Analysis of the compound inflammable Gases. 283 



siduary oxygen being deducted from the quantity at the out- 

 set of the experiment, shows how much oxygen has been ex- 

 pended in the combustion of the inflammable gas. ft is 

 scarcely necessary to observe, that the gases are carefully re- 

 duced., tl each stage of the operation, to a mean temperature 

 aud pressure, (60 J of the thermometer, and 30 "inches of the 

 barometer) *. 



The process of combustion, as thus stated in general 

 terms, appears sufficiently simple. It is often, however, ren- 

 dered complicated by the imperfect combustion of the in- 

 flammable gas, a part of which escapes through the orifice 

 of the burner, either wholly unaltered, or only partially . 

 burned. As this portion is not absorbed by sulphuret of 

 lime, it gives a fallacious appearance of an actual addition of 

 nitrogen to the oxygen gas remaining in the receiver b. I 

 am unacquainted with any method of entirely obviating this 

 difficulty ; but its amount may be diminished by an attention 

 to certain precautions. With this view, the pressure upon 

 the gas, contained in the receiver o c, should, on first open- 

 ing the cocks q and r, be no more than is sufficient for its 

 gentle expulsion through the tube ss. When, however, the 

 stream is once kindled, the larger the flame, and the more 

 active the combustion, within certain limits, the more com- 

 pletely is the gas consumed. It is necessary, also, to stop 

 the combustion, before it is rendered languid by the admix- 

 ture of carbonic acid with the gas in the receiver b, and bv 

 the diminished purity of the oxygen gas. If this be not 

 attended to, a large proportion of the inflammable gas to- 

 wards the close of the process, makes its escape unaltered into 

 the receiver b. In general I have found, that setting out with 

 oxygen gas ef equal purity, the more combustible the inflam- 

 mable gas submitted to experiment, the more complete is its 

 decomposition by slow combustion. The apparatus, there- 

 fore, is better adapted to the analysis of defiant gas, of car- 

 bureted hydrogen gas, or of mixtures of these two, than of 

 carbonic oxide^ or any gas of which that oxide forms a large 

 proportion. 



* The rules observed in these calculations, are stated in my Epitome of 

 Chemistry, 5th sdition, p. 441. 



The 



