摘要:

The gas contained in the air cells of day old eggs had a high carbon dioxide content, but during storage the gas composition approached that of the surrounding atmosphere. Oiling of the egg, or otherwise sealing the shell, tended to retain carbon dioxide in the air cell. Growth of mold in the air cell, or of bacteria in the egg contents, markedly reduced the oxygen content and increased the carbon dioxide content of the air cell gas. Permeability of the shell of unoiled eggs to moisture vapor was low and the relative humidity in the air cell was shown to be 99% or higher. Oiling of the eggs cannot therefore promote mold growth by increasing the humidity in the air cell.

ISSN:1923-4287    

DOI:10.1139/cjr50f-008

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Enterococci were present in all samples of liquid and frozen egg products examined. They survived spray drying and storage in egg powder better than the coliforms andEscherichia coliand are therefore considered a better index of fecal contamination. There was no relation between the occurrence ofSalmonellaorganisms and the number of enterococci present.Streptococcus faecaliswas the species most commonly found. The addition of 0.5% yeast extract to SF medium reduced the number of false negatives and improved the sensitivity, although confirmation on agar was still necessary. Winter and Sandholzer's medium, with bromocresol purple as indicator, could be used without confirmation but was not as sensitive for products containing small numbers of enterococci.

ISSN:1923-4287    

DOI:10.1139/cjr50f-009

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The quality of eggs oiled when one day old is maintained better than that of eggs oiled when 6 or 10 days old, the ages between which most commercial eggs are treated. If the pH of the albumen of the older eggs is lowered by exposure to carbon dioxide before oiling (a simple method of treating eggs with carbon dioxide is described), the keeping quality as measured by yolk index, albumen height, and percentage of thick albumen is improved. However, these differences are not apparent on candling, and on this basis the improvement does not justify the added cost of the gassing treatment.

ISSN:1923-4287    

DOI:10.1139/cjr50f-010

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

A simple, rapid polarographic procedure for the determination of titanium in paint pigments has been developed, using a sulphuric acid – tartaric acid medium. The accuracy and precision of the method are satisfactory for routine testing operations. The interference of other common pigment ingredients is discussed, and a procedure suggested for the removal of copper and antimony prior to analysis.

ISSN:1923-4287    

DOI:10.1139/cjr50f-011

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The experiments described are part of a series being made to determine the factors which limit the power and efficiency of an Otto cycle spark ignition engine using Toronto town gas nearly free of sulphur. The air supply was unthrottled and power was varied by varying the gas supply. Mixture strength was "correct" at an air-to-gas ratio of 4:1. Trials were run with jacket coolant temperatures of 100°, 140°, 212°, and 295° F., the compression ratio being always 12:1 and the speed 900 r.p.m. A maximum indicated thermal efficiency of 43% was attained with coolant temperatures of 100° and 140° F. and an air-to-gas ratio of 8:1. Thermal efficiency diminished rapidly as air-to-gas ratio was increased and tended to become zero instead of the air standard value. The brake horsepower became zero for an air–gas ratio of approximately 11:1, the mixture strength being then 64% weak. Thus the engine was run at 900 r.p.m. from zero to full load, that is with 100% quality control. The maximum I.M.E.P. of 144 lb./sq. in. was obtained with a jacket coolant temperature of 100° F. The indicated thermal efficiency was then 36% and the mixture 10.7% rich. The performance of the Otto cycle engine could probably be improved by running at higher speeds but even at the relatively low speed of 900 r.p.m. for that type, it compared favorably in most respects with that of the compression ignition type of Diesel engine.

ISSN:1923-4287    

DOI:10.1139/cjr50f-012

出版商:NRC Research Press    

年代:1950

数据来源: NRC