HEAT 141 



sions, Holland, and the United States, has its zero placed 

 at 32 below the freezing point of water, and the boiling 

 point of water at 212 ; of course, the distance between 

 the freezing and boiling points, is divided into 180 parts. 

 Celsius' thermometer, otherwise called the Centigrade 

 thermometer, is used in Sweden and France ; and the 

 space between the freezing and boiling points is divided 

 into 100 ; the freezing point of water is marked 0. 

 Reaumer's, or in truth, Deluc's thermometer, which was 

 formerly used in France, has its freezing point marked 0, 

 and boiling point 80 . De Lisle's thermometer is used 

 in Russia, and has its space between the freezing and 

 boiling points divided into 150 parts, the zero being 

 placed at the boiling point, and 150 at the freezing point. 

 All gaseous bodies are expanded by heat, as air, car- 

 bonic acid gas, (fixed air, dead air,) which may be slioun 

 by the following 



Experiment. Take a glass tube with a bulb at one 

 end and open at the other, plunge the open end into 

 water, then apply the heat of a lamp to the bulb ; bubbles 

 will be produced from the end under the water, which 

 is owing to the escape of air from the tube ; of course 

 the air has been expanded by the heat. 



The expansion of gaseous bodies differs essentially 

 from that of solids or liquids, as they all undergo the 

 same expansion by the same additions of heat. The 

 steam of water expands just as much as air, when the 

 same addition of heat is made. Air by being heated 

 from 32 to 212 , increases more than one third in bulk. 

 This difference in the expansion of different bodies, 

 arises from the difference in the cohesive force by which 

 their particles are bound together in solids the force 

 of cohesion is great in liquids it is less, and in gaseous 

 bodies it is nothing. Therefore, in the expansion of 

 bodies by heat, there is more force to be overcome in 

 solids than in liquids ; more in water than in air ; con- 

 sequently air expands more than any solid or liquid body. 

 The expansive force of steam is applied to the use of 

 man, in. that magnificent production of human ingenuity, 

 the Steam Engine, a description of which would be 

 out of place in this treatise. 



We have already stated, that there are a few excep- 



VOL. I. NO. VI. 13* 



