118 



PROCEEDINGS OF THE AMERICAN ACADEMY 



Although the so-called soda-water fountains — in which the solution 

 of the gas and water is made — have all in general the same simjDle 

 relation of parts, they are constructed of very different materials and 

 after very different methods. The outside shell may be either of ham- 

 mered copper or of some form of iron, and this may be lined with tin, 

 enamel, or glass. After having determined by experiment that a solu- 

 tion of hydric sulphide — especially when some carbonic dioxide is 

 added — exerts no action on a surface of metallic tin, except a very 

 slight and superficial staining, we selected as best adapted to our 

 purpose the steel fountains, also manufactured by the firm of John 

 Matthews, Fig. 6. These are made of plates of steel, united in a 



K.VkKi.'i^^^^'^^^ 



Fig. G. 



peculiar way invented by themselves so as to secure with comparative 

 lightness very great strength. They are lined on the inside with sheet tin, 

 and the tin lining forms an independent vessel, which alone is connected 

 with the bungs. The tubes and valve cocks are also either made or 

 lined with tin, so that the solution never comes in contact with any 

 other metal. For making ordinary soda-water, the fountain requires 

 only a single valve, which connects with a tube leading to the bottom 

 of the vessel, and this serves both to charge the fountain and to draw 



