What thickness of insulation do you find gives the best result with the materials used in your experiment? Is it necessary to assume that the same thickness will be required with all insulating materials?
5. The effect of the density of foods upon the temperature maintained.
Materials:
- One cooker or hay-box
- Starch
- Water
- Salt
- Cooking thermometer
- Scales
- Litre or quart measure
- Notebook and pencil
Bring one or more litres or quarts of water to a boil, boil it for one minute, and put it into the cooker for one hour or more. Repeat the test, using, successively, five grams of salt to each litre, or one teaspoonful to each quart, and 5, 10, and 20 per cent. mixtures of starch with water. Record the temperatures in tabular form, and compare the results. What would you gather to be the effect of density upon the temperatures maintained?
6. The effect on temperature of filling the cooker-pails one-fourth, one-half, three-quarters, and entirely full.
Materials:
- Cooker or hay-box pail of eight quarts’ capacity
- Pail of two quarts’ capacity
- “Space adjuster”
- Water
- Thermometer
- Notebook and pencil
Fill the large cooker-pail one-fourth full of water. Bring it to a boil and put it into the cooker for a definite period of time, not less than one hour. Record the resulting temperature. If desired to make the test more comprehensive, leave the water in the cooker for six, nine, or twelve hours, being careful to allow the cooker to become cold between each test. Perform the same experiment with the same pail one-half full, again when it is three-fourths full, and again when entirely full. Record the results in tabular form and compare them. Repeat these tests with a pail of two quarts’ capacity. What is the influence on temperature of having pails partially, or completely, filled?
The explanation is that evaporation takes place in partially filled pails.