IS PNEUMAT0-CHE31ICAL APPARATUS. 



nently elastic fluids or gases are disengaged, which 

 are required to be preserved and examined. For 

 tliis purpose, a very useful apparatus is employed, 

 called the 



PNEUMATO-CHEMICAL APPARATUS. 



Fig. 7, represents an improved pneumato-chemi- 

 cal apparatus and lamp-furnace connected with it. 



A, is a vessel filled with water. In this vessel 

 a shelf is placed, so as to be a little under the 

 surface of the fluid, having several holes bored 

 through it, to which small funnels are attached 

 underneath. 



The glass air-jar, or receiver, B, which is to re- 

 ceive and contain the gas, is filled with water, and 

 being inverted wdth its mouth under water, it is 

 raised up gently till its mouth is nearly out of the 

 water, but not quite ; and it is then placed upon 

 the shelf over one of the holes. The receiver will 

 remain full of water, w^iich is kept up by the 

 pressure of the atmosphere upon the principle of 

 the barometer described under pneumatics. 



The materials from w^iich the gas is to be dis- 

 engaged, are now to be put into a glass retort, C, 

 which is put through, and suspended in one of the 

 rings of the lamp-furnace, D. An improved Ar- 

 gand's lamp, £, having teo co7icentric wic/cs,* 

 afl^brds a much greater degree of heat than the 

 common Argand's lamp, wdiich has only a single 

 circular Xiick; this is placed upon the shelf, F. 



* This lamp with two concentric tvicks was first contrived by 

 the editor some years ago, and is extremely useful m some 

 chemical operations, as it gives a much greater heat than the 

 common Argand's lump with one circular wick. 



