Wells's principles and applications of chemistry; . QuEGTioxs.—What is the thermometer of Negrette and Zambra ? What is a differentialthermometer? Describe its construction. Describe the metallic, or Breguets thermom-eter. THE EFFECTS OF HEAT. 81. Fig. 36. tract unequally, and the spiral to twist Fig. 34. in opposite directions. Tliese mo-tions imparted to the index, cause itto move over a graduated circle, onwhich degrees are mdicated. So sen-sitive is this instrument, that wheninclosed in a large receiver, which wasrapidly exhausted by an air pump, itindicated a reduction of temperaturefrom
Wells's principles and applications of chemistry; . QuEGTioxs.—What is the thermometer of Negrette and Zambra ? What is a differentialthermometer? Describe its construction. Describe the metallic, or Breguets thermom-eter. THE EFFECTS OF HEAT. 81. Fig. 36. tract unequally, and the spiral to twist Fig. 34. in opposite directions. Tliese mo-tions imparted to the index, cause itto move over a graduated circle, onwhich degrees are mdicated. So sen-sitive is this instrument, that wheninclosed in a large receiver, which wasrapidly exhausted by an air pump, itindicated a reduction of temperaturefrom 66° to 25°==41°, while a mer-curial thermometer fell only to 36^. For chemical purposes, thermom-eters are sometimes constructed insuch a way, that the lower part of thescale turns up by a hinge, in order toallow the bulb to be immersed in cor-rosive liquids. (See Fig. 35.) 126. Air Thermometers.—The first thermometer used consisted of a column of au- confined in a glassFig. 35. tube over colored water. Heat ex-pands the air and increases the lengthof the column downward, pushing thewater before it: cold produces a con-trary eflfect. The temperature is thusindicated by the height at which thewater is elevated in the tube. Fig. 36repre
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectchemistry, bookyear18
