# A Handbook of Physics Measurements, Volume 2

John Wiley & sons, Incorporated, 1918 - Physical measurements

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### Contents

 CHAPTER III 63 Reduction of Barometric Readings 69 The Mechanical Equivalent of Heat 80 AST Page 87 CHAPTER IV 137
 Determination of the Energy Dissipated in 217 APPENDIX 223 Table Pag 228 Copyright

### Popular passages

Page 89 - If an alcohol lamp is employed for heating the water-bath, the wick should be carefully trimmed and adjusted to a small flame. A small Bunsen burner may be used in place of the lamp. The rate of heating should be about two degrees per minute, and in no case exceed three degrees. As a flash torch, a small gas jet J inch in length, should be employed.
Page 89 - F., the testings should commence. To this end insert the torch into the opening in the cover, passing it in at such an angle as to well clear the cover, and to a distance about half way between the oil and the cover. The motion should be steady and uniform, rapid and without any pause. This should be repeated at every two degrees...
Page 88 - Replace the oil cup and pour in enough oil to fill it to within % inch of the flange joining the cup and the vapor chamber above. Care must be taken that the oil does not flow over the flange. Remove all air bubbles with a piece of dry paper. Place the glass cover on the oil cup, and so adjust the thermometer that its bulb shall be just covered by the oil.
Page 89 - The appearance of a slight bluish flame shows that the flashing point has been reached. In every case note the temperature of the oil before introducing the torch. . The flame of the torch must not come in contact with the oil. The water bath should be filled with cold water for each separate test, and the oil from a previous test carefully wiped from the oil cup.
Page 88 - Health, 1882. of an inch of the flange joining the cup and the vapor chamber above. Care must be taken that the oil does not flow over the flange. Remove all air bubbles with a piece of dry paper. Place the glass cover on the oil cup, and so adjust the thermometer that its bulb shall be just covered with oil.
Page 138 - The International Ohm is the resistance offered to an unvarying electric current by a column of mercury at the temperature of melting ice, 14.4521 grams in mass, of a constant cross-sectional area and of a length of 106.300 centimeters.
Page 73 - Since cw is unity, the specific heat of a substance is numerically equal to its thermal capacity. In a loose sense the thermal capacity is often called specific heat, but the student should observe that the same relation holds between these two quantities as between density and specific gravity. The former is a definite physical quantity ; the latter is simply a ratio or a pure number. 173. The Method of Mixtures.
Page 74 - The rate at which a body cools is proportional to the difference between the temperature of the body and that of the surrounding air. If a body in air at 25°C will cool from 100" to 75° in one minute, find its temperature at the end of three minutes.
Page 71 - ... the muslin envelope is thoroughly moist. CHAPTER XIV CALORIMETRY CALOEIMETRY is the theory and art of measuring quantities of heat. Unfortunately there is no single quantity of heat that is universally adopted as the unit. A common unit in scientific work is the amount of heat required to raise the temperature of one gram of water from 15° C. to 16° C. This unit is called the 15° calorie or simply the calorie or the gram-degree-centigrade thermal unit. In the British system the unit adopted...
Page 72 - ... 1)° is called its specific heat at t°. The specific heat of bodies is slightly different at different temperatures, but the difference is so minute that except in the most refined measurements it need not be" considered. The average specific heat of a body between any two temperatures is the number of heat units required to raise a unit mass of it from one of those temperatures to the other, divided by the difference in the two temperatures. That is, the quantity of heat H required to raise...