166 CHEMISTRY. 



Humboldt's, that the air of the atmosphere, although 

 perfectly stagnant, could in no possible circumstances 

 be heated above 140, and this only within three feet 

 of the ground. On the west coast of Africa, the 

 thermometer is said to rise to 130 in the sun; a 

 thermometer placed in the sand at Magpures, rose 

 to 140 Fahrenheit. 



Another author says, that at no place of the earth's 

 surface, nor at any season, will a thermometer, raised 

 two or three yards above the soil and sheltered from 

 reverberation, attain 115 Fahrenheit, nor on the 

 open sea, in any circumstances, reach 88 Fahr. 



Solidification and Liquefaction. 



When water is poured on quick-lime, a great de- 

 gree of heat is produced by the solidification that 

 takes place. Congelation, therefore, to surrounding 

 bodies is a heating process, and liquefaction a cool- 

 ing one. 



Compression. 



In gases expansion produces cold, and compres- 

 sion heat. A sudden compression of air produces 

 heat enough to inflame tinder.* 



Latent Heat of Steam. 



The latent heat of steam is somewhere between 

 900 and 1000 of Fahrenheit. 



When, therefore, it is again condensed into water, 

 the latent heat becomes sensible ; the consequence of 

 which is, that a small quantity of steam will, during 



* Take a small tube, either of glass or metal, about three- 

 eighths of an inch in diameter, and four inches long, securely 

 stopped at one extremity. Fix a bit of dried fungus to the end 

 of the rammer, then thrust it smartly down the tube, and the 

 heat of the compressed air therein contained will cause the fun- 

 gus to ignite. 



