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B. Heating a Liquid in a Test Tube Take an uncalibrated test tube and fill half of its volume with water. Hold the test tube using a test tube holder at about 45 angle, move the tube slowly back and forth through the Bunsen flame in such a way that the top of the flame is near the top of the liquid but does not touch the empty part of the tube. Caution: When heating liquids, never point the open end of the test tube toward a person. What is formed on the walls of the test tube? Why should the flame be near the upper portion of the liquid rather than at the bottom? Place the test tube with the liquid in a test tube rack and reserve for procedure C. C. Measuring Temperature of a Liquid Dip the mercury/alcohol bulb of the thermometer in the test tube with hot water from procedure B Read and record the temperature scale in "C. Temperature of hot water Measure the room temperature using a thermometer. Take the room temperature by recording the scale reading of the mercury or alcohol level in "C. Room temperature