Hydro-Oxygen Blcmpipefor the Fusion of Platinum. 363 



boiler iron, each capable of holding forty gallons. They are 

 lined internally with copper, being situated upon a wooden 

 frame, so that the bottom of one is two-thirds as high as the 

 top of the other. The upper portions of these vessels com- 

 municate by a leaden pipe B, of about half an inch bore, fur- 

 nished with a cock, while the lower portions communicate by 

 another leaden pipe of a bore of one and a half inch. 



The upper vessel is surmounted by a globular copper vessel, 

 of about twelve inches in diameter, which, from its construc- 

 tion, renders it possible to introduce an additional supply of 

 concentrated acid, while the apparatus is in operation, with- 

 out reducing the pressure within the reservoir, by permitting 

 the excess above the pressure of the atmosphere to escape. 

 This object is accomplished as follows : — 



The valve at the end of the rod attached to the lever L 

 being kept shut by the catch M, the screw-plug H removed, 

 the acid is introduced through the aperture thus opened. In 

 the next place, the plug being replaced, and the valve depressed 

 by means of the lever and rod, so as no longer to close the 

 opening which it had occupied, the acid descends from the 

 chamber into the cavity of the vessel beneath it. The valve 

 is of course restored to its previous position as soon as the acid 

 has effected its descent. 



The lowermost vessel is furnished with a perforated copper 

 tray, supported by a copper sliding rod, in a way quite ana- 

 logous to that already described in the case of the copper 

 reservoir. It is also supplied with zinc and its solvent in like 

 manner, being made half-full of the diluted sulphuric acid. 

 Of course, on contact being produced between the zinc and 

 its solvent, the generation of hydrogen will take place. So 

 long as the communication between the upper portions of the 

 two vessels is open, the gas will extend itself into both, occu- 

 pying the whole of the upper vessel, and that half of the lower 

 one which is unoccupied by the liquid. But if in this way 

 the pressure reaches to two atmospheres, as indicated by the 

 gauge*, on shutting the communication through the pipe B, 

 the pressure in the inferior vessel will augment, that in the 

 superior vessel remaining as before ; but the liquid will con- 

 sequently begin to pass out of the inferior vessel through the 

 pipe A, and thus may lessen the contact between the acid and 

 zinc, and finally suspend it altogether. Meanwhile the gas in 

 the upper vessel being condensed to nearly half its previous 

 bulk, the pressure, will be nearly four atmospheres. It will, 



* I have used for a gauge an instrument like G, fig. 5, the tube being 

 Sbout two feet in length, and sealed at the upper end. 



