Apparatus for Rapid Gas- Analysis. 375 



T]]e excess of gtis in A is expelled by opening the stoj) cock 

 /"and raising the bottle L. The gas remaining in the capillary 

 tube between C'and the vertical part is disregarded, or its vahie 

 may be ascertained and an allowance made ; but usually it is too 

 trifling to be worth notice. 



Having measured the gas, it is now transferred by means of 

 the bottles K and L into the tube A, and the fluid chemicals 

 added by placing them in the funnel M and allowing them to 

 flow down the sides of the tube A slowly, care being taken never 

 to let the fluids run Ijelow the level of the top of the vertical 

 tube in the funnel. It is best to have a mark on the outside of 

 the funnel at least three-fourths of an inch above the top of 

 the level of the vertical tube, and never to draw the fluid down 

 below this point. 



Having treated the gas with the chemical, it is transferred by 

 means of the bottles to the tube B, to be measured. If the 

 chemical gets into the horizontal capilLuy tube, the passage of 

 a little water from the bottle A" will remove it, before transfer- 

 ring the gas. When the gas i-esidue is in B, and the fluid of 

 A has been adjusted at the mark f on the horizontal tube, the 

 stop-cock G is closed, the bottle A^is lowered till the level of 

 liquid in it and in the tube B are the same, and the reading is 

 then made. The tube A is now filled with the chemical just 

 used as absorbent, and Avater; by turning the stem of the three- 

 way cock /, so that it communicates with A, and is open below, 

 and by also opening the stop-cock F, the contents of the tube 

 can be run out, and water added through the funnel M to clean 

 the tube for a new absorption. When the tube is clean, by turn- 

 ing the stop-cock /, so that A and L are connected, the water 

 is forced into A, and the whole is ready to receive the gas in B 

 for new treatment. 



In using the apparatus, the chemicals are added in the fol- 

 lowing order : — 



1. Potassic Hydrate (I in 20) to absorb carbonic acid. If illu- 

 minating gas is under examination, a very little of the reagent 

 will be necessiiry, and it is better to use a solution of potassic 

 hydrate of four times the above strength, in order to prevent 



