378 Ajjparatus for Bapid Gas -Analysis. 



the absorptioii-apjiaratiis is now attached to a ])iece of rubber 

 tubing long enough to reach to the corresponding bent tube of 

 the explosion-burette." The aspirator-bottle, G, is filled with 

 water, and by raising it and opening the stop-cock, B, and clos- 

 ing E, the explosion-burette is filled with water, including the 

 bent tube, H, fitted over the end of the stopcock, B. By a 

 similar movement of the aspirator-bottle attached to the absorb- 

 tion-apparatus, the corresponding bent tube and its rubber tube 

 are also filled with water. Care should be taken that the water 

 completely expels all air-bubbles from the capillary tubes and the 

 rubber tube. The explosion-burette is now attached to the ab- 

 sor2)tion-burette by means of the rubber tubing already filled with 

 Avater, by slipping this rubber tubing over the bent tube of the 

 explosion-buiette ; taking care to exclude all iiir-bnbbles Avhen 

 making the attachment. To facilitate the connecting of the bent 

 tubes and the rubber tubing, the ends of these tubes should be 

 drawn out so that the rubber tubing will easily slip over them. 



Having connected the explosion-buretre with the absorption- 

 apparatus in the manner described above, we are noAV ready to 

 transfer the gas-mixture for the explosion. For this purpose, 

 the three-way cock of the absorption-apparatus is turned so that 

 the bottom of the absorption-tube is closed. By now opening 

 the stop-cocks above on the absorption-apparatus, and also on 

 the explosion-burette, and by moving the aspirator-bottles, any 

 desired quantity of gas can be transferred from the absorption 

 apparatus to the explosion-burette. When the proper quantity 

 (about eighteen or twenty cubic centimeti'es is sufficient) of gas 

 has been transferred, the stop-cocks of the absorption-apparatus 

 are closed, also the stop-cock of the explosion-burette. By 

 means of the aspirator-bottle, G, the level of the water is ad- 

 justed so that the gas is at atmospheric pressure, by bringing 

 the level of the water in the aspirator-bottle to the same higlit 

 as that in the explosion-burette. This gives the correct reading 

 of the quantity of gas used. We now have to mix this gas with 

 the proper quantity of oxygen to cause an explosion on passing a 

 spark through the wires, C. This oxygen is admitted through 

 the stop cock, E, — most conveniently from a gas-holder.Or cylin- 



