AND VOLATILIZATION OF PLATINUM. 103 



The air-cell formed in front of the partition K K, and 

 that constituted hy the smaller chest C, are used to contain 

 factitious air; especially to confine sufficient quantities of the 

 hydrogen and oxygen gases, for the production of intense heat, 

 or the composition of water. As the contamination of hy- 

 drogen gas with atmospheric or pure air, might be attended 

 with dangerous consequences, the air-cell constituted by the 

 chest C, should be employed for this gas; as its separate 

 situation, renders it secure from this danger. In order to 

 prepare these cells for the reception of the gases, all the atmos- 

 pheric air should be allowed to pass out, so diat they may be 

 completely filled with water. When they are to be filled 

 with gas, the syphons s s, annexed to the hoses 1 1, inserted 

 into the suction-pipes at d h, must be passed into the jars; 

 and the bellows E, F, must be extended. The air of the jars 

 will be drawn into the bellows, and from thence be expelled 

 into the air-cells, from which it will displace an equal bulk of 

 water. But, lest the expulsion of the water from the cells 

 should cause it to rise too high in the tub, and to overflow; 

 a correspondent depression should be effected in the mean- 

 time, by the escape of air from the regulator. 



Gas may also be made to pass into the cells immediately 

 from the retort, bottle, or matrass made use of in obtaining it 

 without the intervention of the bellows, for if an elastic fluid 

 be geuerated in the matrass at q, it must of necessity pass thro' 

 the syphon inserted therein, and enter the air-cell at r. 



It must be obvious, that as long as the chests are covered with 

 water, any gases contained in the air-cells, will be subjected to 

 hydrostatic pressure, and that of course when the cocks H II, 

 are open, they will be propelled through the pipes of delivery, 

 and pass out through any adjutages, inserted into their conical 

 mouths at I, I. 



If the upper parts of the chests C, D, E, F, be made of thick 

 plank, they may be used as shelves to support the jars; as the 

 thickness of the plank, will alone depress the aeriform fluid 

 contained in the cells, sufficiently below the surface of the 

 water, to afford the necessary pressure. But if from any cause, 

 the pressure be not great enough, the chests should be depres- 



