| 摘要 |
PROBLEM TO BE SOLVED: To obtain a freezing agent producible in common freezers and capable of retaining a peculiar freezing temperature for a long period of time by constituting itself of a material affording a thermostatic iced form capable of continuously retaining a specific freezing temperature. SOLUTION: This freezing agent is obtained by constituting itself of a material affording a thermostatic iced form capable of continuously retaining a freezing temperature between -5 and -25 deg.C within temperatures with -30 deg.C as the lower limit temperature. Because of the fact as described above, the iced form is defined as a thermostatic iced form. The material affording such a thermostatic iced form is e.g. ammonium chloride, sodium thiosulfate, ammonium nitrate, ammonium sulfate, potassium chloride, sodium chloride, sodium nitrate. The above-mentioned iced form maintains a peculiar low temperature at an ambient temperature of 17-20 deg.C for 2-3 h when 125-150 g thereof is placed in a polyethylene container 1 mm thick; when held in a thermal insulation container, it maintains such a temperature as to enable other object(s) to be frozen for 7-15 h.
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