On an Apparatus for Gas-analysis 



on />, and the temperature of the water in r 

 ascertained. These, with the height of the ban mi. the 



:me >f tlu gas, ( >n the tube r marks are made (not shown 

 in the drawing) corresponding to and on the same level with 

 those on q. When the difference of level of the mercury in the 

 two tubes is to be measured, p is applied to r and the level of 

 the mercury in q read off, the marks on r giving the direction 

 for the eye ; that in p is then read off in the ordinary way, the 

 difference giving the column of mercury to be added to or 



:om the barometer-reading. 



I t u- -uppose that we have a sample of air extracted from 



It ( onsists of oxygen, nitrogen, and carbonic acid, the 



of which is determined first, by absorption with caustic 



potash. For this purpose men urv is run out of n by means 



ised, and the stopcocks c, b, and a opened. The 



thus drawn over out of q into m t mercury bein^ allotted 



tn till the capillary, when the cocks are again shut. The cup e 



i- now tilled with -trong solution of caustic potash, and, the 



I- vel in n being still kept low, the stopcock a is opened full, and 



then d very carefully, caustic potash bcim; allowed to run 



h a into m, where it meets the gas in the most 



mtageous way for quick absorption. When enough can 



di has been allowed to niter, d i< closed, some mercury 



poured into e, d again opened and the solution in the capillary 



iced by mercury. When the absorption is finished, the 



I'-vrl of the mercury in n is again rai-ed ,md the stopco< ' 



md c opened. The stopcock a is now very carefully opened. 



the Mott ^ns bein- hnth< r n -ulated by rni-in 



/>, and the gas allowed to pass over into q until the 

 potash -olution jnM ton. ha tin- loWCI MUl.i. ,- ,.( ihr itOpOO 



^ open, has the position -liown in I The 



hitt.-d to that -hown in I hen the 



hition i- eliminated. The p. now br<i 



back ite.l in I 



i-t out by mercury and the volume me.i-- 



If the o.\ N) be determined i>\ .d>-.ipti"n. the mami>u- 



ns are cxa-tlv th- ^ a me as in the case of carbon 



