40 ttOtV CEOPS li-KEi). 



a burning; toper in the second bottle, when, if the exjieriment was rij^^ht- 

 ]y conducted, the flume will be extinguished. 



c. Into a bottle filled as in the last experiment with carbonic acid, 

 some lime-water is poured and agitated. The previously clear lime-wa- 

 ter immediately becomes turbid and railliv from the formation oicarbcm- 



ate of lime, which is iieaily insoluble in water. 



Carbonic Acid iu the Atmospliere.— To show the pres- 

 ence of carl)oi)ic acid in the atmosphere, it is only neces- 

 sary to expose lime-water in an open vessel. But a little 

 time elapses before the liqtiid is covered with a white film 

 of carbonate. As already stated, the average proportion 

 of carbonic acid in the atmosphere is 6-lOOOOths 

 (l-16()0th nearly) by weight, or 4-lOOOOths (l-2500th) 

 by bulk. Its quantity varies somewhat, however. Among 

 over 300 analyses made by De Saussure in Switzerland, 

 Verver in Holland, Lewy in New Granada, and Gilm in 

 Austria, the extreme range was from 47 to 86 parts by 

 weight in 100,000. 



Deportment of Carbonic Acid towards Water. — Water 



dissolves carljonic acid to a greater or less extent, accord- 

 ing to the temperature and pressure. Under the best or- 

 dinary conditions it takes up about its own volume of the 

 gas. At the freezing point it may absorb nearly twice as 

 much. This gas is therefore usually found in spring, well, 

 and river waters, as well as in dew and rain. The consid- 

 erable amount held in solution in cold springs and wells 

 is a principal reason of the refreshing quality of their wa- 

 ter. Under pressure the proportion of carbonic acid ab- 

 sorbed by water is much larger, and when the pressure is 

 removed, a portion of the gas escapes, resuming its gase- 

 ous form and causing effervescence. The liquid that flows 

 from a soda-fountain is an aqueous solution of carbonic 

 acid, made under pressure. Bottled cider, ale, champagne, 

 and all effervescent beverages, owe their sparkle and much 

 of their refreshing qualities to the carbonic acid they con- 

 tain. 



