376 Apparatus for Bapid Gas-Analysis. 



washing out of the illuminants. For traces of carbonic acid, 

 and also for the determination of sulphurous acid and sulphur- 

 etted hydrogen, special methods are necessary. 



2. Bromine, to absorb illuminants. This is added to some 

 water placed in the funnel. It is best handled with a very 

 small pipette, since only a few drops are necessary. Add it till 

 the tube is filled with its vapor; then absorb the vapor with 

 potassic hydrate used for carbonic acid. 



3. Potassic Pyrogallate, to absorb oxygen. Solution of po- 

 tassic hydrate (1 in 8), containing about three per cent, of 

 pyrogallic acid. 



4. Cuprous Chloride, to absorb carbonic oxide. This is a 

 solution (1 in 4) in concentrated hydrochloric acid. After 

 using it, and before transferring the gas to the nicasuring-tnbe, 

 a little water is added to absorb the acid vapors. 



By this method, a mixture contiiining carbonic acid, oxygen, 

 illuminants and carbonic oxide, can be analyzed in from twenty 

 to thirty minutes, according to the amount of practice the 

 operator has had with the apparatus. 



Compared with Orsat's process, the work can be done with 

 the above-described apparatus in one-fourth the amount of time, 

 and with identical results. 



The water used in the apparatus should have the same tem- 

 perature as the room in which the analysis is made ; and by 

 careful handling, little or none of the chemicals get into the 

 bottle L. When working in a warm place, the tube B should 

 be surrounded with a water-jacket to prevent change of volume 

 in the gas while under treatment. * 



Having added the above absorbents, the residue of gas may 

 consist of hydrogen, marsh-gas, and nitrogen; and for the de- 

 termination of these, I have devised a simple form of explosion- 

 burette, shown in Plate XX HI. It consists of a burette, D, of 



* Whenever possible, it is better to collect the gas in tubes and transfer it 

 to tlie apparatus in a position away from sources of heat. 



