thermobarometer

An instrument for measuring altitudes by means of determining the boil ing point of water. They consist e entially of a small metallic ve el for boiling water, fitted with very delicate thermometers, which are only graduated from 80° to 100°; so that each degree occupying a considerable space on the scale, the tenths, even the hundredths of a degree, may be estimated, and thus it is po ible to determine the height of a place by means of the boiling point to within about ten feet. thermo-call, s. An electric alarm or call-bell operated by thermo-electricity. It is generally used as a fire-alarm. thermo-chemistry, s. Chem.: That branch of the science which deals with the heat liberated or absorbed during a chem ical reaction; thus, 2 grammes of hydrogen, in combining with 16 grammes of oxygen to form water, liberates a certain definite amount of heat, viz., 69,000 calories (units of heat); while water, on being decomposed into its elements, is found to absorb the same amount of heat. IMG:content-1000.png:[blocks in formation]