362 Dr. R. Hare o?i Improvements in the 



the tray, regulate or suspend the reaction between the zinc 

 and its solvent, accordingly as the supply of hydrogen is to be 

 produced, suspended, increased, or diminished. 



The communication with the reservoir is open and regulated 

 by means of a cock P, furnished with a gallows- screw G, for 

 the attachment of a leaden pipe, as above described, in the 

 process for supplying the reservoir with oxygen. 



Another apparatus for producing a supply of hydrogen is 

 represented in fig. 6. It consists of two similar vessels of 



