Jlccoiint of a neiv Eudiometer. 195 



re-agcnts are to be employed, as from the depositions of 

 former solutions on the glass measure a source of considera- 

 ble error would arise. 



The residual oxygen gas being thus transferred into a clean 

 dry measure, the processes before described for examining 

 oxyo-en gas may be then used ;. or the quantity of carbonic 

 acid gas (for examination) being found by lime water, an- 

 other measure of the gas may be tried, first with the green 

 sulphate of iron impregnated with nitrous gas, and then with 

 the 'green sulphate in solution only : these will take up both 

 the carbonic acid gas and the oxygen gas, leaving only such 

 residual gas as the oxygen might have originally contained. 



Transferring is not here necessary, as the two solutions 

 may be used one after the other, taking care to use the so- 

 lution of green sulphate last. 



Where it is not requisite to transfer the gas into a dried 

 or clean measure previous to the use of another solution, as 

 in the instance I have just mentioned, a quantity of the first 

 solution may be withdrjftvn, by simply filling the elastic 

 bottle with mercury, then joining it to the measure, and by 

 inclining the measure, the mercury by its gravity will dis- 

 place the former solution. 



If at any time the gas should get drawn into the elastic 

 bottle, it may be very easily returned into the measure, by 

 inclining sometimes the bottle, and sometimes the measure. 

 The only error that could arise from this is, an increase of 

 temperature in the gas, which may be rectified by plunging 

 the whole apparatus into mercury or water of the standard 

 temperature. 



The advantages of this construction of the eudiometer will 

 be readily perceived by all those who are in the habit of 

 making chemical experiments. The portion of gas to be 

 examined is completely nnder command ; it may be agitated 

 without the least fear of the intrusion of any atmospheric 

 air, and the process thereby very materially shortened. The 

 gum-clastic is a substance so little acted upon by chemical 

 agents, that a great variety may be employed; and, above 

 all, we can very convcnientlv use hot solutions, which will 



be. 



