202 Intelligence and Miscellanies. 



"to 



side of the shelf, and thence rising through the hole, into the 

 inverted vessel, will occupy it to the exclusion of the water. 



Having filled one vessel with gas, it may be transferred to 

 another, filled with water, and inverted upon the shelf, B, 

 by depressing the brim of the vessel containing the gas, un- 

 der the shelf, and then inclining it so as to allow the gas to 

 escape gradually into the cavity under the shelf, whence it 

 rises into the other vessel, as already described. 



When the air cells under the shelves, A A, are to be filled 

 with gas, a flexible leaden pipe, passing from a vessel con- 

 taining the generating materials, is curved into a hook, and 

 placed so that the orifice may be within the cell. As the gas 

 enters the cell, the water must of course be displaced from 

 it, and would in consequence overflow the cistern, were not 

 the cock, /, opened. 



This cock communicates with the bore of the arched pipe, 

 gg, to which it is soldered. The orifices of this pipe enter 

 severally the chests, C C, so that their cavities communicate 

 with each other and with the cock, /. Hence by opening 

 this cock, the air may be allowed to escape from those chests 

 in such quantities, as to compensate the gas introduced into 

 the upper air cells. 



The gas, contained in the cells, is easily transferred to any 

 vessel, by bringing it over a hole, which communicates with 

 the cell, through one of the cocks, e e, in the shelves, A A. 



The vessels may be previously filled with water and inver- 

 ted, but in the case of oxigen gas, if an open neck bell glass, 

 or a tall cylindrical vessel, open at both ends, be placed over 

 the hole, and a jet of the gas allowed to enter it, the atmos- 

 pheric air being lighter, is driven out before the entering gas. 

 It may be easily ascertained when the vessel is full of oxigen, 

 by the greater brightness of a taper flame held over the up- 

 per orifice. 



As the escape of gas from the cells, permits the subsidence 

 of the water into them, it is necessary to countervail the de- 

 ficiency thus produced, by the action of the bellows pump, 

 formed as already mentioned, by the kettle and its appurte- 

 nances, in duly replenishing the chests, C C, with air. 



17. Improved Scale of Chemical Equivalents. — Profes- 

 sors Lewis C. Beck and Joseph Henry, have published an 

 *' improved scale of chemical equivalents" founded upon the 

 well known scale of Dr. Wollaston, which has contributed 



