2S2 Description of an Apparatus for the 



little practice, this may be done with the admission of very 

 little common air. A transferring vessel- is then screwed 

 upon the cock f ; and a portion of oxygen gas removed for 

 eudiometrical examination. To allow room for the ex- 

 pansion of the oxygen gas, the water is raised by a syphon 

 to a proper height within the receiver b, as appears in the 

 drawing. 



The apparatus being thus disposed, the cocky is connect- 

 ed by the chain h, with the prime conductor of an electrical 

 machine ; and a rapid succession of sparks is made to pass 

 between the copper ball at the end of the wire g, and the 

 orifice of the burner. The cocks q and r being now opened, 

 the stream of gas is kindled ; and in order to prevent the 

 fiame from playing upon the wire, the jar nn is moved a lit- 

 tle nearer to the cistern o, which brings the point of the 

 burner into the axis of the receiver. At the same time, by 

 opening the cock x, water falls into the jar nn, and finds its 

 way into the receiver, through two small ho\zs.wiv drilled 

 near its mouth. 



The combustion continues, until either the whole of the 

 inflammable gas is consumed, or till the cocks q and r are 

 shut. The wedges vv are removed; the receiver oo un- 

 screwed ; and the bent tube removed from its place. It is 

 at this moment that the cock r is useful, by preventing the 

 escape of the gas from the receiver b through the tubes s s. 

 The upper part of the receiver is cooled by the application of 

 a wet sponge. Without waiting, however, till the gas has 

 attained the temperature of the atmosphere, a very small and 

 sensible thermometer is introduced into it ; and the height 

 of the mercury is noted, as soon as it becomes stationary. 

 The volume of the residuary gas is then observed, and is re« 

 duced by calculation, to the bulk which it would occupy at 

 60° of Fahrenheit. Either the whole, or an aliquot part of 

 it, is removed by a transferring vessel, screwed upon the 

 cocky, to a mercurial cistern, where the proportion of car- 

 bonic acid is determined by liquid potash. The proportions 

 of oxygen and nitrogen gases, in the unabsorbed residue, are 

 lsarned by agitation with sulphuret of lime, observing the 

 precautions which have been stated by De Marti. The re- 



siduarjf 



