from a vessel in a thermoregulated bath, and the use of multiple thermocouple elements contained in the mirror, enable the dew-point temperature to be gradually approached and accurately determined. Precise measurements of relative humidity at low temperatures, where the moisture content of the air is small, are therefore possible. A precision of ± 0.5% relative humidity was readily attained at temperatures down to − 15 °C.

ISSN:1923-4287    

DOI:10.1139/cjr39d-005

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

The meadow nematode completes its life cycle in 54 to 65 days—25 to 31 days from the larval stage to the adult, and 29 to 34 days from maturation to the second generation. Eggs are deposited by a single female at the rate of not more than one a day. The largest number of eggs laid by a single female in one place was sixteen, owing apparently to migratory habits. The total number of eggs from a single female could not be determined.The adult male and female and all larval stages of this species are capable of entering the roots of oats. They are very susceptible to desiccation. No living nematodes were recovered from invaded root tissue that was allowed to dry. In moist excised oat roots, the nematodes remained viable for more than 30 days, but in water the majority died within the same period. A ten-minute immersion of infested oat roots in hot water will destroy the meadow nematode only when the temperature is 120° F., or higher.

ISSN:1923-4287    

DOI:10.1139/cjr39d-006

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

Forty microbial types, in which micrococci predominated, were found as representative of pre-curing contamination, including strains resembling organisms found in bacon slime.Varying degrees of salt tolerance were noted, micrococci showing the greatest ability to grow at higher concentrations. With 25% sodium chloride only two species showed growth. Tests with species reducing nitrate to nitrite at 5% salt concentration showed that as the salt concentration increases, nitrate reduction occurs with a progressively smaller proportion of those showing growth. This suggests that nitrate reduction in curing pickle is a function of the true halophiles rather than of the pre-curing contaminants.The organisms could be placed in five groups depending upon their salt resistance (ability to survive) in salt solutions and in curing pickle. Much greater resistance to salt was displayed in curing pickle than in salt broths of similar sodium chloride content. Pickle appeared to possess substances tending to neutralize the toxic effect of salt, the action being "protective" rather than "stimulative".Many types of bacteria constituting original contamination are considered able to survive the pickling process. Although the findings do not point to any pronounced activity of these in pickle, their ability to survive opens the possibility of their becoming active after pickling and contributing to storage defects. The results justify the adoption of measures for the utmost plant sanitation in Wiltshire processing.

ISSN:1923-4287    

DOI:10.1139/cjr39d-007

出版商:NRC Research Press    

年代:1939

数据来源: NRC