372 SCIENTIFIC RECREATIONS. 



monoxide, or carbonic oxide (CO). The dioxide is the more important, 

 being held in the atmosphere, and combined with lime in chalk. All 

 sparkling beverages contain carbonic acid, to which their effervescence is 

 due. The soda and other mineral waters owe their sparkle to this gas. 

 Soda-water consists of a weak solution of carbonate of soda and the acid. 



Fig. 369. Seltzer-water manufactory. 



There is a vessel holding chalk and water, and another containing some 

 sulphuric acid. When the sulphuric acid is permitted to unite with the 

 chalk and water, carbonic acid is liberated. A boy turning a wheel forces 

 the gas into the water in the bottles, or the water and carbonate of soda is 

 drawn off thus impregnated into bottles and corked down, in the manner 

 so familiar to all. The bottles are made of the shape depicted, so that the 



