PURPOSE: To illustrate the function of silvering a dewar.

DESCRIPTION: Hot water is put into two dewars, one unsilvered and one silvered. The temperature of both in centigrade degrees is monitored as time passes; the photographs above show the temperatures immediately after the water is poured into the dewars and about thirty minutes later. A typical set of temperature data is tabulated below:

time (min)	silvered	unsilvered
0	84.5	84.5
15	83.5	80.0
40	83.0	74.5
70	82.0	68.5

SUGGESTIONS:

REFERENCES: (PIRA 4B50.10)

EQUIPMENT: Two dewars in stands with cork stoppers, one silvered and one unsilvered, hot plate and water, digital thermometers

SETUP TIME: 10 min.