432 J. P. Cooke — New Mode of Manipulating Hydric Sulphide. 



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 



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 with comparative Witness 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 foun- 

 tain and to draw off the solution when made. But since a 

 solution of hydric sulphide is rendered turbid if left in contact 

 with even a small quantity of air, and since a variable amount 

 of free hydrogen is always formed by the action of sulphuric 

 acid on common sulphide of iron, it was necessary for our pur- 

 pose to add to the ordinary fountain a vent cock as shown m 

 the last figure. This enables us to connect together several 

 fountains after the manner of Woolfs bottles, as already de- 

 scribed, and, by passing the current of gas through the whole 



