252 Apparatus and Processes. 



4. Apparatus for separating Carbonic Oxide from Carbonic Acid, 

 by means of Lime Water. 



Lime water being introduced in sufficient quantity, into the inver- 

 ted bell glass, another smaller bell glass, C, is supported within it as 

 represented in this figure. Both of the bells have perforated necks. 

 The inverted bell is furnished with a brass cap having a stuffing box 

 attached to it, through which the tube D of copper slides air-tight. 

 About the lower end of this tube, the neck of the gum elastic bag is 

 tied. The neck of the other bell is furnished with a cap and cock, 

 surmounted by a gallows screw, by means of which a lead pipe P P, 

 with brass knob at the end suitably perforated, may be fastened to it, 

 or removed at any moment. Suppose this pipe, by aid of another 

 brass knob at the other extremity, to be attached to the perforated 

 neck of a very tall bell glass filled with water upon the shelf of a 

 pneumatic cistern : on opening a communication between the bells, 

 the water will subside in the tall bell glass, over the cistern, and the 

 air of the bell glass C being drawn into it, the lime water will rise 

 into and occupy the whole of the space within the latter. As soon 

 as this is effected, the cocks must be closed and the tall bell glass re- 

 placed by a small one filled with water, and furnished with a gallows 

 screw and cock. This bell being attached to the knob of the lead 

 pipe to which the tall bell had been fastened before, the apparatus is 

 ready for use. I have employed it in the new process for obtaining 

 carbonic oxide from oxalic acid, by distillation with sulphuric acid in 

 a glass retort. The gaseous product consists of equal volumes of 

 oxide and carbonic acid, which, being received in a bell glass com- 

 municating as above described by a pipe with the bell glass C, may 

 be transferred into the latter, through the pipe, by opening the cocks. 

 As the gaseous mixture enters the bell C, the lime water subsides. 

 As soon as a sufficient quantity of the gas has entered, the gaseous 

 mixture may, by means of the gum elastic bag and the hand, be sub- 

 jected to repeated jets of lime water, and thus depurated of all the 

 carbonic acid. By raising the water in the outer bell A, the purified 

 carbonic oxide may be propelled, through the cock and lead pipe, 

 into any vessel to which it may be desirable to have it transferred. 



